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...

This document presents forest ecosystem carbon yield tables, representing stand-level merchantable volume and carbon stocks as a function of stand age, for 53 forest types within 11 regions of the United States. These tables are an update from previous forest carbon stock estimates and were developed in support of U.S. Department of Agriculture greenhouse gas estimation guidelines for agriculture and forestry. The uncertainty of results obtained with these methods may be high relative to other techniques that use site- or project-specific data. The estimates presented here nonetheless...

To properly evaluate the reliability of lumber structures, good models for the strength distributions of their components are needed. Modulus of rupture (MOR) distributions of grades of structural lumber have often been modeled as two-parameter Weibulls. However, in a series of papers, Verrill and others have established that strength properties of visual and machine stress rated grades of lumber are not distributed as two-parameter Weibulls and that modeling them as two-parameter Weibulls can yield large over- or underestimates of probabilities of breakage. Instead, grades of lumber have...

A critical load (CL) is a science-based threshold that identifies the amount of pollutant deposition below which no significant ecological harm to an ecosystem component is expected. This report provides baseline critical load (CL) analyses for nitrogen (N) and sulfur (S) as required under the 2012 Planning Rule for forest plan assessments. The data also can be used to inform land management decisions where the effects of N and S deposition are relevant, including the evaluation of large projects through the National Environmental Policy Act, Prevention of Significant Deterioration (PSD)...

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...