Characteristics And Decomposition Process Of Litters Of Larix Principis-rupprechtii And Its Associated Plant In The Northern Hebei Mountainous

Litter decomposition is the main way of the forest ecosystem nutrient return, It is animportant part of forest ecosystems material circulation and energy flow. Larch Forests isthe most widely distributed and the largest area of forest type in the mountains of northernHebei. In recent years, studies have shown that the larch plantation in the presence Soildegradation problems, soil degradation may be related to plant litter decomposition relatedto the situation. In this study,21common species of North China larch forest littercollected,determination of the decomposition of chemical indicators of its impact, throughthe gray correlation of different plant species litter decomposition rate theoretical sort,analyze the effect of chemical factors on litter decomposition. Using mesh bag Law fielddecomposition experiment in Chengde Meng Luan forest of larch and associated treespecies, observation of different plant species and mixed species litter decomposition rate.Results are as follows:(1)The content of N, P, K in the Hazelnut, Lespedeza etc.shrub litter wassignificantly higher than the content in the litter of Herbs and Larch, Aspen, Mongolianoak etc. tree species, and the difference is significant; Pine, Aspen, Birch and other treespecies litter have the highest crude fat content, Hazelnut, Honeysuckle, etc. most shrublitter have lower crude fat content, Larch fat content at a medium level.In the aspect of difficult to break down components,21species of carbon content areall in50%of the upper and lower, carbon content among various types of trees, shrubs,herbs did not show significant difference. Lignin and cellulose content in the litter of Pine,Linden, Spruce and other trees plant species is higher,the content in the litter of herbs,shrubs type such as Honeysuckle, Lespedeza,Grasses is lower; There was no significantdifference among litter lignin and cellulose content in tree species or in shrub species.For the composite indicator of the impact of litter decomposition, the C/N values ofLarch, Aspen Mongolian oak etc.tree species and most shrub species is low except Cloves, Grasses, Birch; the C/P values of Aspen, Mongolian oak and other tree species litter ishigher than the value of Rowan, mountain Choji, Honeysuckle etc. shrubs and small trees;Most tree species such as Pine, Birch lignin/N value is higher than the majority ofLespedeza and sea Buckthorn etc.shrub species; Similarly, litter lignin/P value of treespecies such as Pine, Mongolian oak was significantly higher than Honeysuckle,Lespedeza etc.shrub species.(2)Through the gray relational analysis,we accout the decomposition theoreticalsort of21plant species from easy to difficult: Sea Buckthorn>Sorbus> MountainChoji>Honeysuckle>Spruce>Rhamnose>Lespedeza> Hazelnut>Wildapricot>Larch>Forbs>Horseradish>Spiraea>Birch>Clove>Grasses>Acer mono>Quercus mongolica>Aspen>Chinese pine>Linden. For each impact indicators weightedSort results as follows: Sea Buckthorn>Sorbus> MountainChoji>Honeysuckle>Spruce>Rhamnose>Lespedeza> Hazelnut>Wildapricot>Larch>Forbs>Horseradish>Spiraea>Birch>Clove> Acer mono>Grasses>Aspen>Quercus mongolica>Chinese pine>Linden. The weighted sorting andinitial sort results are basically the same.(3)Larch and accompanying plant litter decomposition has several key features:1)Different plant litter decomposition trend is basically the same, both have rapid and slowstages.2)in the stage of the211-279days (June and July), litter decomposition rate ishighest, and residual rate is lowest; Followed by279-366days (August, September,October);0-211days(November, December, January, February, March, April, May) thisthe initial stage of decomposition, is a time when the year’s coldest winter and spring,litterdecomposes slowly,so,the decomposition rate is lowest. Wherein the rate of residual ofForbs, Larch and Grasses mixed leaves, Birch, Hazel, Larch and Lespedeza mixed leavesis lower,generally at about70%; The rate of residual of Mongolian oak, Larch andMongolian oak mixed leaves, Larch and Pine mixed leaves, Larch, Aspen etc.tree plantlitter leaves is higher, generally more than80%.(4)Olson exponential decay model show that there is significant difference betweenthe thinning area and not thinning area of plant litter and mixed litter decomposition rate,reflects the effect of thinning on litter decomposition of different plant species. whereintime of half decomposition of thinning area plants is between1.7-6.8years, time of95%decomposition is between7.4-29.3years; time of half decomposition of not thinning areaplants is between1.8-8.6years, time of95%decomposition is between7.8-37.3years. For different plant species, Thinning played an significant role in promoting the litterdecomposition of those species such as Hazelnut, non-grass Herbaceous and tree speciesexcept for Chinese pine. The promotion to other types is not obvious.(5)For the release of the N elements, most tree species and mixed litter in thinningand not thinning areas expressed as Leaching-enrichment mode, some species have notobvious trend; For the release of the P elements, the release patterns of different plantspecies and mixed types of litter in thinning and not thinning areas are quite different, andthere is no obvious trend.The trend of K elements release is also not obvious, the releasemode of same kind of litter in thinning and not thinning area are difference,and have noregular pattern.(6)There is no mutual role in promoting between tree species mixed leaf in thinningarea.And even some such as Larch Pine mixed leaf, the mixed decomposition rate is lowerthan the theoretical value of each decompose alone,only Lespedeza shrub species as well assome Herbs promoted the decomposition of Larch litter; The interaction of main treespecies litter decomposition is not obvious, those mixed types which have interaction allappear to promote each other.