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He M.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Dijkstra F.A.,University of Sydney | Zhang K.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Li X.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | And 5 more authors.
Scientific Reports | Year: 2014

In desert ecosystems, plant growth and nutrient uptake are restricted by availability of soil nitrogen (N) and phosphorus (P). The effects of both climate and soil nutrient conditions on N and P concentrations among desert plant life forms (annual, perennial and shrub) remain unclear. We assessed leaf N and P levels of 54 desert plants and measured the corresponding soil N and P in shallow (0-10 cm), middle (10-40 cm) and deep soil layers (40-100 cm), at 52 sites in a temperate desert of northwest China. Leaf P and N5P ratios varied markedly among life forms. Leaf P was higher in annuals and perennials than in shrubs. Leaf N and P showed a negative relationship with mean annual temperature (MAT) and no relationship with mean annual precipitation (MAP), but a positive relationship with soil P. Leaf P of shrubs was positively related to soil P in the deep soil. Our study indicated that leaf N and P across the three life forms were influenced by soil P. Deep-rooted plants may enhance the availability of P in the surface soil facilitating growth of shallow-rooted life forms in this N and P limited system, but further research is warranted on this aspect. Source


Hu Y.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Hu Y.,Key Laboratory of Stress Physiology and Ecology in Cold and Arid Regions of Gansu Province | Wang Q.,CAS Institute of Tibetan Plateau Research | Wang Q.,University of Chinese Academy of Sciences | And 10 more authors.
Plant and Soil | Year: 2016

Aims: A lacking of understanding about cooling effects on methane (CH4) fluxes and potential asymmetrical responses to warming and cooling causes uncertainty about climate change effects on the atmospheric CH4 concentration. We investigated CH4 fluxes in an alpine meadow on the Tibetan Plateau in response to climate warming and cooling. Methods: A 2-year reciprocal translocation experiment was implemented to simulate climate warming (i.e. downward translocation) and cooling (i.e. upward translocation) along an elevation gradient with four different vegetation types (at 3200, 3400, 3600 and 3800 m elevation) during the growing season (May to October) in 2008 and 2009. Results: Although the effects of warming and cooling varied depending on vegetation type, elevation and timescale (i.e., daily and seasonally), warming increased average seasonal CH4 uptake by 60 %, while cooling reduced it by 19 % across all vegetation types, based on a 1.3–5.1 °C difference in soil temperature at 20 cm depth. Soil temperature over the range of 4–10 °C explained 11–25 % of the variation in average seasonal CH4 fluxes, while there was no relationship with soil moisture over the range of 13–39 % and soil NH4 +-N and NO3 −N content. Methane uptake was more sensitive to warming than to cooling. Conclusions: Because of warming and cooling spells in the alpine region, warming effects on CH4 uptake would be over-estimated by 64 % if cooling effects on it are not considered. Our findings suggest that asymmetrical responses of CH4 fluxes to warming and cooling should be taken into account when evaluating the effects of climate change on CH4 uptake in the alpine meadow on the Tibetan plateau. © 2016 Springer International Publishing Switzerland Source


Huang L.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Huang L.,Key Laboratory of Stress Physiology and Ecology in Cold and Arid Regions of Gansu Province | Zhang Z.S.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Zhang Z.S.,Key Laboratory of Stress Physiology and Ecology in Cold and Arid Regions of Gansu Province | And 2 more authors.
Journal of Arid Land | Year: 2014

