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Historically, drought has been viewed in terms of its agricultural, hydrological, and socioeconomic impacts. How drought affects ecosystems - and the services they provide human communities - is often not discussed. In response, the U.S. Geological Survey's National Climate Adaptation Science Center (NCASC) initiated a national-scale effort that’s addressing this gap in drought research. A new concept – ecological drought – was defined as part of this effort. This geo-narrative explains the concept of ecological drought, and highlights the research and products that were initiated as part of this effort.
Abstract (from http://journals.ametsoc.org/doi/abs/10.1175/WCAS-D-15-0042.1): Drought is a natural part of the historical climate variability in the northern Rocky Mountains and high plains region of the United States. However, recent drought impacts and climate change projections have increased the need for a systematized way to document and understand drought in a manner that is meaningful to public land and resource managers. The purpose of this exploratory study was to characterize the ways in which some federal and tribal natural resource managers experienced and dealt with drought on lands managed by the U.S. Department of the Interior (DOI) and tribes in two case site examples (northwest Colorado and southwest...
The Wind River Indian Reservation (WRIR) in west-central Wyoming is home to the Eastern Shoshone and Northern Arapaho tribes, who reside near and depend on water from the streams that feed into Wind River. In recent years, however, the region has experienced frequent severe droughts, which have affected tribal livelihoods and cultural activities. Scientists with the North Central Climate Adaptation Science Center (NCCASC) at Colorado State University, the National Drought Mitigation Center (NDMC) at the University of Nebraska-Lincoln, and several other university and agency partners in the region worked in close partnership with tribal water managers to assess how drought affects the reservation, which included...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.12847/full): Climate models predict increasing drought intensity and frequency for many regions, which may have negative consequences for tree recruitment, growth and mortality, as well as forest ecosystem services. Furthermore, practical strategies for minimizing vulnerability to drought are limited. Tree population density, a metric of tree abundance in a given area, is a primary driver of competitive intensity among trees, which influences tree growth and mortality. Manipulating tree population density may be a mechanism for moderating drought-induced stress and growth reductions, although the relationship between tree population density and...
This 2-pager describes the Evaporative Demand Drought Index (EDDI), which is a drought index that can serve as an indicator of both rapidly evolving “flash” droughts (developing over a few weeks) and sustained droughts (developing over months but lasting up to years).
Abstract (from AGU100): Forest conservation and carbon sequestration efforts are on the rise, yet the long‐term stability of these efforts under a changing climate remains unknown. We generate nearly three decades of remotely sensed canopy water content throughout California, which we use to determine patterns of drought stress. Linking these patterns of drought stress with meteorological variables enables us to quantify spatially explicit biophysical drought resistance in terms of magnitude and duration. These maps reveal significant spatial heterogeneity in drought resistance and demonstrate that almost all forests have less resistance to severe, persistent droughts. By identifying the spatial patterning of biophysical...
The responses of individual species to environmental changes can be manifested at multiple levels that range from individual-level (i.e., behavioral responses) to population-level (i.e., demographic) impacts. Major environmental changes that ultimately result in population level impacts are often first detected as individual-level responses. For example, herbivores respond to limited forage availability during drought periods by increasing the duration of foraging periods and expanding home range areas to compensate for the reduction in forage. However, if the individual-level responses are not sufficient to compensate for reduced forage availability, reduced survival and reproductive rates may result. We studied...
The responses of individual species to environmental changes can be manifested at multiple levels that range from individual-level (i.e., behavioral responses) to population-level (i.e., demographic) impacts. Major environmental changes that ultimately result in population level impacts are often first detected as individual-level responses. For example, herbivores respond to limited forage availability during drought periods by increasing the duration of foraging periods and expanding home range areas to compensate for the reduction in forage. However, if the individual-level responses are not sufficient to compensate for reduced forage availability, reduced survival and reproductive rates may result. We studied...
Abstract (from http://journals.ametsoc.org/doi/abs/10.1175/JAMC-D-15-0167.1): Annual precipitation in California is more variable than in any other state and is highly influenced by precipitation in winter months. A primary question among stakeholders is whether low precipitation in certain months is a harbinger of annual drought in California. Historical precipitation data from 1895 to 2013 are investigated to identify leading monthly indicators of annual drought in each of the seven climate divisions (CDs) as well as statewide. For this study, drought conditions are defined as monthly/annual (October–September) precipitation below the 20th/30th percentile, and a leading indicator is defined as a monthly drought...
