粤北石灰岩山区不同森林类型土壤以及树种根系、叶片生态化学计量特征OA

[Objective]This study aims to reveal the nutrient utilization strategies and calcareous habitat adaptation mechanisms of different forest types in the limestone mountainous ecosystem of northern Guangdong,and to provide a theoretical basis for ecological restoration.[Method]We investigated plantations(Cornus wilsoniana,Chukrasia tabularis,Liquidambar formosana)and natural secondary forests(Zenia insignis,Triadica rotundifolia,Celtis sinensis)in northern Guangdong,where the carbon(C),nitrogen(N),phosphorus(P),potassium(K),calcium(Ca),and magnesium(Mg)contents and ecological stoichiometric characteristics of soil,roots,and leaves were measured and analyzed.[Result]The soil contents of C,N,Ca,and Mg in natural secondary forests(59.02,3.65,7.43,and 4.61 g/kg,respectively)were higher than those in plantations(17.72,1.74,1.95,and 1.95 g/kg,respectively).Both forest types exhibited high Ca levels(soil Ca:1.95 g/kg in plantations and 7.43 g/kg in natural secondary forests;leaf Ca:32.91 g/kg in plantations and 38.60 g/kg in natural secondary forests).In plantations,root P content was significantly positively correlated with leaf N content(P<0.05),root K/P was highly significantly negatively correlated with leaf N/K and Ca/K(P<0.01),root C/P was highly significantly positively correlated with leaf C/N(P<0.01),and soil C/K was significantly negatively correlated with leaf C/N(P<0.05).These correlations indicate that plantations probably experience N limitation and may also face potential P or K limitations.In natural secondary forests,soil P content was significantly positively correlated with leaf P content(P<0.05),soil N content was significantly positively correlated with leaf C/P(P<0.05),and soil Ca content was significantly positively correlated with root N/P and leaf C/K(P<0.05),suggesting that natural secondary forests may be co-limited by P and K.[Conclusion]The nutrient sequestration capacity of natural secondary forests is superior to that of plantations.Plantations require sustained increased inputs of N,while supplementation of P and K should be emphasized in natural secondary forests.