黄土丘陵区退耕草地群落冠层降雨截留容量特征及其量化

Vegetation canopy rainfall interception is an important factor affecting limited rainfall partition and earth surface eco-hydrological processes in dry regions. To systematically investigate the canopy rainfall interception is of great importance for clarifying the rainfall availability and water cycle effects of vegetation withdrawn from farmlands. The research will take natural grassland communities withdrawn from farmlands for different years in loess hilly-gully region as research objects, after carrying on vegetation characteristics survey and in-situ observation, species water interception and holding performance measurements, and rainfall manipulation experiments. The objectives include: to investigate the water-holding capacity of each composition and leaf wettability characteristics of each species in grassland community, for investigating the interception traits of each species and their relative contribution to whole canopy interception capacity; to clarify the variations after comparing the canopy rainfall storage capacity of grassland communities withdrawn from farmlands at different growth years and seasons; to analyze the influence of grassland community structure and species composition change on the canopy rainfall interception capacity, and clarify the relationship between grassland community structure characteristics and canopy interception capacity, and thus to uncover the canopy rainfall interception loss and rainfall seasonal effectiveness. The study aims to provide the basic data and scientific basis for clarifying the eco-hydrological effects, and to evaluate the benefits of soil and water conservation and recovery potential of the grasslands withdrawn from farmlands in loess hilly-gully region.

植被冠层截留是影响旱区有限降雨再分配和地表生态水文过程的重要因素。系统研究黄土高原半干旱地区退耕植被冠层降雨截留特征，对揭示该区降雨有效性与植被恢复的水循环效应具有重要意义。本项目选取黄土丘陵区不同退耕年限的草地群落为研究对象，采用群落特征调查与观测、物种截留持水性能分析及模拟降雨试验相结合的研究方法，通过研究草地群落中构成物种各组分的持水能力及叶片润湿性特征，明确各构成物种截留持水量对群落冠层降雨截留容量的相对贡献；比较不同退耕年限草地群落不同生长阶段冠层截留容量特征及其差异，揭示草地群落冠层截留容量随退耕年限和生长季节的变化规律；分析退耕草地群落结构与物种构成改变对冠层降雨截留容量的影响，探明草地群落结构特征与冠层截留容量的相互关系，明确草地群落冠层降雨截留损失及其季节降雨有效性。旨在为阐明黄土丘陵区退耕草地的生态水文效应，评估退耕草地的水土保持效益和恢复潜力提供基础资料和科学依据。

降雨是黄土丘陵半旱区土壤水分的单一来源，有限降雨条件下植被冠层降雨截留容量大小直接影响土壤有效水补充量，阐明植被冠层降雨截留容量特征及其影响因素，对揭示该区降雨有效性与植被恢复的水循环效应具有重要意义。项目选取黄土丘陵区不同类型的退耕草地群落及其构成种为研究对象，采用群落特征调查与观测、物种截留持水性能分析及模拟降雨试验相结合的研究方法，揭示了黄土丘陵区退耕草地群落结构特征随退耕年限和生长季节变化规律及其对冠层截留容量的影响，探明了草地群落中各物种截留持水性能及其对冠层截留容量的相对贡献，明确了退耕草地群落冠层截留容量季节变异性及降雨季节有效性，量化了草地群落物种截留属性-结构特征-冠层截留容量间的水文关系。结果表明：黄土丘陵区常见的28科68种植物的叶片接触角变化范围为27.3°-133.4°。植物叶润湿性受叶侧、科别、叶龄物种本身属性影响，与生活型和立地环境关系不显著。叶面积指数和润湿性指数是预测植物截留容量大小的最佳指数。当年新生活体植物截留是不同优势种草地群落冠层截留的主要贡献者。地上部生物量和优势种类型显著影响草地群落冠层截留容量，与群落多样性指数无相关性；草地群落冠层截留降雨容量主要影响高度层是0-20cm。草地群落的降雨有效性受次降雨量、雨强和降雨历时有关，并受群落地上生物量鲜重、茎叶比及枯落物重量影响。6月到9月期间，白羊草群落、达乌里胡枝子群落和铁杆蒿群落冠层降雨截留容量分别为0.58~0.75 mm、0.65~0.82 mm和0.69~0.87 mm；冠层降雨截留率分别为7.88%~10.35%、8.85%~11.27%和9.39%~11.95%。项目执行期间，主要成员共参加7次国内外学术会议（包括1次国际学术会议和6次国内学术会议），其中大会报告1次，分组报告1次。围绕项目研究内容，共发表署项目编号的学术论文18篇（其中SCI收录期刊论文11篇，CSCD期刊论文7篇），培养毕业博士研究生2名、硕士研究生4名。申报国家发明专利1项。