首页 > 分享 > 短花针茅荒漠草原植被群落结构及生物量对水氮变化的响应

短花针茅荒漠草原植被群落结构及生物量对水氮变化的响应

花匠小妙招
2024-11-09 00:26

摘要： 为了解降水变化和氮沉降对荒漠草原植被群落结构和生物量的影响,在内蒙古四子王旗短花针茅荒漠草原进行水氮交互试验,采用裂区试验设计,主区为CK(自然降水)、W(增水30%)、R(减水30%),副区为0 (N0)、30 (N30)、50 (N50)、100 (N100) kg N·hm-2·a-1共12个处理。结果表明:1)水氮的介入导致植物群落组成、重要值发生了明显变化,R中群落物种数最低,提高了优势种在群落中的重要值,氮素添加导致群落物种数呈“抛物线”型,群落物种数先增多后减少。2) CK、W、R条件下随施氮量增加,物种丰富度、Shannon-wiener多样性指数和Pielou均匀度指数均先增大后减小,2016和2018年在CK-N30、W-N30、R-N50达到最大值,干旱年份(2017)分别在CK-N30、W-N50、R-N100达到最大值。水分主效应、氮素和水氮交互作用均对以上3个植物多样性指数有显著影响(P<0.05)。3)水分和氮素刺激了地上生物量的增加,短期氮素添加使多年生禾草生物量在地上总生物量中占比增加,多年生杂草生物量在地上总生物量中占比减小。水分、氮素、水氮交互均对地上生物量有显著影响(P<0.05)。

关键词: 氮沉降, 降水变化, 荒漠草原, 群落结构, 生物量

Abstract: An experiment comprising a factorial combination of three water and four nitrogen levels (12 treatments), laid out in a split plot design, was conducted to understand the effects of precipitation change and nitrogen deposition on vegetation community structure and biomass in Stipa breviflora desert steppe in Siziwang Banner, Inner Mongolia. The main plot treatments were: CK (natural rainfall), W (30% rainfall addition), R (30% rainfall reduction), while the subplot treatments were 0 (N0), 30 (N30), 50 (N50), and 100 (N100) kg N·ha-1·a-1. The results show: 1) The application of water and nitrogen resulted in significant changes in community composition and species importance values. The R treatment had the lowest number of community species, and the importance value of dominant species in community was increased. The addition of nitrogen resulted in a curve of ‘parabola’ shape for number of species present (i.e. the number of community species was higher at medium nitrogen application rates than at N0 or N100). 2) With increased rate of nitrogen addition, species richness, Shannon-wiener diversity and Pielou evenness index were initially increased, but decreased at higher nitrogen application rates. The maximum values were observed in treatments CK-N30, W-N30 and R-N50 in 2016 and 2018, and the lowest value of CK-N30, W-N30, R-N50 in the drought year (2017), respectively. The main effects of water, nitrogen and water-nitrogen interaction all have significant effects on the above three plant diversity indexes (P<0.05). 3) Water and nitrogen both stimulated aboveground biomass increase. Water, nitrogen as well as water and nitrogen interaction have significant effects on aboveground biomass (P<0.05). The proportion of perennial grasses in the total aboveground biomass was increased by short-term nitrogen addition, while the percentage of perennial weeds was decreased.

Key words: nitrogen deposition, precipitation variation, desert steppe, community structure, biomass