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Aim: As climate change increases the frequency and severity of droughts in many regions, conservation during drought is becoming a major challenge for ecologists. Droughts are multidimensional climate events whose impacts may be moderated by changes in temperature, water availability or food availability, or some combination of these. Simultaneously, other stressors such as extensive anthropogenic landscape modification may synergize with drought. Useful observational models for guiding conservation decision‐making during drought require multidimensional, dynamic representations to disentangle possible drought impacts, and consequently, they will require large, highly resolved data sets. In this paper, we develop a two‐stage predictive framework for assessing how drought impacts vary with species, habitats and climate pathways. Location: Central Valley, California, USA. Methods: We used a two‐stage counterfactual analysis combining predictive linear mixed models and N‐mixture models to characterize the multidimensional impacts of drought on 66 bird species. We analysed counts from the eBird participatory science data set between 2010 and 2019 and produced species‐ and habitat‐specific estimates of the impact of drought on relative abundance. Results: We found that while fewer than a quarter (16/66) of species experienced abundance declines during drought, nearly half of all species (27/66) changed their habitat associations during drought. Among species that shifted their habitat associations, the use of natural habitats declined during drought while use of developed habitat and perennial agricultural habitat increased. Main Conclusions: Our findings suggest that birds take advantage of agricultural and developed land with artificial irrigation and heat‐buffering microhabitat structure, such as in orchards or parks, to buffer drought impacts. A working lands approach that promotes biodiversity and mitigates stressors across a human‐induced water gradient will be critical for conserving birds during drought. [ABSTRACT FROM AUTHOR]

Adverse climate changes in Pakistan undermine the water resources and give rise to transient and permanent droughts in different parts of the country. The occurrence of drought cannot be prevented, but its detrimental impacts can be brought down by proper pre‐drought planning. Effective planning owes to using scientific and probabilistic approaches. In this paper, the interarrival time of drought for seven operational drought indices in Pakistan is modelled by using the modified distribution of convolution derived from the Bivariate Affine Linear Exponential (BALE) distribution. A new stochastic variable, interarrival time of drought, is generated from the data of drought indices from 1951 to 2016 used in Pakistan by applying the theory of runs. The proposed model identifies Palmer drought severity index (PDSI) and Reconnaissance drought index (RDI) as the most appropriate meteorological indices for the under‐study country. The quantiles of the model are computed that provide information about the interarrival time of drought and help to anticipate this phenomenon. In addition, return periods for all the seven indices are calculated to report the frequency and duration of drought over a certain period. Finally, some recommendations for the National Drought Monitoring Centre (NDMC) and Pakistan Council of Research in Water Resources (PCRWR) are stated for better future planning to avoid the adverse impacts of drought. [ABSTRACT FROM AUTHOR]

Water is an important key to understand Maya society, especially water availability within a context of climatic changes. Increasing drought would have pushed the Maya water systems into collapse. This paper studies the Maya water systems from an action‐oriented perspective, in order to understand what challenges the Maya had to overcome when dealing with water. The systems found at Tikal serve as main example, allowing comparisons with other Maya sites. In this analysis, hydraulic‐ and agent‐based elements are combined in a model to investigate the performance of the water system within extreme weather conditions and changing human agency. The results suggest that the Tikal water system was able to cope with most of the extreme situations. Furthermore, model results allow proposing that the Maya did not anticipate on short‐term changes in external conditions. Generally, in Tikal surpluses of water may have been as important as shortages of water. The extensive system of drains and canals present at Tikal may have been built to move water from the center of the city rather than to supply water to lower situated reservoirs during the dry season. Such a water‐removal system could be less centrally orientated and organized than is often argued. This could also mean that organizational structures of water systems of different city centers (Tikal, Calakmul, and Caracol) were more similar than usually assumed. This article is categorized under: Human Water > Water as Imagined and Represented Engineering Water > Planning Water Science of Water > Water Quality [ABSTRACT FROM AUTHOR]

Forest dieback caused by drought-induced tree mortality has been observed world-wide. Forecasting which trees in which locations are vulnerable to drought-induced mortality is important to predict the consequences of drought on forest structure, biodiversity and ecosystem function., In this paper, our central aim was to compile a synthesis of tree traits and associated abiotic variables that can be used to predict drought-induced mortality., We reviewed the literature that specifically links drought mortality to functional traits and site conditions (i.e. edaphic variables and biotic conditions), targeting studies that show clear use of tree traits in drought analysis. We separated the review into five climatic zones to determine global vs. regionally restricted relationships between traits and mortality., Our synthesis identifies a number of traits that have clear relationships with drought-induced mortality (e.g. wood density at the species level and tree size and growth at the individual level). However, the lack of direct relationships between most traits and drought-induced mortality highlights areas where future research should focus to broaden our understanding., Synthesis and applications. Our synthesis highlights established relationships between traits and drought-induced mortality, presents knowledge gaps for future research focus and suggests monitoring and research avenues for improving our understanding of drought-induced mortality. It is intended to assist ecologists and natural resource managers choose appropriate and measurable parameters for predicting local and regional scale tree mortality risk in different climatic zones within constraints of time and funding availability. [ABSTRACT FROM AUTHOR]

With the objective of quantifying turbulent heat fluxes in areas with various types of urban land use to improve living and environmental conditions through better urban planning, comparative energy balance measurements using the eddy-covariance (EC) technique were conducted in Oberhausen (Germany) between 15 August 2010 and 15 April 2011. The results of this paper show that the sensible heat flux ( QH) is 20% higher and that the latent heat flux ( QE) is 90% lower at an urban site (URB) compared to a suburban site (SUB). Green spaces in cities counteract the growing thermal stresses on city dwellers and therefore represent a possible urban climate mitigation measure. This positive effect may be reduced or lost entirely during long periods of drought. The Bowen ratio ( QH/ QE) increased from 0.65 to 2.8 with decreasing soil moisture at the SUB, and the monthly average QE value decreased from 94 W m−2 (August 2010, heavy precipitation) to only 47 W m−2 (March 2011, dry period), providing impressive evidence of this relationship. Considering the aspects of urban climate, the creation of urban green spaces can only be effective if an optimum water supply is provided. Furthermore, additional planning recommendations are given for urban planners within cities located at mid-latitudes, as derived from the measured results. Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]