凋落物和根系对沂蒙山区三种森林恢复方式土壤酸性磷酸酶动力学特征的影响

Effects of litter and roots on soil acid phosphatase kinetics under three forest restoration types in the Yimeng mountainous area

酸性磷酸酶动力学特征可反映不同底物供应下土壤磷转化状况。以人工恢复的引进种黑松人工林和本地种栓皮栎人工林以及自然恢复的天然次生林为研究对象,开展凋落物添加去除和根系去除对土壤酸性磷酸酶动力学特征的影响研究。结果表明:(1)三种森林恢复方式下土壤酸性磷酸酶活性和最大反应速度(V_(max))均为双倍凋落物>对照>去除凋落物>去除根系>无输入;(2)改变凋落物和根系输入对酸性磷酸酶的半饱和常数(K_(m))和催化效率(V_(max)/K_(m))影响不大;(3)酸性磷酸酶活性受速效磷含量的反馈调节;土壤氮可利用性和含水量显著影响酸性磷酸酶活性。改变凋落物和根系输入对引进种黑松人工林土壤有机磷转化能力影响最大,天然次生林次之,本地种栓皮栎人工林最稳定。根系对土壤酸性磷酸酶动力学特征的影响大于凋落物。其结果可为暖温带森林恢复,应对气候变化和森林防火、收集凋落物等管理措施提供理论依据。

Acid phosphatase kinetics can reflect phosphorus(P)transformation under different soil substrates.Forest restoration types influence ecosystem services,such as soil fertility maintenance and nutrient cycling.Litter and roots are two main ways that different forest restoration types affect P maintenance and cycling.In the background of climate change and human activity,litter and roots have complex impacts on ecosystem services such as soil P maintenance and P cycling.However,there are few reports on the effects of litter and roots on soil acid phosphatase kinetics under different forest restoration types.Detritus input and removal treatment(DIRT)experiment was conducted in three typical forest restoration types(introduced black pine[Pinus thunbergii Parl.]plantations,native oriental oak[Quercus variabilis Bl.]plantations,and natural secondary forests)in the Yimeng Mountains area.DIRT included double litter treatment,litter removal treatment,roots removal treatment,no inputs treatment,and control.Soil samples were collected on August 21st,2022,which was 7 years and 9 months after DIRT EXPERIMENT was conducted.The effects and mechanisms of changing litter and roots input on soil acid phosphatase dynamics were analyzed.The acid phosphatase activities were as follows:(1)the activity of acid phosphatase and V_(max)(the maximum reaction velocity)under the three forest restoration types showed the order of double litter>control>litter removal>roots removal>no inputs treatment.(2)K_(m)(half-saturation constant)and V_(max)/K_(m)(catalytic efficiency)were relatively stable and less susceptible to changes in litter and root inputs.However,V_(max) was easily affected,double litter treament significantly increased V_(max) in the soils of oriental oak plantations,litter removal,roots removal and no inputs treatments significantly reduced V_(max) of the soil of black pine plantations.(3)The feedback of available P content regulated the acid phosphatase activity.The acid phosphatase activity(substrate at moderate concentrations of 80—160μmol/L)and V_(max) were significantly and positively correlated with available P content.The soil nitrogen availability and moisture content significantly affected the soil acid phosphatase activity of the three forest restoration types.The influence of roots on acid phosphatase kinetics was larger than litter.In the background of climate change,the soil organic P transformation capacity of the introduced black pine plantations was unstable and easily disturbed,followed by the natural secondary forests,with the native oriental oak plantations being the most stable.These results provide insights into forest restoration,climate change responses,and human activities related to forest fire prevention and litter collection in warm temperate areas.