Treesearch

Nonnative invasive herbivores can create complex biotic interactions by differentially feeding on native and nonnative invasive plant species. The herbivores may act as enemies of nonnative plants and prevent them from becoming invasive, or they may facilitate invasion by having a greater negative impact on native plants compared with nonnative plants. It is also possible that within the same ecosystem nonnative herbivores could either facilitate or inhibit invasion under different abiotic or biotic conditions. In this study we experimentally investigated how abiotic (soil nutrients) and...

One of many ecosystem services essential to land management is carbon regulation, but presence of invasive species can influence carbon (C) in undesirable ways. Here we discuss early results of C accumulation from the Liko Nā Pilina hybrid wet forest restoration experiment. The focus of our project is to deliberately increase C storage through a functional trait-based approach to restoration. By choosing plant species mixes with specific functional trait values, a novel ecosystem can be assembled that supports desired ecosystem services such as C regulation. We designed species mixtures...

Wildland fire is the dominant disturbance agent of the boreal forest of Alaska. Currently, about 80% of the population of Alaska resides in communities potentially at risk from wildland fire. The wildland fire threat to these settlements is increasing because of increased suburban construction in or near forested areas. The primary objective of this research was to assess the effectiveness of maturing treatment projects in terms of previously defined risk reduction and fire behavior objectives in order to better understand the contribution of fuel treatments to the broader economics of...

Disturbance is central to maintaining diversity in forest ecosystems. In the dry forests of the western United States, over a century of fire exclusion has altered the fire regimes of these forests, resulting in high fuel loads and a loss of plant diversity. Mechanical thinning and prescribed fire are widely used to restore structural complexity and species diversity in many western U.S. forests. While studies have shown that the reintroduction of fire into these forests initially promotes plant diversity, there is limited information on the persistence of this effect. We evaluated the...

Wildland fire is a significant and growing threat to communities and natural resources on Hawaii and the U.S.- affiliated Pacific Islands, including Wildland fire is a significant and growing threat to communities and natural resources on Hawaii and the U.S.- affiliated Pacific Islands. Collaborative approaches to fire management are critical because multiple interacting factors --including climate, ecosystem composition, land use history, social-ecological impacts, and cultural perceptions --create highly complex problems. However, identifying effective strategies to promote dialogue and...

Prescribed burning (controlled burning) is used to decrease accumulation of combustible materials and reduce impact of uncontrolled wildland fires. Prescribed fires are often used to burn undergrowth in southern forests of the United States. In order to improve prescribed fire application, accomplish desired fire effects, and limit potential runaway fires, an improved understanding of the fundamental processes related to combustion of heterogeneous fuel beds of live and dead fuels is needed. The initial processes of combustion involve pyrolysis and ignition. During this research, fast...

Plants modify development in response to external stimuli, to produce new growth that is appropriate for environmental conditions. For example, gravi‐stimulation of leaning branches in angiosperm trees results in modifications of wood development, to produce tension wood that pulls leaning stems upright. Here, we use gravi‐stimulation and tension wood response to dissect the temporal changes in gene expression underlying wood formation in Populus stems. Using time‐series analysis of seven time points over a 14‐d experiment, we identified 8,919 genes that were differentially expressed...

In two of our recent systems biology studies of forest trees we reconstructed gene networks active in wood tissue development for an undomesticated tree genus, Populus. In the first study, we used time series data to determine gene expression dynamics underlying wood formation in response to gravitational stimulus. In the second study, we integrated data from newly generated and publicly available transcriptome profiling, transcription factor binding, DNA accessibility and genome-wide association mapping experiments, to identify relationships among genes expressed during wood formation. We...

Woody perennial angiosperms (i.e., hardwood trees) are polyphyletic in origin and occur in most angiosperm orders. Despite their independent origins, hardwoods have shared physiological, anatomical, and life history traits distinct from their herbaceous relatives. New high-throughput DNA sequencing platforms have provided access to numerous woody plant genomes beyond the early reference genomes of Populus and Eucalyptus, references that now include willow and oak, with pecan and chestnut soon to follow. Genomic studies within these diverse and undomesticated species have successfully...

Insects are important components of forest ecosystems representing most of the biological diversity and affecting virtually all processes. Some phytophagous species occasionally become so abundant that they threaten ecological, economic, social, and aesthetic values. The western pine beetle (Dendroctonus brevicomis) is a major disturbance in ponderosa pine (Pinus ponderosa) forests throughout much of the western United States. A notable outbreak, regarded by some as among the most severe for this species of bark beetle, occurred in southern California in the early 2000s. What is known...