Forest Inventory and Analysis (FIA) data provides robust information for the United States Forest Service's (USFS) mid-to-broad-scale planning and assessments, but ecological challenges (i.e., climate change, wildfire) necessitate increasingly strategic information without significantly increasing field sampling. Small area estimation (SAE) techniques could provide more precision supported by a rapidly growing suite of landscape-scale datasets. We present three Regional case studies demonstrating current FIA uses, how SAE techniques could enhance existing uses, and steps FIA could take to enable SAE applications that are user-friendly, comprehensive, and statistically appropriate. The Northern Region uses FIA data for planning and assessments, but SAE techniques could provide more specificity to guide vegetation management activities. State and transition simulation models (STSM) are run with FIA data in the Southwestern Region to predict effects of treatments and disturbances, but SAE could support model validation and more precision to identify treatable areas. The Southern Region used FIA to identify existing longleaf pine stands and evaluate condition, but SAE techniques within FIA tools would streamline analyses. Each case study demonstrates a desire to have FIA data on non-forested conditions and non-tree variables. Additional tools to measure statistical confidence would help maximize utility. FIA's SAE techniques could add value to a widely used data set, if FIA can support key supplements to basic data and functionality.

Although many forestry practitioners have a general understanding of the Forest Inventory and Analysis (FIA) program and the type of data collected, most non-expert users of FIA reports and basic data are unlikely to be familiar with the breadth of information available and the many potential uses of the data. We present case studies from three USDA Forest Service regions to highlight a variety of applications of FIA data, from informing the forest plan revision process to supplying managers with timely information on important forest attributes at the stand and landscape scales. These examples illustrate the utility of FIA data in meeting managers' information needs, the importance of the linkages between research and management throughout the agency, and the role that the FIA program can play in fostering those collaborations.

The USDA Forest Service has many national level policies related to multiple use management. However, translating national policy to stand level forest management can be difficult. As an example of how a national policy can be put into action, we examined three case studies in which a desired future condition is evaluated at the national, region, and local scale. We chose to use carbon sequestration as the desired future condition because climate change has become a major area of concern during the last decade. Several studies have determined that the 193 million acres of US national forest land currently sequester 11 to 15% of the total carbon emitted as a nation. This paper provides a framework by which national scale strategies for maintaining or enhancing forest carbon sequestration is translated through regional considerations and local constraints in adaptive management practices. Although this framework used the carbon sequestration as a case study, this framework could be used with other national level priorities such as the National Environmental Protection Act (NEPA) or the Endangered Species Act (ESA).

The USDA Forest Service hosted a two-day drought adaptation workshop in Atlanta, Georgia in January 2017 to share state-of-science information on drought and climate effects in the region and to develop management response strategies. The workshop was attended by regional experts from the Forest Service Southern Region, Southern Research Station, and Office of Sustainability and Climate; the USDA Southeast Regional Climate Hub; and state and federal climate offices. They met to address challenges, cultivate opportunities, and develop and expand the collective understanding of the most effective management strategies to adapt to and mitigate the effects of drought in the region. The workshop focused on the effects of, and management responses to drought in forest, riparian, and aquatic ecosystems. This fact sheet is a synopsis of the workshop.

The area of planted pine in the southern U.S. is predicted to increase by over 70% by 2060, potentially altering the natural hydrologic cycle and water balance at multiple scales. To better account for potential shifts in water yield, land managers and resource planners must accurately quantify water budgets from the stand to the regional scale. The amount of precipitation as rainfall intercepted by forest canopies is an important component of evapotranspiration in forested ecosystems, yet there is little information about intra-and inter-annual canopy interception variability in southern pine plantations. To address this knowledge gap, canopy rainfall interception was measured between 2005 and 2014 in a North Carolina coastal plain loblolly pine (Pinus taeda L.) plantation to quantify the range of annual and seasonal variability in interception rates (IRs) as influenced by stand thinning and natural variation in rainfall rates and intensities. Over the study period, biweekly measured canopy IRs averaged 19% across all years, with a range of 14% to 23%. However, at the annual scale, IRs averaged 12% and ranged from 2% to 17%. Thinning resulted in a 5% decrease in rainfall interception, but IRs quickly returned to pre-thin levels. Across years, the amount of annual rainfall intercepted by the canopy averaged 15% of total evapotranspiration, with a range of 2% to 24%. The decade-long data indicate that inter-annual variability of canopy interception is higher than reported in short-term studies. Local and regional hydrological models must describe the variability of canopy interception to accurately predict the hydrologic impacts of forest management and climate change.

