Desert Communities Research Articles

Stratification and seasonal dynamics of weevil (Coleoptera, Curculionoidea) assemblages in the North Caspian semi-desert

In 2003–2004, 102 species of five weevil families were found in the steppe and desert associations of the Caspian semi-desert (Dzhanybek Station). Representatives of Curculionidae predominated (87 species). The majority of the commonest weevil species (20) were most abundant in the steppe associations, only 6 species being found in the desert ones. The composition of the weevil community changed abruptly from spring to summer. The greatest species richness (86 species) was observed in spring; only in this period weevils living mostly on the soil surface had high densities. In the herbage, both in the steppe and desert communities, detritophagous steppe species Archaeophloeus inermis and Trachyphloeus amplithorax were abundant; the habitats of the solonetz complex (on microelevations and in the depressions), the desert-steppe and steppe species (Humeromima nitida, Mesagroicus poriventris, Temnorhinus strabus) associated with saline substrates were also present. The spring hortobiont assemblage was dominated by the polyphagous steppe weevils, Euidosomus acuminatus, Phyllobius brevis and Omias spp. In summer, 53 species of weevils were recorded; their numbers on the soil surface sharply dropped, the core of the herbage assemblage consisted of the weevils feeding on alfalfa (Stenopterapion tenue, Sitona spp., Tychius spp.) in the steppe associations, with the maximum abundance in the more humid depressions. The summer assemblage of the desert herbage was poor and consisted of the species associated with wormwoods and chenopods (Ptochus porcellus, Phacephorus argyrostomus, Metadonus anceps). The autumn groupings with only 24 species were poor and had low population densities.

Evaluation of Coarse and Fine Particulate Sources Using a Portable Aerosol Monitor in a Desert Community

The purpose of this study was to use a portable aerosol monitor as a preliminary screening tool to identify local sources of coarse (PM(10-2.5)) and fine (PM(2.5)) particulate matter within the Coachella Valley, a low-elevation desert community. The portable aerosol monitor proved to be useful in identifying particle sources unique to the region, namely, sand dunes with sparse ground cover (vegetation), a river wash, and diesel truck and freight train traffic. The general limitations relate to discrepancies in the fraction of PM(10-2.5) when compared to regional air quality data and a lack of accurate mass-based data.

Control of arthropod abundance, richness, and composition in a heterogeneous desert city

There is a demand for mechanistic studies to explore underlying drivers behind observed patterns of biodiversity in urban areas. We describe a two‐year field experiment in which we manipulated bottom‐up (resource availability) and top‐down (bird predation) forces on arthropod communities associated with a native plant, Encelia farinosa, across three land‐use types—urban, desert remnant, and outlying natural desert—in the Phoenix metropolitan area, Arizona, USA. We monitored the trophic structure, richness, and similarity of the arthropod communities on these manipulated plants over a two‐year period. We predicted that (1) increased water resources increase plant productivity, (2) increased productivity increases arthropod abundances, and (3) in the urban habitat, top‐down forces are greater than in other habitats and limit arthropod abundances. We also predicted that urban remnant habitats are more similar to urban habitats in terms of arthropod richness and composition. Strong interannual differences due to an unusual cold and dry winter in the first year suppressed plant growth in all but urban habitats, and arthropod abundances in all habitats were severely reduced. In the following year, arthropod abundances in desert and remnant habitats were higher than in urban habitats. Water had positive effects on plant growth and arthropod abundance, but these water effects emerged through complex interactions with habitat type and the presence/absence of cages used to reduce bird predation. Plants grew larger in urban habitats, and phenology also differed between urban and desert habitats. The results from caging suggest that bird predation may not be as important in cities as previously thought, and that arthropods may retard plant growth. As expected, desert communities are strongly bottom‐up regulated, but contrary to predictions, we did not find evidence for strong top‐down control in the city. Remnant habitats were intermediate between desert and urban habitats in terms of diversity, richness, evenness, arthropod composition and phenology, with urban habitats generally lowest in terms of diversity, richness, and evenness. Our study shows that control of biodiversity is strongly altered in urban areas, influenced by subtle shifts in top‐down and bottom‐up controls that are often superseded by climatic variations and habitat type.

