福建三明格氏栲天然林林窗凋落物-土壤的生态化学计量特征

Ecological stoichiometric characteristics of litter-soil in gap of Castanopsis kawakamii natural forest in Sanming of Fujian

在前期调查的基础上,在福建三明的格氏栲(Castanopsis kawakamii Hay.)天然林内划分不同尺度的林窗(大林窗、中林窗和小林窗,平均面积分别为199.29、78.53和37.86 m2),并以非林窗为对照,研究林窗内凋落物-土壤C、N、P和K的生态化学计量特征,并运用冗余分析(RDA)方法探讨了凋落物-土壤生态化学计量特征之间的关联性。结果显示:大林窗的凋落物C含量、N含量、C∶N比、C∶P比、C∶K比、N∶P比和N∶K比以及土壤C含量、N含量、P含量、K含量和C∶N比均最高,小林窗的凋落物P和K含量以及土壤C∶P比、C∶K比、N∶P比和N∶K比均最高,但各尺度林窗间凋落物和土壤的P∶K比总体差异不明显。在相同尺度林窗中,凋落物的C、N和P含量以及C∶N比、C∶P比、C∶K比、N∶K比和P∶K比总体上均显著高于土壤,但凋落物的K含量则显著低于土壤。与非林窗相比,小林窗的凋落物P和K含量以及土壤C含量、C∶N比、C∶K比和N∶K比,中林窗的土壤P含量,大林窗的土壤C、N和P含量以及C∶N比、C∶K比和N∶K比均显著提高,但各尺度林窗内凋落物-土壤的其他生态化学计量特征均显著降低。RDA分析结果显示:大林窗的凋落物P∶K比、中林窗的凋落物N∶P比和P含量以及小林窗的凋落物P含量对土壤肥力影响最大,而非林窗的凋落物C、P和K含量均对土壤肥力影响较大;且大林窗和中林窗的凋落物P含量和N∶P比分别与土壤P含量和N∶P比呈负相关,小林窗和非林窗的凋落物P含量和N∶P比分别与土壤P含量和N∶P比呈正相关。综合分析表明:格氏栲天然林不同尺度林窗内凋落物-土壤生态化学计量特征有较大差异,其中,大林窗的土壤肥力较高,且林窗土壤肥力主要受凋落物中P含量的限制。建议根据林窗内土壤N∶P比采取适宜的施肥管理措施,以促进植物生长并丰富物种多样性。

On the basis of preliminary investigation,gap of Castanopsis kawakamii Hay. natural forest in Sanming of Fujian is divided into different scales( large,medium and small gaps,with an average area of199. 29, 78. 53 and 37. 86 m2, respectively). And taking non-gap as the control, ecologicalstoichiometric characteristics of C,N,P and K of litter-soil in gap were studied,and the relationship of litter-soil with ecological stoichiometric characteristics was discussed by means of redundancy analysis( RDA). The results show that contents of C and N,ratios of C ∶N,C ∶P,C ∶K,N ∶P and N ∶K in litter,and contents of C,N,P and K,and C ∶ N ratio in soil are the highest in large gap; contents of P and K in litter,and ratios of C ∶ P,C ∶ K,N ∶ P and N ∶ K in soil are the highest in small gap; but the difference in P ∶ K ratio between litter and soil in each scale of gap is not obvious in general. In the gap with the same scale,contents of C,N and P,and ratios of C ∶ N,C ∶ P,C ∶ K,N ∶ K and P ∶ K in litter are generally significantly higher than those in soil,but K content in litter is significantly lower than that in soil. Compared with non-gap,contents of P and K in litter,and C content,ratios of C ∶ N,C ∶ K and N ∶ K in soil in small gap,P content in soil in medium gap,contents of C,N and P,and ratios of C ∶ N,C ∶ K and N ∶ K in soil in large gap increase significantly,but other ecological stoichiometric characteristics of litter-soil in each scale of gap decrease significantly. RDA analysis result show that P ∶ K ratio in litter in large gap,N ∶ P ratio and P content in litter in medium gap,and P content in litter in small gap have the greatest effect on soil fertility,while contents of C,P,and K in litter in non-gap have a great effect on soil fertility; furthermore,P content and N ∶ P ratio in litter are negatively correlated with those in soil in large gap and medium gap,those in litter are positively correlated with those in soil in small gap and nongap. The comprehensive analysis shows that there are great differences in ecological stoichiometric characteristics of litter-soil among different scales of gaps of C. kawakamii natural forest,in which,soil fertility of large gap is high and soil fertility of gap is mainly limited by P content in litter. It is suggested that appropriate fertilization management measures should be taken according to N ∶ P ratio in soil in gap to promote plant growth and enrich species diversity.