Climate-related variability in rainfall, temperature, and extreme weather (e.g., drought, flood, unseasonal frost) pose significant challenges to working land (i.e., range, forest, and agricultural) managers across the southeastern United States. This document outlines the type of risks that southeastern agriculture and forestry currently face and, in some cases, options to address these risks. Finally, this document looks forward to providing direction on the priority needs of Southeast working land managers and an outline of how the USDA Southeast Climate Hub will address those needs.

Our objectives are (1) to compare tree sap flux density (J(s) in g cm(-2) d(-1)) and stomatal conductance (G(s) in mmol m(-2) s(-1)) across five dominant species, red maple (Acer rubrum), sweetgum (Liquidambar styraciflua), tulip poplar (Liriodendron tulipifera), loblolly pine (Pinus taeda), and oak species (Quercus spp.), (2) to quantity riparian buffer stand transpiration (E-s in mm d(-1)), and (3) to link riparian buffer E-s of residual trees to stream discharge. In June 2010, the above species were instrumented with sap flow sensors in a pair (HF1 and HF2) of 12 hectare gauged watersheds. HF1 was clearcut, leaving a 15.2-m riparian buffer around the stream, and HF2 was the reference. Trees were harvested in the riparian buffer reducing HF1 riparian buffer basal area by 27%. The riparian buffer growing season net radiation increased from 11.9 W m(-2) preharvest to an average of 24.3 W m(-2) postharvest. HF1 stream growing season discharge increased dramatically (150%) from the preharvest to postharvest period. HF1 2010 preharvest growing season soil moisture was 22.5%. HF1 postharvest growing season soil moisture was 28.5% in 2011, 26.5% in 2012, and 27.2% in 2013. HF2 canopy cover, energy input, and soil moisture showed little change over the same period. From preharvest to postharvest, mean daily growing season J(s) of trees in HF1 increased in all species. A reduction in HF1 Gs was less evident over the study vapour pressure deficit range in loblolly pine, red maple, and tulip poplar than in oak and sweetgum during the postharvest period. HF1 residual trees in the riparian buffer used 43% more water in growing season postharvest (314 mm) than growing preharvest (220 mm) period. This resulted in an 8% reduction in stream discharge because of an increase in riparian buffer E-s. Although clearcutting increased stream discharge, we conclude that the increase in transpiration by the residual trees in the riparian buffer will, at least, partially mitigate the hydrologic effects of forest removal through increased transpiration. Copyright (C) 2015 John Wiley & Sons, Ltd.