The ecology of pulse events: insights from an extreme climatic event in a polar desert ecosystem

Climate change is occurring globally, with wide ranging impacts on organisms and ecosystems alike. While most studies focus on increases in mean temperatures and changes in precipitation, there is growing evidence that an increase in extreme events may be particularly important to altering ecosystem structure and function. During extreme events organisms encounter environmental conditions well beyond the range normally experienced. Such conditions may cause rapid changes in community composition and ecosystem states. We present the impact of an extreme pulse event (a flood) on soil communities in an Antarctic polar desert. Taylor Valley, McMurdo Dry Valleys, is dominated by large expanses of dry, saline soils. During the austral summer, melting of glaciers, snow patches and subsurface ice supplies water to ephemeral streams and wetlands. We show how the activation of a non‐annual ephemeral stream, Wormherder Creek, and the associated wetland during an exceptional high‐flow event alters soil properties and communities. The flow of water increased soil water availability and decreased salinity within the wetted zone compared with the surrounding dry soils. We propose that periodic leaching of salts from flooding reduces soil osmotic stress to levels that are more favorable for soil organisms, improving the habitat suitability, which has a strong positive effect on soil animal abundance and diversity. Moreover, we found that communities differentiated along a soil moisture gradient and that overland water flow created greater connectivity within the landscape, and is expected to promote soil faunal dispersal. Thus, floods can ‘precondition' soils to support belowground communities by creating conditions below or above key environmental thresholds. We conclude that pulse events can have significant long‐term impacts on soil habitat suitability, and knowledge of pulse events is essential for understanding the present distribution and functioning of communities in soil ecosystems.

Impact of Demographic Trends on Future Development Patterns and the Loss of Open Space in the California Mojave Desert

During the post-World War II era, the Mojave Desert Region of San Bernardino County, California, has experienced rapid levels of population growth. Over the past several decades, growth has accelerated, accompanied by significant shifts in ethnic composition, most notably from predominantly White non-Hispanic to Hispanic. This study explores the impacts of changing ethnicity on future development and the loss of open space by modeling ethnic propensities regarding family size and settlement preferences reflected by U.S. Census Bureau data. Demographic trends and land conversion data were obtained for seven Mojave Desert communities for the period between 1990 and 2001. Using a spatially explicit, logistic regression-based urban growth model, these data and trends were used to project community-specific future growth patterns from 2000 to 2020 under three future settlement scenarios: (1) an "historic" scenario reported in earlier research that uses a Mojave-wide average settlement density of 3.76 persons/ha; (2) an "existing" scenario based on community-specific settlement densities as of 2001; and (3) a "demographic futures" scenario based on community-specific settlement densities that explicitly model the Region's changing ethnicity. Results found that under the demographic futures scenario, by 2020 roughly 53% of within-community open space would remain, under the existing scenario only 40% would remain, and under the historic scenario model the communities would have what amounts to a deficit of open space. Differences in the loss of open space across the scenarios demonstrate the importance of considering demographic trends that are reflective of the residential needs and preferences of projected future populations.

A hierarchical analysis of vegetation on a Mojave Desert landscape, USA

To examine four elements of the hierarchical structure of desert communities, we analyzed plant species composition and 13 environmental variables at 126 sites within a 755 000-ha Mojave Desert landscape, southwestern USA. By a coarse, six-group level (out of 17 groups) in cluster analysis, four generalized community types emerged: widespread, low-elevation communities with Larrea tridentata or Ambrosia dumosa; communities on unique soils (e.g., gypsum) indicated by Atriplex spp.; higher elevation/rugged terrain communities including Coleogyne ramosissima; and disturbance-associated communities such as Bebbia juncea-Hymenoclea salsola. Based on indicator species analysis (ISA), there was no clear level of the community classification that optimized discriminating among communities, because each of four measures of ISA peaked at different hierarchical levels. Three general types of indicator species were identified based on whether their value for discriminating among communities peaked at coarse (e.g., L. tridentata), intermediate (Atriplex hymenelytra), or fine (Krameria grayi) levels of the community hierarchy. Environmental variables differed in their relationships to the hierarchy, with some (e.g., pH) not differing among communities at any level and others, such as rooting depth, differing among communities at multiple levels. Hierarchical analytical techniques can help identify structural patterns within arid land plant communities, species distributions, and vegetation–environment relationships.

