Carbon fractions in wood for estimating embodied carbon in the built environment

Determining wood carbon (C) fractions (CFs)-or the concentration of elemental C in wood on a per unit mass basis-in harvested wood products (HWP) is vital for accurately accounting embodied C in the built environment. Most estimates of embodied C assume that all wood-based building material is comprised of 50 % C on a per mass basis: an erroneous assumption that emerges from the literature on tree- and forest-scale C estimation, which has been shown to lead to substantial errors in C accounting. Here, we use published wood CF data from live trees, alongside laboratory analyses of sawn lumber, to quantify generalizable wood CFs for HWPs. Wood CFs in lumber average 51.7 %, deviating significantly from a 50 % default wood CF, as well as from CFs in live wood globally (which average 47.6 % across all species, and 47.1 % in tree species not typically employed in construction). Additionally, the volatile CF in lumber-i.e., the quantity of C lost upon heating of wood samples, but often overlooked in C accounting-is lower than the volatile CF in live wood, but significantly >0 % suggesting that industrial lumber drying processes remove some, but not all, of volatile C-based compounds. Our results demonstrate that empirically-supported wood CFs for construction material can correct meaningful systematic biases when estimating C storage in the built environment.

Physiological and photochemical profiling of soybean plant using biological and chemical methods of treatment against biotic stress management

Phyto-pathogenic fungal species is a leading biotic stress factor to agri-food production and ecosystem of globe. Chemical (Systemic fungicides) and biological treatment (micro-organism) are globally accepted methods that are being used against biotic stress (disease) management. Plant Growth-Promoting Microbes are being used as an alternative to ease chemical dependency as their overdoses have generated injurious effects on plants and environment. Therefore, present study performs to evaluate the photochemical and physiological profiling of plants exposed to chemical and biological treatment in biotic stress (disease) environment. Two concentrations of each chemical treatment i.e. Topsin-M 70 (Dimethyl 4,4'-o-phenylene bis 3-thioallaphanate, MF1 = 3 g kg-1 and MF2 = 6 g kg-1 seeds) and biological treatment i.e. Trichoderma harzianum strain Th-6 (MT1 = 106 spores mL-1and MT2 = 107 spores mL-1) were used in this experiment. Macrophomina phaseolina (MP) were used as biotic stress factor causing root rot disease in soybean plants. Morpho-physiological assessments and light harvesting efficiency of photosystem II were conducted after 52 days of treatment. Maximum quantum yield (Fv/Fm), number and size of active reaction center (Fv/Fo), photochemical quenching (qP), efficiency of photosystem II (ΦPSII), electron transport rate (ETR), chlorophyll content index (CCI), relative water content (RWC) and stomatal conductance (SC) were increased in MT2 and MF1 treatments as compared to stress plants (MP). Biological (MT2) and chemical (MF1) treatment lessen the production of stress markers showing -48.0 to -54.3% decline in malondialdehyde (MDA) and -42.0 to -53.7% in hydrogen peroxide (H2O2) as compared to stress plant (MP). Biological treatment in both concentration (MF1 & MF2) while chemical treatment at low dose effectively mitigates biotic stress and eases the magnitude of disease. Increasing doses of chemical treatment persuaded deleterious effects on the physiology and light harvesting efficiency of stressed plant suggesting the role of biological treatment (T. harzianum) against biotic stress management in future of crop protection.

Theory and classification of mass extinction causation

Theory regarding the causation of mass extinctions is in need of systematization, which is the focus of this contribution. Every mass extinction has both an ultimate cause, i.e. the trigger that leads to various climato-environmental changes, and one or more proximate cause(s), i.e. the specific climato-environmental changes that result in elevated biotic mortality. With regard to ultimate causes, strong cases can be made that bolide (i.e. meteor) impacts, large igneous province (LIP) eruptions and bioevolutionary events have each triggered one or more of the Phanerozoic Big Five mass extinctions, and that tectono-oceanic changes have triggered some second-order extinction events. Apart from bolide impacts, other astronomical triggers (e.g. solar flares, gamma bursts and supernova explosions) remain entirely in the realm of speculation. With regard to proximate mechanisms, most extinctions are related to either carbon-release or carbon-burial processes, the former being associated with climatic warming, ocean acidification, reduced marine productivity and lower carbonate δ13C values, and the latter with climatic cooling, increased marine productivity and higher carbonate δ13C values. Environmental parameters such as marine redox conditions and terrestrial weathering intensity do not show consistent relationships with carbon-cycle changes. In this context, mass extinction causation can be usefully classified using a matrix of ultimate and proximate factors. Among the Big Five mass extinctions, the end-Cretaceous biocrisis is an example of a bolide-triggered carbon-release event, the end-Permian and end-Triassic biocrises are examples of LIP-triggered carbon-release events, and the Late Ordovician and Late Devonian biocrises are examples of bioevolution-triggered carbon-burial events. Whereas the bolide-impact and LIP-eruption mechanisms appear to invariably cause carbon release, bioevolutionary triggers can result in variable carbon-cycle changes, e.g. carbon burial during the Late Ordovician and Late Devonian events, carbon release associated with modern anthropogenic climate warming, and little to no carbon-cycle impact due to certain types of ecosystem change (e.g. the advent of the first predators around the end-Ediacaran; the appearance of Paleolithic human hunters in Australasia and the Americas). Broadly speaking, studies of mass extinction causation have suffered from insufficiently critical thinking-an impartial survey of the extant evidence shows that (i) hypotheses of a common ultimate cause (e.g. bolide impacts or LIP eruptions) for all Big Five mass extinctions are suspect given manifest differences in patterns of environmental and biotic change among them; (ii) the Late Ordovician and Late Devonian events were associated with carbon burial and long-term climatic cooling, i.e. changes that are inconsistent with a bolide-impact or LIP-eruption mechanism; and (iii) claims of periodicity in Phanerozoic mass extinctions depended critically on the now-disproven idea that they shared a common extrinsic trigger (i.e. bolide impacts).

