| 摘要: |
| 【目的】分析植被自然演替过程中土壤团聚体的动态变化特征，为植被的近自然恢复和适地适树适草提供科学参考。【方法】选取黄土高原中部子午岭林区8个演替阶段（玉米地、退耕10 a草地、退耕20 a草地、白刺花灌木林、白桦林、油松林、辽东栎 油松混交林和辽东栎林）的典型地块设置样地，分层采集土样和植物根系，测定不同粒径（<0.25，0.25~0.5，0.5~1，1~2，2~5和≥5 mm）水稳性团聚体和有机质（SOM）含量及根系生物量(RB)，计算表征土壤团聚体稳定性的指标（平均质量直径（MWD）、分形维数（D）、≥0.25 mm水稳性团聚体含量（R0.25）、团聚体破坏率（PAD）），采用Spearman法分析不同粒径（<0.25，0.25~0.5，0.5~1，1~2，2~5和≥5 mm）水稳性团聚体含量与演替阶段、MWD、D、R0.25、PAD、RB、SOM的相关性。【结果】①在植被演替过程中，与演替初期（玉米地）相比，小粒径（<0.25 mm）水稳性团聚体含量总体减少，大粒径（≥5，2~5和1~2 mm）水稳性团聚体含量总体增加。②在植被演替过程中，MWD呈先增加后下降趋势，最大值出现在退耕20 a草地。与演替初期相比，植被演替总体上增加了MWD、R0.25，增幅分别为77.7%~148.4%和40.1%~71.1%；降低了PAD和D，降幅分别为48.0%~63.2%和3.4%~7.2%。③整个演替过程中，辽东栎 油松混交林直径≤2 mm的RB最大。各土层中，随着植被演替，SOM呈现先波动增加后略下降的变化趋势。④植被演替阶段与RB、SOM呈极显著正相关（P<0.01），MWD与2~5和≥5 mm水稳性团聚体含量、SOM呈极显著正相关（P<0.01），R0.25和SOM分别与D、PAD呈极显著负相关（P<0.01）。【结论】在植被演替过程中，与演替初期（玉米地）相比，土壤有机质含量和植被根系生物量均增加，土壤团聚体结构得以改善，团聚体粒径分布更趋合理，土壤抗蚀抗冲能力提高。 |
| 关键词: 植被演替 土壤团聚体 有机质 根系生物量 子午岭林区 |
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| 基金项目:国家自然科学基金项目（41877083，41440012） |
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| Dynamic characterization of soil aggregates during secondary forest vegetation succession in the Loess Plateau |
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WANG Miaoqian,XU Xiaoming,WANG Haojia,et al
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| Abstract: |
| 【Objective】This study analyzed the changing characteristics of soil aggregates during the natural vegetation restoration succession to provide references for near-natural restoration of vegetation and suitable trees and grasses.【Method】Soil samples and plant roots were collected in stratified layers from eight successional stages (corn field,grassland for 10 years,grassland for 20 years,Sophora davidii shrub,birch forest,Pinus tabulaeformis forest,Quercus liaotungensis-Pinus tabulaeformis mixed forest and Quercus liaotungensis forest) in the Ziwuling Mountain in the central part of the Loess Plateau.Water-stable aggregates,soil organic matter (SOM) content and root biomass (RB) were measured,indicators characterizing stability of soil aggregates including mean weight diameter (MWD),fractal dimension (D),≥0.25 mm water-stable aggregates content (R0.25) and percentage of aggregate destruction(PAD) were calculated,and the correlations of water stable aggregate contents at different particle sizes (<0.25,0.25-0.5,0.5-1,1-2,2-5 and ≥5 mm) with succession stage,MWD,D,R0.25,PAD,RB and SOM were determined based on Spearman method analysis. 【Result】① During vegetation succession,the content of water stable aggregates with small particle size (<0.25 mm) decreased overall,while the contents of water-stable aggregates with large particle sizes (≥5,2-5 and 1-2 mm) generally increased compared with the early stage of succession (corn fields).② During vegetation succession,MWD showed a trend of increasing and then decreasing,with the maximum value in revegetated grassland for 20 a.Compared with the early stage of succession,vegetation succession generally increased MWD and R0.25 by 77.7%-148.4% and 40.1%-71.1%,respectively,while decreased PAD and D by 48.0%-63.2% and 3.4%-7.2%,respectively.③ During the whole succession,Quercus liaotungensis-Pinus tabulaeformis mixed forest ≤2 mm RB had the largest diameter.In each soil layer,SOM showed a fluctuating trend of increasing and then slightly decreasing with vegetation succession.④ Vegetation succession stage had highly significant and positive correlation with RB and SOM (P<0.01).MWD had highly significant and positive correlation with 2-5 and ≥5 mm water-stable aggregate contents and SOM (P<0.01).R0.25 and SOM had highly significant negative correlation with D and PAD (P<0.01).【Conclusion】Compared with the early succession stage (corn field),vegetation succession increased SOM content and vegetation root biomass,improved soil aggregates structure,obtained more reasonable composition of soil aggregates,and enhanced soil resistance against erosion. |
| Key words: vegetation succession soil aggregates organic matter root biomass Ziwuling forest area |