Phylogenetic structure illuminates the mechanistic role of environmental heterogeneity in community organization

1. Diversity begets diversity. Numerous published positive correlations between environmental heterogeneity and species diversity indicate ubiquity of this phenomenon. Nonetheless, most assessments of this relationship are phenomenological and provide little insight into the mechanism whereby such positive association results. 2. Two unresolved issues could better illuminate the mechanistic basis to diversity begets diversity. First, as environmental heterogeneity increases, both productivity and the species richness that contributes to that productivity often increase in a correlated fashion thus obscuring the primary driver. Second, it is unclear how species are added to communities as diversity increases and whether additions are trait based. 3. We examined these issues based on 31 rodent communities in the central Mojave Desert. At each site, we estimated rodent species richness and characterized environmental heterogeneity from the perspectives of standing primary productivity and number of seed resources. We further examined the phylogenetic structure of communities by estimating the mean phylogenetic distance (MPD) among species and by comparing empirical phylogenetic distances to those based on random assembly from a regional species pool. 4. The relationship between rodent species diversity and environmental heterogeneity was positive and significant. Moreover, diversity of resources accounted for more unique variation than did total productivity, suggesting that variety and not total amount of resource was the driver of increased rodent diversity. Relationships between environmental heterogeneity and phylogenetic distance were negative and significant; species were significantly phylogenetically over-dispersed in communities of low environmental heterogeneity and became more clumped as environmental heterogeneity increased. 5. Results suggest that species diversity increases with environmental heterogeneity because a wider variety of resources allow greater species packing within communities.

Vegetation recovery in a desert landscape after wildfires: influences of community type, time since fire and contingency effects

Summary1. Theories of plant succession are poorly developed in arid lands, hindering our understanding of how long communities may take to recover after disturbances such as fire. In desert landscapes vulnerable to fire, information about vegetation recovery is important when deciding whether land managers should facilitate vegetation recovery. The deserts of the southwestern USA are increasingly subject to unprecedented fires, facilitated by fuel from exotic grasses, yet management strategies are unclear.2. We evaluated post‐fire recovery patterns of perennial plant species richness and diversity, compared the rate and direction of succession between two major community types, and explored the relationship of time since fire (TSF) and other environmental factors with vegetation recovery. We sampled perennial plant communities and environmental variables (e.g. soil N) on 32 burns, ranging from 2 to 29 years TSF and each paired with their own unburned area, within a 1·8 million ha landscape in the Mojave Desert, USA.3. Species richness, diversity and composition exhibited different post‐burn recovery patterns, and recovery rates differed between community types. Specifically, diversity in Coleogyne ramosissima communities was greater in burned than unburned areas, but diversity did not differ in Larrea tridentata communities. Species composition in Larrea communities exhibited trajectories that indicate convergence with unburned community composition after 19 years TSF. Conversely, burned and unburned Coleogyne communities lacked convergence irrespective of TSF. Environmental variables (e.g. soil texture and P) accounted for 79–83% of the variation in burned species composition, suggesting environmental characteristics in part control recovery patterns.4. Synthesis and applications. The results indicate that geographically similar vegetation types within the same landscape can have markedly different post‐disturbance successional rates and trajectories. Furthermore, the persistence of fire effects varied depending on the community measure, with fire effects on species composition more long‐lasting than the effects on species diversity. This work supports (i) the use of post‐disturbance successional analyses for helping to prioritize management where it is most needed (e.g. communities not recovering naturally) and (ii) the need to assess whether persistent, early successional desert communities meet functional management objectives.

Abstract A78: Cancer in Hinkley: What was the real problem?

Abstract Background: Hinkley, California, is a poor desert community known for a $333 million legal settlement and for the “Erin Brockovich” film that alleged a cancer excess from groundwater contaminated with chromium 6 [Cr(VI)] released by a public utility. The carcinogenic role for aqueous Cr(VI) in humans is disputed. Methods: We assessed observed and expected counts of new cancers, including 19 cancer subtypes in the Hinkley tract for 1996–2008. Indirect standardization yielded expected counts adjusted for age, sex, race/ethnicity, population size, and change in population size. Observed numbers of cancers divided by adjusted expected counts defined standardized incidence ratios (SIR) with 95 percent confidence intervals (CI). Results: After adjusting for demographic characteristics, the observed number of cervix cancers was significantly above the expected count (SIR; 95% CI=2.83; 1.82, 5.86). Findings for all cancers combined (SIR; 95% CI=0.91; 0.78, 1.04) and each of 15 specific cancers did not differ significantly from expected counts. Observed counts for childhood, hematopoietic, and respiratory cancers were slightly above expected counts, while observed counts for digestive and breast cancers were below expected. No nasopharyngeal carcinoma or pancreatic cancers were identified, and the observed prostate cancer count (SIR; 95% CI=0.65; 0.40, 0.98) was significantly below the expected number. The observed count for colorectal cancer was below the expected number, although a markedly larger fraction of Hinkley cases were diagnosed at advanced stage compared to the county, region and state. Conclusions: These findings do not support claims of a generalized cancer excess in Hinkley, although the cervix, prostate, and colorectal cancer findings reveal underutilization of cancer screening in the Hinkley tract. These findings are consistent with previous assessments that did not identify a cancer excess in the Hinkley tract. Funding: The California Department of Public Health, National Cancer Institute (Grant N01-PC-35136 and N01-PC-35139), and Centers for Disease Control and Prevention (Grant N02-PC-54404) funded cancer surveillance necessary for this study. Citation Information: Cancer Epidemiol Biomarkers Prev 2011;20(10 Suppl):A78.

