退化禾草/白三叶草地植被和土壤特征

Vegetation and soil characteristics of degraded grass/Trifolium repens grassland

禾草/白三叶(Trifolium repens)草地是中国南方喀斯特地区主要刈牧地之一,探究退化禾草/白三叶草地植物个体、种群、群落及土壤养分变化特征,可一定程度为该类草地退化等级的划分提供科学依据。定量分析了显著退化(DG)和未退化(CK)禾草/白三叶草地多年生黑麦草分蘖和白三叶匍匐茎特征、群落特征、生物量构成、土草养分及群落稳定性。结果显示:1)群落高度,盖度和地上生物量及多年生黑麦草分蘖密度和分蘖重均为CK>DG,白三叶匍匐茎密度和匍匐茎重在CK与DG之间相近;2)播种禾草(多年生黑麦草Lolium perenne+鸭茅Dactylis glomerata)地上生物量比例为CK(83.750%±2.067%)>DG(55.100%±4.593%),杂类草和白三叶地上生物量比例为CK<DG;3)0~10 cm土壤pH、OM和全P含量为CK>DG;(4)CK草地植物种Raunkiaer频度直方图接近反J型,群落处于相对稳定状态,群落演替度值为CK(42.25±3.43)<DG(53.27±3.64),退化草地处于更高演替阶段。研究认为,多年生黑麦草分蘖、播种牧草的生物量构成及土壤pH,可作为禾草/白三叶草地退化等级划分依据。

Grass/Trifolium repens grassland is one of the main pastures for grazing and hay harvesting in the karst areas of southern China.Clarifying the characteristics of individual,population and community of plant,and soil nutrients of degraded grass/Trifolium repens grassland will provide scientific basis for its classification.The Lolium perenne tillers,T.repens stolons,community characteristics,biomass composition,soil-herbage chemical characteristics and community stability of degraded grassland(DG)and un-degraded grassland(CK)were quantitatively measured.The results showed that 1)Height,coverage and aboveground biomass of plant community,and tiller density and tiller weight of L.perenne were CK>DG,while the density and weight of ereT.repensere stolons were similar between CK and DG.2)The aboveground biomass composition of the sown grass(L.perenneere+Dactylis glomerataere)was CK(83.750%±2.067%)>DG(55.100%±4.593%),while for the forbs and L.perenne,it was CK>DG.3)The pH,organic matter and total P in 0~10 cm soil layer were CK>DG.The species Raunkiaer frequency histogram of CK was inversely J-type,which was relatively stable,while the community succession value was CK(42.25±3.43)<DG(53.27±3.64),CK was in a higher succession stage.L.perenne tillers,biomass composition of sown grass and T.repens,and soil pH could be used as the basis for classification of graded grass/Trifolium repens grassland.