Response of photosynthesis, morphology and growth of Hedysarum mongolicum seedlings to simulated precipitation change in Maowusu sandland

Response patters were investigated for seedlings of Hedysarum mongolicum, a dominant shrub in Maowusu sandland, to the simulated precipitation change by artificially controlling water supply at four levels. Plant growth characters, in terms of branch number and length, leaf number and area, and biomass, increased while water supply increased. However, the effect of water supply on leaf photosynthetic rate was not significant. Root/shoot biomass ratio significantly decreased with the increase of water supply, which was considered adaptive distribution of biomass investments in the different water supply. Water supply obviously affected branching patter. Branch section number, branch number and length of the same section enhanced as water supply increased. Branch number and length were clearly positive correlation with total and aboveground biomass in four water supply treatments. Branch character fully showed plant growth.

高压电场对毛乌素沙地两种优势植物抗旱性的影响

以毛乌素沙地优势植物柠条(Caraganaintermedia)和沙蒿(Artemisiasongaricaschrenk)种子为对象,采用人工模拟干旱试验方法,研究不同电场处理后这2种植物种子萌发和生物量对土壤干旱胁迫的响应。结果表明,电场处理缓解了2种植物随干旱程度加重出现的负效应,不同处理条件,种子萌发和生物量对干旱胁迫的适应性的影响不同,电场处理能够提高种子在干旱胁迫条件下的发芽率和发芽势,提高2种沙生植物生物量干重和鲜重。这些变化缓解了干旱胁迫对柠条和沙蒿种子的伤害,提高了其对干旱胁迫的适应性。

松嫩沙地末次冰期以来降水量和干燥度的时空变化

根据表土花粉与降水量和干燥度相关的原理,选择对降水量和干燥度有指示意义的花粉的百分含量,运用多元线性回归分析的方法,推算了松嫩沙地末次冰期以来的古降水量和古干燥度,并在此基础上推测了沙地的环境演化过程.

榆林毛乌素沙地针叶树造林技术试验

通过对榆林毛乌素沙地针叶树造林技术的系统研究,提出干旱沙地营造针叶林的综合配套技术是:因地选树、壮苗保湿、根系处理、合理稀植、适当深栽、覆盖保墒等,有效提高了造林成活率。提出合理的造林密度应为3m×3m或3m×4m,造林季节以雨季为主。初步解决了榆林毛乌素沙地以樟子松为主的针叶树造林技术问题。

半干旱地区沙地景观破碎化趋势分析——以科尔沁沙地为例

采用RS和GIS手段 ,对科尔沁沙地典型地区不同时期的农田和固定沙丘景观数量和形状破碎化的趋势进行分析 ,结果表明 :农业生产活动对农田景观的影响主要表现在对斑块数量破碎化的影响 ,而对斑块形状破碎化的影响不大。放牧过程对固定沙丘景观破碎化的影响非常显著 ,这一过程不仅影响到斑块数量破碎化 ,而且也影响到斑块形状破碎化。回归分析结果 ,二者为较复杂的抛物线型关系。此外 ,沙漠化过程对农田和固定沙丘景观破碎化影响的关联分析表明 ,沙漠化过程与所有的破碎化指数呈负关联。其中 ,除农田形状破碎化指数外 ,其他破碎化指数与沙漠化过程无显著的关联 ,说明随着沙漠化程度的增大 ,农田斑块的形状简单化的趋势也加强。