Treesearch

Forest removal for livestock grazing is a striking example of human-caused state change leading to a stable, undesirable invasive grass system that is resistant to restoration efforts. Understanding which factors lead to resilience the alternative grass state can greatly benefit managers when planning forest restoration. We address how thresholds of grass cover and seed rain might influence forest recovery in a restoration project on Hawaiʻi Island, USA. Since the 1980s, over 400,000 Acacia koa (koa) trees were planted across degraded pasture and invasive grasses still dominate the...

Contemporary restoration and management of sagebrush-dominated (Artemisia spp.) ecosystems across the intermountain west of the United States increasingly involves the removal of expanding conifer, particularly juniper (Juniperus spp.) and pinyon pine ( Pinus edulis, P. monophylla). The impetus behind much of this management has been the demonstrated population benefits of sagebrush restoration via conifer removal to greater sage-grouse (Centrocercus urophasianus), a species of conservation concern. One of the challenges with scaling up from a focal-species approach to a community-level...

Anticipating consequences of disturbance interactions on ecosystem structure and function is a critical management priority as disturbance activity increases with warming climate. Across the Northern Hemisphere, extensive tree mortality from recent bark beetle outbreaks raises concerns about potential fire behavior and post-fire forest function. Silvicultural treatments (that is, partial or complete cutting of forest stands) may reduce outbreak severity and subsequent fuel loads, but longevity of pre-outbreak treatment effects on outbreak severity and post-outbreak fuel profiles remains...

Orchid bees are abundant and widespread in the Neotropics, where males are important pollinators of orchids they visit to collect fragrant chemicals later used to court females. Assemblages of orchid bees have been intensively surveyed in parts of Central America, but less so in Belize, where we studied them during the late-wet and early-dry seasons of 2015-2020.

As society grapples with increasing wildfire damage to landscapes and communities, the capacity of the interagency system in the USA designed to protect landscapes and communities from wildfires is degrading. A stressed system will be less capable of protecting life, property, and resources, and increased workloads will likely increase hazards to fire personnel and amplify existing problems with recruitment and retention. We argue that solutions are attainable through increased attention to performance and through more anticipatory, adaptive, and intelligent deployment of fire personnel...

Ecological disturbance regimes across the globe are being altered via direct and indirect human influences. Biodiversity loss at multiple scales can be a direct outcome of these shifts. Fire, especially in dry forests, is an ecological disturbance that is experiencing dramatic changes due to climate change, fire suppression, increased human population in fire-prone areas, and alterations to vegetation composition and structure. Dry western conifer forests that historically experienced frequent, low-severity fires are now increasingly burning at high severity. Relatively little work has...

Although fire is a fundamental ecological process in western North American forests, climate warming and accumulating forest fuels due to fire suppression have led to wildfires that burn at high severity across larger fractions of their footprint than were historically typical. These trends have spiked upwards in recent years and are particularly pronounced in the Sierra Nevada-Southern Cascades ecoregion of California, USA, and neighboring states. We assessed annual area burned (AAB) and percentage of area burned at high and low-to-moderate severity for seven major forest types in this...

Maintenance of connectivity is a commonly recommended strategy for species management and conservation as habitat loss and fragmentation continues. Therefore, functional connectivity modeling is needed for species over large geographic areas. However, sex-specific functional connectivity is rarely considered, even though the results of such an analysis have the potential to influence applied management practices.

Introduction: Tree defense characteristics play a crucial role in modulating conifer bark beetle interactions, and there is a growing body of literature investigating factors mediating tree growth and resin-based defenses in conifers. A subset of studies have looked at relationships between tree growth, resin duct morphology and climate; however, these studies are almost exclusively from lower-elevation, moisture-limited systems. The relationship between resin ducts and climate in higher-elevation, energy-limited ecosystems is currently poorly understood. Methods: In this study, we: (1)...

Peatlands have sequestered atmospheric carbon dioxide (CO2) for millennia and can also act as significant sources of atmospheric methane (CH4). Hydrological processes that control water table dynamics, and climatic conditions such as air temperature, play important roles in mediating peatland-atmosphere exchange of these greenhouse gases. These controls are likely to be impacted by climate change, particularly for those peatlands found in cold environments, including mountain regions. In this study, we developed empirical models to simulate hydrological dynamics and ecosystem-atmosphere C...