Abundance of Dendroctonus frontalis and D. mexicanus (Coleoptera: Scolytinae) along altitudinal transects in Mexico: Implications of climatic change for forest conservation

Bark beetle infestations have historically been primary drivers of stand thinning in Mexican pine forests. However, bark beetle impacts have become increasingly extensive and intense, apparently associated with climate change. Our objective was to describe the possible association between abundance of bark beetle flying populations and the occurrence of given value intervals of temperature, precipitation and their balance, in order to have a better comprehension of the climatic space that might trigger larger insect abundances, an issue relevant in the context of the ongoing climatic change. Here, we monitored the abundance of two of the most important bark beetle species in Mexico, Dendroctonus frontalis and D. mexicanus. We sampled 147 sites using pheromone-baited funnel traps along 24 altitudinal transects in 11 Mexican states, from northwestern Chihuahua to southeastern Chiapas, from 2015 to 2017. Through mixed model analysis, we found that the optimum Mean Annual Temperatures were 17°C-20°C for D. frontalis in low-elevation pine-oak forest, while D. mexicanus had two optimal intervals: 11-13°C and 15-18°C. Higher atmospheric Vapor Pressure Deficit (≥ 1.0) was correlated with higher D. frontalis abundances, indicating that warming-amplified drought stress intensifies trees' vulnerability to beetle attack. As temperatures and drought stress increase further with projected future climatic changes, it is likely that these Dendroctonus species will increase tree damage at higher elevations. Pine forests in Mexico are an important source of livelihood for communities inhabiting those areas, so providing tools to tackle obstacles to forest growth and health posed by changing climate is imperative.

Functional traits and climate drive interspecific differences in disturbance-induced tree mortality

With climate change, natural disturbances such as storm or fire are reshuffled, inducing pervasive shifts in forest dynamics. To predict how it will impact forest structure and composition, it is crucial to understand how tree species differ in their sensitivity to disturbances. In this study, we investigated how functional traits and species mean climate affect their sensitivity to disturbances while controlling for tree size and stand structure. With data on 130,594 trees located on 7617 plots that were disturbed by storm, fire, snow, biotic or other disturbances from the French, Spanish, and Finnish National Forest Inventory, we modeled annual mortality probability for 40 European tree species as a function of tree size, dominance status, disturbance type, and intensity. We tested the correlation of our estimated species probability of disturbance mortality with their traits and their mean climate niches. We found that different trait combinations controlled species sensitivity to disturbances. Storm-sensitive species had a high height-dbh ratio, low wood density and high maximum growth, while fire-sensitive species had low bark thickness and high P50. Species from warmer and drier climates, where fires are more frequent, were more resistant to fire. The ranking in disturbance sensitivity between species was overall consistent across disturbance types. Productive conifer species were the most disturbance sensitive, while Mediterranean oaks were the least disturbance sensitive. Our study identified key relations between species functional traits and disturbance sensitivity, that allows more reliable predictions of how changing climate and disturbance regimes will impact future forest structure and species composition at large spatial scales.

Assessment of the effects of the biotic and abiotic harmful factors on the amount of industrial wood production with deep learning

The protection and sustainability of forest assets is possible with planned production of forest products to lead to minimum loss. One of the products obtained from forests is the industrial wood, which is the most important raw material for many sectors. Thus, changes in industrial wood production amounts directly affect these sectors. For this reason, it is important to detect and examine the factors affecting industrial wood production amounts for optimum production and use of this raw material. This study aims to investigate and assess the effects of two biotic and two abiotic harmful factors on the amount of industrial wood production by building a deep learning estimation model. These factors are forest fires, insect outbreaks, diseases, and severe weather events. The study shows that the most harmful factor decreasing the industrial wood production level is diseases. The second effective factor, however, appears to be severe weather events. The third and the fourth factors were determined to be insect outbreaks and burned forest areas, respectively.

Management Implications for the Nantucket Pine Tip Moth From Temperature-Induced Shifts in Phenology and Voltinism Attributed to Climate Change

Forest insect pest phenology and infestation pressure may shift as temperatures continue to warm due to climate change, resulting in greater challenges for sustainable forest management . The Nantucket pine tip moth (NPTM) (Rhyacionia frustrana Comstock) (Lepidoptera: Tortricidae) is a native forest regeneration pest in the southeastern U.S. with multiple generations per year. Changes in NPTM voltinism may result from temperature-induced shifts in NPTM phenology. Degree-day models have been used to develop optimal spray dates (OSDs) for NPTM. The 2000 Spray Timing Model (STM), based on temperature data from 1960 to 2000, provided generation-specific 5-d OSDs to effectively time applications of contact insecticides. An updated degree-day model, the 2019 STM, is based on temperature data from 2000 to 2019 and was used to detect changes in voltinism as well as shifts in phenology and OSDs. Based on the model, increased voltinism occurred at 6 of the 28 study locations (21%). Changes in voltinism occurred in the Piedmont and Coastal Plain of Georgia, U.S., with shifts from three to four or four to five generations a year, depending on location. The OSDs from the 2019 STM were compared to the 2000 STM OSDs. Over half (57%) of the OSDs differed by 5-15 d, with the majority (66%) resulting in earlier spray dates. The 2019 STM will help growers adapt NPTM control tactics to temperature-induced phenology shifts. NPTM serves as an example of temperature-induced changes attributed to climate change in a forest insect pest with important implications to forest management.

Restoration and fuel hazard reduction result in equivalent reductions in crown fire behavior in dry conifer forests

Over the past several decades, the management of historically frequent-fire forests in the western United States has received significant attention due to the linked ecological and social risks posed by the increased occurrence of large, contiguous patches of high-severity fire. As a result, efforts are underway to simultaneously reduce potential fire and fuel hazards and restore characteristics indicative of historical forest structures and ecological processes that enhance the diversity and quality of wildlife habitat across landscapes. Despite widespread agreement on the need for action, there is a perceived tension among scientists concerning silvicultural treatments that modify stands to optimally reduce potential fire behavior (fuel hazard reduction) versus those that aim to emulate historical forest structures and create structurally complex stands (restoration). In this work, we evaluated thinning treatments in the Black Hills National Forest that exemplify the extremes of a treatment continuum that ranges from fuel hazard reduction to restoration. The goal of this work was to understand how the differing three-dimensional stand structures created by these treatment approaches altered potential fire behavior. Our results indicate that restoration treatments created higher levels of vertical and horizontal structural complexity than the fuel hazard reduction treatments but resulted in similar reductions to potential crown fire behavior. There were some trade-offs identified as the restoration treatments created larger openings, which generated faster mean rates of fire spread; however, these increased spread rates did not translate to higher levels of canopy consumption. Overall, our results suggest that treatments can create vertical and horizontal complexity desired for restoration and wildlife habitat management while reducing fire hazard and that they can be used in concert with traditional fuel hazard reduction treatments to reduce landscape scale fire risk. We also provide some suggestions to land managers seeking to design and implement prescriptions that emulate historical structures and enhance forest complexity.