Effects of a nonnative, invasive lovegrass on Agave palmeri distribution, abundance, and insect pollinator communities

Nonnative Lehmann lovegrass (Eragrostis lehmanniana) has invaded large areas of the Southwestern United States, and its impact on native plants is not fully understood. Palmer’s agave (Agave palmeri), an important resource for many pollinators, is a key native plant potentially threatened by E. lehmanniana. Understanding potential impacts of E. lehmanniana on A. palmeri is critical for anticipating the future of the desert community where they coexist and for addressing management concerns about associated threatened and endangered species. Our study provides strong indications that E. lehmanniana negatively impacts A. palmeri in several ways. Areas of high E. lehmanniana abundance were associated with significantly lower densities and greater relative frequencies of small A. palmeri, suggesting that E. lehmanniana may exclude A. palmeri. There were no significant differences in species richness, abundance, or community composition when comparing flower associates associated with A. palmeri in areas of high and low E. lehmanniana abundance. However, we did find significantly lower connectedness within the pollination network associated with A. palmeri in areas with high E. lehmanniana abundance. Although E. lehmanniana forms thick stands that would presumably increase fire frequency, there was no significant association between E. lehmanniana and fire frequency. Interestingly, medium to high densities of A. palmeri were associated with areas of greater fire frequency. The complex ramifications of E. lehmanniana invasion for the long-lived A. palmeri and interlinked desert community warrant continued study, as these species are likely to continue to be found in close association due to their similar soil preferences.

Development of Ecosystem Research

Experimental studies established the major community-physiological processes that determine the structure, growth and biodiversity of overstorey and understorey plants and resident vertebrates in an ecosystem. These community-physiological studies were promoted internationally by the UNESCO Arid Zone Research Program, the International Biological Program (Sections Productivity, Production Processes and Conservation), the International Union for the Conservation of Nature and, finally, the International Geosphere-Biosphere Program that is studying the impact of Global Warming on the World's ecosystems. During the short period of annual foliage growth in evergreen plant communities, aerodynamic fluxes (frictional, thermal, evaporative) in the atmosphere as it flows over and through a plant community determine the foliage projective covers and leaf attributes in overstorey and understorey strata. These foliar attributes determine the community-physiological constant, the evaporative coefficient, of the plant community. An increase in air temperature of during this period of annual foliage growth will affect the structure of the plant community, so that tall open-forests open forests woodlands open scrub low open-shrubland desert communities. Variation in available soil water during this short period of annual foliage growth will influence vertical shoot growth but not foliage projective covers and leaf attributes produced in the overstorey stratum.

Beetles of the superfamily Curculionoidea (Coleoptera) in a complex semi-desert in relation to climate changes in the North Caspian region

In desert and steppe habitats of the complex North Caspian semi-desert, more than twofold differences in the number of hortobiont Curculionoidea species (33 and 75 species, respectively) were observed between the “dry” (1972–1974) and “humid” (2003–2005) climatic phases. The abundance of most species changed. Polyphagous steppe weevils of the subfamily Entiminae (Otiorhynchus velutinus, Euidosomus acuminatus, Omias verruca, and O. rotundatus) with spring activity of adults were the most stable, representing the main dominants of the spring communities both in the 1970s and 2000s. Nearly all of the weevils that changed their abundance since the 1970s were specialized herbivores with summer adult activity. In the more humid 2000s, the abundance of some desert-steppe weevils dominating the desert communities (Phacephorus nebulosus, Metadonus anceps and especially Ptochus porcellus) dropped drastically. Most of the species whose abundance increased most strongly (Phyllobius brevis, Trachyphloeus amplithorax, Archaeophloeus inermis, Stenopterapion tenue, Sitona inops, S. longulus, Tychius spp.) are associated with Medicago romanica, the plant that considerably raised its density in the microdepressions during the “humid” phase. The data show an evident reduction of the most xerophilic (desertsteppe) components of the weevil community and an increase in the fraction of mesophilic species. These changes seem to follow a cyclic pattern.

