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Displaying 12,401 - 12,410 of 65,176 Publications- Remote sensing data have increasingly been employed in combination with field plot data to estimate aboveground carbon (C) stocks across heterogeneous forested landscapes around the world. The Forest Inventory and Analysis (FIA) program of the US Forest Service offers a gridded network of field plots which potentially can be linked to airborne Light Detection and Ranging (LiDAR) data to estimate forest aboveground carbon density (ACD; units of Mg C ha−1). Here we utilized FIA plot and airborne LiDAR data sets collected across two contrasting landscapes known as Laupahoehoe and Pu‘u...AuthorsFlint F. Hughes, Gregory P. Asner, Jim Baldwin, Joseph Mascaro, Lori Bufil, David E. KnappKeywordsSourceForest Ecology and Management. 424: 323-337Year2018
- Solar-induced chlorophyll fluorescence (SIF) has been increasingly used as a proxy for terrestrial gross primary productivity (GPP). Previous work mainly evaluated the relationship between satellite-observed SIF and gridded GPP products both based on coarse spatial resolutions. Finer resolution SIF (1.3 km × 2.25 km) measured from the Orbiting Carbon Observatory-2 (OCO-2) provides the first opportunity to examine the SIF–GPP relationship at the ecosystem scale using flux tower GPP data. However, it remains unclear how strong the relationship is for each biome and whether a robust, universal...AuthorsXing Li, Jingfeng Xiao, Binbin He, M. Altaf Arain, Jason Beringer, Ankur R. Desai, Carmen Emmel, David Hollinger, Alisa Krasnova, Ivan Mammarella, Steffen M. Noe, Penélope Serrano Ortiz, A. Camilo Rey-Sanchez, Adrian V Rocha, Andrej VarlaginKeywordsSourceGlobal Change BiologyYear2018
- The large, highly glacierized Copper River basin is an important water resource for the south-central region of Alaska. Thus, information is needed on the reaction of its hydrologic timing and streamflow volumes to historical changes in climate, in order to assess the possible impact of future changes. However, the basin is remote, and therefore, it has proved difficult to collect field data in a frequent temporal and spatial manner. An extension of the distributed-parameter, physical-process code Precipitation Runoff Modeling System, PRMSglacier, has been specifically developed to...AuthorsAshley Van Beusekom, Roland J. VigerKeywordsSourceWater Resources ResearchYear2018
- Changing climate will impact species’ ranges only when environmental variability directly impacts the demography of local populations. However, measurement of demographic responses to climate change has largely been limited to single species and locations. Here we show that amphibian communities are responsive to climatic variability, using >500,000 time-series observations for 81 species across 86 North American study areas. The effect of climate on local colonization and persistence probabilities varies among eco-regions and depends on local climate, species life-histories, and taxonomic...AuthorsDavid A. W. Miller, Evan H. Campbell Grant, Erin Muths, Staci M. Amburgey, Michael J. Adams, Maxwell B. Joseph, J. Hardin Waddle, Pieter T. J. Johnson, Maureen E. Ryan, Benedikt R. Schmidt, Daniel L. Calhoun, Courtney L. Davis, Robert N. Fisher, David M. Green, Blake R. Hossack, Tracy A. G. Rittenhouse, Susan C. Walls, Larissa L. Bailey, Sam S. Cruickshank, Gary M. Fellers, Thomas A. Gorman, Carola A. Haas, Ward Hughson, David S. Pilliod, Steven J. Price, Andrew M. Ray, Walt Sadinski, Daniel Saenz, William J. Barichivich, Adrianne Brand, Cheryl S. Brehme, Rosi Dagit, Katy S. Delaney, Brad M. Glorioso, Lee B. Kats, Patrick M. Kleeman, Christopher A. Pearl, Carlton J. Rochester, Seth P. D. Riley, Mark Roth, Brent H. SigafusKeywordsSourceNature CommunicationsYear2018
- The Luquillo Mountains of eastern Puerto Rico are home to the only tropical rainforest managed by the United States Forest Service, with cloud-immersed forests historically occupying the highest elevations. However, within the past 50 yr, studies of the Luquillo cloud forest have suggested an increase in cloud base heights (CBH), although the CBH in the area was not quantified until recently. The present work uses radiosonde observations from nearby San Juan, Puerto Rico, to contextualize the present-day CBH within a 42 yr (1975−2016) proxy record and determine evidence for rising cloud...AuthorsPaul W. Miller, Thomas L. Mote, Craig A. Ramseyer, Ashley Van Beusekom, Martha Scholl, Grizelle GonzalezKeywordsSourceClimate ResearchYear2018
