Cold Desert Ecosystem Research Articles

Habitat suitability of biocrust communities in a cold desert ecosystem.

Drylands are unique among terrestrial ecosystems in that they have a significant proportion of primary production facilitated by non-vascular plants such as colonial cyanobacteria, moss, and lichens, i.e., biocrusts, which occur on and in the surface soil. Biocrusts inhabit all continents, including Antarctica, an increasingly dynamic continent on the precipice of change. Here, we describe in-situ field surveying and sampling, remote sensing, and modeling approaches to assess the habitat suitability of biocrusts in the Lake Fryxell basin of Taylor Valley, Antarctica, which is the main site of the McMurdo Dry Valleys Long-Term Ecological Research Program. Soils suitable for the development of biocrusts are typically wetter, less alkaline, and less saline compared to unvegetated soils. Using random forest models, we show that gravimetric water content, electrical conductivity, and snow frequency are the top predictors of biocrust presence and biomass. Areas most suitable for the growth of dense biocrusts are soils associated with seasonal snow patches. Using geospatial data to extrapolate our habitat suitability model to the whole basin predicts that biocrusts are present in 2.7 × 105 m2 and contain 11-72 Mg of aboveground carbon, based on the 90% probability of occurrence. Our study illustrates the synergistic effect of combining field and remote sensing data for understanding the distribution and biomass of biocrusts, a foundational community in the carbon balance of this region. Extreme weather events and changing climate conditions in this region, especially those influencing snow accumulation and persistence, could have significant effects on the future distribution and abundance of biocrusts and therefore soil organic carbon storage in the McMurdo Dry Valleys.

Population genomics and morphological data bridge the centuries of cyanobacterial taxonomy along the continuum of Microcoleus species

The filamentous cyanobacterium Microcoleus is among the most important global primary producers, especially in hot and cold desert ecosystems. This taxon represents a continuum consisting of a minimum of 12 distinct species with varying levels of gene flow and divergence. The notion of a species continuum is poorly understood in most lineages but is especially challenging in cyanobacteria. Here we show that genomic diversification of the Microcoleus continuum is reflected by morphological adaptation. We compiled a dataset of morphological data from 180 cultured strains and 300 whole genome sequences, including eight herbarium specimens and the type specimen of Microcoleus. We employed a combination of phylogenomic, population genomic, and population-level morphological data analyses to delimit species boundaries. Finally, we suggest that the shape of the filament apices may have an adaptive function to environmental conditions in the soil.

Diversity, Distribution and Vegetation Assessment of Woody Plant Species in the Cold Desert Environment, North-Western Himalaya, India

The species richness, distribution and community structure in cold desert regions across the world are poorly understood because of their inaccessibility and remoteness. Similarly, the structure and composition of forest resources, including other management units (i.e., agroforestry and forestry systems), have hardly been studied in the cold desert of the Lahaul valley. However, such information is a prerequisite to understanding the trends and changes in the vegetation distribution under global climate change scenarios, especially considering the sensitivity of plant species in high-altitude areas of the Himalayan region. High anthropogenic activity has exerted tremendous pressure on available forest resources, including other management units in the cold desert of the Lahaul valley. Standard ecological methods were used to obtain an ecological (i.e., status, structure, composition and vegetation patterns) understanding of the region for biodiversity conservation and environmental sustainability. The present study was aimed at understanding the trend, structure and composition of plant species in the cold desert region of the western Himalaya. A total of 64 species (27 trees and 37 shrubs) of vascular plants were recorded in the present study. Tree diversity demonstrated greater variation along the gradients and slope aspects. Salix fragilis trees, with a 102 tree ha−1 density and a few trees of Populus nigra, were found to be sparsely distributed under the agroforestry system on the south-facing slopes in Khoksar. In Jahlma, Salix fragilis grew in an agroforestry system with a density of 365 tree ha−1. However, in Hinsa, Juniperus polycarpos was a dominant tree species in the agroforestry system, with a density of 378 tree ha−1. On the north-facing slopes in Kuthar, a higher number of trees and bushes were present due to natural regeneration maintained by farmers along the edges of terraced agricultural fields. The south-facing slopes showed a relatively lower species richness and diversity as compared to north-facing slopes at similar locations due to relatively less favourable growth conditions under sun-exposed, extremely xeric soil conditions. The highest level of species turnover was found between the altitudes of 2400 m and 3000 m. Betula utilis showed the highest adaptability at higher altitudes (>3500 m). The vegetation analysis results and information generated in the present study are useful for gaining an ecological understanding of the cold desert ecosystem in the Lahaul valley. Sustainable forest resource management, including other management units (e.g., agroforestry and forestry systems), is crucial for improving the vegetation pattern, structure and function of the cold desert ecosystem, thereby contributing to climate change mitigation, adaptation, biodiversity and ecosystem service conservation.