An application of the edge effect in measuring accessibility to multiple food retailer types in Southwestern Ontario, Canada

BackgroundTrends in food retailing associated with the consolidation of smaller-format retailers into fewer, larger-format supercentres have left some rural areas with fewer sources of nutritious, affordable food. Access to nutritious, affordable food is essential for good dietary habits and combating health issues such as type-2 diabetes, obesity, and cardiovascular disease. Many studies on food environments use inaccurate or incomplete methods for locating food retailers, which may be responsible for mischaracterising food deserts. This study uses databases of every residence in and every food retailer in and around Middlesex County, Ontario, Canada. Residences were geocoded to their precise address, and network analysis techniques were performed in a geographic information system (GIS) to determine distances between every residence and different types of food retailers (grocery stores, fast food, fruit and vegetable sources, grocery stores plus fruit and vegetable sources, variety stores), both when considering and neglecting facilities outside the area of study, to account for a deficiency in analysis termed the 'edge effect'.ResultsAnalysis of household accessibility to food outlets by neighbourhood socioeconomic distress level indicated that residents in the most distressed neighbourhoods tended to have better accessibility to all types of food retailers. In the most distressed neighbourhoods, 79 percent of residences were within walking distance of a grocery store, compared to only 10 percent in the least distressed neighbourhoods. When the edge effect was neglected, 37 percent of distance estimates proved inaccurate. Average accessibility to all food retailer types improved dramatically when food outlets adjacent to the study area were considered, thereby controlling for the edge effect.ConclusionBy neglecting to consider food retailers just outside study area boundaries, previous studies may significantly over-report the actual distance necessary to travel for food. Research on food access spanning large rural regions requires methods that accurately geocode residents and their food sources. By implementing methods akin to those in this paper, future research will be better able to identify areas with poor food accessibility. Improving identification of food desert communities is a first step in facilitating more effective deployment of food policies and programs in those communities.

Locating groundwater resources for Aboriginal communities in remote and arid parts of South Australia

Finding and utilizing reliable water supplies for desert communities is important but difficult and expensive. This is especially the case in the remote north and northwest of South Australia, where there are a number of small Aboriginal communities with populations of less than a hundred people. Rainfall is sparse and intermittent (less than 200 mm/yr), and residents rely on groundwater for nonpotable supplies. Previous drilling in shallow sediments aiming for porous aquifers has led to problems with long-term well production. More recent wells targeting deeper fractured rock aquifers are showing more promise; unfortunately, such boreholes are more expensive and difficult to install. The aim of our work is to use natural-source magnetotelluric (MT) imaging to try and identify better sites for bores, and therefore reduce the risk of drilling a dry well. We hope to do this by imaging the 3D conductivity structure, allowing the identification of possible aquifers, and also by measuring the anisotropy due to water-bearing fractures, through the sensitivity of natural-source MT responses to electrically anisotropic layers in the subsurface. The first phase of our work, described here, is to test the method at a site where the hydrogeology is relatively well understood. The second phase will apply it to a community in need.

The Ngaanyatjarra Lands Telecommunications project: A quest for broadband in the Western Desert

Vast regions in Australia still have limited access to adequate telecommunications. With the rollout of the National Broadband Network underway, remote Indigenous Australia risks being left out, increasing its isolation and widening the 'digital divide'. In the past, the vast Ngaanyatjarra Lands of south-eastern Western Australia have had one of the poorest levels of telecommunications service in Australia. However, the regional shire, land council and the community media organisation have worked together with the WA Government to address this problem. This effective collaboration led to the Ngaanyatjarra Lands Telecommunications Project (NLTP): a fibre optic network connecting six remote desert communities, a broadband satellite solution to connect the remaining six outer communities and community-wide WiFi in all twelve sites. This article describes the process of creating the NLTP and some of the flow-on benefits for the region and Yarnangu (Ngaanyatjarra people).