Pest defences under weak selection exert a limited influence on the evolution of height growth and drought avoidance in marginal pine populations

While droughts, intensified by climate change, have been affecting forests worldwide, pest epidemics are a major source of uncertainty for assessing drought impacts on forest trees. Thus far, little information has documented the adaptability and evolvability of traits related to drought and pests simultaneously. We conducted common-garden experiments to investigate how several phenotypic traits (i.e. height growth, drought avoidance based on water-use efficiency inferred from δ¹³C and pest resistance based on defence traits) interact in five mature lodgepole pine populations established in four progeny trials in western Canada. The relevance of interpopulation variation in climate sensitivity highlighted that seed-source warm populations had greater adaptive capability than cold populations. In test sites, warming generated taller trees with higher δ¹³C and increased the evolutionary potential of height growth and δ¹³C across populations. We found, however, no pronounced gradient in defences and their evolutionary potential along populations or test sites. Response to selection was weak in defences across test sites, but high for height growth particularly at warm test sites. Response to the selection of δ¹³C varied depending on its selective strength relative to height growth. We conclude that warming could promote the adaptability and evolvability of growth response and drought avoidance with a limited evolutionary influence from pest (biotic) pressures.

Managing for the unexpected: Building resilient forest landscapes to cope with global change

Natural disturbances exacerbated by novel climate regimes are increasing worldwide, threatening the ability of forest ecosystems to mitigate global warming through carbon sequestration and to provide other key ecosystem services. One way to cope with unknown disturbance events is to promote the ecological resilience of the forest by increasing both functional trait and structural diversity and by fostering functional connectivity of the landscape to ensure a rapid and efficient self-reorganization of the system. We investigated how expected and unexpected variations in climate and biotic disturbances affect ecological resilience and carbon storage in a forested region in southeastern Canada. Using a process-based forest landscape model (LANDIS-II), we simulated ecosystem responses to climate change and insect outbreaks under different forest policy scenarios-including a novel approach based on functional diversification and network analysis-and tested how the potentially most damaging insect pests interact with changes in forest composition and structure due to changing climate and management. We found that climate warming, lengthening the vegetation season, will increase forest productivity and carbon storage, but unexpected impacts of drought and insect outbreaks will drastically reduce such variables. Generalist, non-native insects feeding on hardwood are the most damaging biotic agents for our region, and their monitoring and early detection should be a priority for forest authorities. Higher forest diversity driven by climate-smart management and fostered by climate change that promotes warm-adapted species, might increase disturbance severity. However, alternative forest policy scenarios led to a higher functional and structural diversity as well as functional connectivity-and thus to higher ecological resilience-than conventional management. Our results demonstrate that adopting a landscape-scale perspective by planning interventions strategically in space and adopting a functional trait approach to diversify forests is promising for enhancing ecological resilience under unexpected global change stressors.

A review of the global climate change impacts, adaptation, and sustainable mitigation measures

Climate change is a long-lasting change in the weather arrays across tropics to polls. It is a global threat that has embarked on to put stress on various sectors. This study is aimed to conceptually engineer how climate variability is deteriorating the sustainability of diverse sectors worldwide. Specifically, the agricultural sector's vulnerability is a globally concerning scenario, as sufficient production and food supplies are threatened due to irreversible weather fluctuations. In turn, it is challenging the global feeding patterns, particularly in countries with agriculture as an integral part of their economy and total productivity. Climate change has also put the integrity and survival of many species at stake due to shifts in optimum temperature ranges, thereby accelerating biodiversity loss by progressively changing the ecosystem structures. Climate variations increase the likelihood of particular food and waterborne and vector-borne diseases, and a recent example is a coronavirus pandemic. Climate change also accelerates the enigma of antimicrobial resistance, another threat to human health due to the increasing incidence of resistant pathogenic infections. Besides, the global tourism industry is devastated as climate change impacts unfavorable tourism spots. The methodology investigates hypothetical scenarios of climate variability and attempts to describe the quality of evidence to facilitate readers' careful, critical engagement. Secondary data is used to identify sustainability issues such as environmental, social, and economic viability. To better understand the problem, gathered the information in this report from various media outlets, research agencies, policy papers, newspapers, and other sources. This review is a sectorial assessment of climate change mitigation and adaptation approaches worldwide in the aforementioned sectors and the associated economic costs. According to the findings, government involvement is necessary for the country's long-term development through strict accountability of resources and regulations implemented in the past to generate cutting-edge climate policy. Therefore, mitigating the impacts of climate change must be of the utmost importance, and hence, this global threat requires global commitment to address its dreadful implications to ensure global sustenance.

Revealing the Complex Relationship Among Hyperspectral Reflectance, Photosynthetic Pigments, and Growth in Norway Spruce Ecotypes

Norway spruce has a wide natural distribution range, harboring substantial physiological and genetic variation. There are three altitudinal ecotypes described in this species. Each ecotype has been shaped by natural selection and retains morphological and physiological characteristics. Foliar spectral reflectance is readily used in evaluating the physiological status of crops and forest ecosystems. However, underlying genetics of foliar spectral reflectance and pigment content in forest trees has rarely been investigated. We assessed the reflectance in a clonal bank comprising three ecotypes in two dates covering different vegetation season conditions. Significant seasonal differences in spectral reflectance among Norway spruce ecotypes were manifested in a wide-ranging reflectance spectrum. We estimated significant heritable variation and uncovered phenotypic and genetic correlations among growth and physiological traits through bivariate linear models utilizing spatial corrections. We confirmed the relative importance of the red edge within the context of the study site's ecotypic variation. When interpreting these findings, growth traits such as height, diameter, crown length, and crown height allowed us to estimate variable correlations across the reflectance spectrum, peaking in most cases in wavelengths connected to water content in plant tissues. Finally, significant differences among ecotypes in reflectance and other correlated traits were detected.

