Recent Drought Conditions Research Articles

A chromosome-scale genome assembly and evaluation of mtDNA variation in the willow leaf beetle Chrysomela aeneicollis.

The leaf beetle Chrysomela aeneicollis has a broad geographic range across Western North America but is restricted to cool habitats at high elevations along the west coast. Central California populations occur only at high altitudes (2,700-3,500 m) where they are limited by reduced oxygen supply and recent drought conditions that are associated with climate change. Here, we report a chromosome-scale genome assembly alongside a complete mitochondrial genome and characterize differences among mitochondrial genomes along a latitudinal gradient over which beetles show substantial population structure and adaptation to fluctuating temperatures. Our scaffolded genome assembly consists of 21 linkage groups; one of which we identified as the X chromosome based on female/male whole genome sequencing coverage and orthology with Tribolium castaneum. We identified repetitive sequences in the genome and found them to be broadly distributed across all linkage groups. Using a reference transcriptome, we annotated a total of 12,586 protein-coding genes. We also describe differences in putative secondary structures of mitochondrial RNA molecules, which may generate functional differences important in adaptation to harsh abiotic conditions. We document substitutions at mitochondrial tRNA molecules and substitutions and insertions in the 16S rRNA region that could affect intermolecular interactions with products from the nuclear genome. This first chromosome-level reference genome will enable genomic research in this important model organism for understanding the biological impacts of climate change on montane insects.

Examining ground and surface water changes in response to environmental variables, land use dynamics, and socioeconomic changes in Canada

Canada's abundant and high-quality water resources support a growing human population, as well as thriving industrial and agricultural economies. However, recent intense drought conditions have raised concerns for current water resource availability. Patterns of long-term ground and surface water (GSW) changes, and their response to environmental conditions, land-use dynamics, and socioeconomic changes are not well-understood across this large and diverse country. To address this crucial gap, we identified regions of ground and surface water (GSW) changes in all the Provinces of Canada between 2002 and 2016 from the Gravity Recovery and Climate Experiment (GRACE) and Global Land Data Assimilation System (GLDAS) datasets. We explored the relationships between GSW changes and environmental, socioeconomic, and land-use dynamics over time. We found that all the Provinces of Canada gained a net 4.46 mm Liquid Water Equivalent (LWE) per year, equivalent to a total increase of 66.9 mm LWE. GSW increases were significantly associated with the normalized difference vegetation index and evapotranspiration rates. In contrast, GSW declines were significantly related to deforestation rate, urban expansion, and economic development (median household income). Despite apparent widespread post-drought recovery detected from 2002 to 2016, the rapid GSW declines were also observed in almost all of Western Canada and part of Ontario, amounting to a net loss of 66.13 mm. This indicates that a pronounced drought had emerged. It is anticipated that Canada will be experiencing more frequent and severe droughts under ongoing climate change and increasing demand for water resources.

A Decade of Hydrological Drought in Central-Western Argentina

Most of the water used for the development of the main socio-economic activities in Central-Western Argentina (CWA), an arid to semi-arid region, home to most of the Argentinean wine production, relies on surface streamflow from several snow-fed rivers. During the last decade (2010-2020), reduced snow accumulation over the higher elevations of the Andes mountains triggered the occurrence of hydrological drought over CWA, affecting winter tourism, restricting water use for irrigation and domestic use, and leading to socio-political disputes. This study provides a detailed description of the recent hydrological drought conditions through the use of streamflow records from 15 river basins, which were complemented by precipitation, snowpack, and water equivalent thickness measurements to provide a comprehensive picture of the water losses over the last decade. Hydrological drought indices derived from the threshold level method and the standardized streamflow index allowed characterizing the unusualness of this dry period in the context of the last 49 years. The hydrological deficit over the last decade highlighted the challenges faced by the water managers to provide water for irrigation in the main agricultural oases, with a likely overexploitation of the groundwater resources to supplement the limited surface runoff. The hydrological drought severity increased since 2017, with record-breaking levels in several basins, particularly during the period between July 2019 and June 2020 for the rivers located between 35° and 36°S. We identified the main hydrological drought impacts in CWA, as well as the need for improved mitigation strategies to cope with current and future drought conditions. We also analyzed the current limitations in terms of snow and groundwater observations, highlighting the necessity for an effective hydrological drought monitoring system, together with an improved forecast of snow accumulation in the headwaters, which can contribute to better regional water management plans.

