两种芒箕覆盖度下毛竹林土壤团聚体的稳定性及生态化学计量特征比较研究

Comparative Study on Soil Aggregate Stability and Ecological Stoichio-metric Characteristics Under Two Coverage of Dicranopteris dichoyoma in Phyllostachys edulis Forest

为了解毛竹林下不同盖度芒萁种群对土壤碳含量和养分状况的影响,研究了四川长宁县芒萁(Dicranopteris dichoyoma)盖度分别为7.75%(PE)和63.25%(DD)下的毛竹(Phyllostachys edulis)林土壤团聚体稳定性和生态化学计量特征。结果表明,DD样方土壤大团聚体含量显著低于PE样方,进而导致团聚体稳定性降低。DD样方土壤总有机碳(TOC)、全氮(TN)、全磷(TP)含量显著低于PE样方,且TP降幅最大,使得土壤C:N、C:P和N:P显著增加。毛竹凋落叶和细根的TOC、TN、TP、C:N、C:P和N:P在DD和PE样方间无显著差异,但DD样方芒萁凋落叶和细根的TN和TP含量显著高于毛竹。相关分析表明PE毛竹细根的TP含量仅与大团聚体的TP含量呈显著正相关;DD毛竹和芒萁细根的TP含量与大团聚体、微团聚体和中团聚体的TP含量均呈显著正相关。毛竹林下高盖度的芒萁种群降低了土壤团聚体稳定性和土壤C、N、P含量,通过改变土壤生态化学计量特征进而增加毛竹和芒萁细根对土壤不同粒径团聚体N和P的吸收,尤其是对P的吸收。因此,在川南地区粗放经营毛竹林中应考虑调整林下芒萁盖度,以保证土壤养分供给的长期可持续。

In order to understand the effects of the Dicranopteris pedata population with different coverage on soil carbon content and nutrient status of Phyllostachys edulis forest,the stability and ecological stoichiometric characteristics of soil aggregates in P.edulis forest under 7.75%(PE)and 63.25%(DD)coverage of D.dichoyoma in Changning County,Sichuan Province were studied.The results showed that the content of large aggregates in DD plot was significantly lower than that in PE plot,which caused the decrease of aggregate stability.Moreover,the contents of total organic carbon(TOC),total nitrogen(TN)and total phosphorus(TP)in DD plot were significantly lower than those in PE plot,and the decrease of TP was the largest,which made significant increase of soil C:N,C:P and N:P.There was no difference in the contents of TOC,TN,TP,C:N,C:P and N:P in litter leaves and fine roots of P.edulis between DD and PE plots,but the contents of TN and TP in litter leaves and fine roots of D.dichoyoma were significantly higher than those of P.edulis in DD plots.The correlation analysis showed that the TP content in fine roots of P.edulis and D.dichoyoma were significantly positively correlated with that in soil large marcroaggregate,microaggregate and small marcroaggregate.So the high coverage of D.dichoyoma in moso bamboo forest could decrease the stability of soil aggregates,and reduced the contents of TOC,TN and TP in soil,which could increase the absorption of N and P in soil aggregates with different size classes by changing the soil ecological stoichiometric characteristics,especially the absorption of P.It should be considered to adjust the coverage of D.dichoyoma in the extensive management of moso bamboo forest in southern Sichuan,in order to ensure the long-term sustainability of soil nutrient supply.