Assessing Simple Versus Complex Restoration Strategies for Industrially Disturbed Forests

Stochasticity-induced persistence in coupled social-ecological systems

Stochasticity is often associated with negative consequences for population dynamics since a population may die out due to random chance during periods when population size is very low (stochastic fade-out). Here we develop a coupled social-ecological model based on stochastic differential equations that includes natural expansion and harvesting of a forest ecosystem, and dynamics of conservation opinions, social norms and social learning in a human population. Our objective was to identify mechanisms that influence long-term persistence of the forest ecosystem in the presence of noise. We found that most of the model parameters had a significant influence on the time to extinction of the forest ecosystem. Increasing the social learning rate and the net benefits of conservation significantly increased the time to extinction, for instance. Most interestingly, we found a parameter regime where an increase in the amount of system stochasticity caused an increase in the mean time to extinction, instead of causing stochastic fade-out. This effect occurs for a subset of realizations, but the effect is large enough to increase the mean time to extinction across all realizations. Such "stochasticity-induced persistence" occurs when stochastic dynamics in the social system generates benefits in the forest system at crucial points in its temporal dynamics. We conclude that studying relatively simple social-ecological models has the benefit of facilitating characterization of dynamical states and thereby enabling us to formulate new hypothesis about mechanisms that could be operating in empirical social-ecological systems.

Vegetation- and Environmental Changes on Non-Reclaimed Spoil Heaps in Southern Poland

The study focused on the changes in vegetation and soils on an undeveloped area of coal mine spoil heaps. The process of vegetation changes was evaluated on the basis of historical cartographic materials and fieldwork. Changes of vegetation in nearly 200 years are presented herein. The main purpose of this study is to present an analysis of spatio-temporal changes in vegetation and their influence on soil features. The diversity of ecological species in terms of habitat requirements, tendency of hornbeam communities formation, and the relationship between forest communities and soil features was found. The basic soil properties were examined under selected plant communities (pH, Corg, Nt), available forms of elements (P, K, Mg), and as plant nutrients and heavy metal occurrence (Fe, Zn, Mn, Co, Cd, Pb, Sr, Cr, Cu). The soil organic carbon (Corg) content varied from 3.17 ± 0.007% to 17.7 ± 0.21% and significant differences were observed between sites. The highest total nitrogen (Nt) content was recorded in the soils of the sites that were represented by Populus-Betula stands (0.60 ± 0.01%). Soil acidity (pH) varied greatly, ranging from acidic (pH = 4.1) to weakly acidic (pH = 5.9). The highest value for Mgavail (205.43 ± 0.5 mg·kg-1) was noted in the soils under Calamagrostis epegijos (L.) Roth community and for Pavail (184.07 ± 3.77) and Kavail (346.19 ± 2.92 mg·kg-1) under the Quercus-Pinus stand. On all sites, Zn was a dominant element and its concentration ranged from 526.1 to 1060.4 mg·kg-1. Obtained results show how important it is to study the issue of vegetation changes and the formation of the landscape within an industrial city. The described results are important for the management of urban greening issues. Human influence on the disintegration and development of the natural environment is clearly visible. Due to the diversity of former mining areas and their time of creation, the studied area is one of the most important experimental areas for the determination link between vegetation and soil.

Terrestrial Ecosystem Impacts of Sulfide Mining: Scope of Issues for the Boundary Waters Canoe Area Wilderness, Minnesota, USA