Influence of fine-scale habitat characteristics on sage-grouse nest site selection and nest survival varies by mesic and xeric site conditions

AbstractResource managers and scientists across western U.S. agencies seek methodologies for identifying environmental attributes important to both wildlife conservation and broad-scale land stewardship. The Greater Sage-Grouse (Centrocercus urophasianus; hereafter, sage-grouse) exemplifies a species in need of this broad-scale approach given widespread population declines that have resulted from loss and degradation of habitat from natural and anthropogenic disturbances. These include agricultural land conversion, conifer expansion, energy development, and wildfire coupled with ecological conversion by invasive plants such as cheatgrass (Bromus tectorum). Development of habitat assessments and conservation actions for sage-grouse benefit from studies that link demographic responses to habitat selection patterns. To address this, we examined nest survival of sage-grouse in relation to fine-scale habitat patterns (i.e., field-based habitat measurements) that influenced nest site selection, using data from nests of telemetered females at 17 sites over 6 years in Nevada and northeastern California, USA. Importantly, sites spanned mesic and xeric average precipitation conditions that contributed substantially to vegetation community structure across cold desert ecosystems of the North American Great Basin. Vegetative cover immediately surrounding sage-grouse nests was important for both nest site selection and nest survival, but responses varied between mesic and xeric sites. For example, while taller perennial grasses were selected at xeric sites, we found no evidence of selection for perennial grass at mesic sites, indicating a functional response to availability of habitat features between hydrographic regions. Furthermore, perennial grass height and forb height both had positive effects on nest survival at xeric sites, but we found varying effects at mesic sites. We emphasize that precipitation conditions driving ecosystem productivity vary regionally among sagebrush communities, shaping vegetation structure and suitable habitat conditions for nesting sage-grouse.

Vegetation Shift of Juniperus macropoda Boisser Forest in Response to Climate Change in North-Western Himalayas, India

The cold desert ecosystem of the north-western Himalaya in India’s is considered to be the most vulnerable region to climate change. In this region, Juniperus macropoda Boisser grows across an altitudinal gradient and is highly sensitive to biotic, physiographic, and climatic factors. Keeping this in view, the present study aimed at ascertaining the response of Juniperus macropoda to changing climatic conditions. To achieve the target of the study, the area (elevation ranges from 3525 to 4150 m asl) was divided into thirteen elevation ranges in the cold desert of Lahaul valley (Himachal Pradesh). The NDVI change detection map from 1994–2017 revealed an increase in the area under the vegetation in the NDVI range of 0–0.15 (240%) and 0.15–0.30 (32%), which indicated the emergence of grasses and new recruits in the area. An increase in the minimum and maximum temperature during monsoon and post-monsoon season correlated positively with the emergence of the recruits in a significant manner. Furthermore, a decline in rainfall during the monsoon period was also recorded which bears a significant positive correlation with the establishment of recruits. However, the increase in the precipitation during winter resulted in a positive effect on the emergence of recruits. The biophysical parameters, like average height, diameter as well as the average age of the dominant trees showed a declining trend with the elevation. However, the age histogram revealed that the majority of the establishment occurred around 1900 and between 1975–2010. The tree ring analysis of J. macropoda revealed that the species is shifting upward at a rate of 3.91 m year−1. Besides this, the area is experiencing the impact of climate change resulting in an increase in the area under vegetation and migration towards the higher elevation, and many species of lichens were also found to invade the bare rock.

