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| 1 | Combined effects of snow depth and nitrogen addition on ephemeral growth at the southern edge of the Gurbantunggut Desert,China显示文摘Water and nitrogen(N) inputs are considered as the two main limiting factors affecting plant growth.Changes in these inputs are expected to alter the structure and composition of the plant community,thereby influencing biodiversity and ecosystem function.Snowfall is a form of precipitation in winter,and snow melting can recharge soil water and result in a flourish of ephemerals during springtime in the Gurbantunggut Desert,ChinaA bi-factor experiment was designed and deployed during the snow-covering season from 2009 to 2010.The experiment aimed to explore the effects of different snow-covering depths and N addition levels on ephemerals.Findings indicated that deeper snow cover led to the increases in water content in topsoil as well as density and coverage of ephemeral plants in the same N treatment;by contrast,N addition sharply decreased the density of ephemerals in the same snow treatment.Meanwhile,N addition exhibited a different effect on the growth of ephemeral plants:in the 50% snow treatment,N addition limited the growth of ephemeral plants,showing that the height and the aboveground biomass of the ephemeral plants were lower than in those without N addition;while with the increases in snow depth(100% and 150% snow treatments),N addition benefited the growth of the dominant individual plants.Species richness was not significantly affected by snow in the same N treatment.However,N addition significantly decreased the species richness in the same snow-covering depth.The primary productivity of ephemerals in the N addition increased with the increase of snow depth.These variations indicated that the effect of N on the growth of ephemerals was restricted by water supply.With plenty of water(100% and 150% snow treatments),N addition contributed to the growth of ephemeral plants;while with less water(50% snow treatment),N addition restricted the growth of ephemeral plants. | LianLian FAN Yan LI LiSong TANG Jian MA | 2013 | Journal of Arid Land2013，5，4： | 19 |
| 2 | 安西极旱荒漠自然保护区植物群落的季节变化和年际变化以及气候对变化的影响显示文摘在安西极旱荒漠自然保护区的典型植物群落中选取6个平行样方,连续3年调查植物数量、盖度和物种数量的季节变化和年际变化以及气候对植物群落季节变化和年际变化的影响.结果显示:植物群落物种数量和植株数量的季节变化主要是由一年生草本植物的季节变化引起的,而多年生灌木盖度的季节变化是植物群落盖度变化的主要原因.植物群落物种数量、植株数量和盖度的年际变化主要源于一年生草本植物物种数量、植株数量和盖度的变化.植物群落物种数量、植株数量和盖度的季节变化与降雨量和气温的变化正相关,而年际变化与降雨量和气温的变化关系不大.因此,降雨和气温仅影响荒漠植物群落结构的季节变化,而对年际变化影响不大.在气候条件变化较小的范围内,荒漠植物群落结构保持相对稳定的结构. | 郑凯 袁建立 王亮 宋晓谕 马强 高天鹏 | 2013 | 兰州大学学报(自然科学版)2013，49，5： | 10 |
| 3 | Desert vegetation distribution and species-environment relationships in an oasis-desert ecotone of northwestern China显示文摘Environmental heterogeneity significantly affects the structure of ecological communities.Exploring vegetation distribution and its relationship with environmental factors is essential to understanding the abiotic mechanism(s)driving vegetation succession,especially in the ecologically fragile areas.In this study,based on the quantitative analysis of plant community and environmental factors in 68 plots at 10 different transects in the Minqin oasis-desert ecotone(ODE)of northwestern China,we investigated desert vegetation distribution and species-environment relationships using multivariate analysis.Two-way indicator species analysis(TWINSPAN),detrended correspondence analysis(DCA),and canonical correspondence analysis(CCA)methods were used.A total of 28 species,belonging to 27 genera in 8 families,were identified.Chenopodiaceae,Zygophyllaceae,Gramineae,and Leguminosae were the largest families.Annual and perennial herbs accounted for 28.60%of the total number of plants,while shrubs(42.90%)were the most dominant.Nitraria tangutorum was the constructive species of the desert plant community.We divided the 68 plots surveyed in this study into 7 community types,according to the results of TWINSPAN.The distribution of these 7 communities in the DCA ordination graph showed that species with a similar ecotype were clustered together.Results of CCA indicated that groundwater was the dominant factor influencing vegetation distribution,while distance between plot and oasis(Dis)and soil electrical conductivity(EC)were the local second-order factors.Our study suggests that optimizing the utilization of groundwater in oases is key to controlling the degradation of desert vegetation.The favorable topographic conditions of sand dunes should be fully utilized for vegetal dune stabilization,and the influence of soil salinity on the selection of afforestation tree species should be considered. | ZHAO Peng QU Jianjun XU Xianying YU Qiushi JIANG Shengxiu ZHAO Heran | 2019 | Journal of Arid Land2019，11，3： | 2 |
| 4 | Phenology of desert plants from an arid gravel plain in eastern United Arab Emirates显示文摘Phenological events for desert plants were recorded and rainfall and temperature data were gathered over a three-year time scale at a gravel plain in the eastern region of the United Arab Emirates. Variations of phenological periods were analyzed and correlations between phenological periods and climate factors were discussed. The study showed that the growth and flowering of therophytes were significantly correlated with air temperature. The timing and abundance of rainfall came to be another factor significantly correlated with the onset and duration of chamaephyte flowering as well as the duration of therophyte growth and flowering. The variation in rainfall did not affect the onset of flowering in phanerophytes. Peak growing seasons were from November to March and flowering from November to December(also February to March depending on the availability of rainfall). Flowering in phanerophytes and chamaephytes occurs 4–6 weeks and in therophytes 4–8 weeks after rain. The results showed that variations in growth and phenology between species were correlated with environmental factors, such as temperature and rainfall or, maybe, differences in life form and photosynthetic pathways, each being adapted for utilizing a particular phase of the seasonally and yearly variable rainfall. The sequence of flowering for the species under study was more or less constant despite the difference in the amount of rainfall. The fruiting patterns of most of the species were also found parallel to their flowering patterns. Our results emphasized the need to study multiple species at many sites for the understanding and forecast of regional changes in phenology. | Sabitha SAKKIR Junid N SHAH Abdul J CHERUTH Maher KABSHAWI | 2015 | Journal of Arid Land2015，7，1： | 0 |
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