Surface gold mining severely degrades landscapes, causing deforestation, soil erosion and displacement, and toxic contamination. The prevalence of both large‐scale and artisanal, small‐scale surface gold mining in the tropics has risen over recent decades. Restoration strategies developed for less‐severe forms of degradation may not sufficiently address the unique ecological conditions of former gold mines. In this review, we summarize biophysical challenges to the restoration and reforestation of large‐ and small‐scale gold mines in the tropics and synthesize the findings of studies that test restoration strategies at these sites. Certain practices, such as the backfilling of mined pits, topsoil conservation, and the preservation of local seed sources, emerge from the literature as crucial for the timely and effective restoration of gold mines. However, because the severity of ecological degradation varies greatly within and between individual mines, and given the relatively small number (n = 42) of published tropical field studies found in our literature review, we highlight a clear need for continued research and development of restoration strategies specific to ecological conditions of former gold mines in the tropics.

Many studies have demonstrated the importance of early‐successional forest habitat for breeding bird abundance, composition, and diversity. However, very few studies directly link measures of bird diversity, composition and abundance to measures of forest composition, and structure and their dynamic change over early succession. This study examines the relationships between breeding bird community composition and forest structure in regenerating broadleaf forests of southern New England, USA, separating the influences of ecological succession from retained stand structure. We conducted bird point counts and vegetation surveys across a chronosequence of forest stands that originated between 2 and 24 years previously in shelterwood timber harvests, a silvicultural method of regenerating oak‐mixed broadleaf forests. We distinguish between vegetation variables that relate to condition of forest regeneration and those that reflect legacy stand structure. Using principal components analyses, we confirmed the distinction between regeneration and legacy vegetation variables. We ran regression analysis to test for relationships between bird community variables, including nesting and foraging functional guild abundances, and vegetation variables. We confirmed these relationships with hierarchical partitioning. Our results demonstrate that regenerating and legacy vegetation correlate with bird community variables across stand phases and that the strength with which they drive bird community composition changes with forest succession. While measures of regeneration condition explain bird abundance and diversity variables during late initiation, legacy stand structure explains them during stem exclusion. Canopy cover, ground‐story diversity, and canopy structure diversity are the most powerful and consistent explanatory variables. Our results suggest that leaving varied legacy stand structure to promote habitat heterogeneity in shelterwood harvests contributes to greater bird community diversity. Interestingly, this is particularly important during the structurally depauperate phase of stem exclusion of young regenerating forests.

The American quaking aspen (Populus tremuloides Michx.) and its close relative, the Eurasian quaking aspen (Populus tremula L.), cover a realm that is perhaps the most expansive of all tree species in the world. In North America, sudden aspen decline (SAD) is a growing concern that marks the rapid decline of quaking aspen trees leading to mortality at the stand and landscape scale. Research suggests that drought and water stress are the primary causes of SAD. Predisposing factors (age, structure, and landscape position), as well as associated stressors (i.e., pests and pathogens), have been linked to mortality in affected stands. The conflation of multiple interacting factors across the aspen’s broad geographic range in North America has produced significant debate over the classification of SAD as a disease and the proper management of affected stands. Interestingly, no such effects have been reported for the Eurasian aspen. We here review and synthesize the growing body of literature for North America and suggest that SAD is a novel decline disease resulting from multiple inciting and interacting factors related to climate, land-use history, and successional dynamics. We suggest that the range of aspen observed at the onset of the 21st Century was bolstered by a wet period in western North America that coincided with widespread regional cutting and clearing of late-successional forests for timber and grazing. No comparable land-use history, successional status, or age-class structure is apparent or linked for Eurasian forests. Eurasian aspen is either absent or young in managed forests, or old and decadent in parks in Fenno-Scandinavia, or it grows more intimately with a more diverse mixture of tree species that have arisen from a longer period of frequent timber cutting in Russia. Based on these insights we provide recommendations for practical management techniques that can promote stand resilience and recovery across a range of stand conditions in North America. Managers should attempt to identify SAD-prone stands using the presence of predisposing conditions and focus treatments such as coppice or prescribed fire on stands with suitable topographies, elevations, and climates. We conclude that SAD will persist throughout the coming decades, given the enormity of past cutting history, fire exclusion, and current changes in climate until a more active restoration agenda is implemented.

Tropical dry forests (TDF) are among the most‐threatened terrestrial ecosystems, experiencing ongoing conversion to agricultural fields, pasture, and human settlements. Human disturbances are often precursors to invasion of ecosystems by non‐native species, but research on invasion patterns in tropical ecosystems is sparse, and there is no comprehensive synthesis of invasive species in TDF. We conducted a review of published scientific literature to catalog and synthesize information about invasion by non‐native plants in TDF ecosystems across the globe, drawing out patterns in the invasion of these ecosystems. We found that 130 invasive plant species were documented as present in TDF, but only 25 of these species were mentioned in three or more articles. Almost all 25 of these more‐studied invasive species—mostly pasture grasses, woody legumes, and climbers—have been intentionally cultivated for agricultural or ornamental purposes. Many of these plants are native to open‐canopy savanna or forest edge habitats and benefit from human‐altered disturbance regimes (burning, grazing, and fuelwood and timber harvesting) of TDF fragments within agricultural landscapes. Field studies show that management approaches incorporating invasive removal, native plantings, and reduction in agricultural disturbance (e.g. ungulate fencing and fire control) simultaneously are often the most successful at reducing invasive plant cover. However, management studies in TDF have focused on a limited number of invasive species, and most were conducted in India and Hawaii. Global differences in TDF soils, natural fire regimes, and historic and current land use by humans influence modern biogeographic patterns of invasion and the feasibility of restoration options.