Transcriptional and biochemical analyses of Planomicrobium strain AX6 from Qinghai-Tibetan Plateau, China, reveal hydrogen peroxide scavenging potential

BackgroundThe bacterial mechanisms responsible for hydrogen peroxide (H2O2) scavenging have been well-reported, yet little is known about how bacteria isolated from cold-environments respond to H2O2 stress. Therefore, we investigated the transcriptional profiling of the Planomicrobium strain AX6 strain isolated from the cold-desert ecosystem in the Qaidam Basin, Qinghai-Tibet Plateau, China, in response to H2O2 stress aiming to uncover the molecular mechanisms associated with H2O2 scavenging potential.MethodsWe investigated the H2O2-scavenging potential of the bacterial Planomicrobium strain AX6 isolated from the cold-desert ecosystem in the Qaidam Basin, Qinghai-Tibet Plateau, China. Furthermore, we used high-throughput RNA-sequencing to unravel the molecular aspects associated with the H2O2 scavenging potential of the Planomicrobium strain AX6 isolate.ResultsIn total, 3,427 differentially expressed genes (DEGs) were identified in Planomicrobium strain AX6 isolate in response to 4 h of H2O2 (1.5 mM) exposure. Besides, Kyoto Encyclopedia of Genes and Genomes pathway and Gene Ontology analyses revealed the down- and/or up-regulated pathways following H2O2 treatment. Our study not only identified the H2O2 scavenging capability of the strain nevertheless also a range of mechanisms to cope with the toxic effect of H2O2 through genes involved in oxidative stress response. Compared to control, several genes coding for antioxidant proteins, including glutathione peroxidase (GSH-Px), Coproporphyrinogen III oxidase, and superoxide dismutase (SOD), were relatively up-regulated in Planomicrobium strain AX6, when exposed to H2O2.ConclusionsOverall, the results suggest that the up-regulated genes responsible for antioxidant defense pathways serve as essential regulatory mechanisms for removing H2O2 in Planomicrobium strain AX6. The DEGs identified here could provide a competitive advantage for the existence of Planomicrobium strain AX6 in H2O2-polluted environments.

Population Dynamics of Juniperus macropoda Bossier Forest Ecosystem in Relation to Soil Physico-Chemical Characteristics in the Cold Desert of North-Western Himalaya

Juniperus macropoda is the only tree species of a cold desert ecosystem that is experiencing high anthropogenic pressure and has a poor regeneration status due to harsh environmental conditions. Due to the limited distribution of Juniperus macropoda in this region, the species have remained largely unexplored in terms of understanding the distribution pattern along the elevation and soil fertility gradients. Therefore, the current research was carried out along the elevational gradient, starting from the base line at 3000 m above sea level (m asl) asl with an elevational plot distance of 180 m. The study revealed that the average density of J. macropoda declined gradually from the first elevation range, i.e., 3000–3180 m asl onward, and extended up to the elevation range of 3900–4080 m asl. However, the average seedling and sapling densities were highest at mid-elevation and extended up to an elevation range of 4080–4260 m asl. The J. macropoda population formed a reverse J-shaped structure only up to 3540–3720 m asl. The maximum total biomass and carbon density were recorded in the lowest elevational range, and decreased subsequently. The primary soil nutrients under study decreased sharply along the elevational gradient. Seedling, sapling and tree distributions had a significantly positive relationship (p < 0.05) with available N, P, K, SOC, silt and clay contents and were negatively correlated (p < 0.05) with sand contents. The outcome of the study will form the basis for devising a plan for the management and conservation of J. macropoda forests.

Species Diversity Assessment along Altitudinal Gradient in Cold Desert Juniperus Forest of North-Western Himalaya

