Li Z.,Cold and Arid Region Environment and Engineering Research Institute |
Li Z.,University of Chinese Academy of Sciences |
He Y.,Cold and Arid Region Environment and Engineering Research Institute |
He Y.,Lanzhou University |
And 9 more authors.
Acta Geographica Sinica | Year: 2010
Based on daily temperature and precipitation data of 27 stations in the Mts. Hengduan region, methods of spline interpolation, regression analysis, least square, moving average were employed to analyze the climatic changing trend and spatial differences under the background of global warming. Results indicated that temperature patterns are consistent with warming at statistical significance level during 1960-2008, and relatively low in the 1960s and 1980s, whereas it started to rise after the 1980s which can be proved by a 0.46 °C temperature increase in 2000-2008. The average temperature of all the year, spring, summer, autumn and winter exhibited an obvious increasing trend roughly centered in the area of Mt. Meili and the southernmost between Mt. Shaluli and Mt. Daxue with the velocity of 0.15 °C 10a-1, 0.589 °C 10a-1, 0.153 °C 10a-1, 0.167 °C 10a-1 and 0.347 °C 10a-1, respectively. And what's more, temperature increase is more obvious from lower to higher altitude. Precipitation is relatively more after the 1980s, which can be confirmed by a 29.84 mm increase in the 1990s, but it started to decrease after 2000. The average precipitation of all the year, spring, summer, autumn and winter changed by 9.09 mm 10a -1, 8.62 mm 10a-1, -1.5 mm 10a-1, 1.53 mm 10a-1 and 1.47 mm 10a-1, respectively, roughly centered in the area of Mt. Meili and the southernmost between Mt. Shaluli and Mt. Daxue, and only the spring is significant at the 0.05 level. Under the influence of the longitudinal range-gorge, the regional trend in precipitation was on the decrease from southwest to northeast and from south to north in the Mts. Hengduan region. In summer monsoon, the regional trends of temperature and precipitation are 0.117 °C 10a-1 and 6.01 mm 10a-1, respectively, but the precipitation also started to decrease after 2000. There is also a 0.25 °C 10a-1 and 7.47 mm 10a-1 increase of temperature and precipitation in winter monsoon.
Liu P.-X.,Northwest Normal University |
Lu C.-Y.,Northwest Normal University |
Yao X.-J.,Northwest Normal University |
Yao X.-J.,Cold and Arid Region Environment and Engineering Research Institute |
Cao L.-G.,Northwest Normal University
Beijing Linye Daxue Xuebao/Journal of Beijing Forestry University | Year: 2011
In order to investigate the age structure and spatial distribution patterns of Populus euphratica populations in different habitats, five plots, totally 6.25 hm 2, were established in the Dunhuang Oasis, western China. Seven aggregation indices were measured using a contiguous quadrat method and tally inventory. The results indicated that the study area was short of saplings, and juveniles were scarce, resulting in an inverse pyramidal age structure of P. euphratica populations and showing a trend of declining populations. The P. euphratica stands were aged, sparse and dwarfish. The age structure of P. euphratica populations varied remarkably among different habitats, among which, that of HK population was the most incomplete with the rapidest declining succession. In general, the spatial distribution of P. euphratica populations conformed to a clumped distribution pattern except for the DMMT population. The age structure and the spatial distribution pattern of P. euphratica populations were closely related to biological and ecological characteristics of the species and the heterogeneous environmental factors such as landform, water resources, climate and soil.