Anthropogenic and climate induced trace element contamination in a water reservoir in northwestern Mexico.

Water reservoirs are essential for regional economic development, as populations depend on them for agriculture irrigation, flood control, hydroelectric power generation, water supply for human consumption, and subsistence fishing activities. However, the reservoir environmental quality can be disturbed by enhanced sediment input and trace metal contamination, affecting human health as a consequence of contaminated water and fish consumption. With the purpose to understand the trends and extent of sediment accumulation and trace element contamination in the Oviachic reservoir (OV, northwestern Mexico) since its construction, the temporal variations of sediment accumulation, and As, Cr, Cu, Hg, Ni, Pb, and Zn concentrations, enrichment, and fluxes, were evaluated through the study of two 210Pb-dated sediment cores. We assumed that siltation and trace element contamination were driven by the development of anthropogenic activities in the region within the past ~ 70 years. Elemental concentrations accounted from null to minor enrichment for most elements, but moderate to significant enrichment by Hg. Mercury, As, and Cu fluxes have notably increased since the past decade, most likely because of a combination of anthropogenic and natural processes, including catchment erosion, artisanal gold mining, and recent drought conditions in the region. Arsenic and Hg concentrations may pose deleterious risks to biota in the reservoir, and consequently to humans through fish consumption, for which further biological and toxicological tests are advisable. This study highlights the importance of using sediment dating to assess historical trends of metal contamination and identify possible sources, to support decision-making in programs addressed to reduce environmental and health risks in aquatic ecosystems.

Prediction of Impending Drought Scenarios Based on Surface and Subsurface Parameters in a Selected Region of Tropical Queensland, Australia

Droughts occur in all climatic regions around the world costing a large expense to global economies. Reasonably accurate prediction of drought events helps water managers proper planning for utilization of limited water resources and distribution of available waters to different sectors and avoid catastrophic consequences. Therefore, a means to create a simplistic approach for forecasting drought conditions with easily accessible parameters is highly desirable. This study proposes and evaluates newly developed accurate prediction models utilizing various hydrologic, meteorological, and geohydrology parameters along with the use of Artificial Neural Network (ANN) models with various forecast lead times. The present study develops a multitude of forecasting models to predict drought indices such as the Standard Precipitation Index with a lead-time of up to 6 months, and the Soil Moisture Index with a lead-time of 3 months. Furthermore, prediction models with the capability of approximating surface and groundwater storage levels including the Ross River Dam level have been developed with relatively high accuracy with a lead-time of 3 months. The results obtained from these models were compared to current values, revealing that ANN based approach can be used as a simple and effective predictive model that can be utilized for prediction of different aspects of drought scenarios in a typical study area like Townsville, North Queensland, Australia which had suffered severe recent drought conditions for almost six recent years (2014 to early 2019).

Fungi associated with associated with declined oak trees in in Chaharmahal va Bakhtiary province