The present study was carried out in the cold desert ecosystem of pure Juniperus forest in Northwestern Himalayan region to assess the species diversity along the altitudinal gradient. The entire study area was divided into eight main plots along altitudinal gradient starting from 3000m up to >4260m amsl with 180m elevational distance between two adjacent main plots. A total of 9 shrub and 19 herb species were reported in the entire study area at different altitudes. The maximum density among shrubs was reported for Ephedra vulgaris (853.33 N ha -1 ) at A 6 and whereas, Juniperus communis has the highest basal area (6642.77 cm 2 ha -1 ) at A 2 elevation. Ephedra vulgaris was the most dominant shrub with an IVI value of 206.19 at A 8, which contributed 33. 11 % of shrub species. Â Artemisia maritima was the most frequently occurring herb species with the highest density (47666. 67 N ha -1 ) at A 1 . The maximum basal area was reported for Waldhemia tomentosa (45373.67 cm 2 ha -1 ) at A 4 elevation. Species richness was found to be markedly declined with an increase in altitude. However, the richness was found to be maximum at mid of the elevation gradient A 4 and A 5 . Shannon-Wiener diversity index (H') and concentration of dominance (Cd) have shown a negative relationship. The study provides necessary information about the distribution and diversity of essential shrubs and herb species at different altitudes for regeneration, sustainable forest management and conservation actions around the mid-altitudes of the cold desert of northwestern Himalayas.

Physiological and transcriptome analyses reveal the response of Ammopiptanthus mongolicus to extreme seasonal temperatures in a cold plateau desert ecosystem

Ammopiptanthus mongolicus is the only evergreen broad-leaved shrub present in arid areas of Northwest China and plays an important role in maintaining the stability of the local desert ecosystem. It can survive under extreme temperatures (e.g., extreme low temperature: − 24.8 °C and extreme high temperature: 37.7 °C). To understand the gene expression-physiological regulation network of A. mongolicus in extreme temperature environments, we monitored the changes in gene expression and photosynthetic traits of the leaves. The results showed that at low temperatures, the net photosynthetic rates (A), Fv'/Fm' and electron transport rate (ETR) decreased, the Fv/Fm ratio was only 0.32, and the proportion of nonregulatory heat dissipation Y(NO) increased. Based on a KEGG analysis of the differentially expressed genes, 15 significantly enriched KEGG pathways were identified, which were mainly related to circadian rhythm, photosynthesis, lipid metabolism, carbohydrate metabolism, plant hormones and other life activities. At high temperatures, the A value increased, and the proportion of regulatory energy dissipation Y(NPQ) increased. The KEGG analysis identified 24 significantly enriched KEGG pathways, which are mainly related to circadian rhythm, carbon sequestration of photosynthesis, carotenoid biosynthesis, secondary metabolites, cofactors and vitamin metabolism. In general, at the expense of photosynthesis, A. mongolicus can ensure the survival of leaves by increasing Y(NO) levels, regulating the circadian rhythm, increasing the synthesis of unsaturated fatty acids and changing the role of plant hormones. Under high-temperature stress, a high photosynthetic capacity was maintained by adjusting the stomatal conductance (gsw), increasing Y(NPQ), consuming excess light energy, continuously assembling and maintaining PSII, and changing the production of antioxidants.

Nitrogen deposition stimulated winter nitrous oxide emissions from bare sand more than biological soil crusts in cold desert ecosystem

Dryland ecosystems are often nitrogen-limited, and small nitrogen inputs may produce large responses to dryland ecological processes, such as gaseous nitrogen emission. The effect of increased anthropogenic nitrogen deposition on N2O and NO emissions in desert ecosystems is unclear, especially in non-growing seasons when the surface is covered with snow. In this study, nitrogen applications were performed on biological soil crusts (lichen crust and moss crust, bare sand for control) in the Gurbantunggut Desert, Northwest China. We measured the fluxes of N2O and NO and related nitrogen cycle functional gene abundances in winter for three-years period. Nitrogen addition significantly affected N2O emissions and increased the abundances of key functional gene for nitrogen cycle, while it only slightly influenced NO emissions. These effects of nitrogen addition depended on composition of biological soil crusts. For bare sand and lichen crust, nitrogen addition significantly increased N2O emissions, whereas for moss crust, only a negligible effect was observed. Meanwhile, significant differences in nitrogen cycle functional gene abundances were found among different composition of biological soil crusts. Abundance of amoA, narG, and nosZ genes were highly related to N2O and NO emissions. Thus, our results indicate that gaseous nitrogen emissions were generally increased by nitrogen addition through their effects on related functional microbial groups. The effects were regulated by composition of biological soil crusts which can buffer the effects of increasing nitrogen addition during winter.