Threshold Responses of Canopy Cover and Tree Growth to Drought and Siberian silk Moth Outbreak in Southern Taiga Picea obovata Forests

The consecutive occurrence of drought and insect outbreaks could lead to cumulative, negative impacts on boreal forest productivity. To disentangle how both stressors affected productivity, we compared changes in tree canopy cover and radial growth after a severe outbreak in Siberian spruce (Picea obovata) southern taiga forests. Specifically, we studied the impacts of the 2012 severe drought followed by a Siberian silk moth (Dendrolimus sibiricus, hereafter SSM) outbreak, which started in 2016, on spruce forests by comparing one non-defoliated site and two, nearby fully defoliated sites, using remote sensing and tree-ring data. The SSM outbreak caused total defoliation and death of trees in the infested stands. We found a sharp drop (–32%) in the normalized difference infrared index and reduced radial growth in the defoliated sites in 2018. The growth reduction due to the 2012 drought was –37%, whereas it dropped to 4% of pre-outbreak growth in 2018. Tree growth was constrained by warm and dry conditions from June to July, but such a negative effect of summer water shortage was more pronounced in the defoliated sites than in the non-defoliated site. This suggests a predisposition of sites where trees show a higher growth responsivity to drought to SSM-outbreak defoliation. Insect defoliation and drought differently impacted taiga forest productivity since tree cover dropped due to the SSM outbreak, whereas tree growth was reduced either by summer drought or by the SSM outbreak. The impacts of abiotic and biotic stressors on boreal forests could be disentangled by combining measures or proxies of canopy cover and radial growth which also allow the investigation of drought sensitivity predisposes to insect damage.

Future climate risks from stress, insects and fire across US forests

Forests are currently a substantial carbon sink globally. Many climate change mitigation strategies leverage forest preservation and expansion, but rely on forests storing carbon for decades to centuries. Yet climate‐driven disturbances pose critical risks to the long‐term stability of forest carbon. We quantify the climate drivers that influence wildfire and climate stress‐driven tree mortality, including a separate insect‐driven tree mortality, for the contiguous United States for current (1984–2018) and project these future disturbance risks over the 21st century. We find that current risks are widespread and projected to increase across different emissions scenarios by a factor of >4 for fire and >1.3 for climate‐stress mortality. These forest disturbance risks highlight pervasive climate‐sensitive disturbance impacts on US forests and raise questions about the risk management approach taken by forest carbon offset policies. Our results provide US‐wide risk maps of key climate‐sensitive disturbances for improving carbon cycle modeling, conservation and climate policy.

Insect infestations and the persistence and functioning of oak-pine mixedwood forests in the mid-Atlantic region, USA

Damage from infestations of Lymantria dispar L. in oak-dominated stands and southern pine beetle (Dendroctonus frontalis Zimmermann) in pine-dominated stands have far exceeded impacts of other disturbances in forests of the mid-Atlantic Coastal Plain over the last two decades. We used forest census data collected in undisturbed and insect-impacted stands combined with eddy covariance measurements made pre- and post-disturbance in oak-, mixed and pine-dominated stands to quantify how these infestations altered forest composition, structure and carbon dynamics in the Pinelands National Reserve of southern New Jersey. In oak-dominated stands, multi-year defoliation during L. dispar infestations resulted in > 40% mortality of oak trees and the release of pine saplings and understory vegetation, while tree mortality was minimal in mixed and pine-dominated stands. In pine-dominated stands, southern pine beetle infestations resulted in > 85% mortality of pine trees but had minimal effect on oaks in upland stands or other hardwoods in lowland stands, and only rarely infested pines in hardwood-dominated stands. Because insect-driven disturbances are both delaying and accelerating succession in stands dominated by a single genus but having less effect in mixed-composition stands, long-term disturbance dynamics are favoring the formation and persistence of uneven age oak-pine mixedwood stands. Changes in forest composition may have little impact on forest productivity and evapotranspiration; although seasonal patterns differ, with highest daily rates of net ecosystem production (NEP) during the growing season occurring in an oak-dominated stand and lowest in a pine-dominated stand, integrated annual rates of NEP are similar among oak-, mixed and pine-dominated stands. Our research documents the formation of mixedwood stands as a consequence of insect infestations in the mid-Atlantic region and suggests that managing for mixedwood stands could reduce damage to forest products and provide greater continuity in ecosystem functioning.

Pine processionary moth outbreaks cause longer growth legacies than drought and are linked to the North Atlantic Oscillation

Climatic warming is assumed to expand the geographic range of insect pests whose distribution is mainly constrained by low temperatures. This is the case of the pine processionary moth (Thaumetopoea pityocampa), which is one of the main conifer defoliators in the Mediterranean Basin. Warmer winters may lead to a northward/upward expansion of this insect, as short-term studies have shown. However, no long-term data, i.e. spanning at least one century, has been used to examine these projections. We test the hypotheses that climatic warming (i) has caused an upward shift of the pine processionary moth, and (ii) has increased the frequency of severe defoliations. We used dendrochronological methods to reconstruct defoliations over the period 1900-2006 in 14 sites spanning a wide altitudinal range (1070-1675 m) in Teruel, eastern Spain. We built local ring-width chronologies for four co-occurring pine species with different degree of susceptibility against the moth defoliations, from highly suitable or palatable species (Pinus nigra) to moderately (Pinus sylvestris, Pinus halepensis) or rarely defoliated species (Pinus pinaster). We validated the tree-ring reconstructions of outbreaks using a field record of stand defoliations spanning the period 1971-2006. Outbreaks in the most affected P. nigra stands corresponded to abrupt one- to two-year growth reductions (70-90% growth loss). Reconstructed outbreaks occurred on average every 9-14 years. The growth memory of outbreaks was weaker but lasted longer (1-6 years) than that due to droughts (1-3 years). Neither an upward expansion nor an increase in outbreak frequency was observed. Severe PPM defoliations did not increase as climate warmed, rather they were positively related to the winter North Atlantic Oscillation.

Warming increased bark beetle-induced tree mortality by 30% during an extreme drought in California

Quantifying the responses of forest disturbances to climate warming is critical to our understanding of carbon cycles and energy balances of the Earth system. The impact of warming on bark beetle outbreaks is complex as multiple drivers of these events may respond differently to warming. Using a novel model of bark beetle biology and host tree interactions, we assessed how contemporary warming affected western pine beetle (Dendroctonus brevicomis) populations and mortality of its host, ponderosa pine (Pinus ponderosa), during an extreme drought in the Sierra Nevada, California, United States. When compared with the field data, our model captured the western pine beetle flight timing and rates of ponderosa pine mortality observed during the drought. In assessing the influence of temperature on western pine beetles, we found that contemporary warming increased the development rate of the western pine beetle and decreased the overwinter mortality rate of western pine beetle larvae leading to increased population growth during periods of lowered tree defense. We attribute a 29.9% (95% CI: 29.4%-30.2%) increase in ponderosa pine mortality during drought directly to increases in western pine beetle voltinism (i.e., associated with increased development rates of western pine beetle) and, to a much lesser extent, reductions in overwintering mortality. These findings, along with other studies, suggest each degree (°C) increase in temperature may have increased the number of ponderosa pine killed by upwards of 35%-40% °C^-1 if the effects of compromised tree defenses (15%-20%) and increased western pine beetle populations (20%) are additive. Due to the warming ability to considerably increase mortality through the mechanism of bark beetle populations, models need to consider climate's influence on both host tree stress and the bark beetle population dynamics when determining future levels of tree mortality.