Large-scale metal mining operations are planned or underway in many locations across the boreal forest biome in North America, Europe, and Asia. Although many published analyses of mining impacts on water quality in boreal landscapes are available, there is little guidance regarding terrestrial impacts. Scoping of potential impacts of Cu-Ni exploration and mining in sulfide ores are presented for the Boundary Waters Canoe Area Wilderness (BWCAW), Minnesota USA, an area of mostly boreal forest on thin soils and granitic bedrock. Although the primary footprint of the proposed mines would be outside the BWCAW, displacement and fragmentation of forest ecosystems would cause spatial propagation of effects into a secondary footprint within the wilderness. Potential negative impacts include disruption of population dynamics for wildlife species with migration routes, or metapopulations of plant species that span the wilderness boundary, and establishment of invasive species outside the wilderness that could invade the wilderness. Due to linkages between aquatic and terrestrial ecosystems, acid mine drainage can impact lowland forests, which are highly dependent on chemistry of water flowing through them. The expected extremes in precipitation and temperature due to warming climate can also interact with mining impacts to reduce the resilience of forests to disturbance caused by mining.

The impact of human-environment interactions on the stability of forest-grassland mosaic ecosystems

Forest-grassland mosaic ecosystems can exhibit alternative stables states, whereby under the same environmental conditions, the ecosystem could equally well reside either in one state or another, depending on the initial conditions. We develop a mathematical model that couples a simplified forest-grassland mosaic model to a dynamic model of opinions about conservation priorities in a population, based on perceptions of ecosystem rarity. Weak human influence increases the region of parameter space where alternative stable states are possible. However, strong human influence precludes bistability, such that forest and grassland either co-exist at a single, stable equilibrium, or their relative abundance oscillates. Moreover, a perturbation can shift the system from a stable state to an oscillatory state. We conclude that human-environment interactions can qualitatively alter the composition of forest-grassland mosaic ecosystems. The human role in such systems should be viewed as dynamic, responsive element rather than as a fixed, unchanging entity.

Patterns of insect communities along a stress gradient following decommissioning of a Cu-Ni smelter

The diversity, estimated richness and abundance of terrestrial insect communities were examined along a stress gradient of past pollution in the region of Sudbury, Ontario, Canada. This gradient represents the natural recovery and lingering effects of a decommissioned copper-nickel smelting complex. Ant genera and sixteen higher taxonomic groups (family and order) had the highest abundance at the sites with intermediate stress. Eight families increased in abundance with distance from the decommissioned source of pollution and eleven families decreased reflecting a complex response of diversity to pollution. Carabid beetles show an increase in diversity further from the smelter; however, examination of the species composition reveals a distinct carabid community closest to the smelter, emphasizing the unique habitat created by severe pollution. Although almost forty years since decomissioning of the smelter complex, the terrestrial insect community in the vicinity remains significantly impacted suggesting slow recovery.

Recreating a functioning forest soil in reclaimed oil sands in northern alberta: an approach for measuring success in ecological restoration

During oil-sands mining all vegetation, soil, overburden, and oil sand is removed, leaving pits several kilometers wide and up to 100 m deep. These pits are reclaimed through a variety of treatments using subsoil or a mixed peat-mineral soil cap. Using nonmetric multidimensional scaling and cluster analysis of measurements of ecosystem function, reclamation treatments of several age classes were compared with a range of natural forest ecotypes to discover which treatments had created ecosystems similar to natural forest ecotypes and at what age this occurred. Ecosystem function was estimated from bioavailable nutrients, plant community composition, litter decomposition rate, and development of a surface organic layer. On the reclamation treatments, availability of nitrate, calcium, magnesium, and sulfur were generally higher than in the natural forest ecotypes, while ammonium, P, K, and Mn were generally lower. Reclamation treatments tended to have more bare ground, grasses, and forbs but less moss, lichen, shrubs, trees, or woody debris than natural forests. Rates of litter decomposition were lower on all reclamation treatments. Development of an organic layer appeared to be facilitated by the presence of shrubs. With repeated applications of fertilizers, measured variables for the peat-mineral amendments fell within the range of natural variability at about 20 yr. An intermediate subsoil layer reduced the need for fertilizer and conditions resembling natural forests were reached about 15 yr after a single fertilizer application. Treatments over tailings sand receiving only one application of fertilizer appeared to be on a different trajectory to a novel ecosystem.