不同退化程度赤桉人工林土壤生态功能变化对比

Changes of Soil Ecological Function in Eucalyptus camaldulensis Plantations with Different Degrees of Degradation

人工林退化会对地表植被和土壤生态功能(养分循环、水源涵养、碳汇功能等)造成影响,揭示土壤生态功能变化与人工林退化的关系,有利于对现有人工林的后期管护和已退化人工林的“复壮”。以地表植被盖度为划分依据,选取元谋干热河谷地区盖度大约在90%、60%和30%的轻(SD)、中(MD)、重度(HD)退化赤桉(Eucalyptus camaldulensis Dehnh.)人工林为研究对象,比较地表植被状况、土壤氮磷养分、土壤持水性能和活性碳及其分配比例的变化。结果显示:在元谋干热河谷地区,随着人工林退化,灌草的覆盖度和物种多样性降低,表层土壤硝态氮和有效磷质量分数分别从3.67和259.18 mg·kg^(-1)下降到1.67和109.29 mg·kg^(-1),土壤最大持水量也从581.43 t·hm^(-2)下降至534.44 t·hm^(-2),同时土壤碳储量从原有的84.0 t·hm^(-2)变为36.2 t·hm^(-2),土壤碳库稳定性减弱,孔隙度结构和土壤养分结构也发生改变。研究表明随着人工林退化程度的加剧,土壤生态功能呈现出退化趋势,地表植被破坏可能是人工林土壤生态功能退化的驱动因子之一。

Plantation degradation will affect surface vegetation and soil ecological functions(Nutrient cycling,water conservation,carbon sink function),revealing the relationship between soil ecological function changes and plantation degradation,which is conducive to the later management and protection of existing plantations and the“rejuvenation”of degraded plantations.With the surface vegetation coverage,Slight(SD),medium(MD)and Heavy(HD)degraded Eucalyptus camaldulensis Dehnh plantations with coverage of about 30%,60%and 90%in Yuanmou Dry-hot valley were selected as the research subjects.The changes of surface vegetation status,soil nitrogen and phosphorus nutrients,soil water holding capacity,active carbon and its distribution ratio were compared.In the Yuanmou dry-hot valley area,with the degradation of plantation,the coverage of shrub and grass layer and species diversity decrease,the contents of nitrate nitrogen and available phosphorus in surface soil decreased from 3.67 and 259.18 mg·kg^(-1)to 1.67 and 109.29 mg·kg^(-1),respectively,and the maximum soil water holding capacity also decreased from 581.43 to 534.44 t·hm^(-2).Meanwhile,soil carbon storage changed from 84.0 to 36.2 t·hm^(-2).The stability of the soil carbon pool is weakened,and the porosity structure and soil nutrient structure also change.Studies have shown that as the degree of degradation of plantation forests intensifies,soil ecological functions also show a trend of degradation,and the destruction of surface vegetation is one of the driving factors leading to the degradation of soil ecological functions of degraded plantations.