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Life in extreme habitats: diversity of endolithic microorganisms from cold desert ecosystems of Eastern Pamir

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Khomutovska N., Jerzak M., Kostrzewska-Szlakowska I., Kwiatkowski J., Suska-Malawska M., Syczewski M., Jasser I.

Polish Journal of Ecology

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2017

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tom 65

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nr 4

The aim of this study was to identify cyanobacteria diversity in rock communities from the cold desert ecosystem in Eastern Pamir Mountains (Tajikistan) and assess if the rock type and rock`s porosity can be indicators of microbial diversity in this extreme environment. Seven samples were collected in July 2015 from hillsides (ca 4000–4500 m a.s.l.) of the Eastern Pamir Mountains. Petrographic and scanning microscopy (SEM) allowed for the characterization of the rocks inhabited by endolithic communities as granite, gneiss and limestone with variable porosity. Based on next-generation sequencing (NGS) of amplicon of V3–V4 hypervariable region of 16S rRNA gene, we established that Actinobacteria,Proteobacteria and Cyanobacteria dominated the endolithic communities of microorganisms in the rocks studied, which distinguishes these communities from those described for other cold arid regions. Chroococcidiopsis and Leptolyngbya were dominant genera in the cyanobacterial communities according to culture-dependent analysis, as well as microscopic analyses of endoliths scraps from the rocks. Culture-independent metagenomic analyses revealed that Microcoleus, Acaryochloris, Chroococcidiopsis and Thermosynechococcus reads were the most abundant from all reads and dominated interchangeably in the samples. Endolithic communities of microorganisms in the rocks from the cold desert shrubland of Eastern Pamir Mts. appear to be diverse and different from communities described for other cold deserts.

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Soil organic carbon of different decomposition rate and its relation to microbial activity in saline-alkali desert ecosystem

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Fang F., Hu Y.-K., Gong Y.-M., Tang H.-P.

Polish Journal of Ecology

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2015

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tom 63

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nr 1

Soil microbes' activity is very important for forming of the nutrient stock and , soil structure, as well as the carbon cycle simulation. This is particularly crucial for deep soil layers. Effect of soil microbes on the rate of accumulation and decomposition of the soil organic carbon (SOC) has been found for different regions. However, it is known still a little on the SOC performance for different decomposition rates and its relation to the microbial activity in the saline-alkali desert ecosystem. Therefore, the main task of our research was investigation of interrelation between the soil organic carbon and microbial carbon (SMC) at different depths in the original saline-alkali Gurbantünggüt Desert. Our results showed in the soil vertical profile, (i) SMC and SOC presented a very significant positive linear correlation (R² = 0.63, P = 0.0003); (ii) SMC exhibited two obvious changed-interfaces - 20 cm and 80 cm, the SMC at depth of 0–20 cm, 20–80 cm and 80–500 cm was 2.24–3.06, 0.19–0.72, and 0.0017–0.0097 mg kg⁻¹, respectively; (iii) in the depth of 0–20 cm and 20–80 cm, the SMC had highly significant difference (P < 0.0001) and at 20–80 cm and 80–500 cm, significant difference (P = 0.013); (iv) according to the soil division based on the SMC, SOC also had some certain stratification; (v) organic carbon layers can be respectively defined according to different microbial activities as active, inert, and stable organic carbon pool. Therefore, these three kinds of organic carbon pools can be quantitatively measured by analyzing their location at different depths of the soil profile.

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The effect of the halophytic shrub Lycium ruthenicum (Mutt) on selected soil properties of a desert ecosystem in Central Iran

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Jalali G. A., Akbarian H., Rhoades C., Yousefzadeh H.