Does the legacy of historical thinning treatments foster resilience to bark beetle outbreaks in subalpine forests?

Promoting ecological resilience to increasing disturbance activity is a key management priority under warming climate. Across the Northern Hemisphere, tree mortality from widespread bark beetle outbreaks raises concerns for how forest management can foster resilience to future outbreaks. Density reduction (i.e., thinning) treatments can increase vigor of remaining trees, but the longevity of treatment efficacy for reducing susceptibility to future disturbance remains a key knowledge gap. Using one of the longest-running replicated experiments in old-growth subalpine forests, we measured stand structure following a recent (early 2000s) severe mountain pine beetle (MPB; Dendroctonus ponderosae) outbreak to examine the legacy of historical (1940s) thinning treatments on two components of resilience. We asked: 'How did historical thinning intensity affect (1) tree-scale survival probability and stand-scale survival proportion (collectively "resistance" to outbreak) for susceptible trees (lodgepole pine [Pinus contorta] ≥ 12 cm diameter) and (2) post-outbreak stand successional trajectories?' Overall outbreak severity was high (MPB killed 59% of susceptible individuals and 78% of susceptible basal area), and historical thinning had little effect on tree-scale and stand-scale resistance. Tree-scale survival probability decreased sharply with increasing tree diameter and did not differ from the control (uncut stands) in the historical thinning treatments. Stand-scale proportion of surviving susceptible trees and basal area did not differ from the control in historically thinned stands, except for treatments that removed nearly all susceptible trees, in which survival proportion approximately doubled. Despite limited effects on resistance to MPB outbreak, the legacy of historical treatments shifted dominance from large-diameter to small-diameter lodgepole pine by the time of outbreak, resulting in historically thinned stands with ~2× greater post-outbreak live basal area than control stands. MPB-driven mortality of large-diameter lodgepole pine in control stands and density-dependent mortality of small-diameter trees in historically thinned stands led to convergence in post-outbreak live tree stand structure. One exception was the heaviest historical thinning treatments (59-77% basal area removed), for which sapling dominance of shade-tolerant, unsusceptible conifers was lower than control stands. After six decades, thinning treatments have had minimal effect on resistance to bark beetle outbreaks, but leave persistent legacies in shaping post-outbreak successional trajectories.

Widespread regeneration failure in forests of Greater Yellowstone under scenarios of future climate and fire

Changing climate and disturbance regimes are increasingly challenging the resilience of forest ecosystems around the globe. A powerful indicator for the loss of resilience is regeneration failure, that is, the inability of the prevailing tree species to regenerate after disturbance. Regeneration failure can result from the interplay among disturbance changes (e.g., larger and more frequent fires), altered climate conditions (e.g., increased drought), and functional traits (e.g., method of seed dispersal). This complexity makes projections of regeneration failure challenging. Here we applied a novel simulation approach assimilating data-driven fire projections with vegetation responses from process modeling by means of deep neural networks. We (i) quantified the future probability of regeneration failure; (ii) identified spatial hotspots of regeneration failure; and (iii) assessed how current forest types differ in their ability to regenerate under future climate and fire. We focused on the Greater Yellowstone Ecosystem (2.9 × 10⁶  ha of forest) in the Rocky Mountains of the USA, which has experienced large wildfires in the past and is expected to undergo drastic changes in climate and fire in the future. We simulated four climate scenarios until 2100 at a fine spatial grain (100 m). Both wildfire activity and unstocked forest area increased substantially throughout the 21st century in all simulated scenarios. By 2100, between 28% and 59% of the forested area failed to regenerate, indicating considerable loss of resilience. Areas disproportionally at risk occurred where fires are not constrained by topography and in valleys aligned with predominant winds. High-elevation forest types not adapted to fire (i.e., Picea engelmannii-Abies lasiocarpa as well as non-serotinous Pinus contorta var. latifolia forests) were especially vulnerable to regeneration failure. We conclude that changing climate and fire could exceed the resilience of forests in a substantial portion of Greater Yellowstone, with profound implications for carbon, biodiversity, and recreation.

Asymmetric root distributions reveal press-pulse responses in retreating coastal forests

The impacts of climate change on ecosystems are manifested in how organisms respond to episodic and continuous stressors. The conversion of coastal forests to salt marshes represents a prominent example of ecosystem state change, driven by the continuous stress of sea-level rise (press), and episodic storms (pulse). Here, we measured the rooting dimension and fall direction of 143 windthrown eastern red cedar (Juniperus virginiana) trees in a rapidly retreating coastal forest in Chesapeake Bay (USA). We found that tree roots were distributed asymmetrically away from the leading edge of soil salinization and towards freshwater sources. The length, number, and circumference of roots were consistently higher in the upslope direction than downslope direction, suggesting an active morphological adaptation to sea-level rise and salinity stress. Windthrown trees consistently fell in the upslope direction regardless of aspect and prevailing wind direction, suggesting that asymmetric rooting destabilized standing trees, and reduced their ability to withstand high winds. Together, these observations help explain curious observations of coastal forest resilience, and highlight an interesting nonadditive response to climate change, where adaptation to press stressors increases vulnerability to pulse stressors.

Tropicalization of temperate ecosystems in North America: The northward range expansion of tropical organisms in response to warming winter temperatures

Tropicalization is a term used to describe the transformation of temperate ecosystems by poleward-moving tropical organisms in response to warming temperatures. In North America, decreases in the frequency and intensity of extreme winter cold events are expected to allow the poleward range expansion of many cold-sensitive tropical organisms, sometimes at the expense of temperate organisms. Although ecologists have long noted the critical ecological role of winter cold temperature extremes in tropical-temperate transition zones, the ecological effects of extreme cold events have been understudied, and the influence of warming winter temperatures has too often been left out of climate change vulnerability assessments. Here, we examine the influence of extreme cold events on the northward range limits of a diverse group of tropical organisms, including terrestrial plants, coastal wetland plants, coastal fishes, sea turtles, terrestrial reptiles, amphibians, manatees, and insects. For these organisms, extreme cold events can lead to major physiological damage or landscape-scale mass mortality. Conversely, the absence of extreme cold events can foster population growth, range expansion, and ecological regime shifts. We discuss the effects of warming winters on species and ecosystems in tropical-temperate transition zones. In the 21st century, climate change-induced decreases in the frequency and intensity of extreme cold events are expected to facilitate the poleward range expansion of many tropical species. Our review highlights critical knowledge gaps for advancing understanding of the ecological implications of the tropicalization of temperate ecosystems in North America.