Persian oak (Quercus branti Lindl) is the most important forest tree of the Zagros mountains. During the recent drought conditions, the oak decline has widely been observed in the areas of Chaharmahal and Bakhtiari Province, especially the town Lordegan. Symptoms include early fall coloration, early leaf drop, vascular discoloration in the twigs (Fig. A-1), drying of the branches, discoloration of the main trunk and branches, cracks and splitting of the trunk, the presence fungal organs as black and olive powdery under the bark (Fig. B-1) and death of the trees. While up to 70% of the trees may suffer from the disease on south-facing slopes (Fig. D-1), north-facing slopes are normally unaffected(Fig. C-1). In 2018, samples of bark, main trunk, and a branch of trees with symptoms (16 specimens) and some specimens (7 specimens) of apparently healthy trees were collected in Lordegan town and isolated by standard methods of isolation of pathogenic fungi on malt agar and potato-dextrose-agar media. The fungal isolates were purified after growth and sent to Botany Research Department of Iranian Research Institute of Plant Protection for identification. Identification results showed that isolates of Biscogniauxia Mediterranea, Paecilomyces cf variotii and Paraconiothyrium sp. are fungi associated with charcoal rot and oak decay in Chaharmahal va Bakhtiari province. From 16 samples with described symptoms, 9 samples of Paraconiothyrium sp, 5 samples of B. mediterranea and 4 samples of Paecilomyces cf variotii were isolated. Two samples of asymptomatic samples were also isolated Paraconiothyrium sp and B. mediterranea.

An Integrated Method for Identifying Present Status and Risk of Drought in Bangladesh

The occurrence and severity of agricultural droughts may not be dependent upon climatic variables alone. Rather increasingly, drought is affected by human interventions such as irrigation. Anthropogenic activity has introduced uncertainty in the assessment of current drought and future drought risk in many parts of the world; neither climatic nor remote sensing data alone are able to assess drought conditions effectively. In response, we present a simple approach to assess drought by combining a remote sensing-based drought index, the Temperature Vegetation Dryness Index (TVDI), climate data (i.e., rainfall and temperature), and field observations to evaluate recent drought conditions in northwestern Bangladesh (NWB). Applying this approach, we gained five insights: (i) the TVDI successfully indicated the drought conditions of NWB and agrees with field observations, (ii) the integrated use of TVDI and climate data (such as rainfall and temperature) provides the best understanding of the difference between meteorological drought and droughts resulting from surface moisture conditions, (iii) the TVDI results agree with rainfall data (r2 = 0.40 in March and r2 = 46 in April) in a part of the study area (NWB) where irrigation is not available, (iv) the TVDI can be used along with climate data to predict the potential risk of drought, and (v) while meteorological drought exists due to low rainfall and high temperature in this NWB in pre-monsoon season, because of widespread irrigation practices, meteorological drought is unable to trigger agricultural drought over most parts of the study area. The findings imply that there is a potential risk of drought in NWB, since any disruption of irrigation water supply could trigger a severe agricultural drought over the whole region. This is similar to what is currently observed over a small part of NWB.

Recharge Estimation Using CMB and Environmental Isotopes in the Verlorenvlei Estuarine System, South Africa and Implications for Groundwater Sustainability in a Semi-Arid Agricultural Region

Groundwater recharge remains one of the most difficult hydrogeological variables to measure accurately, especially for semi-arid environments where the recharge flux is much smaller than in humid conditions. In this study, groundwater recharge was estimated using chloride mass balance (CMB) in the Verlorenvlei catchment, South Africa where the effects of recent severe drought conditions in an already semi-arid environment have impacted both agricultural activity as well as the RAMSAR-listed Verlorenvlei estuarine system. Chloride, 18O and 2H tracers were used to improve understanding of the groundwater flow patterns and allowed the fresh parts of the groundwater system, defined by Ca2+-HCO3− groundwater types, to be separated from those where additional salts were being introduced through groundwater mixing, and thus characterized as Na+-Cl− groundwater types. Recharge rates calculated from CMB in the fresh parts of the system were between 4.2–5.6% and 11.4–15.1% of mean annual precipitation for the headwater valley and mountains of the Krom Antonies and are largely consistent with previous studies. However, much lower recharge rates in the valleys where agriculture is dominant contrasts with previous results, which were higher, since groundwater-mixing zones were not recognised. Although the chloride concentration in precipitation is based on only one year of data between 2015 and 2016, where 2015 had on average 28% less precipitation than 2016, the results provide a snapshot of how the system will respond to increasing drought frequency in the future. The results suggest that low rates of groundwater recharge under dry spell conditions will impact on low flow generations which are required to sustain the Verlorenvlei estuarine lake system. Overall, the study highlights the importance of combining hydrochemical tracers such as bulk chloride and stable isotopes with numerical modelling in data-scarce catchments to fully understand the nature of hydrological resilience.