Polish Journal of Ecology

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2012

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tom 60

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nr 4

We compared soil properties beneath naturally-occurring patches of Lycium ruthenicum Murray (fam. Solanaceae) to evaluate the shrub’s potential to improve the fertility of saline soils. Soil pH, total nitrogen and carbon and extractable potassium, magnesium and phosphorus were respectively significantly higher in the A and B horizons of Lycium shrub patches compared to adjacent unvegetated soils. The influence of Lycium on these soil properties increased with shrub density. Total soil N and extractable Mg and K concentrations were 1.8, 2.6- and 6.6-fold higher under dense Lycium shrub patches compared to unvegetated, bare areas and soil pH was 0.5 units higher. In contrast, the presence of shrubs and shrub density had no clear affect on the EC, Na or CEC of the A horizon soils. The shrub effect extended to the gypsum-rich By horizon (20–50 cm depth) and underlying B horizon (30–80 cm depth) for several soil properties. Total soil C and N were 1.8- and 1.6-fold higher beneath dense Lycium patches than bare soil areas. Soil pH remained 0.4 units higher under dense Lycium than bare soil patches. In the B horizon total soil C was twice as high beneath dense Lycium patches compared to the other patch types. Lycium ruthenicum not only tolerates the saline and drought conditions, it also produces sufficient biomass to increase the nutrient and organic matter content of surface mineral soils in this arid ecosystem and may have potential to improve soil conditions, facilitate ecosystem development and slow desertification.

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Impacts of environmental heterogeneity on distribution pattern of moss crust patches in temperate desert in Central Asia

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Ji X.-H., Pang S.-Q., Zheng Q.

Polish Journal of Ecology

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2018

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tom 66

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nr 2

Moss crusts are the highest developmental stage of biological crusts in arid and semiarid ecosystems worldwide. Under natural conditions, elementary functional units of moss crusts are patches. However, to date, the quantitative features, distribution pattern, ecological effect and relationship with environmental factors of moss patches in desert ecosystems remain unclear. In this study, 3303 moss patches in 22 plots and relevant environmental variables were investigated and quantified in the Gurbantunggut Desert, China. Thirty-six patch classes were defined. Moss crusts accounted on average for 11.7% of the plot area, and the mean moss patch area was 23.4 cm². Small patches dominated, indicating a serious fragmentation of moss crusts. Significant density-dependent effects between patch density and size, humped relationships between patch size and moss plant density, and soil water content under moss patches were observed. The overall distribution of moss crusts showed a tendency of moss patch size and moss plant density decreasing from the southeastern part of the desert to the northwestern part, while moss patch density showed the opposite trend. Pearson's correlation analysis and nonmetric multidimensional scaling analysis consistently demonstrated that the distributions of moss patches were dominantly influenced by non-moss crust coverage, sand particle size, latitude, mean annual precipitation (MAP) and mean annual temperature. Of these parameters, fine sand, high MAP and low latitude were beneficial to the development of moss crusts. Consequently, the factors influencing the distribution pattern of moss crusts are complex and contain the soil factor, current climatic conditions and natural and human disturbances.

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Remote sensing variables as predictors of habitat suitability of the viscacha rat (Octomys mimax), a rock-dwelling mammal living in a desert environment

100%

Campos V. E., Gatica G., Bellis L. M.

Acta Theriologica

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2015

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tom 60

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nr 2

Identifying high-quality habitats across large areas is a central goal in biodiversity conservation. Remotely sensed data provide the opportunity to study different habitat characteristics (e.g., landscape topography, soil, vegetation cover, climatic factors) that are difficult to identify at high spatial and temporal resolution on the basis of field studies. Our goal was to evaluate the applicability of remotely sensed information as a potential tool for modeling habitat suitability of the viscacha rat (Octomys mimax), a rock-dwelling species that lives in a desert ecosystem. We fitted models considering raw indices (i.e., green indices, Brightness Index (BI) and temperature) and their derived texture measures on locations used by and available for the viscacha rat. The habitat preferences identified in our models are consistent with results of field studies of landscape use by the viscacha rat. Rocky habitats were well differentiated by the second-order contrast of BI, instead of BI only, making an important contribution to the global model by capturing the heterogeneity of the substratum. Furthermore, rocky habitats are able to maintain more vegetation than much of the surrounding desert; hence, their availability might be estimated using SATVI (Soil Adjusted Total Vegetation Index) and its derived texture measures: second-order contrast and entropy. This is the first study that evaluates the usefulness of remotely sensed data for predicting and mapping habitat suitability for a small-bodied rock dwelling species in a desert environment. Our results may contribute to conservation efforts focused on these habitat specialist species by using good predictors of habitat quality.

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Relationship between groundwater depth and pattern of net primary production in oasis-desert ecotone

80%

Wu F.-J., Yu Z.-L., Wei X.-P., Deng J. M., Li T., Zhao C.-M., Wang G.-X.