Nine Maxims for the Ecology of Cold-Climate Winters

Frozen winters define life at high latitudes and altitudes. However, recent, rapid changes in winter conditions have highlighted our relatively poor understanding of ecosystem function in winter relative to other seasons. Winter ecological processes can affect reproduction, growth, survival, and fitness, whereas processes that occur during other seasons, such as summer production, mediate how organisms fare in winter. As interest grows in winter ecology, there is a need to clearly provide a thought-provoking framework for defining winter and the pathways through which it affects organisms. In the present article, we present nine maxims (concise expressions of a fundamentally held principle or truth) for winter ecology, drawing from the perspectives of scientists with diverse expertise. We describe winter as being frozen, cold, dark, snowy, less productive, variable, and deadly. Therefore, the implications of winter impacts on wildlife are striking for resource managers and conservation practitioners. Our final, overarching maxim, “winter is changing,” is a call to action to address the need for immediate study of the ecological implications of rapidly changing winters.

Effects of Bark Beetle Outbreaks on Forest Landscape Pattern in the Southern Rocky Mountains, U.S.A

Since the late 1990s, extensive outbreaks of native bark beetles (Curculionidae: Scolytinae) have affected coniferous forests throughout Europe and North America, driving changes in carbon storage, wildlife habitat, nutrient cycling, and water resource provisioning. Remote sensing is a crucial tool for quantifying the effects of these disturbances across broad landscapes. In particular, Landsat time series (LTS) are increasingly used to characterize outbreak dynamics, including the presence and severity of bark beetle-caused tree mortality, though broad-scale LTS-based maps are rarely informed by detailed field validation. Here we used spatial and temporal information from LTS products, in combination with extensive field data and Random Forest (RF) models, to develop 30-m maps of the presence (i.e., any occurrence) and severity (i.e., cumulative percent basal area mortality) of beetle-caused tree mortality 1997–2019 in subalpine forests throughout the Southern Rocky Mountains, USA. Using resultant maps, we also quantified spatial patterns of cumulative tree mortality throughout the region, an important yet poorly understood concept in beetle-affected forests. RF models using LTS products to predict presence and severity performed well, with 80.3% correctly classified (Kappa = 0.61) and R2 = 0.68 (RMSE = 17.3), respectively. We found that ≥10,256 km2 of subalpine forest area (39.5% of the study area) was affected by bark beetles and 19.3% of the study area experienced ≥70% tree mortality over the twenty-three year period. Variograms indicated that severity was autocorrelated at scales < 250 km. Interestingly, cumulative patch-size distributions showed that areas with a near-total loss of the overstory canopy (i.e., ≥90% mortality) were relatively small (<0.24 km2) and isolated throughout the study area. Our findings help to inform an understanding of the variable effects of bark beetle outbreaks across complex forested regions and provide insight into patterns of disturbance legacies, landscape connectivity, and susceptibility to future disturbance.

Why is Tree Drought Mortality so Hard to Predict?

Widespread tree mortality following droughts has emerged as an environmentally and economically devastating 'ecological surprise'. It is well established that tree physiology is important in understanding drought-driven mortality; however, the accuracy of predictions based on physiology alone has been limited. We propose that complicating factors at two levels stymie predictions of drought-driven mortality: (i) organismal-level physiological and site factors that obscure understanding of drought exposure and vulnerability and (ii) community-level ecological interactions, particularly with biotic agents whose effects on tree mortality may reverse expectations based on stress physiology. We conclude with a path forward that emphasizes the need for an integrative approach to stress physiology and biotic agent dynamics when assessing forest risk to drought-driven morality in a changing climate.

Review: Plant eco-evolutionary responses to climate change: Emerging directions

Contemporary climate change is exposing plant populations to novel combinations of temperatures, drought stress, [CO₂] and other abiotic and biotic conditions. These changes are rapidly disrupting the evolutionary dynamics of plants. Despite the multifactorial nature of climate change, most studies typically manipulate only one climatic factor. In this opinion piece, we explore how climate change factors interact with each other and with biotic pressures to alter evolutionary processes. We evaluate the ramifications of climate change across life history stages,and examine how mating system variation influences population persistence under rapid environmental change. Furthermore, we discuss how spatial and temporal mismatches between plants and their mutualists and antagonists could affect adaptive responses to climate change. For example, plant-virus interactions vary from highly pathogenic to mildly facilitative, and are partly mediated by temperature, moisture availability and [CO₂]. Will host plants exposed to novel, stressful abiotic conditions be more susceptible to viral pathogens? Finally, we propose novel experimental approaches that could illuminate how plants will cope with unprecedented global change, such as resurrection studies combined with experimental evolution, genomics or epigenetics.

Chemically-mediated colonization of black cherry by the peach bark beetle, Phloeotribus liminaris

The peach bark beetle (Phloeotribus liminaris Harris, PBB) affects the health, quality, and value of black cherry (Prunus serotina Ehrh.) within the Central Hardwoods Forest Region of North America. When colonized by adult beetles, black cherry trees produce a defensive exudate, or 'gum', staining the wood and decreasing its value up to 90%. Current management tactics are inadequate to avoid extensive damage to most veneer-sized black cherry in the region. We test the hypothesis that PBB colonization behavior is chemically-mediated and determine the extent to which PBB is attracted to compounds associated with wounded or PBB-infested cherry wood. Through olfactometer and field bioassays, we determined that adult PBB were attracted to cherry branches infested with female beetles. We then used dynamic headspace sampling to collect volatiles associated with wounded and infested bolts of black cherry. The volatile benzaldehyde dominated these collections and was more abundant in aerations of female-infested bolts than other odor sources. In subsequent field bioassays, we evaluated the bioactivity of benzaldehyde, as well as α-longipinene, in combination with several chemical carriers. Traps baited with benzaldehyde captured more PBB than all other treatments, irrespective of other lure components. Moreover, PBB were not attracted to traps baited solely with ethanol, a common attractant for bark beetles that colonize hardwood trees. This is the first report of benzaldehyde as an attractant for a species of bark beetle and could aid in developing semiochemical-based management tactics for this important pest.

