Defining historical baselines for conservation: ecological changes since European settlement on Vancouver Island, Canada

Using leaf functional traits to remotely detect Cytisus scoparius (Linnaeus) Link in endangered savannahs

Identification of invasive plant species must be accurate and timely for management practices to be successful. Currently, Cytisus scoparius (Scotch broom) is expanding unmonitored across North America’s west coast, threatening established ecological processes and altering biodiversity. Remote detection of leaf functional traits presents opportunities to better understand the distribution of C. scoparius. This paper demonstrates the capacity for remotely sensed leaf functional traits to differentiate C. scoparius from other common plant species found in mixed grassland-woodland ecosystems at the leaf- and canopy-levels. Retrieval of leaf nitrogen percent, specifically, was found to be significantly higher in C. scoparius than each of the other 22 species sampled. These findings suggest that it may be possible to accurately detect introduced C. scoparius individuals using information collected from leaf and imaging spectroscopy at fine spatial resolutions.

Multiscale determinants of Pacific chorus frog occurrence in a developed landscape

Pacific chorus frog (Pseudacris regilla) populations have persisted despite urban and rural development throughout the species’ range; yet it is possible that P. regilla, like other anurans with which it historically co-occurred, will become extirpated from cities and suburbs if urbanization intensifies as predicted. An improved understanding of the conditions that enable this species to persist in developed landscapes is needed to identify and conserve suitable habitats. We investigated species-habitat relationships for P. regilla in a mixed urban-rural landscape in southwestern British Columbia, Canada, to identify potential criteria for habitat suitability. We conducted repeat auditory surveys of chorusing males at 52 potential breeding wetlands and modeled occupancy at 26 of these sites using local and landscape variables representing competing hypotheses and spatial scales of influence. The models that best explained P. regilla occupancy included a combination of terrestrial habitat and connectivity factors and the presence of non-native predators. We found that the proportion of impervious cover within 250 m of a wetland had the strongest negative impact on occupancy. Our findings suggest that availability of terrestrial habitat adjacent to breeding sites is the primary driver of species presence in the developed landscape. Conservation efforts should seek to limit impervious cover to less than 20% within a 250-m buffer around breeding wetlands. Further, restored and created wetlands in urban and rural areas may be more likely to support P. regilla if they are designed with a seasonal hydroperiod that excludes non-native aquatic predators and are placed in an area of high pond density.

Reference state and benchmark concepts for better biodiversity conservation in contemporary ecosystems

Measuring the status and trends of biodiversity is critical for making informed decisions about the conservation, management or restoration of species, habitats and ecosystems. Defining the reference state against which status and change are measured is essential. Typically, reference states describe historical conditions, yet historical conditions are challenging to quantify, may be difficult to falsify, and may no longer be an attainable target in a contemporary ecosystem. We have constructed a conceptual framework to help inform thinking and discussion around the philosophical underpinnings of reference states and guide their application. We characterize currently recognized historical reference states and describe them as Pre-Human, Indigenous Cultural, Pre-Intensification and Hybrid-Historical. We extend the conceptual framework to include contemporary reference states as an alternative theoretical perspective. The contemporary reference state framework is a major conceptual shift that focuses on current ecological patterns and identifies areas with higher biodiversity values relative to other locations within the same ecosystem, regardless of the disturbance history. We acknowledge that past processes play an essential role in driving contemporary patterns of diversity. The specific context for which we design the contemporary conceptual frame is underpinned by an overarching goal-to maximize biodiversity conservation and restoration outcomes in existing ecosystems. The contemporary reference state framework can account for the inherent differences in the diversity of biodiversity values (e.g. native species richness, habitat complexity) across spatial scales, communities and ecosystems. In contrast to historical reference states, contemporary references states are measurable and falsifiable. This 'road map of reference states' offers perspective needed to define and assess the status and trends in biodiversity and habitats. We demonstrate the contemporary reference state concept with an example from south-eastern Australia. Our framework provides a tractable way for policy-makers and practitioners to navigate biodiversity assessments to maximize conservation and restoration outcomes in contemporary ecosystems.

