Treesearch

Canopy temperature Tcan is a key driver of plant function that emerges as a result ofinteracting biotic and abiotic processes and properties. However, understanding controls on Tcan and forecasting canopy responses to weather extremes and climate change are difficultdue to sparse measurements of Tcan at appropriate spatial and temporal scales. Burgeoning observations of Tcan from thermal cameras enable evaluation of energy budget theory andbetter understanding of how environmental controls, leaf traits and canopy structure influence temperature patterns. The canopy scale is relevant for...

Many research and monitoring networks in recent decades have provided publicly available data documenting environmental and ecological change, but little is known about the status of efforts to synthesize this information across networks. We convened a working group to assess ongoing and potential cross-network synthesis research and outline opportunities and challenges for the future, focusing on the US-based research network (the US Long-Term Ecological Research network, LTER) and monitoring network (the National Ecological Observatory Network, NEON). LTER-NEON cross-network research...

Ecosystems are changing in complex and unpredictable ways, and analysis of these changes is facilitated by coordinated, long-term research. Meeting diverse societal needs requires an understanding of what populations and communities will be dominant in 20, 50, and 100 yr. This paper is a product of a synthesis effort of the U.S. National Science Foundation funded Long-Term Ecological Research (LTER) network addressing the LTER core research area of populations and communities. This analysis revealed that each LTER site had at least one compelling story about what their site would look like...

Cold-air drainage and pooling can have wide-ranging impacts, including affecting ecosystem processes and agricultural crops, and contributing to decreased air quality associated with temperature inversions. Future climate changes may alter both the frequency and intensity of cold-air drainage. This study estimates the response of nocturnal cold-air drainage to warming resulting from anthropogenic greenhouse gases, specifically CO2, considering radiative and thermodynamic effects but not changes in background air flow (dynamic effects). A simple index is proposed to represent the propensity...

The complexity of forest structures plays a crucial role in regulating forest ecosystem functions and strongly influences biodiversity. Yet, knowledge of the global patterns and determinants of forest structural complexity remains scarce. Using a stand structural complexity index based on terrestrial laser scanning, we quantify the structural complexity of boreal, temperate, subtropical and tropical primary forests. We find that the global variation of forest structural complexity is largely explained by annual precipitation and precipitation seasonality (R² = 0.89). Using the structural...

Tree encroachment threatens the biodiversity and ecological functioning of grasslands worldwide. Reversing effects of encroachment requires not only removing trees, but limiting subsequent invasions, which can stall grassland reassembly. We quantified rates and patterns of conifer reinvasion of mountain grasslands (meadows) in western Oregon, 7 and 15 years after experimental tree removal with or without burning. We assessed frequency (percentage of 100 m2 subplots) and density of reinvading trees in six 1-ha plots as a function of burn treatment, abundance in the adjacent forest (a proxy...

Food webs show the architecture of trophic relationships, revealing the biodiversity and species interactions in an ecosystem. Understanding which factors modulate the structure of food webs offers us the ability to predict how they will change when influential factors are altered. To date, most of the research about food webs has focused on species interactions whereas the influences of surrounding environments have been overlooked. Here, using network analysis, we identified how the structure of aquatic food webs varied across a range of geophysical conditions within a whole stream...

The influences of inter- and intraspecific variation in leaf litter quality on aquatic food webs are well understood. However, the timing and type of organic matter inputs also varies within a species based on plant phenophase, including litterfall and flowering, which may influence instream communities and ecosystem processes including decomposition. We investigated how leaf and flower litters of a willow shrub species (Salix sitchensis) influenced decomposition and aquatic invertebrate colonization in a headwater stream. We collected abscised willow catkins and leaves from female plants,...

Between 1989 and 2012, three Forest Service programs collected more than 8,300 surveys of epiphytic lichen communities, providing a baseline for tracking lichen responses to air quality, climate, and other changes on forest land in the United States. This national atlas of lichen species combines these datasets into distribution maps for more than 400 taxa and 6,000 forested locations across the country. All 115,500 lichen records presented in the maps link to voucher specimens, most of which can be accessed from herbaria. Unlike mapped herbarium records, most surveys were collected on a...

A description of major biotic and abiotic features within the North Fork Hunter Creek and Hunter Creek Bog areas of critical environmental concern in southwestern Oregon. Extensive lists of vascular plants, fungi, lichens, bryophytes, and wildlife species known or likely to occur are provided in appendices. This guidebook is part of a continuing series of guidebooks on federal research natural areas that began in 1972.