A New Perspective of Pseudomonas-Host Interactions: Distribution and Potential Ecological Functions of the Genus Pseudomonas within the Bark Beetle Holobiont

Symbiosis between microbes and insects has been raised as a promising area for understanding biological implications of microbe-host interactions. Among them, the association between fungi and bark beetles has been generally recognized as essential for the bark beetle ecology. However, many works investigating bark beetle bacterial communities and their functions usually meet in a common finding: Pseudomonas is a broadly represented genus within this holobiont and it may provide beneficial roles to its host. Thus, we aimed to review available research on this microbe-host interaction and point out the probable relevance of Pseudomonas strains for these insects, in order to guide future research toward a deeper analysis of the importance of these bacteria for the beetle's life cycle.

Impacts of Climate Change on Hydroclimatic Conditions of U.S. National Forests and Grasslands

The conterminous United States includes national forests and grasslands that provide ecological, social, economic, recreational, and aesthetic services. Future climate change can alter long-term hydroclimatic conditions of national forests and grasslands and lead to negative consequences. This study characterizes shifts in hydroclimatology and basin characteristics of US National Forests (NFs) and National Grasslands (NGs) in response to climate change over the 21st century under the DRY, MIDDLE, and WET climate models with the representative concentration pathway (RCP) 8.5 emission scenario. Climatic projections for three climate models ranging from the driest to wettest conditions were obtained from the Multivariate Adaptive Constructed Analogs (MACA) dataset. Then, the variable infiltration capacity (VIC) model was used to model hydrological responses of the selected future climates. Changes in regional hydroclimatic conditions of NFs and NGs were assessed by the magnitude and direction of movements in the Budyko space. The Fu’s equation was applied to estimate changes in basin characteristics. The results indicate that NFs and NGs are likely to experience larger changes in basin characteristics compared to the average of the United States. In general, across the conterminous US, the NFs in mountainous regions are likely to have larger changes in hydroclimatic variables than NFs with lower elevation and NGs. Comparing Forest Service regions, Pacific Northwest, Intermountain, and Northern regions may have a less arid climate with lower freshwater availability. The Southwestern, Northern, Intermountain, and Rocky Mountain regions are likely to experience higher shifts in their basin characteristics. This study can help environmental scientists, and land and water managers improve future land management plans.

Over half of western United States' most abundant tree species in decline

Changing forest disturbance regimes and climate are driving accelerated tree mortality across temperate forests. However, it remains unknown if elevated mortality has induced decline of tree populations and the ecological, economic, and social benefits they provide. Here, we develop a standardized forest demographic index and use it to quantify trends in tree population dynamics over the last two decades in the western United States. The rate and pattern of change we observe across species and tree size-distributions is alarming and often undesirable. We observe significant population decline in a majority of species examined, show decline was particularly severe, albeit size-dependent, among subalpine tree species, and provide evidence of widespread shifts in the size-structure of montane forests. Our findings offer a stark warning of changing forest composition and structure across the western US, and suggest that sustained anthropogenic and natural stress will likely result in broad-scale transformation of temperate forests globally.

Network analysis can guide resilience-based management in forest landscapes under global change

Forests are projected to undergo dramatic compositional and structural shifts prompted by global changes, such as climatic changes and intensifying natural disturbance regimes. Future uncertainty makes planning for forest management exceptionally difficult, demanding novel approaches to maintain or improve the ability of forest ecosystems to respond and rapidly reorganize after disturbance events. Adopting a landscape perspective in forest management is particularly important in fragmented forest landscapes where both diversity and connectivity play key roles in determining resilience to global change. In this context, network analysis and functional traits combined with ecological dynamic modeling can help evaluate changes in functional response diversity and connectivity within and among forest stands in fragmented landscapes. Here, we coupled ecological dynamic modeling with functional traits analysis and network theory to analyze forested landscapes as an interconnected network of forest patches. We simulated future forest landscape dynamics in a large landscape in southern Quebec, Canada, under a combination of climate, disturbance, and management scenarios. We depicted the landscape as a functional network, assessed changes in future resilience using indicators at multiple spatial scales, and evaluated if current management practices are suitable for maintaining resilience to simulated changes in regimes. Our results show that climate change would promote forest productivity and favor heat-adapted deciduous species. Changes in natural disturbances will likely have negative impacts on native conifers and will drive changes in forest type composition. Climate change negatively impacted all resilience indicators and triggered losses of functional response diversity and connectivity across the landscape with undesirable consequences on the capacity of these forests to adapt to global change. Also, current management strategies failed to promote resilience at different spatial levels, highlighting the need for a more active and thoughtful approach to forest management under global change. Our study demonstrates the usefulness of combining dynamic landscape-scale simulation modeling with network analyses to evaluate the possible impacts of climate change as well as human and natural disturbances on forest resilience under global change.

The Bark Beetle Phloeotribus rhododactylus (Coleoptera: Curculionidae) Has a Stable Range in Europe

Simple Summary

The abundance of bark beetles is generally explained by resource-related parameters. The bark beetle Phloeotribus rhododactylus feeds mainly on the shrub Cytisus scoparius. Other host plants include Spartium junceum, Cytisus sp., Ulex europaeus, Calicotome sp., Coronilla emeroides, Genista florida, Adenocarpus complicatus, and Ficus carica. Phloeotribus rhododactylus seems to have a stable range that is centred in Western Europe and extends to Eastern Europe. Its abundance is highest in Western Europe and decreases to the east, which coincides with the distribution of the host tree, Cytisus scoparius. Even though Cytisus scoparius is an invasive plant in agricultural and natural ecosystems out of Europe, Phloeotribus rhododactylus has not been found in any of the areas invaded by Cytisus scoparius.

Abstract

The bark beetle Phloeotribus rhododactylus feeds mainly on the shrub Cytisus scoparius. The range of P. rhododactylus extends from Spain in the south to southern Sweden, Denmark, and Scotland in the north. Its range to the east extends to Poland, Slovakia, and Hungary, but single localities are known further east in Romania, Bulgaria, and Greece. It is clear that the range of the beetle matches that of its main host. C. scoparius is adapted to Mediterranean and coastal climates, and its range is limited by low winter temperatures. P. rhododactylus is, therefore, rare in Central Europe. It infests either individuals of C. scoparius that have been damaged by mammalian herbivores or snow or that are drought-stressed. Although C. scoparius is an invasive plant in agricultural and natural ecosystems, P. rhododactylus has not been found in any of the areas where C. scoparius has invaded.