Effect of artificial night lighting on temporally partitioned spiny mice

Abstract We studied the effect of ecological light pollution on a rocky desert community, focusing on 2 spiny mouse congeners, nocturnal Acomys cahirinus (common spiny mouse) and diurnal Acomys russatus (golden spiny mouse). We hypothesized that in response to artificial illumination A. cahirinus will decrease its activity and A. russatus will increase its activity, and thus temporal overlap and interspecific competition could increase. Our study took place in 4 field enclosures: the 1st and 3rd months were controls with natural light, and in the 2nd month artificial illumination, simulating low levels of light pollution, was set for the first 3 h of the night. We implanted temperature-sensitive radiotransmitters to monitor mouse activity, and individual identification tags with automonitored foraging patches were used to track foraging behavior. A. cahirinus decreased activity and foraging with artificial lighting, restricting movement particularly in less-sheltered microhabitats, probably because of inc...

Spatial and temporal structure of the spider community in the clay semi-desert of western Kazakhstan

The spatial and temporal structure of spider communities was studied in the clay semi-desert of the north-western Caspian Lowland, western Kazakhstan (49°23' N, 46°47' E). The soils and vegetation are complex, being composed of a mosaic of desert and steppe plant communities. Besides the native associations, there are plantations of different tree species. The ground-dwelling spider assemblages in the native habitats are the most diverse. The number of species inhabiting forest plantations is three times as small. Gnaphosidae is the leading family in the ground layer. They show high abundance and diversity levels during the whole season. Thomisidae, Lycosidae, Philodromidae, and Salticidae are abundant as well. The species diversity of herbage-dwelling spiders in different open native habitats is very similar. The spectrum of dominant families (Thomisidae, Oxyopidae, Araneidae, and Salticidae) and the seasonal dynamics of their ratio in desert and steppe associations have much in common. Spider assemblages of native and artificial habitats are characterised by change from multispecies polydominant spring-summer communities to impoverished imbalanced autumn ones. Seasonal changes in the species structure of mature spider groupings in native habitats are well pronounced, while the impact of seasonal conditions is even stronger than between-habitat differences. Complexes of typical species with different levels of habitat preference are revealed.

The other side of the story

When people chose to share stories with me during my fieldwork, in the Australian Central Desert community of Alpurrurulam, it was common for the story to be prefaced with the idiom ‘I’m gonna give you that story’. These sorts of statements emphasize the relationship between myself and the speaker, pointing to the unique nature of the stories I was given. I was not regarded as a passive listener in this context, but rather I, as a particular person, helped to shape the narratives of the past that were shared with me. We all share our memories in significant ways with the world around us. It is the case across cultures that we learn to remember with, around and through engaging with people. In this, culture plays an important role in shaping the ways that people remember, recall and recount their lives. This article will look at the interdisciplinary and intercultural challenges which face the re-telling of tales in memory studies from the perspective of the listener and, in the case of researchers, the reporter.

Solar powered RO desalination: Investigations on pilot project of PV powered RO desalination system

Water scarcity are serious problem in many areas of the world, such as the Middle East and North African countries (MENA), the Southern European Mediterranean Islands (SEMI) and isolated communities in desert or arid areas of Central Asian countries. One of the promising solutions for this problem is developing of autonomous system of drinking water supply or desalination systems working on RES, particularly solar energy. However, RES especially solar energy potential of the most arid areas is usually high. In addition, the cost of primary fuel is getting up while the need to maintain clean environment is becoming an important issue worldwide [1, 2]. There are a number of desalination methods proposed by scientists and available on the market. Among them, reverse osmosis (RO) is quite suitable for small to medium capacity systems and also has good perspectives for cost reduction and improvement in efficiency in the near future. And a number of research works on solar powered RO systems, from pilot project to industrial scale developed and proposed by researches which can be found from literature. This paper presents a review of the highlights that have been achieved during the last years in solar powered RO desalination. Also proposed the preliminary investigations on developed small scale PV powered RO desalination system, which supposed to be feasible system to use by small farmers in rural areas of Central Asia.

Floristic diversity of arboreal communities in the high altitude deserts of Ladakh

Analysis of woody components of 4 communities in Nubra valley of Ladakh revealed that Hippophae rhamnoides was the most dominant species sharing 31 per cent of total importance value. Across the communities within landscape relative dominance of this species decreased from 77.76 per cent on most hydric sites (along river bank) to merely 0.27 per cent on most xeric sites (dry rocks). On the other hand, relative dominance of Ephedra gerardiana and Berberis ulicina increased with increasing aridity of sites. Productivity-diversity relationship followed unimodal curve which peaked at sites along streams. Maximum species turnover rate was found across the sites along steams while the most xeric sites were more uniform within.