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林业科学 ›› 2021, Vol. 57 ›› Issue (12): 1-12.doi: 10.11707/j.1001-7488.20211201

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荒漠草原灌丛转变土壤水分与地上生物量空间异质性及阈值响应

赵亚楠1,赵亚峰1,王红梅1,2,*,马彦平1,李志丽1   

  1. 1. 宁夏大学农学院 银川 750021
    2. 西北退化生态系统恢复与重建教育部重点实验室 银川 750021
  • 收稿日期:2020-05-11 出版日期:2021-12-25 发布日期:2022-01-26
  • 通讯作者: 王红梅
  • 基金资助:
    国家自然科学基金项目(31860677);宁夏科技支撑计划项目(2015惠民计划);宁夏高等学校一流学科建设(草学学科)资助项目(NXYLXK2017A01)

Response of Spatial Heterogeneity and Threshold Value for Soil Water and Aboveground Biomass of Desert Grassland-Shrubland Anthropogenic Transition in Desert Steppe of Ningxia, China

Yanan Zhao1,Yafeng Zhao1,Hongmei Wang1,2,*,Yanping Ma1,Zhili Li1   

  1. 1. School of Agriculture, Ningxia University Yinchuan 750021
    2. Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest China of Ministry of Education Yinchuan 750021
  • Received:2020-05-11 Online:2021-12-25 Published:2022-01-26
  • Contact: Hongmei Wang

摘要:

目的: 研究宁夏东部荒漠草原灌丛转变土壤含水量和植被地上生物量的空间特征,探求荒漠草原植被承载的适宜土壤水分生态阈值,以期为优化荒漠草原植被恢复模式提供理论依据。方法: 利用GIS和地统计学方法,对该地区43个典型的荒漠草原-灌丛镶嵌体区域分别进行草地和相邻灌丛0~200 cm土层土壤含水量及植被地上生物量的空间异质性分析。结果: 经典统计分析表明:0~200 cm土层的平均土壤含水量表现为草地(6.23%)大于灌丛(5.47%),在80~200 cm土层尤为明显,草地和灌丛土壤含水量分别为1.37%~25.36%和1.5%~19.58%;草地和灌丛的0~200 cm土层土壤含水量变异系数为28.94%~62.30%,均属中等变异,且灌丛土壤含水量的变异系数较高;草地和灌丛地上生物量分别为0.06和0.56 kg·m-2,两者的变异系数均为中等变异。地统计分析表明:0~200 cm土层土壤含水量的结构方差比[C/(C0+C)]表现为草地(0.75)大于灌丛(0.64),且均随土层加深而逐渐减小;土壤含水量的变程(A0)表现为灌丛(45.84 km)显著大于草地(18.56 km)(P < 0.05),两者在120~200 cm土层的最佳半变异函数模型均为纯块金效应模型;植被地上生物量的结构方差比表现为灌丛(0.76)大于草地(0.37),变程表现为草地(43.91 km)显著大于灌丛(12.77 km)(P < 0.05)。基于植被转变地上生物量和土壤含水量现状分析,荒漠草原0~200 cm土层土壤含水量响应阈值为8.11%~14.19%。结论: 荒漠草原灌丛转变显著增加了地上植被生物量,使其在景观尺度上的空间异质性增强,并加速了深层土壤水分的利用消耗,降低了土壤含水量及其在景观尺度上的异质性,因调查年份及前期数年降雨偏多,草地、灌丛的较深层土壤含水量均呈纯块金效应。

关键词: 荒漠草原, 灌丛引入, 土壤水分, 生物量, 空间异质性

Abstract:

Objective: In order to provide theoretical foundation for desert steppe vegetation conservation, the spatial characteristics of soil water content and above-ground vegetation biomass and the appropriate soil moisture threshold in desert steppe-shrubland transition in eastern Ningxia were analyzed. Method: Spatial heterogeneity of soil moisture in 0-200 cm soil layer and the related above-ground biomass were investigated in 43 shrubland sites and 43 grassland sites of desert steppe in eastern Ningxia via GIS and geostatistics methods. Result: It was shown that soil moisture was higher in grassland (6.23%) than that in shrubland (5.47%), with the variation ranging from 1.37% to 25.36% in the former and 1.5% to 19.58% in the latter, especially in the 80-200 cm soil layer. The coefficient of variation (CV) of soil moisture moderately ranged from 28.94% to 62.30% in both vegetation types between which soil moisture in shrubland was generally higher than that in grassland. And the related above-ground biomass was higher in shrubland (0.56 kg·m-2) than that in grassland (0.06 kg·m-2), and the coefficients of variation were moderate for both. Geostatistical results showed that the structural variation ratio [C/(C0+C)] of soil moisture in 0-120 cm soil layer was higher in grassland (0.75) than that in shrubland (0.64). The structural variation ratio of soil moisture between 0-120 cm soil layer gradually decreased along with the increase of soil depth. The range (A0) in shrubland (45.84 km) was higher than that in grassland (18.56 km) (P < 0.05), and the soil moisture in 120-200 cm soil layer followed a pure nugget effect model. The structural variation ratio of above-ground biomass was higher in shrubland (0.76) than that of grassland (0.37), and the range (A0) in grassland (43.91 km) was significantly higher than that of shrubland (12.77 km) (P < 0.05). We obtained the suitable soil moisture threshold 8.11%-14.19% in the transition from desert grassland to shrubland according to the response characteristics of above-ground biomass and soil moisture. Conclusion: During the transition from desert grassland to shrubland, accelerated deep soil water consumption accompanied with the increased above-ground biomass and related spatial heterogeneity and the decreased spatial heterogeneity of soil moisture in landscape scale. And the pure nugget effect model was found for deeper soil layer moisture in grassland and shrubland due to increased rainfall in the survey and previous years.

Key words: desert steppe, introduced shrub, soil moisture, biomass, spatial heterogeneity

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