Forest restoration treatments in a ponderosa pine forest enhance physiological activity and growth under climatic stress

As the climate warms, drought will increasingly occur under elevated temperatures, placing forest ecosystems at growing risk of extensive dieback and mortality. In some cases, increases in tree density following early 20th-century fire suppression may exacerbate this risk. Treatments designed to restore historical stand structure and enhance resistance to high-severity fire might also alleviate drought stress by reducing competition, but the duration of these effects and the underlying mechanisms remain poorly understood. To elucidate these mechanisms, we evaluate tree growth, mortality, and tree-ring stable-carbon isotope responses to stand-density reduction treatments with and without prescribed fire in a ponderosa pine forest of western Montana. Moderate and heavier cutting experiments (basal area reductions of 35% and 56%, respectively) were initiated in 1992, followed by prescribed burning in a subset of the thinned units. All treatments led to a growth release that persisted to the time of resampling. The treatments had little effect on climate-growth relationships, but they markedly altered seasonal carbon isotope signals and their relationship to climate. In burned and unburned treatments, carbon isotope discrimination (Δ¹³ C) increased in the earlywood (EW) and decreased in the latewood (LW) relative to the control. The sensitivity of LW Δ¹³ C to late-summer climate also increased in all treatments, but not in the control. Such increased sensitivity indicates that the reduction in competition enabled trees to continue to fix carbon for new stem growth, even when the climate became sufficiently stressful to stop new assimilation in slower-growing trees in untreated units. These findings would have been masked had we not separated EW and LW. The importance of faster growth and enhanced carbon assimilation under late-summer climatic stress became evident in the second decade post-treatment, when mountain pine beetle activity increased locally, and tree mortality rates in the controls of both experiments increased to more than twice those in their respective treatments. These findings highlight that, when thinning is used to restore historical forest structure or increase resistance to high-severity fire, there will likely be additional benefits of enhanced growth and physiological activity under climatic stress, and the effects may persist for more than two decades.

Species, Climatypes, Climate Change, and Forest Health: A Conversion of Science to Practice for Inland Northwest (USA) Forests

Research Highlights: This paper integrates disparate research results pertaining to climate change impacts to 12 co-occurring forest tree species and their climatypes such that management options for the ecosystem as a whole become discernible. Background and Objectives: The ecosystem under analysis is the Thuja-Tsuga forest ecosystem, occupying ca. 121,500 km2 in a largely mountainous setting in the interior northwest, USA. Our goal is to present land management options tied directly to climate-change in a straightforward framework for both the current and future generations. Materials and Methods: By merging synecological and genecological concepts in a climatic framework, we simplify complex interactions in a manner that relates directly to climate change impacts. Species and climatype distributions are redefined in terms of mean annual temperature and elevation of forested landscapes. Results: For each 2 °C increase in temperature, plant associations should shift upwards ca. 400 m, provided precipitation remains at or near contemporary levels, which, for this ecosystem, vary between 300 mm and 1450 mm. Management guidelines are developed for (a) selecting climatypes of the species suited to the climate at the leading edge of the migration front, (b) anticipating decline at the trailing edge, and (c) converting climatypes in areas where species should persist. Conclusions: Our results can provide robust strategies for adapting forest management to the effects of climate change, but their effectiveness is dependent on the implementation of global warming mitigation actions.

Identifying areas at risk of drought-induced tree mortality across South-Eastern Australia

South-East Australia has recently been subjected to two of the worst droughts in the historical record (Millennium Drought, 2000-2009 and Big Dry, 2017-2019). Unfortunately, a lack of forest monitoring has made it difficult to determine whether widespread tree mortality has resulted from these droughts. Anecdotal observations suggest the Big Dry may have led to more significant tree mortality than the Millennium drought. Critically, to be able to robustly project future expected climate change effects on Australian vegetation, we need to assess the vulnerability of Australian trees to drought. Here we implemented a model of plant hydraulics into the Community Atmosphere Biosphere Land Exchange (CABLE) land surface model. We parameterized the drought response behaviour of five broad vegetation types, based on a common garden dry-down experiment with species originating across a rainfall gradient (188-1,125 mm/year) across South-East Australia. The new hydraulics model significantly improved (~35%-45% reduction in root mean square error) CABLE's previous predictions of latent heat fluxes during periods of water stress at two eddy covariance sites in Australia. Landscape-scale predictions of the greatest percentage loss of hydraulic conductivity (PLC) of about 40%-60%, were broadly consistent with satellite estimates of regions of the greatest change in both droughts. In neither drought did CABLE predict that trees would have reached critical PLC in widespread areas (i.e. it projected a low mortality risk), although the model highlighted critical levels near the desert regions of South-East Australia where few trees live. Overall, our experimentally constrained model results imply significant resilience to drought conferred by hydraulic function, but also highlight critical data and scientific gaps. Our approach presents a promising avenue to integrate experimental data and make regional-scale predictions of potential drought-induced hydraulic failure.

Climate change effects on biodiversity, ecosystems, ecosystem services, and natural resource management in the United States

Climate change is a pervasive and growing global threat to biodiversity and ecosystems. Here, we present the most up-to-date assessment of climate change impacts on biodiversity, ecosystems, and ecosystem services in the U.S. and implications for natural resource management. We draw from the 4th National Climate Assessment to summarize observed and projected changes to ecosystems and biodiversity, explore linkages to important ecosystem services, and discuss associated challenges and opportunities for natural resource management. We find that species are responding to climate change through changes in morphology and behavior, phenology, and geographic range shifts, and these changes are mediated by plastic and evolutionary responses. Responses by species and populations, combined with direct effects of climate change on ecosystems (including more extreme events), are resulting in widespread changes in productivity, species interactions, vulnerability to biological invasions, and other emergent properties. Collectively, these impacts alter the benefits and services that natural ecosystems can provide to society. Although not all impacts are negative, even positive changes can require costly societal adjustments. Natural resource managers need proactive, flexible adaptation strategies that consider historical and future outlooks to minimize costs over the long term. Many organizations are beginning to explore these approaches, but implementation is not yet prevalent or systematic across the nation.