Immediate effects of burning sagebrush vegetation on soil nutrient dynamics and fertile islands in a cold desert ecosystem

Immediate effects of burning sagebrush vegetation on soil nutrient dynamics and fertile islands in a cold desert ecosystem

Gullies and Moraines Are Islands of Biodiversity in an Arid, Mountain Landscape, Asgard Range, Antarctica.

Cold, dry, and nutrient-poor, the McMurdo Dry Valleys of Antarctica are among the most extreme terrestrial environments on Earth. Numerous studies have described microbial communities of low elevation soils and streams below glaciers, while less is known about microbial communities in higher elevation soils above glaciers. We characterized microbial life in four landscape features (habitats) of a mountain in Taylor Valley. These habitats varied significantly in soil moisture and include moist soils of a (1) lateral glacial moraine, (2) gully that terminates at the moraine, and very dry soils on (3) a southeastern slope and (4) dry sites near the gully. Using rRNA gene PCR amplicon sequencing of Bacteria and Archaea (16S SSU) and eukaryotes (18S SSU), we found that all habitat types harbored significantly different bacterial and eukaryotic communities and that these differences were most apparent when comparing habitats that had macroscopically visible soil crusts (gully and moraine) to habitats with no visible crusts (near gully and slope). These differences were driven by a relative predominance of Actinobacteria and a Colpodella sp. in non-crust habitats, and by phototrophic bacteria and eukaryotes (e.g., a moss) and predators (e.g., tardigrades) in habitats with biological soil crusts (gully and moraine). The gully and moraine also had significantly higher 16S and 18S ESV richness than the other two habitat types. We further found that many of the phototrophic bacteria and eukaryotes of the gully and moraine share high sequence identity with phototrophs from moist and wet areas elsewhere in the Dry Valleys and other cold desert ecosystems. These include a Moss (Bryum sp.), several algae (e.g., a Chlorococcum sp.) and cyanobacteria (e.g., Nostoc and Phormidium spp.). Overall, the results reported here broaden the diversity of habitat types that have been studied in the Dry Valleys of Antarctica and suggest future avenues of research to more definitively understand the biogeography and factors controlling microbial diversity in this unique ecosystem.

Bacterial Diversity and Community Composition Distribution in Cold-Desert Habitats of Qinghai-Tibet Plateau, China.

Bacterial communities in cold-desert habitats play an important ecological role. However, the variation in bacterial diversity and community composition of the cold-desert ecosystem in Qinghai–Tibet Plateau remains unknown. To fill this scientific gape, Illumina MiSeq sequencing was performed on 15 soil samples collected from different cold-desert habitats, including human-disturbed, vegetation coverage, desert land, and sand dune. The abundance-based coverage estimator, Shannon, and Chao indices showed that the bacterial diversity and abundance of the cold-desert were high. A significant variation reported in the bacterial diversity and community composition across the study area. Proteobacteria accounted for the largest proportion (12.4–55.7%) of all sequences, followed by Actinobacteria (9.2–39.7%), Bacteroidetes (1.8–21.5%), and Chloroflexi (2.7–12.6%). Furthermore, unclassified genera dominated in human-disturbed habitats. The community profiles of GeErMu, HongLiangHe, and CuoNaHu sites were different and metagenomic biomarkers were higher (22) in CuoNaHu sites. Among the soil physicochemical variables, the total nitrogen and electric conductivity significantly influenced the bacterial community structure. In conclusion, this study provides information regarding variation in diversity and composition of bacterial communities and elucidates the association between bacterial community structures and soil physicochemical variables in cold-desert habitats of Qinghai–Tibet Plateau.

Seed germination responses to temperature and dry storage of seven Caragana (Fabaceae) species from northwest China

