|
|
|
| Evolution and evaluation of soil fertility in forest land in <i>Larix gmelinii</i> plantations at different development stages in Daxinganling forest region |
| Chen Lixin,Xiao Yang |
| College of Forestry,Northeast Forestry University,150040,Harbin,China |
|
|
|
|
Abstract The research object was based on larch(Larix gmelinii) plantations at different development stages and natural secondary forest in the forest area of Daxinganling Mountains.Using the combined methods of field investigation and quantitative analysis,the changes of soil organic matter,the composition of soil humus,soil acidity indices and their chief nutrition content were determined and analyzed.By the methods of principal component analysis,the contribution rate of each principal component character was used as weight;Integrated fertility index in every forest type was computed by the weighted calculation The results were shown as follows: with the increase of the stand age,the soil acidity presented increasing tendency in larch plantations of different development stages,the soil began to acidify.The content of total phosphorus and available kalium presented decreasing tendency,and the content of organic matter,hydrolysable nitrogen,humic acid and humin increased slightly in near mature stand,but totally decreased.Comprehensive evaluation of soil fertility showed the(results:) natural forest>young stand>near mature stand>half-mature stand>mature forest,namely,with the stand ages increasing,soil fertility began to decrease rapidly because of the slow litter decomposition.It is proposed that the intensity of partial cutting should be increased properly in order to adjust community structure,increasing forestland light,inducing the entrance of natural broad-leaved trees into larch plantations,forming coniferous and broad-leaved mixed forests,regulating the contradiction of larch plantations litter between(decomposition) and accumulation,keeping the soil fertility balance and raising forest productivity.
|
|
Received: 05 January 2006
|
|
|
|
|
|
|
