晋西北丘陵风沙区不同人工植被恢复模式生态效应研究

Sandy-Hilly region of northwest Shanxi where the severe water erosion and wind erosion happened is the most extremely frail eco-environment of Shanxi province. It is also the important sand blocking of Jingjintang region. Vegetation such as Populus simonii, Caragana korshinskii have degraded obviously and need to be updated in this region. Though the single ecological effects research of artificial vegetation restoration pattern in vegetation succession, soil properties changes, soil and water conservation has been studied respectively, the total ecological effects had become much more complicated and have few studies in this region. The experimental site of this research located in a small basin which is a typical sandy-hilly region in Youyu County. Based on field observation, laboratory experiment and data analysis, the total ecological effects of different artificial vegetation restoration patterns will be compared from vegetation population, species diversity,community stability,soil physical and chemical properties,soil hydro-ecological effect,etc. The interaction between vegetation restoration and soil properties changes also will be studied. Selection and optimization of suitable vegetation pattern is the purpose of the study. This research will have great importance in instructing the ecological environment construction and optimizing vegetation patterns existed in this region.

晋西北丘陵风沙区水蚀风蚀交错发育，土壤侵蚀强烈，土地沙化严重，是山西省生态环境极脆弱区，也是环京津塘地区防风固沙的前沿阵地。研究区种植的大量小叶杨、柠条锦鸡儿灌丛现已明显退化，亟待进行抚育更新。目前针对晋西北丘陵风沙区的植被恢复研究多为植被群落演替、土壤质量动态、水土保持功能等单一效应的研究，系统的综合效应研究尚不多见。本研究从区分晋西北丘陵风沙区的生态环境异质性开始，通过不同人工植被模式的生态效应对比，探讨植被对生态环境的影响机理，达到筛选适宜植被模式并进行优化的目标。本研究为晋西北地区植被建设提供科学的理论指导，有助于加速现有植被结构的优化调控。

晋西北丘陵风沙区土壤侵蚀强烈，生态环境脆弱。从上世纪70年代开始，这里陆续开展了“三北”防护林、退耕还林和京津风沙源治理工程。经过多年植被建设，如何正确认识和评估人工植被恢复的生态效应？该问题的解决有助于加速现有植被结构的优化调控，为区域植被工程建设提供科学指导。.本研究通过野外调查、实地观测和实验室测定分析，对不同坡向（全阴、全阳和半阴半阳）不同坡位（上、下）的不同人工植被恢复模式从植被群落特征和演替动态、土壤水分特征、土壤养分特征（全氮、全磷、有效磷、有效钾、PH、有机质）、土壤微生物数量（细菌、真菌、放线菌、固氮菌、反硝化细菌）、土壤微生物学性质（土壤微生物量碳、土壤微生物量氮）和主要酶活性特征（蔗糖酶、脲酶、过氧化氢酶、多酚氧化酶、碱性磷酸酶）以及粒径（黏土含量、中沙、粗沙含量）等方面进行比较，分析各指标之间的相互关系，运用主成分分析法计算不同人工植被模式的综合生态效应。主要结论如下：. （1）乔灌混交林结构复杂，物种丰富度和物种多样性指数均较高；. （2）表层土壤水分空间分布相对均质，随着土层深度增加，空间异质性增强。土壤水分空间变异是坡向、坡度和植被模式综合作用的结果；. （3）雨季雨量充沛可以提供土壤层有效补给，但植被恢复仍存在不同程度的水分亏缺。自然恢复草地水分亏缺最少，灌木次之，乔木最多；恢复时间越长，造林密度越大，亏缺越严重；. （4）4种植被模式蓄水保土效应由大到小依次为：油松与柠条混交林、柠条纯林、油松纯林和草地；草地蓄水保土作用显著大于农地和裸地；撂荒和自然恢复能够明显增强蓄水保土能力；. （5）晋西北丘陵风沙区植被恢复和结构配置应以立地土壤水分承载力为前提。新增植被应以灌草为主体，阴坡可配置沙棘，阳坡宜引入柠条和针茅、蒿类等草本植物，避免大面积营造乔木纯林；加紧对不同等级的退化人工林实施结构调整和密度控制，开展疏伐，并适时引入灌草；保护天然草地，重视自然恢复，倡导草田轮作。