Forestlands across the world are experiencing increased threats from fire, insect and plant invasions, disease, extreme weather, and drought. Scientists project increases in temperature and changes in rainfall patterns that can make these threats occur more often, with more intensity, and/or for longer durations. Although many of the effects of future changes are negative, natural resource management can help mitigate these impacts. Management strategies informed by the best current science enable natural resource professionals within the Forest Service to better protect the land and resources and conserve the region's forestlands into the future. Climate Trends – Average temperatures in El Yunque have increased over the past 30 years, and scientists predict warming will continue at an accelerated pace, however, climate models vary in the degree of warming. Projected decreases in precipitation in the Caribbean suggest drier wet seasons, and even drier dry seasons. Increasing sea surface temperatures may lift the base altitude of cloud formation and alter atmospheric circulation patterns. Any change in the cloud base height will further decrease precipitation in El Yunque. Extreme Weather – In the Caribbean, the occurrence of very warm days and nights is accelerating, while very cool days and nights are becoming less common, increasing the likelihood of extreme heat waves. The frequency of extreme precipitation events is expected to increase, leading to potential increases in inland flooding and landslides. Hurricane events are likely to become less frequent but more severe, with increased wind speeds, rainfall intensity, and storm surge height. As annual rainfall decreases over time in the Caribbean region, longer periods of drought are expected in the future. In Puerto Rico, where nearly all wildfires are associated with human activity, the interactions between climate warming and drying and increased human development have the potential to increase the effects of fire. Biological Diversity – Plants and animals at risk will respond to environmental changes by adapting, moving, or declining. Species with high genetic variation will be better able to survive in new conditions. Higher temperatures will cause many species to shift ranges up in elevation. However, in some cases, the rate of warming combined with land use changes will restrict the ability of plants and animals to move into suitable habitat. Highland species with restricted habitats and are more likely to be negatively impacted by climate change than are lower elevation species. In montane cloud forests in El Yunque, narrow thermal ranges may …

Increasing variability of rainfall patterns requires detailed understanding of the pathways of water loss from ecosystems to optimize carbon uptake and management choices. In the current study we characterized the usability of three alternative methods of different rigor for quantifying stand-level evapotranspiration (ET), partitioned ET into tree transpiration (T), understory transpiration, interception, and soil evaporation (E-S) and determined their sensitivity to drought, and evaluated the reliability of soil moisture measurements by taking into account deep soil moisture dynamic. The analyses were conducted in an early- and in a mid-rotation stand of loblolly pine, the predominant species of southern US forest plantations. The three alternative methods for estimating ET were the eddy covariance measurements of water vapor fluxes (ETEC), the water table fluctuation (ETWT), and the soil moisture fluctuation (ETSM). On annual and monthly scales, the three methods agreed to within 10-20%, whereas on a daily scale, the values of ETSM and ETEC differed by up to 50% and ETSM and ETWT differed by up to 100%. The differences between the methods were attributed to root water extraction below measurement depth and to the sampling at different spatial scales. Regardless of the method used, ET at the early-rotation site was 15-30% lower than that at the mid-rotation site. The dry years did not affect ET at the mid-rotation site but reduced significantly ET at the early-rotation site. Soil moisture trends revealed the importance of measuring water content at several depths throughout the rooting zone because less than 20% of the water is stored in the top 30 cm of soil. Annually, Es represented approximately 9 and 14% of ETEC at the mid-rotation site and the early-rotation site, respectively. At the mid-rotation site, T accounted for approximately 70% of ETEC. Canopy interception was estimated to be 5-10% of annual precipitation and 6-13% of total ETEC. At the early-rotation site, T accounted for only 35% of ETEC. At this site, transpiration from subdominant trees and shrubs represented 40-45% of ETEC, indicating that understory was a significant part of the water budget. We concluded that the eddy covariance method is best for estimating ET at the fine temporal scale (i.e., daily), but other soil moisture and water table-based methods were equally reliable and cost-effective for quantifying seasonal ET dynamics. FOR. SCI. 58(5):497-512.

