Supervisory Research Ecologist
Email:
sperakis@usgs.gov
Office Phone:
541-750-0991
Fax:
541-758-7761
ORCID:
0000-0003-0703-9314
Location
3200 S.W. Jefferson Way
Corvallis
, OR
97331
US
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Abstract Atmospheric deposition of nitrogen (N) influences forest demographics and carbon (C) uptake through multiple mechanisms that vary among tree species. Prior studies have estimated the effects of atmospheric N deposition on temperate forests by leveraging forest inventory measurements across regional gradients in deposition. However, in the United States (U.S.), these previous studies were limited in the number of species and the spatial scale of analysis, and did not include sulfur (S) deposition as a potential covariate. Here, we present a comprehensive analysis of how tree growth and survival for 71 species vary with N and S deposition across the conterminous U.S. Our analysis of 1,423,455 trees from forest...
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Comma-separated values (.csv) files containing data related to plant biomass and seed production responses of invasive Bromus tectorum (cheatgrass) and Taeniatherum caput-medusae (medusahead) to varying sucrose treatments.
Categories: Data;
Tags: Botany,
Ecology,
Land Use Change,
Snake River Plain,
USGS Science Data Catalog (SDC), All tags...
carbon,
eastern Oregon,
environment,
northern Great Basin,
plants (organisms),
western Idaho, Fewer tags
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Nitrogen deposition is altering forest dynamics, terrestrial carbon storage, and biodiversity. However, our ability to forecast how different tree species will respond to N deposition, especially key response thresholds, is limited by a lack of synthesis across spatial scales and research approaches. To develop our best understanding of N deposition impact on tree growth and survival, we will integrate plot-‐ level studies describing plant growth and survival responses to N inputs and plant-‐ available soil nutrients with a continental scale analysis across a N deposition gradient. Our primary outcome will be estimates of tree response to N deposition with explicit representation of uncertainty and the identification...
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Biological nitrogen fixation (BNF) is a critical biogeochemical process that converts inert atmospheric N2 gas into biologically usable forms of the essential nutrient nitrogen. A variety of free-living and symbiotic organisms carry out BNF, and in most regions worldwide, BNF is the largest source of nitrogen that fuels terrestrial ecosystems. As a result, BNF has far reaching effects on ecosystem properties (water quality, carbon storage), sustainability (plant growth, soil fertility), and the global climate system. Despite this cross-cutting importance, existing syntheses of BNF have major gaps, with particular challenges in upscaling local measurements across large areas. These gaps, and a corresponding lack...
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This data release includes metadata and tabular data that document estimates of litterfall, koa moth (Scotorythra paludicola) caterpillar frass production, soil nutrients, and foliar nutrients during 2013-2014 at Hakalau Forest National Wildlife Refuge. During this time, there was a massive defoliation event of Acacia koa (koa) trees by the koa moth. We monitored these metrics in 4 sites that varied in forest structure and composition at Hakalau. We used litter traps to monitor koa litter fall over time and foliar %N to estimate N inputs from litter. We used caterpillar counts, koa canopy estimates, frass production rates, and frass %N to estimate N inputs from frass on the landscape. We used resin bags under koa...
Tags: Ecology,
Hakalau Forest National Wildlife Refuge,
Hawaii Island,
USGS Science Data Catalog (SDC),
biota, All tags...
defoliation,
foliar nutrients,
frass,
insect outbreak,
litter fall,
nutrient pulse,
soil nitrogen,
soil phosphorus, Fewer tags
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