Evaluation of the ability of CMIP6 models to simulate precipitation over Southwestern South America: Climatic features and long-term trends (1901–2014)

This study evaluates the performance of precipitation simulated in the historical runs of the Climate Model Intercomparison Project Phase 6 (CMPI6) in capturing the complex spatial and temporal patterns observed over Southwestern South America (SWSA). Precipitation outputs from 14 general circulation models (GCMs) were compared with observations from CRU TS 4.03 database for the period 1901–2014, using a set of statistical metrics, with particular focus in the quantification of the long-term precipitation decline that triggered recent recurrent drought conditions over SWSA. The main features of regional precipitation were adequately captured by the majority of CMIP6 models, although with a wet bias south of 35°S especially along the Andes ranges and in southern Chile, which can exceed 100 mm during the winter rainy season. The magnitude of the long-term precipitation decline was reasonably captured by the different GCMs, but model outputs tend to locate the maximum in precipitation decrease south of the position of the observed trends. The precipitation decline can be linked to the observed positive long-term trend in SLP over the subtropical southeast Pacific Ocean. Nevertheless, only few GCMs were able reproduce the spatial patterns of observed SLP trends. Finally, considering a comprehensive rating index, we selected a subset of five GCMs that best reproduced the climatological features of precipitation and its temporal and spatial changes over the study area, with a brief discussion of implications for the assessment of future precipitation over SWSA.

Recent Ogallala Aquifer Region Drought Conditions as Observed by Terrestrial Water Storage Anomalies from GRACE

AbstractRecent severe drought events have occurred over the Ogallala Aquifer region (OAR) during the period 2011–2015, creating significant impacts on water resources and their use in regional environmental and economic systems. The changes in terrestrial water storage (TWS), as indicated by the Gravity Recovery and Climate Experiment (GRACE), reveals a detailed picture of the temporal and spatial evolution of drought events. The observations by GRACE indicate the worst drought conditions occurred in September 2012, with an average TWS deficit of ~8 cm in the northern OAR and ~11 cm in the southern OAR, consistent with precipitation data from the Global Precipitation Climatology Project. Comparing changes in TWS with precipitation shows the TWS changes can be predominantly attributable to variations in precipitation. Power spectrum and squared wavelet coherence analysis indicate a significant correlation between TWS change and the El Nino‐Southern Oscillation, and the influence of equatorial Pacific sea surface temperatures on TWS change is much stronger in the southern OAR than the northern OAR. The results of this study illustrate the value of GRACE in not just the diagnosis of significant drought events, but also in possibly improving the predictive power of remote signals that are impacted by nonregional climatic events (El Nino), ultimately leading to improved water resource management applications on a regional scale. Editor’s note: This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series.

Correction to: Evaluation of recent drought conditions by standardized precipitation index and potential evapotranspiration over Indonesia

In the original publication of this article, the co-author Komariah Komariah has been included incorrectly.

Evaluation of recent drought conditions by standardized precipitation index and potential evapotranspiration over Indonesia

