林地覆盖对雷竹林土壤碳氮磷化学计量特征的影响

Effects of mulching management on stoichiometry of soil C, N and P in Phyllostachys praecox plantations

关键词:  雷竹  林地覆盖  土壤养分  化学计量  竹林退化

Key words:  Phyllostachys praecox  mulching of bamboo land  soil nutrients  stoichiometry  degradation of bamboo stand

摘要:

林地覆盖措施可明显促进雷竹笋芽提早萌发,显著提高竹林经济效益,但长期连年覆盖会导致雷竹林退化为雷竹林。对不同覆盖年限(1、3、6 a)雷竹林和不覆盖雷竹林土壤C、N、P含量和化学计量比及相关性进行了研究。结果表明:不同覆盖年限雷竹林和不覆盖雷竹林土壤C、N、P含量均随土壤深度的增加而极显著降低。不同土层土壤C、N、P含量不同覆盖年限雷竹林极显著地高于不覆盖雷竹林。随覆盖年限的延长,雷竹林0～20 cm土壤C、N含量极显著提高。覆盖1 、3 a雷竹林和不覆盖雷竹林0～50 cm土壤P含量和20～50 cm土壤C、N含量差异均不显著,均显著地低于覆盖6 a雷竹林土壤。不同覆盖年限雷竹林各土层土壤C:N差异不显著,而C:P、N:P随覆盖年限的延长呈升高趋势。随覆盖年限的延长,土壤C、N、P间正相关关系减弱,C与N、P协同变化速率降低。研究表明:雷竹鞭根系统主要分布区0～20 cm土壤养分过量积累及引起的土壤养分失衡是林地覆盖雷竹林退化的主要原因。应实行轮闲覆盖和测土配方平衡施肥,并在雷竹自然出笋开始时(3月上旬)及时撤除有机覆盖物。为雷竹林可持续经营提供理论依据。

Abstract:

In order to gain better price and incomes by shoot earlier sprouting,the practice of mulching management of Phyllostachys praecox plantations in Zhejiang Province has been carried out,while mulching management for years led to the stand degradation. Thus the contents of soil carbon,nitrogen and phosphorus elements and its stoichiometry for the treatments of 6,3,1 a mulching and non-mulching(NM)in P. praecox stands were analyzed to provide theoretical basis for sustainable management of the stand. The results showed that contents of soil C,N and P for mulching and NM P. praecox stands decreased significantly with soil depth increasing,and the contents of soil C,N and P for mulching stand were significantly higher than that of NM stand. Meanwhile C and N contents in topsoil(0-20 cm)increased significantly with the extended years of mulching management. There was no significant difference on P content at soil layers 0-50 cm and C,N contents at soil layers 20-50 cm among 3,1 a and NM stands,while that for 6 a mulching stand was significant higher than those for 3,1 a and in NM stand. Moreover it was found that there was no significant difference for soil C:N in the same soil layers,while with the extended years of mulching management,soil C:P and N:P increased on the whole,and positive correlation coefficient and coordinated variations of C and N,P decreased. All results indicated that excessive accumulations of C and N at distribution area of rhizome-root system(0-20 cm soil layers)and imbalance of soil nutrients were the main reasons of stand degradation for P. praecox plantations. Hence it was concluded that management measures including scientific fertilization,removal of mulching materials after mulching management in time,rotated mulching should be conducted to avoid stand degradation further.