Caragana shrublands are the main type of vegetation in some cold desert ecosystems in Xinjiang in northwest China, and information on seed dormancy and germination of Caragana species is needed to help restore disturbed areas. Freshly matured seeds of Caragana aurantiaca, C. dasyphylla C. polourensis, C. roborovskyi, C. soongorica, C. spinosa and C. tekesiensis, collected from three natural ecosystems were tested for germination in light at 15/5, 20/10, 25/15 and 30/15 °C after dry storage at room temperature for 1 week and 9 months. Depending on the species, 1–84% of the seeds had physical dormancy (i.e., water-impermeable seeds). At 15/5, 20/10, 25/15 and 30/15 °C, fresh seeds of C. aurantiaca, C. spinosa and C. dasyphylla germinated from 74% to 100%, those of C. soongorica 15% to 52% and those of C. roborovskyi and C. polourensis 13–73%. After 9 months of storage, germination percentages increased significantly over wide range of temperatures for seeds of C. soongorica, C. tekesinsis C. roborovskyi and C. polourensis but decreased significantly for C. spinosa and C. dasyphylla. Most fresh seeds of the floodplain species and desert species are water-permeable and can germinate over a wide range of temperatures; consequently, they could be planted in the field at any time during the growing season. Dry storage of seeds of C. roborovski and C. tekesiensis increased the percentage of water-permeable seeds. Seeds of these species germinate best at high temperatures and should be planted in summer. If C. polourensis is used for restoration, the seeds need to be scarified before planting.

Population ecology and niche modelling of endangered Arnebia euchroma in Himachal Pradesh, India-An approach for conservation

For the restoration and rehabilitation of a species, comprehensive information on the ecological elements and potential habitats are essentially required to the conservationists. This has necessitated initiating studies on habitat and population ecology of the threatened species. Keeping this in view, population ecology and niche modelling of endangered Arnebia euchroma in Himachal Pradesh was studied. Total 49 populations of A. euchroma were studied between 3325-4587m amsl in the Lahaul and Spiti and Kinnaur districts of Himachal Pradesh. Most of the populations (25) were found in steep slope and fall in east, north, north-east, north-west, south, south-east, south-west and west aspects. Maximum populations (11) were represented in the east aspect, followed by north and west (9 each) and northeast and northwest (6 each) aspects. Among the populations, richness of shrubs ranged from 1–7 and herbs 4–36; total shrubs density 2–119 Ind 100 m−2; total herbs density 460–7055 Ind 100 m−2; Concentration of dominance for shrubs 0.26–1 and herbs 0.05–0.37 and Species diversity (H’) for shrubs 0.0–1.56 and herbs 1.26–3.29. Biological features, aspects, slope and pressure contributed to the critical population status of the A. euchroma. The particular geographical distribution (2022 km2) under semi-arid conditions of the species indicated its habitat specificity. The present investigation revealed that A. euchroma populations showed fragmented pattern of distribution in the cold desert ecosystem. Therefore, re-introduction of A. euchroma in highly suitable habitat i.e., north-western gentle dry slope with high pH (alkaline soils) and low total nitrogen, moisture, carbon and organic matter is suggested.

Prioritization of habitats and communities for conservation in Cold Desert Biosphere Reserve, Trans Himalaya, India

AbstractThe rapid degradation of habitats and communities throughout the globe has necessitated the need for conservation to avoid biodiversity crisis. For framing conservation and management plan for flora of any region, it is very necessary to prioritize species of that region, their preferred habitats and communities with reliable information. In the present study, prioritization of habitats and communities has been done in the Cold Desert Biosphere Reserve. Ten habitats and 73 plant communities (45 shrubs and 28 herbs) distributed between 3,109 and 5,019 m were identified. Each habitat and community has been evaluated based on the ecological and socioeconomical parameters. Of the 10 habitats identified, the Moist alpine groove habitat showed highest conservation priority index (CPI), that is, 50 hence prioritized for conservation. The Ephedra gerardiana—Lonicera asperifolia mixed community showed highest CPI, that is, 62; followed by Hippophae rhamnoides ssp. turkestanica—Caragana versicolor—Ephedra intermedia mixed, Rosa webbiana—Ribes orientale mixed and Salix denticulata‐ H. rhamnoides ssp. turkestanica mixed (CPI: 60, each) communities. Regular monitoring of the prioritized habitats and communities has been suggested. Also, mass propagation of native, endemic, economically important and threatened species following biotechnological approaches and their plantation in the natural habitats of Spiti valley have been suggested. This would help in the management of habitats and communities in particular and cold desert ecosystem in general.

Effects of increased precipitation on the life history of spring- and autumn-germinated plants of the cold desert annual Erodium oxyrhynchum (Geraniaceae).