In South Asia, an increasing population and frequent droughts have been significant factors deeply affecting water deficits in the region. In this study, recent drought conditions were evaluated by calculating the standardized precipitation index (SPI) for the period of 1991–2006, based on past data during the period from 1961 to 1990. In addition, the Thornthwaite equation was used to compute monthly potential evapotranspiration for the entire area of Indonesia. The APHRODITE data set was utilized for precipitation and temperature. Monthly rainfall data from April to September for 30 years (1961–1990) were used to obtain the gamma function for the computation of SPI values. Calculated probability of SPI for which values were < − 2 during the period from 1991 to 2006 was used to evaluate recent Indonesian drought conditions. Regarding potential soil water deficits, under the very simple assumption that the root zone is 30 cm, soil porosity is 0.4, and field capacity is 80% of soil porosity, the critical threshold of soil water deficit was set as − 96 mm. Frequency of potential water deficits < − 96 mm was counted during 1991–2006. The results of the SPI in Indonesia indicate that most parts of Indonesia have encountered severe and extreme drought for the period 1991–2006. Based on SPI interpretation, Borneo Island and West Papua are the islands that encountered the most extreme drought during the dry seasons. Borneo Island seems to have encountered extreme drought at the beginning and the middle of the dry seasons (April, May, and July). On the other hand, based on the Thornthwaite interpretation, Java and Bali Islands, and especially in Central Java and East Java, seem to have encountered the greatest soil water deficit at the middle and the end of the dry seasons (May, June, July, and September).

The Australian Museum Lord Howe Island Expedition 2017—Balls Pyramid Survey for Phasmids

The Australian Museum in partnership with Melbourne Zoo, the New South Wales Office of Environment and Heritage (NSW OEH), the Lord Howe Island (LHI) Board and the LHI Museum along with a team of experienced climbers, landed on the remote and almost inaccessible Balls Pyramid on 21 March 2017. The expedition objectives were to (a) determine the extent to which the critically endangered Lord Howe Island Phasmid (LHIP) (Dryococelus australis) existed beyond the restricted area in which it had previously been observed; (b) bring back four individuals for the Melbourne Zoo breeding program; and (c) sample other invertebrate taxa. A team of eleven climbers and support staff spent eight days on Balls Pyramid establishing suitable infrastructure for exploring and sampling LHI phasmid habitat from base to summit, and during daylight and after dark when conditions become particularly perilous. Survey results clearly established that the LHI phasmid is distributed widely across Balls Pyramid with 17 individuals being observed on Melaleuca howeana at more than five different elevations from below Gannett Green right up to Cheval Ridge just below the summit. Although less than expected, possibly because of recent drought conditions on Balls Pyramid, the 17 sightings meant that a single female LHI phasmid was able to be returned to Melbourne Zoo to bolster the breeding program.

Central Valley Spring-Run Chinook Salmon and Ocean Fisheries: Data Availability and Management Possibilities

Author(s): Satterthwaite, William H.; Cordoleani, Flora; O'Farrell, Michael R.; Kormos, Brett; Mohr, Michael S. | Abstract: Central Valley spring-run Chinook Salmon (CVSC) are designated threatened by state and federal authorities. Although CVSC are caught in ocean fisheries, their harvest is not actively managed, because it is assumed that measures currently in place to protect endangered Sacramento River winter-run Chinook Salmon (SWRC) will also sufficiently protect CVSC. Recoveries of tags and genetically-identified CVSC suggest these fish have a more northerly distribution than SRWC. Further, escapement data and cohort reconstructions suggest that CVSC mature later than SRWC. Thus, regulations (time/area restrictions and minimum size limits) crafted to protect SRWC alone may not adequately protect CVSC; on the other hand, regulations to constrain impacts on Klamath River and California coastal Chinook Salmon populations may also reduce impacts on CVSC. Trends in CVSC escapement were deemed acceptable in recent status updates, but concerns remain because of the negative effects caused by recent drought and ocean conditions. Should more active management of CVC be desired, current options are limited. The most promising approach is based on estimating age-specific ocean fishing mortality rates by using cohort reconstructions applied to tagged Chinook Salmon that originate from the Feather River Hatchery. At a minimum, ocean fishing mortality rates could be monitored and compared to proxy thresholds. If reference harvest rates were established, harvest models could be developed to predict how CVSC would be affected by fishing regulations, similar to the way fall-run Chinook Salmon fisheries are evaluated. Abundance forecasts would require improved juvenile production data (e.g., from genetic sampling of juvenile emigrants), since sibling-based forecasts commonly used for fall-run Chinook Salmon would not be available in time for pre-season planning. It is unclear if ocean fishing mortality rate estimates derived from hatchery proxies for natural-origin fish are truly representative, but existing data do not demonstrate obvious differences in ocean distribution or size-at-age fish. Substantial new investments in tagging or sampling would be needed to directly estimate ocean fishing mortality rates for natural-origin CVSC. Establishing specific harvest targets or limits for CVSC requires an improved understanding of production throughout their life cycle through juvenile production estimates and long-term information on spawner age structure.