Severe droughts cause widespread tree mortality and decreased growth in forests across the globe. Forest managers are seeking strategies to increase forest resistance (minimizing negative impacts during the drought) and resilience (maximizing recovery rates following drought). Limited experimental evidence suggests that forests with particular structural characteristics have greater capacity to resist change and or recover ecosystem function in the face of drought. However, the applicability of these results to practical forest conservation and management remains unclear. This project utilized an existing network of eight long-term, operational-scale, forest management experiments from Arizona to Maine to examine...
Drought is a common occurrence in Nebraska and agriculture is the primary economic sector affected. Because of repeated and widespread severe drought impacts, more emphasis on drought risk management is warranted. This study develops an agricultural drought risk assessment model using multivariate techniques. The model is specific to corn and soybeans and is able to assess real-time agricultural drought risk associated with crop yield losses at critical phenological stages prior to and during the growing season. The assessment results are presented in a Geographic Information System to provide a better visualization. This model provides information in a timely manner about potential agricultural drought risks on...
Social factors, such as farming methods, have an impact on farm vulnerability to drought, but have received little research or policy attention. Some researchers and advocates have argued that sustainable agriculture systems are less vulnerable to climate risk than conventional systems because sustainable agriculture requires producers to have skills promoting adaptability. In this paper, we investigate producers' perceptions on the use of sustainable agriculture in reducing drought risk, and what they believe would help them better adapt to drought. We surveyed and interviewed farmer members of two sustainable agriculture organizations in Nebraska, USA, during a multi-year drought period from 1999 to 2007. Producers...
Categories: Publication; Types: Citation; Tags: Northeast CASC, Other Landscapes
This management brief summarizes the results of a project evaluating the scientific body of research on climate adaptation actions relevant to ecological drought. This adaptation science assessment evaluated strategies developed and prioritized by participants at regional adaptation workshops by synthesizing supporting evidence from the literature. The brief presents findings on the benefits and limitations of these climate adaptation options from the accompanying report, Extremes to Ex-Streams: Ecological Drought Adaptation in a Changing Climate.
Abstract (from PNAS): Recent decades have seen droughts across multiple US river basins that are unprecedented over the last century and potentially longer. Understanding the drivers of drought in a long-term context requires extending instrumental data with paleoclimatic data. Here, a network of new millennial-length streamflow reconstructions and a regional temperature reconstruction from tree rings place 20th and early 21st century drought severity in the Upper Missouri River basin into a long-term context. Across the headwaters of the United States’ largest river basin, we estimated region-wide, decadal-scale drought severity during the “turn-of-the-century drought” ca. 2000 to 2010 was potentially unprecedented...
Drought is a signifcant climate feature in Hawai‘i and the U.S.-Affliated Pacifc Islands (USAPI), at times causing severe impacts across multiple sectors. Below-average precipitation anomalies are often accompanied by higher-than-average temperatures and reduced cloud cover. The resulting higher insolation and evapotranspiration can exacerbate the effects of reduced rainfall. These altered meteorological conditions lead to less soil moisture. Depending on the persistence and severity of the conditions, drier soil can cause plant stress, affecting both agricultural and natural systems. Hydrological effects of drought include reductions in streamfow, groundwater recharge, and groundwater discharge to springs, streams,...
Abstract (from AGU): The prolonged 2012–2016 California drought has raised many issues including concerns over reduced vegetation health. Drought impacts are complicated by geographical differences in hydroclimatic variability due to a climatic dipole influenced by the Pacific. Analysis of MODIS‐derived Normalized Difference Vegetation Index and self‐calibrated Palmer Drought Severity Index from 2000 to 2018 reveals differences in drought and vegetation responses in Northern versus Southern California (NorCal vs SoCal, see definition in section 2.1). The greatest declines in Normalized Difference Vegetation Index were focused in the SoCal, while NorCal appears not severely affected thus far. It appears that both...
This paper investigates the impact of climate change on drought by addressing two questions: (1) How reliable is the assessment of climate change impact on drought based on state-of-the-art climate change projections and downscaling techniques? and (2) Will the impact be at the same level from meteorological, agricultural, and hydrologic perspectives? Regional climate change projections based on dynamical downscaling through regional climate models (RCMs) are used to assess drought frequency, intensity, and duration, and the impact propagation from meteorological to agricultural to hydrological systems. The impact on a meteorological drought index (standardized precipitation index, SPI) is first assessed on the...
Categories: Publication; Types: Citation; Tags: Northeast CASC, Other Landscapes