- Amazon forests have experienced frequent and severe droughts in the past two decades. However, little is known about the large-scale legacy of droughts on carbon stocks and dynamics of forests. Using systematic sampling of forest structure measured by LiDAR waveforms from 2003 to 2008, here we show a significant loss of carbon over the entire Amazon basin at a rate of 0.3 ± 0.2 (95% CI) PgC yr−1 after the 2005 mega-drought, which continued persistently over the next 3 years (2005–2008). The changes in forest structure, captured by average LiDAR forest height and converted to above ground...AuthorsYan Yang, Sassan S. Saatchi, Liang Xu, Yifan Yu, Sungho Choi, Nathan Phillips, Robert Kennedy, Michael Keller, Yuri Knyazikhin, Ranga B. MyneniKeywordsSourceNature CommunicationsYear2018
Quantifying climate-growth relationships at the stand level in a mature mixed-species conifer forest
A range of environmental factors regulate tree growth; however, climate is generally thought to most strongly influence year-to-year variability in growth. Numerous dendrochronological (tree-ring) studies have identified climate factors that influence year-to-year variability in growth for given tree species and location. However, traditional dendrochronology methods have limitations that prevent them from adequately assessing stand-level (as opposed to species-level) growth. We argue that stand-level growth analyses provide a more meaningful assessment of forest response to climate...AuthorsAaron Teets, Shawn Fraver, Aaron R. Weiskittel, David HollingerKeywordsSourceGlobal Change BiologyYear2018- Heterotrophic respiration (Rh), microbial processing of soil organic matter to carbon dioxide (CO2), is a major, yet highly uncertain, carbon (C) flux from terrestrial systems to the atmosphere. Temperature sensitivity of Rh is often represented with a simple Q10 function in ecosystem models and earth system models (ESMs), sometimes accompanied by an empirical soil moisture modifier. More explicit representation of the effects of soil moisture, substrate supply, and their interactions with temperature has been proposed as a way to disentangle the confounding factors of apparent temperature...AuthorsDebjani Sihi, Eric A. Davidson, Min Chen, Kathleen E. Savage, Andrew D. Richardson, Trevor F. Keenan, David HollingerKeywordsSourceAgricultural and Forest MeteorologyYear2018
- Cerrado is the second largest biome in South America and accounted for the second largest contribution to carbon emissions in Brazil for the last 10 years, mainly due to land-use changes. It comprises approximately 2 million km2 and is divided into 22 ecoregions, based on environmental conditions and vegetation. The most dominant vegetation type is cerrado sensu stricto (cerrado ss), a savanna woodland. Quantifying variation of biomass density of this vegetation is crucial for climate change mitigation policies. Integrating remote sensing data with adequate allometric equations and...AuthorsIris Roitman, Mercedes M. C. Bustamante, Ricardo F. Haidar, Julia Z. Shimbo, Guilherme C. Abdala, George Eiten, Christopher W. Fagg, Maria Cristina Felfili, Jeanine Maria Felfili, Tamiel K. B. Jacobson, Galiana S. Lindoso, Michael Keller, Eddie Lenza, Sabrina C. Miranda, José Roberto R. Pinto, Ariane A. Rodrigues, Wellington B. C. Delitti, Pedro Roitman, Jhames M. SampaioKeywordsSourcePLOS ONEYear2018
- Stabilization of SOM (soil organic matter) is regulated in part by sorption and desorption reactions happening at mineral surfaces, as well as precipitation and dissolution of organo-metal complexes. Fe and Al hydroxides play a particularly significant role in SOM stabilization in soils due to their ubiquitous distribution and their highly reactive surface properties. Iron and Al hydroxides exist in soils across a wide spectrum of crystallinity, ranging from dissolved Fe and Al cations which combine with organics to form organo-metal precipitates to the more crystalline end members,...AuthorsKatherine A. Heckman, Corey R. Lawrence, Jennifer W. HardenSourceGeodermaYear2018