Building “Natural” Beauty: Drought and the Shifting Aesthetics of Nature in Santa Barbara, California

This article analyzes the tension between the built and intrinsic elements that constitute Santa Barbara, California, as a place, by investigating two related questions: How is Santa Barbarans’ sense of place impacted by citywide cultural preferences for a specific plant aesthetic? and How have recent drought conditions affected that plant aesthetic, and its population’s cultural relationship to nature and the environment? The analysis focuses primarily on two key informant interviews, with Madeline Ward, the city’s water conservation coordinator, and Timothy Downey, the city arborist, and is further supported by ethnographic field notes. I argue that the California drought has brought parallel changes to both the city’s physical appearance and its residents’ aesthetic preferences regarding plants. This has further prompted changes to popular conceptions of Santa Barbara as a place, stemming from residents’ desire for an aesthetic that is better in tune with the ecological conditions of the area.

Impact of urbanization coupled with drought situations on groundwater quality in shallow (basalt) and deeper (granite) aquifers with special reference to fluoride in Nanded-Waghala Municipal Corporation, Nanded District, Maharashtra (India).

Rapid expansion in urbanization and industrialization coupled with recent drought conditions has triggered unplanned groundwater development leading to severe stress on groundwater resources in many urban cities of India, particularly cities like Nanded, Maharashtra. In the quest of tapping drinking water requirement, due to recent drought conditions, people from the city are piercing through entire thickness of shallow basalt aquifers to reach productive deeper granite aquifers. Earlier reports from Nanded and surrounding districts suggest that deeper granite aquifer is contaminated with fluoride (geogenic). The study aimed to find out variations in fluoride concentration in shallow basalt (10-167m) and deeper granite aquifers (below 167m) and to find out the relationship between fluoride and other ions. Study suggests that concentration of fluoride in shallow basalt aquifer is within maximum permissible limits of Bureau of Indian Standards and deeper granite aquifer contains as high as 4.9mg/l of fluoride and all samples from granite aquifers are unfit for human consumption. The groundwater from basalt aquifer is mainly Ca-HCO3-Cl type, and from granite aquifer, it is Ca-Na-Cl type. The correlation plot between F- vs. pH, Na+ and HCO3- shows a positive correlation and an inverse relationship with Ca2+ in both aquifers. As recommendations, it is suggested that granite aquifers should not be tapped for drinking purposes; however, in drought situations, water from this aquifer should be blended with treated surface water before supplying for drinking purposes. Efforts may be made to utilize 1.35 MCM of rainwater from available rooftop, which is sufficient to cater for the needs of ~40,800 people annually. Most effective defluoridation techniques like electrolytic de-fluoridation (EDF), ion exchange and reverse osmosis may be adopted along with integrated fluorosis mitigation measures.

