不同建植期人工草地优势种植物根系活力、群落特征及其土壤环境的关系

Relationships of dominant species root activity,plant community characteristics and soil micro-environment in artificial grassland over different cultivation periods

以三江源区重度退化草地("黑土滩")作为对照试验,研究了6年人工草地和10年人工草地优势种植物-垂穗披碱草根系活力、植物群落数量特征、土壤理化特征、6种土壤酶活性,分析人工草地优势种植物根系活力、群落数量结构与土壤微环境的关系。研究结果表明,6年人工草地的禾本科植物生物量最大、豆科植物开始入侵;10年人工草地的禾本科植物较6年人工草地生物量降低,杂类草生物量最大,豆科植物大量入侵,开始出现莎草科植物;人工草地根层土壤理化性质明显发生变化,土壤含水量、有机质、全氮、速效氮、全磷和速效磷的含量提高,土壤容重、温度、pH值降低;6年和10年人工草地的蔗糖酶、碱性磷酸酶、蛋白酶、脲酶的活性提高,多酚氧化酶活性降低,过氧化氢酶活性变化规律不明显。植物群落特征与土壤含水量、有机质、速效氮、全磷和水解酶类正相关,与土壤容重、pH值、多酚氧化酶负相关;垂穗披碱草根系活力与土壤含水量、pH值、蛋白酶、碱性磷酸酶和多酚氧化酶活性负相关;垂穗披碱草根系活力变化的趋势是6年人工草地高于10年人工草地,土壤微环境的改变使得植物间对于土壤资源利用竞争增大,植物根系活力随群落物种组成、生物量的分配而改变。

Three river source regions were contrasted with heavily degraded grassland（black soil patch） by studying,the root activity of Elymus nutans（the dominant species）,plant community quantity characteristics,soil physicochemical properties and activities of six soil enzymes over six and ten years of artificial grassland.The relationship of root activity of the dominant species,community quantity structure and soil micro-environment of artificial grassland were analysed.The biomass of grass became the largest part of the plant community and legumes began to invade in six year old artificial grassland.The biomass of grass in ten year old artificial grassland was lower than that of the six year artificial grassland,in which the biomass of forbs became the largest component of the plant community.There was an immense invasion of legumes,and sedges also began to emerge.Soil physicochemical properties had marked changes in artificial grassland.Soil moisture,organic matter,total nitrogen,available nitrogen,total phosphorus and available phosphorus increased while soil bulk density,temperature and pH value decreased.The activities of invertase,alkali phosphatase,protease and urease of six year and of ten year artificial grassland increased but the polyphenol oxidase activity was reduced.The catalase activity was not obviously changed.Plant community characteristics were positively related to soil moisture,organic matter,available nitrogen,total phosphorus and hydrolysis enzymes whereas plant community characteristics were negatively related to soil bulk density,pH value and polyphenol oxidase.The root activity of E.nutans was negatively related to soil compaction,soil moisture,pH value,protease,alkali phosphatase,polyphenol oxidase.Analysis showed that the variation trend of root activity of E.nutans in 6 year artificial grassland was more than that in 10 year artificial grassland.The changes in soil micro-environment led to increasing plant competition for soil resource utilization.The root activity of plants changed with the different species composition and biomass distribution of the plant community.