不同恢复类型植被细根分布及与土壤理化性质的耦合关系

Fine root biomass distribution and coupling to soil physicochemical properties under different restored vegetation types

针对陕北典型黄土丘陵区吴起县主要人工造林和自然封育植被恢复类型,确定5、15年和40年不同退耕年限下的沙棘、山杏及自然恢复草地样地,进行剖面采样,分析不同植被恢复类型下细根生物量、土壤理化性质,研究了不同恢复类型和不同年限植被细根生物量与土壤理化性质随时间的变异规律及耦合关系。结果表明,(1)总体上,主要造林树种和退耕自然封育草地细根生物量都随林龄和退耕年限的增长呈增加趋势,同年限人工造林树种细根生物量大于自然恢复的草地,不同植被群落细根生物量均表现出随着深度的增加呈指数递减规律。(2)自然封育的草地生态系统土壤含水量大于人工山杏林和沙棘林。人工造林和自然封育植被恢复下,土壤团聚体稳定性都随退耕年限的增加而增强,有机质、全氮、全磷含量也都呈增加趋势,土壤平均含水量则呈减小趋势。(3)细根生物量与土壤容重和团聚体稳定性显著相关,植物细根在土壤结构改善中起到了重要作用。

In this study, according to the main types of artificial afforestation and natural enclosure vegetation restoration in Wuqi county in a typical loess hilly region of northern Shaanxi, samples of Hippophae reamnoides and Prunus armeniaca forests and natural restoration grassland under different cropping years after 5, 15, and 40 years were selected and sampled to determine soil profiles. The fine root biomass and soil physicochemical properties were analyzed, and variations in the regularity and coupling relationships between samples were evaluated under different restoration types and at different years. The results were as follows：（1） In general, the fine root biomass of abandoned grassland and P. armeniaca forests increased with an increase in the number of abandoned years and stand age. The fine root biomass of artificial tree species was larger than that of natural restoration grassland, and the biomass showed a decreasing exponential law with increasing depth. （2） The soil water content of the grassland ecosystem was significantly higher than that of artificial P. armeniaca and H. reamnoides forests. The stability of soil aggregates increased both under artificial afforestation and natural enclosure vegetation coverage, and the content of organic matter, total nitrogen, and total phosphorus were also improved. The soil average water content was reduced with the increase in abandoned years. （3） Fine root biomass showed an obvious correlation with soil bulk density and agglomerate stability, and fine roots played an important role in soil structure improvement.