Treesearch

Cogongrass (Imperata cylindrica), an invasive grass species native to Asia, has been shown to reduce tree vigor in loblolly pine (Pinus taeda) plantations, which comprise more than 50% of growing stock in commercial forests of the United States. I. cylindrica produces exudates with possible allelopathic effects that may influence abundance of P. taeda symbionts, such as soil microbes and ectomycorrhizal fungi. Soil microbial communities and root colonization by mycorrhizal fungi were sampled in intensively managed P. taeda stands in Greene County, Mississippi, in I. cylindrica present and...

Contemporary wildfires in southwestern US ponderosa pine forests can leave uncharacteristically large patches of tree mortality, raising concerns about the lack of seed-producing trees, which can prevent or significantly delay ponderosa pine regeneration. We established 4-ha plots in high-severity burn patches in two Arizona wildfires, the 2000 Pumpkin and 2002 Rodeo-Chediski Fires, to determine if: (1) distance from forest edge influences the density and spatial patterns of regenerating ponderosa pine and sprouting tree species, (2) interactions with re-sprouting trees affect spatial...

This paper reports and reflects on the pilot application of an 11-step policy learning protocol that was developed by Cashore and Lupberger (2015) based on several years of Cashore's multi-author collaborations. The protocol was applied for the first time in Peru in 2015 and 2016 by the IUFRO Working Party on Forest Policy Learning Architectures (hereinafter referred to as the project team). The protocol integrates insights from policy learning scholarship (Hall 1993, Sabatier 1999) with Bernstein and Cashore's (2000, 2012) four pathways of influence framework. The pilot implementation in...

We quantified long-term successional trajectories of canopy arthropods on six tree species in a tropical rainforest ecosystem in the Luquillo Mountains of Puerto Rico that experienced repeated hurricane-induced disturbances during the 19-yr study (1991–2009). We expected: 1) differential performances of arthropod species to result in taxon- or guild-specific responses; 2) differences in initial conditions to result in distinct successional responses to each hurricane; and 3) the legacy of hurricane-created gaps to persist despite subsequent disturbances. At least one significant effect of...

This report presents a methodology for identifying land parcels that have an increased probability of being heirs property. Heirs property is inherited land passed to successive generations intestate, without clear title, typically to family members. This land ownership type is widespread among rural, African-American populations and is also thought to be pervasive in Appalachia, among some Native American groups, and in southwest Texas communities called colonias. The lack of title severely limits property owners’ ability to access credit, to sell natural resources, or to participate in...

Convection and downbursts are connected meteorological phenomena with the potential to affect fire behavior and thereby alter the evolution of a wildland fire. Meteorological phenomena related to convection and downbursts are often discussed in the context of fire behavior and smoke. The physical mechanisms that contribute to these phenomena are interrelated, but the phenomena are often misinterpreted or misunderstood in the fire/smoke context. In this article, we discuss the physical mechanisms associated with convection and downbursts, and we discuss terminology used in reference to...

Novel forests are naturally regenerating forests that have established on degraded lands and have a species composition strongly influenced by introduced species. We studied ecophysiological traits of an introduced species (Castilla elastica Sessé) and several native species growing side by side in novel forests dominated by C. elastica in Puerto Rico. We hypothesized that C. elastica has higher photosynthetic capacity and makes more efficient use of resources than co-occurring native species. Using light response curves, we found that the photosynthetic capacity of C. elastica is similar...

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...

With the global warming, frequencies of drought are rising in the humid area of southern China. In this study, the effects of meteorological drought on the agricultural water resource based on the agricultural water resource carrying capacity (AWRCC) in southern China were investigated. The entire study area was divided into three regions based on the distributions of climate and agriculture. The concept of the maximum available water resources for crops was used to calculate AWRCC. Meanwhile, an agricultural drought intensity index (ADI), which was suitable for rice planting areas, was...

Forest health is affected by multiple factors, including topography, climate, and soil characteristics, as well as pests, pathogens, competitive interactions, and anthropogenic deposition. Species within a stand may respond differently to site factors depending on their physiological requirements for growth, survival, and regeneration. We determined optimal ranges of topographic (elevation, aspect, slope gradient), climatic (average temperature for January, July, and May to September; annual and May to September precipitation), and soil (pH, percent clay, percent coarse sand, permeability,...