Polish Journal of Ecology

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2010

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tom 58

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nr 4

Pattern of plant biomass and net primary production was investigated in two localities (Minqin and Linze) of oasis-desert ecotone (ODE) in Northwest China, in order to recognize the spatial and temporal variability of vegetation under same regional climate with different groundwater depth. The average depth to groundwater was over 14.02 m at Minqin -- marked further as DG (deep groundwater) and about 4.96 m at Linze -- marked further as SG (shallow groundwater). We have measured plant biomass and Netprimary productivity (NPP) across species, threetimes per year for three consecutive years, in sixplots along Minqin and Linze oasis-desert ecotone(further marked as DG and SG ODE), respectively.Our results showed that DG and SGODEs had different growth responses to differentgroundwater depths. DG ODE exhibited higherinter-annual variation in annual NPP (rangedfrom 0.18 to 9.30 g m⁻²) than did SG ODE (rangedfrom 0.42 to 17.99 g m⁻²). Decrease of groundwaterdepth had apparently altered the seasonalityof productivity in DG ODE systems, where precipitationin summer maintained plant growth,while ODE with high groundwater depth tendedto have higher spring NPP in SG ODE. Spatialand temporal heterogeneity of NPP at the scaleof our measurements was significantly greater inDG ODE than in SG ODE. SG ODE tended tosupport higher NPP than did DG ODE. In addition,the groundwater depth strongly influenced spatial and temporal heterogeneity of NPP in thedesert ecosystems. Clearly, the desert ecosystemwith higher groundwater depth is more stable andmore resistant to long-term drought or climateshifts in arid regions. These investigations andquantitatively analysis are very significant for theexecution of conservation and restoration in aridecosystems.

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Ecophysiological mechanisms of succulent survival in natural conditions: photosynthetic carbon fixation in Caralluma acutangula (Decne. N.E.Br.) (Asclepiadaceae)

80%

Masrahi Y. S., Al-Yemeni M. N., Al-Turki T. A., Sayed O. H.

Polish Journal of Ecology

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2011

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tom 59

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nr 3

Physiological adaptation to arid environments in many desert succulents involves crassulacean acid metabolism (CAM) with modified photosynthetic carbon acquisition aimed at improving water use efficiency. The leafless perennial Caralluma acutangula is an abundant stem succulent in the arid regions of subtropical zones of the Arabian Peninsula. These arid regions southwest of Saudi Arabia are characterized by a short three months wet season (June–August) and a long dry season. The wet season is characterized by high temperature, high evaporation, and strong sand storms. Research presented in this paper involved water status, diffusive conductance, and crassulacean acid metabolism (CAM) of both seedlings and mature C. acutangula plants growing under natural conditions. Plant water status was determined by monitoring changes in stem water content, diffusive conductance was monitored using porometry technique, and CAM was detected by determining chlorenchyma titratable acidity. Seedling establishment of C. acutangula takes place in the short wet season during which seedlings depend on the high productivity C3 mode of photosynthesis. Mature plants are obligate CAM plants exhibiting this mode of carbon fixation during both the wet and the dry seasons. As the dry season progresses dampening of CAM acidification-deacidification cycles and low stomatal conductance denote the switch of mature plants from CAM to CAM-idling in response to protracted water stress. Our results show that the C3 mode of photosynthesis in C. acutangula seedlings during early ontogeny is due to exposure of seedlings to suboptimal irradiance in the shade of other plant species at the study site. This C3 mode of photosynthesis is beneficial for fast seedling establishment. Our results also show that the shift from CAM to CAM-idling in mature C. acutangula plants occurs in response to protracted water stress, which is favourable for survival of this succulent in its inimical arid habitat.

Ograniczanie wyników

Life in extreme habitats: diversity of endolithic microorganisms from cold desert ecosystems of Eastern Pamir

Soil organic carbon of different decomposition rate and its relation to microbial activity in saline-alkali desert ecosystem

The effect of the halophytic shrub Lycium ruthenicum (Mutt) on selected soil properties of a desert ecosystem in Central Iran

Impacts of environmental heterogeneity on distribution pattern of moss crust patches in temperate desert in Central Asia

Remote sensing variables as predictors of habitat suitability of the viscacha rat (Octomys mimax), a rock-dwelling mammal living in a desert environment

Relationship between groundwater depth and pattern of net primary production in oasis-desert ecotone

Ecophysiological mechanisms of succulent survival in natural conditions: photosynthetic carbon fixation in Caralluma acutangula (Decne. N.E.Br.) (Asclepiadaceae)