Treesearch

Throughout eastern North America, chronic white-tailed deer overbrowsing and widespread exotic plant invasions degrade native plant diversity and abundance. However, because deer densities are high across entire regions, it is challenging to find large areas where deer have been at low density for long periods. We predicted native plant diversity and abundance would be significantly higher during gap-phase regeneration where deer have been maintained at low densities (~ 7 deer/km2) compared to where deer have been chronically overabundant. Simultaneously, we predicted that exotic plant...

A fundamental question in bryology is to identify what environmental factors influence bryophyte distribution in an ecosystem and how they respond to disturbances. We investigated the distribution of the moss Thuidium urceolatum and species of the liverwort Plagiochila, representing distinct life-forms (wefts and fans), in the Luquillo Forest Dynamic Plot, where the environment and disturbance history is well described. We hypothesized that if the presence of T. urcealutum and Plagiochila spp. are affected by habitat (riparian versus upland) and past land use, then there will be differences...

This study evaluates the secondary successional pathways of Hawaiian lowland rainforest following anthropogenic disturbance. Whereas primary succession on lava flows has been well studied in Hawaii, secondary successional dynamics on disturbed habitats in the presence of nonnative species has been poorly researched and documented. Our study was based on two vegetation sampling efforts conducted on 200–400-year-old lava flows 2 and 27 years following a 400-hectare clearcutting operation in the Puna District of the southeast quadrant of Hawaii Island. Intact forest adjacent to the clearcut...

1. Defoliators cause extensive damage in boreal and temperate forests of the world. Considerable effort has been invested to understand their individual population dynamics, and despite ample theorising, there is little empirical evidence on factors causing spatial synchrony of pest eruptions at landscape scales. 2. We report on the landscape-level effect of forest configuration and composition on the intensity of outbreaks of spruce budworm and forest tent caterpillar in a mixedwood boreal forest in northern Minnesota (USA) and adjacent Ontario (Canada), and how this is related to the...

The U.S. Department of Agriculture’s Forest Inventory and Analysis (FIA) program provides nationwide estimates of forest resources. It is important that these estimates are both unbiased and precise. The portion of this inventory conducted in the Rocky Mountain states uses an ecological stratification layer to increase the precision of these estimates. This divides plots into groups where the response variable is more similar within each group than between the groups to help minimize the variance, which is equivalent to greater precision. Here we examine several potential new ecological...

Applying remote sensing models outside the temporal range of their training data, referred to as temporal model transfer, has become common practice for large area monitoring projects that extrapolate models for hindcasting or forecasting to time periods lacking reference data. However, the development of appropriate validation methods for temporal transfer has lagged behind its rapid adoption. Breaking temporal transfer’s assumption of temporal consistency in both remote sensing and reference data and their relationship to each other could lead to biased pixel-level predictions and small...

Context: Preserving functional connectivity is a conservation priority to secure the long-term viability of geographically dispersed subpopulations, such as the jaguar (Panthera onca) populations in Central America. However, managing connectivity in this region is limited due to the scarcity of local assessments of the connectivity between existing populations, some of which exhibit low levels of gene flow and genetic admixture.Objectives: We selected the jaguar as a model species to understand how gene flow of large carnivores is shaped in a heavily human-impacted landscape in the...

We know that we need bees to maintain healthy ecosystems. Pollinators help plants reproduce and flourish, and these plants, in turn, maintain soils and provide cover and food for animals. But what do bees need to survive, to thrive?

Reducing encroachment of pinyon-juniper woodlands is a proven management tool to restore sagebrush habitat for the greater sage grouse and other sagebrush-obligate species. However, these woodlands have their own obligate species, such as the pinyon jay whose population has seen significant declines over the decades. This places managers in a conundrum: where to prioritize conifer removal for sagebrush species without negatively impacting woodland species?

Premise: Herbivore pressure can vary across the range of a species, resulting in different defensive strategies. If herbivory is greater at lower latitudes, plants may be better defended there, potentially driving a latitudinal gradient in defense. However, relationships that manifest across the entire range of a species may be confounded by differences within genetic subpopulations, which may obscure the drivers of these latitudinal gradients.Methods: We grew plants of the widespread perennial grass Panicum virgatum in a common garden that included genotypes from three genetic subpopulatio...