An Overview of San Diego County’s Ongoing Feral Pig Eradication Project

Until 2006, San Diego County remained one of two counties in California that did not have a resident population of non-native wild pigs. Since that time, three or more introductions of pigs resulted in the establishment of several populations of wild pigs that grew and were believed to span the backcountry of San Diego County. Feral pigs have the potential to harm sensitive habitats, compete with native species, negatively impact drinking water quality, damage agriculture and rangelands, destroy archeological sites, and transmit diseases. They also pose a significant threat to the network of protected areas in San Diego County. In 2009, affected public land management agencies began working together to address San Diego’s pig problem in an alllands approach by forming an Intergovernmental Pig Group. The Group determined that eradicating pigs was feasible, especially given recent drought conditions, and should be the ultimate goal of the project. In the summer of 2014, USDA APHIS Wildlife Services began a large-scale effort to remove pigs across San Diego County. We provide an update on the status of the eradication effort and share information we have gathered on the San Diego pig population from remote cameras and samples collected from pigs taken during this effort. We also outline our strategy for the future to achieve eradication, including how an independent monitoring study will be used to certify that eradication has been, and remains, successful.

Decline of the Black Tern (Chlidonias niger) Population in the Klamath Basin, Oregon, 2001–2010

Abstract We monitored the Black Tern (Chlidonias niger) population at Agency and Upper Klamath Lakes, in the Klamath Basin, Oregon, from 2001–2010. We estimated that the population of adult Black Terns declined at these 2 joined waterbodies by 8.4% annually. In contrast, our analysis of Breeding Bird Survey data for the Bird Conservation Region 9/Great Basin during the same period did not detect a trend. Knowledge of local short-term trends in the Klamath Basin can contribute to understanding regional and continental population declines of this species. Water levels, which may affect both habitat availability and suitability, were relatively stable from 2001–2009, but dropped in 2010 and remained depressed from 2010–2014. The direct effect of water-level fluctuations on habitat availability (hectares of habitat loss) is not well understood. Water allocation is a management challenge in this region and has been exacerbated by recent drought conditions. In combination, understanding trends and causal factor...

Long-term droughtiness and drought tolerance of eastern US forests over five decades

Abstract Droughts can influence forest composition directly by limiting water or indirectly by intensifying other stressors that affect establishment, growth, and mortality. Using community assemblages of eastern US tree species and drought tolerance characteristics assessed from literature, we examine recent drought conditions in relation to the spatial distribution of species and their tolerance to drought. First we calculate and compare a cumulative drought severity index (CDSI) for the conterminous US for the periods 1960–1986 and 1987–2013 using climate division Palmer Drought Severity Index (PDSI) values and a gridded self-calibrated PDSI dataset. This comparison indicates that drought conditions in the East tend to be less frequent and generally less severe than those in the West, and that the West has had a large increase in CDSI values in the latter period. Then we focus on the past and potential future role of droughtiness in eastern forests, which are relatively more diverse than western forests but have individual species that are uniquely affected by drought conditions. We found that eastern US forests tend to be relatively balanced in the composition of drought-tolerant and -intolerant species and that drought conditions are relatively uncommon in the East. Understanding the composition and distribution of drought tolerance levels within forests is crucial when managing for the impacts of drought (e.g., managing for survival), especially given the expected rise of drought in the future.

The role of personal experience in frequency of rainwater tank maintenance and policy implications

Domestic rainwater tanks have a long history in Australia, although more recently they have been common only in remote and rural areas. However, in some urban areas, recent drought conditions have led to the promotion of rainwater tanks to supplement domestic water supplies. Evidence suggests that water tank maintenance may be insufficient in many cases, leading to problems with water quality and the potential spread of vector-borne disease. Drawing on research into the impact of personal experience (i.e. procedural knowledge) relating to pro-environmental behaviour, a survey of urban residents with mandated rainwater tanks (N = 746) was conducted. The study assessed whether past personal history of living with a tank influenced the frequency of tank maintenance behaviours. Analyses indicated that both childhood and prior adult experience with rainwater tanks were important in predicting adequate tank maintenance behaviour, particularly among males. The results also showed that attitudinal perceptions of water culture did not influence maintenance behaviour, whereas direct past experiences did, suggesting an important role for procedural knowledge. These results are discussed with reference to the promotion of tank maintenance and other pro-environmental behaviours through the development of future environmental policies designed to foster the development of pro-environmental skills to empower citizens.