'Neo-Europe' and its ecological consequences: the example of systematic degradation in Australia's inland fisheries

The antiquity of human impact on ecosystems is increasingly understood, though the arrival of settlers to new lands remains a defining period. Colonization of the 'neo-Europes', a reference from the discipline of history, precipitated changes in aquatic ecosystems through modification of waterways and introductions of non-native species. We considered historical fisheries and fish market records from South Australia (1900-1946) against contemporary production statistics (1987-2011). Native inland species historically contributed large quantities to the market but have deteriorated such that fishing is now limited, and conservation regulations exist. This pattern mirrors the demand-driven transition from freshwater to marine fisheries in Europe; hence, we propose that this pattern was predicated on societal expectations and that European settlement and introduction of non-native fishes led to systematic overexploitation and degradation of native inland fisheries species in Australia, representing a further consequence of neo-European colonization to ecology. Accurate interpretation of ecological change can ensure more appropriate management intervention. Concepts, such as neo-Europe, from alternative disciplines can inform the recognition and evaluation of patterns at regional and global scales.

Specialists in ancient trees are more affected by climate than generalists

Ancient trees are considered one of the most important habitats for biodiversity in Europe and North America. They support exceptional numbers of specialized species, including a range of rare and endangered wood-living insects. In this study, we use a dataset of 105 sites spanning a climatic gradient along the oak range of Norway and Sweden to investigate the importance of temperature and precipitation on beetle species richness in ancient, hollow oak trees. We expected that increased summer temperature would positively influence all wood-living beetle species whereas precipitation would be less important with a negligible or negative impact. Surprisingly, only oak-specialist beetles with a northern distribution increased in species richness with temperature. Few specialist beetles and no generalist beetles responded to the rise of 4°C in summer as covered by our climatic gradient. The negative effect of precipitation affected more specialist species than did temperature, whereas the generalists remained unaffected. In summary, we suggest that increased summer temperature is likely to benefit a few specialist beetles within this dead wood community, but a larger number of specialists are likely to decline due to increased precipitation. In addition, generalist species will remain unaffected. To minimize adverse impacts of climate change on this important community, long-term management plans for ancient trees are important.

From myopia to clarity: sharpening the focus of ecosystem management through the lens of palaeoecology

Maintaining biodiversity and ecosystem services in a changing environment requires a temporal perspective that informs realistic restoration and management targets. Such targets need to be dynamic, adaptive, and responsive to changing boundary conditions. However, the application of long-term data from palaeoecology is often hindered as the management and policy implications are not made explicit, and because data sets are often not accessible or amenable to stakeholders. Focussing on this translation gap, we explore how a palaeoecological perspective can change the focus of biodiversity management and conservation policy. We embed a long-term perspective (decades to millennia) into current adaptive management and policy frameworks, with the aim of encouraging better integration between palaeoecology, conservation management, and mainstreaming viable provision of ecosystem services.

Historical ecology: using unconventional data sources to test for effects of global environmental change

Predicting the future ecological impact of global change drivers requires understanding how these same drivers have acted in the past to produce the plant populations and communities we see today. Historical ecological data sources have made contributions of central importance to global change biology, but remain outside the toolkit of most ecologists. Here we review the strengths and weaknesses of four unconventional sources of historical ecological data: land survey records, "legacy" vegetation data, historical maps and photographs, and herbarium specimens. We discuss recent contributions made using these data sources to understanding the impacts of habitat disturbance and climate change on plant populations and communities, and the duration of extinction-colonization time lags in response to landscape change. Historical data frequently support inferences made using conventional ecological studies (e.g., increases in warm-adapted species as temperature rises), but there are cases when the addition of different data sources leads to different conclusions (e.g., temporal vegetation change not as predicted by chronosequence studies). The explicit combination of historical and contemporary data sources is an especially powerful approach for unraveling long-term consequences of multiple drivers of global change. Despite the limitations of historical data, which include spotty and potentially biased spatial and temporal coverage, they often represent the only means of characterizing ecological phenomena in the past and have proven indispensable for characterizing the nature, magnitude, and generality of global change impacts on plant populations and communities.