Future increased precipitation in cold desert ecosystems may impact annual/ephemeral plant species that germinate in both spring and autumn. Our primary aim was to compare the life history characteristics of plants from spring-germinating (SG) and autumn-germinating (AG) seeds of Erodium oxyrhynchum. Plants in field plots with simulated increases in precipitation of 0, 30 and 50 % in spring and summer were monitored to determine seedling survival, phenology, plant size, seed production and biomass accumulation and allocation. Germination characteristics were determined in the laboratory for seeds produced by plants in all increased precipitation treatments. Increased precipitation in spring significantly improved survival of seedlings from SG and AG seeds, but survival was less for AG than SG. An increase in precipitation increased the number of seeds per plant for both SG and AG, but AG produced more seeds per plant than SG. With increased precipitation, percentage of dormant seeds from SG increased significantly, while that of AG decreased slightly. Our study suggests that with increased spring and summer rainfall AG will produce an increased number of nondormant seeds that could germinate in autumn and SG an increased number of dormant seeds that become part of the soil seed bank. However, ability of some seeds to germinate in autumn and others in spring will be maintained as long as soil moisture is limited in autumn.

Effects of Changing Climate on the Hydrological Cycle in Cold Desert Ecosystems of the Great Basin and Columbia Plateau

Climate change is already resulting in changes in cold desert ecosystems, lending urgency to the need to understand climate change effects and develop effective adaptation strategies. In this review, we synthesize information on changes in climate and hydrologic processes during the past century for the Great Basin and Columbia Plateau and discuss future projections for the 21st century. We develop midcentury projections of temperature and climate for the Great Basin and Columbia Plateau at timescales relevant to managers (2020−2050) and discuss concepts and strategies for adapting to the projected changes. For the instrumented record in the Great Basin and Columbia Plateau (1985−2011), a temperature increase of 0.7−1.4°C has been documented, but changes in precipitation have been relatively minor with no clear trends. Climate projections for 2020−2050 indicate that temperatures will continue to increase, especially in winter and during the night. Precipitation is more difficult to project, and estimates range from an 11% decrease to 25% increase depending on location. Recent records indicate that the Great Basin and Columbia Plateau are becoming more arid, a trend that is projected to continue. Droughts are likely to become more frequent and last longer, invasive annual grasses are likely to continue to expand, and the duration and severity of wildfire seasons are likely to increase. Climate projections can help in developing adaptive management strategies for actual or expected changes in climate. Strategies include reducing the risks of nonnative invasive plant spread and wildfires that result in undesirable transitions, planning for drought, and where necessary, facilitating the transition of populations, communities, and ecosystems to new climatic conditions. A proactive approach to planning for and adapting to climate change is needed, and publicly available Internet-based resources on climate data and planning strategies are available to help meet that need.

Identification of Discriminating Morphological Descriptors for Characterization of Seabuckthorn (Hippophae rhamnoides L.) Germplasm in Himachal Pradesh

Identification of discriminating morphological descriptors for characterization of Seabuckthorn (Hippophae rhamnoides L.) germplasm in Himachal Pradesh was undertaken in ten different major gene pool areas of Seabuckthorn in Spiti Valley, where 80 per cent population is of Hippophae rhamnoides L. Twenty plants of each gene pool area were selected during the end of growing season. Plant shoot, leaf blade, pubescence and fruit characteristics were recorded. Twenty two morphological traits were recorded for vegetative and reproductive descriptors, which is comprised of Qualitative and Quantitative characteristics. Study concluded with preparation of DUS (Distinctiveness, Uniformity and Stability) guidelines for developing a new species/sub species or variety or new clone which will help in further breeding and genetic improvement programme. The present study identifies the morphological descriptors that are most relevant for characterization of Seabuckthorn (Hippophae rhamnoides L.) in cold desert eco-system of Himachal Pradesh.

Photosynthetic acclimation of an evergreen broadleaved shrub (Ammopiptanthus mongolicus) to seasonal climate extremes on the Alxa Plateau, a cold desert ecosystem

Key message Survival of Ammopiptanthus mongolicus in a cold desert environment is facilitated by high photosynthesis rates in spring and summer, and efficient photoprotective strategies in winter cold.