Biological soil crusts (BSCs) are an important type of land cover in arid desert landscapes and play an important role in the carbon source-sink exchange within a desert system. In this study, two typical BSCs, moss crusts and algae crusts, were selected from a revegetated sandy area of the Tengger Desert in northern China, and the experiment was carried out over a 3 year period from January 2010 to November 2012. We obtained the effective active wetting time to maintain the physiological activity of BSCs based on the continuous field measurements and previous laboratory studies on BSCs photosynthesis and respiration rates. And then we developed a BSCs carbon fixation model that is driven by soil moisture. The results indicated that moss crusts and algae crusts had significant effects on soil moisture and temperature dynamics by decreasing rainfall infiltration. The mean carbon fixation rates of moss and algae crusts were 0.21 and 0.13 g C/(m2·d), respectively. The annual carbon fixations of moss crusts and algae crusts were 64.9 and 38.6 g C/(m2·a), respectively, and the carbon fixation of non-rainfall water reached 11.6 g C/(m2·a) (30.2% of the total) and 8.8 g C/(m2·a) (43.6% of the total), respectively. Finally, the model was tested and verified with continuous field observations. The data of the modeled and measured CO2 fluxes matched notably well. In desert regions, the carbon fixation is higher with high-frequency rainfall even the total amount of seasonal rainfall was the same. © 2014 Xinjiang Institute of Ecology and Geography, the Chinese Academy of Sciences and Springer - Verlag GmbH. Source


Zhang Z.S.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Zhang Z.S.,Key Laboratory of Stress Physiology and Ecology in Cold and Arid Regions of Gansu Province | Chen Y.L.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Chen Y.L.,Key Laboratory of Stress Physiology and Ecology in Cold and Arid Regions of Gansu Province | And 7 more authors.
Journal of Arid Land | Year: 2014

Biological soil crusts (BSCs) play an important role in surface soil hydrology. Soils dominated with moss BSCs may have higher infiltration rates than those dominated with cyanobacteria or algal BSCs. However, it is unnown whether improved infiltration in moss BSCs is accompanied by an increase in soil hydraulic conductivity or water retention capacity. We investigated this question in the Tengger Desert, where a 43-year-old revegetation program has promoted the formation of two distinct types of BSCs along topographic positions, i.e. the moss-dominated BSCs on the interdune land and windward slopes of the fixed sand dunes, and the algal-dominated BSCs on the crest and leeward slopes. Soil water retention capacity and hydraulic conductivity were measured using an indoor evaporation method and a field infiltration method. And the results were fitted to the van Genuchten-Mualem model. Unsaturated hydraulic conductivities under greater water pressure (<-0.01 MPa) and water retention capacities in the entire pressure head range were higher for both crust types than for bare sand. However, saturated and unsaturated hydraulic conductivities in the near-saturation range (>-0.01 MPa) showed decreasing trends from bare sand to moss crusts and to algal crusts. Our data suggested that topographic differentiation of BSCs significantly affected not only soil water retention and hydraulic conductivities, but also the overall hydrology of the fixed sand dunes at a landscape scale, as seen in the reduction and spatial variability in deep soil water storage. © 2015, Xinjiang Institute of Ecology and Geography, the Chinese Academy of Sciences and Springer - Verlag GmbH. Source


He M.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Dijkstra F.A.,University of Sydney | Zhang K.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Tan H.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | And 4 more authors.
Plant and Soil | Year: 2015

Aim: Desert herbs, a crucial component of desert ecosystems, are sensitive to water and nutrient availability and therefore to environmental change. We aimed to determine element concentrations in desert herbs and their relationships with life form, taxonomy, climate, and soil environment. Methods: We measured concentrations of 11 elements in shoots and roots of 26 dominant desert herb species from 45 sites in a temperate desert. Results: Shoots of desert herbs had greater concentrations of elements related to photosynthesis and water use efficiency (N, P, Mg, K) than roots. Concentrations of these elements (except N and P) were also greater in annual herbs than in perennial herbs. Greater Mg, K, and Na concentrations were observed in shoots of Chenopodiaceae (mostly C4 species) than in Poaceae (mostly C3 species). Soil properties and taxonomy explained 3.6–26 % and 2.8–24 % of the variation in shoot element concentrations, respectively, whereas climate factors explained only 0.05–6.5 % of the variation. Conclusions: Water and nutrient availability, which are affected by environmental change, influence concentrations of mineral elements in desert plants and their biogeochemical cycles in desert ecosystems. © 2015 Springer International Publishing Switzerland Source

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