Treesearch

Negative population feedbacks mediated by natural enemies can promote species coexistence at the community scale through disproportionate mortality of numerically dominant (common) tree species. Simultaneously, associations with arbuscular mycorrhizal fungi (AMF) can result in positive effects on tree populations. Coupling data on seedling foliar damage from herbivores and pathogens and DNA sequencing of soil AMF diversity, we assessed the effects of these factors on tree seedling mortality at local (1 m2) and community (16 ha plot) scales in a tropical rainforest in Puerto Rico. At the...

This paper examines laws, policies, organizations and other governance elements and arrangements that influence forest conservation and sustainable resource management in the U.S. through a set of 10 Indicators associated with Criterion Seven of the Montréal Process Criteria and Indicators Framework. The applicability and utility of these indicators as a measure of forest governance at the national level is examined and associated quantitative and qualitative data are presented and discussed. In the U.S., a broad range of laws governs public lands, dictating management processes and...

Premise of research. Tropical epiphytes are susceptible to climatic changes, as evidenced by documented population declines, range contractions, and range shifts; however, physiological changes in individual plants may also be indicative of deteriorating climate conditions. Consequently, physiological analyses of tropical epiphytes whose natural habitats are constrained by climatic conditions are warranted to evaluate their responses to potential changes in these conditions, to assess their vulnerability, and to guide conservation actions. Methodology. Here we investigate photosynthetic...

Amazonia has experienced large-scale regional droughts that affect forest productivity and biomass stocks. Space-borne remote sensing provides basin-wide data on impacts of meteorological anomalies, an important complement to relatively limited ground observations across the Amazon’s vast and remote humid tropical forests. Morning overpass QuikScat Ku-band microwave backscatter from the forest canopy was anomalously low during the 2005 drought, relative to the full instrument record of 1999–2009, and low morning backscatter persisted for 2006–2009, after which the instrument failed. The...

Changes in tropical-forest structure and aboveground biomass (AGB) contribute directly to atmospheric changes in CO2, which, in turn, bear on global climate. This paper demonstrates the capability of radar-interferometric phase-height time series at X-band (wavelength = 3 cm) to monitor changes in vertical structure and AGB, with sub-hectare and monthly spatial and temporal resolution, respectively. The phase-height observation is described, with a focus on how it is related to vegetation-density, radar-power vertical profiles, and mean canopy heights, which are, in turn, related to AGB....

Tropical dry forests on calcareous substrate constitute the main vegetation cover in many islands of the Caribbean. Dry climate and nutrient scarcity in those environments are ideal to investigate the potential role of high levels of soil calcium (Ca) in regulating plant selection and productivity. We analyzed the elemental composition of soil, loose litter, and leaf samples of the woody vegetation on the plateau of Mona Island, an emergent block of carbonate rock in the Caribbean located between Puerto Rico and the Dominican Republic, to explore the nutrient relationships of plants...

The U.S. Forest Service has found itself in an era of intense human activity, a changing climate; development and loss of open space; resource consumption; and problematic introduced species; and diversity in core beliefs and values. These challenges test our task-relevant maturity and the ability and willingness to meet the growing demands for services. The Forest Service is now on a transformative campaign to improve abilities and meet these challenges. The “All-Lands Approach to Conservation” brings agencies, organizations, landowners and stakeholders together across boundaries to...

Tropical forest management increasingly is challenged by multiple, complex, intersecting, and in many cases unprecedented changes in the environment that are triggered by human activity. Many of these changes are associated with the Anthropocene—a new geologic epoch in which humans have become a dominating factor in shaping the biosphere. Ultimately, as human activity increasingly influences systems and processes at multiple scales, we are likely to see more extraordinary and surprising events, making it difficult to predict the future with the level of precision and accuracy needed for...

Global food security concerns emphasize the need for sustainable agriculture and local food production. In Puerto Rico, over 80 percent of food is imported, and local production levels have reached historical lows. Efforts to increase local food production are driven by government agencies, non-government organizations, farmers, and consumers. Integration of geographic information helps plan and balance the reinvention and invigoration of the agriculture sector while maintaining ecological services. We used simple criteria that included currently protected lands and the importance of slope...