喀斯特高原石漠化区次生林叶片—枯落物—土壤连续体碳氮磷生态化学计量特征

C:N:P stoichiometry of leaf-litter-soil continuum in secondary forests of the rocky desertification regions of the karst plateau

探究喀斯特高原石漠化区贵州青冈[Cyclobalanopsis argyrotricha(A.Camus)Chun et Y.T.Chang]-云贵鹅耳枥(Carpinus pubescens Burk)林、麻栎(Quercus acutissima Carruth)林、猴樟(Cinnamomum bodinieri Levl)林和华山松(Pinus armandii Franch)林4种次生林叶片—枯落物—土壤连续体C、N、P生态化学计量特征及相关性,可为喀斯特森林恢复重建和经营管理提供依据.对4种次生林叶片、枯落物及土壤进行野外取样,室内测定C、N、P含量及计算生态化学计量比.结果显示:4种次生林叶片组分的C、N、P元素含量为474.34、18.59、1.78 g/kg;枯落物组分C、N、P元素含量为444.21、12.84、0.96 g/kg;土壤组分(0-10 cm)的C、N、P元素含量为80.40、2.80、0.86 g/kg,叶片—枯落物—土壤连续体C、N、P含量皆表现为高—中—低变化趋势.4种森林叶片—枯落物—土壤连续体各组分C:N:P计量比依次为266:10:1、490:14:1、93:3:1,叶片-枯落物-土壤连续体C:N:P质量比呈中—高—低的变化趋势.C/N、C/P、N/P在叶片—枯落物—土壤连续体各组分中变化趋势不同,C/N在4种森林中变化规律不一致,而C/P与N/P在4种森林中皆表现为中—高—低变化趋势.土壤组分N/P与叶片组分C/P、N/P,枯落物组分N/P与叶片组分C/P、N/P之间皆为显著正相关,而枯落物和土壤组分的N/P之间没有表现出显著的相关性.与已有的研究结果相比,喀斯特次生林叶片—枯落物—土壤连续体C含量呈中—低—高格局,N含量为中—高—高格局,P含量为高—高—高格局,C:N:P化学计量为低—低—高格局,叶片N/P、枯落物C/N较低,土壤C/N相对较高,C/P、N/P相对较低.综上所述,喀斯特高原石漠化区次生林枯落物分解较快,土壤中P回归充分而N回归不足,植被生长主要受到N的限制,且养分循环速度与优势种相关,优势种选择是森林恢复与经营的核心内容.

We examined the C,N,and P concentrations,and the related stoichiometry of the leaf-litter-soil continuum in four types of secondary forests(Cyclobalanopsis argyrotricha(A.Camus)Chun et Y.T.Chang ex Y.C.Hsu et H.W.Jen,Carpinus pubescens Burk forest,Quercus acutissima Carruth forest,Cinnamomum bodinieri Levl forest and Pinus armandii Franch forest)to provide a scientific reference for the restoration and management of forest ecosystem of rocky desertification regions in the karst plateau of central Guizhou,China.Field sampling was used to collect soil,litter,and leaves from four types of secondary forests,and then,the C,N,and P content in the samples and their C:N:P stoichiometry were determined and analyzed.Results showed that C,N,and P in the karst secondary forest occurred in leaves,litters,and top 0-10 cm soil layer were 474.34 g/kg,18.59 g/kg,1.78 g/kg;444.21 g/kg,12.84 g/kg,0.96 g/kg;80.40 g/kg,2.80 g/kg,0.86 g/kg,respectively,and the C:N:P ratios were 266:10:1,491:14:1,93:3:1,respectively.C,N,and P contents in the leaf-litter-soil continuum exhibited a trend from high-medium-low,while C:N:P ratios were medium-high-low.The variation between the trend of C/N,C/P,and N/P were different in the leaf-litter-soil continuum components:C/P and N/P were ordered as litters>leaves>soils,while C/N was inconsistent in different forest types.A significantly positive relationship was observed between soil N/P and leaf C/P,N/P,as well as litter N/P,however,there was no significant correlation between litter N/P and soil N/P.Compared with the results from other regions,the C content in the karst secondary forest leaf-litter-soil continuum showed a medium-low-high pattern,N was a medium-high-high pattern,P was a high-high-high pattern,and C:N:P ratios had a low-low-high pattern,at the same time,the karst secondary forest presented a lower leaf N/P,litter C/N,soil C/N,and higher soil C/N and N/P.These results revealed that the litter in secondary forests decomposed quickly,P regression is sufficient in the soil,N regression is insufficient,vegetation growth is mainly restricted by N,and nutrient cycling is related to dominant species.Therefore,selecting dominant species should be the core content for forest restoration and management of the karst forest ecosystem in central Guizhou,China.