Deep root water uptake and hydraulic redistribution (HR) have been shown to play a major role in forest ecosystems during drought, but little is known about the impact of climate change, fertilization and soil characteristics on HR and its consequences on water and carbon fluxes. Using data from three mid-rotation loblolly pine plantations, and simulations with the process-based model MuSICA, this study indicated that HR can mitigate the effects of soil drying and had important implications for carbon uptake potential and net ecosystem exchange (NEE), especially when N fertilization is considered. At the coastal site (C), characterized by deep organic soil, HR increased dry season tree transpiration (T) by up to 40%, and such an increase affected NEE through major changes in gross primary productivity (GPP). Deep-rooted trees did not necessarily translate into a large volume of HR unless soil texture allowed large water potential gradients to occur, as was the case at the sandy site (S). At the Piedmont site (P) characterized by a shallow clay-loam soil, HR was low but not negligible, representing up to 10% of T. In the absence of HR, it was predicted that at the C, S and P sites, annual GPP would have been diminished by 19, 7 and 9%, respectively. Under future climate conditions HR was predicted to be reduced by up to 25% at the C site, reducing the resilience of trees to precipitation deficits. The effect of HR on T and GPP was predicted to diminish under future conditions by 12 and 6% at the C and P sites, respectively. Under future conditions, T was predicted to stay the same at the P site, but to be marginally reduced at the C site and slightly increased at the S site. Future conditions and N fertilization would decrease T by 25% at the C site, by 15% at the P site and by 8% at the S site. At the C and S sites, GPP was estimated to increase by 18% and by >70% under future conditions, respectively, with little effect of N fertilization. At the P site, future conditions would stimulate GPP by only 12%, but future conditions plus N fertilization would increase GPP by 24%. As a consequence, in all sites, water use efficiency was predicted to improve dramatically with future conditions. Modeling the effect of reduced annual precipitation indicated that limited water availability would decrease all carbon fluxes, including NEE and respiration. Our simulations highlight the interactive effects of nutrients and elevated CO(2), and showed that the effect of N fertilization would be greater under future climate conditions.

[1] We developed a water-centric monthly scale simulation model (WaSSI-C) by integrating empirical water and carbon flux measurements from the FLUXNET network and an existing water supply and demand accounting model (WaSSI). The WaSSI-C model was evaluated with basin-scale evapotranspiration (ET), gross ecosystem productivity (GEP), and net ecosystem exchange (NEE) estimates by multiple independent methods across 2103 eight-digit Hydrologic Unit Code watersheds in the conterminous United States from 2001 to 2006. Our results indicate that WaSSI-C captured the spatial and temporal variability and the effects of large droughts on key ecosystem fluxes. Our modeled mean (+/- standard deviation in space) ET (556 +/- 228 mm yr(-1)) compared well to Moderate Resolution Imaging Spectroradiometer (MODIS) based (527 +/- 251 mm yr(-1)) and watershed water balance based ET (571 +/- 242 mm yr(-1)). Our mean annual GEP estimates (1362 +/- 688 g C m(-2) yr(-1)) compared well (R-2 = 0.83) to estimates (1194 +/- 649 g C m(-2) yr(-1)) by eddy flux-based EC-MOD model, but both methods led significantly higher (25-30%) values than the standard MODIS product (904 +/- 467 g C m(-2) yr(-1)). Among the 18 water resource regions, the southeast ranked the highest in terms of its water yield and carbon sequestration capacity. When all ecosystems were considered, the mean NEE (-353 +/- 298 g C m(-2) yr(-1)) predicted by this study was 60% higher than EC-MOD's estimate (-220 +/- 225 g C m(-2) yr(-1)) in absolute magnitude, suggesting overall high uncertainty in quantifying NEE at a large scale. Our water-centric model offers a new tool for examining the trade-offs between regional water and carbon resources under a changing environment.

*Hydraulic redistribution (HR) of water via roots from moist to drier portions of the soil occurs in many ecosystems, potentially influencing both water use and carbon assimilation. *By measuring soil water content, sap flow and eddy covariance, we investigated the temporal variability of HR in a loblolly pine (Pinus taeda) plantation during months of normal and below-normal precipitation, and examined its effects on tree transpiration, ecosystem water use and carbon exchange. *The occurrence of HR was explained by courses of reverse flow through roots. As the drought progressed, HR maintained soil moisture above 0.15 cm(3) cm(-3) and increased transpiration by 30-50%. HR accounted for 15-25% of measured total site water depletion seasonally, peaking at 1.05 mm d(-1). The understory species depended on water redistributed by the deep-rooted overstory pine trees for their early summer water supply. Modeling carbon flux showed that in the absence of HR, gross ecosystem productivity and net ecosystem exchange could be reduced by 750 and 400 g C m(-2) yr(-1), respectively. *Hydraulic redistribution mitigated the effects of soil drying on understory and stand evapotranspiration and had important implications for net primary productivity by maintaining this whole ecosystem as a carbon sink.