Study On The Characteristics Of Aspen Woody Debris In The Secondary Forest Area Of Hanshan,Inner Mongolia

In the secondary forest area of Hanshan Mountain,Inner Mongolia,thesis selects Inner Mongolia Saihanwula National Nature Reserve(hereinafter referred to as Saihanwula Nature Reserve),Inner Mongolia Hanshan National Nature Reserve(hereinafter referred to as Hanshan Reserve),Inner Mongolia Qingshan National Nature Reserve The first-level nature reserve(hereinafter referred to as: Qingshan Reserve)is used as the experimental site,taking the woody residues of the typical tree species aspen as the research object,and taking the accumulation of woody residues after the abnormal death of a large area of the forest as the breakthrough point to investigate and study the woody residues The characteristics of storage,decomposition and nutrient release,and ecological functions in terms of the impact on regeneration and retention of soil and water.The sample plot survey method was used to investigate and record the wood residue storage and forest regeneration in the sample plot,and the wood residues of different decomposition grades were collected and brought back to the laboratory for analysis of nutrient content,water holding capacity and their impact on forest regeneration,the result shows:(1)The reserves of wood residues in the three study areas mainly exist in the form of fallen wood and dead standing wood.The reserves,diameter classes and mortality of wood residues distributed from south to north in the three study areas showed a relationship between high reserves and high diameter classes and low mortality,and low reserves and low diameter classes with high mortality.With the distribution of woody residues from south to north in the study area,the stand density and size class gradually decreased;the decomposition grades were mainly III and IV in Saihanwula Reserve,Hanshan Reserve and Qingshan Reserve were in Ⅱ,Ⅲ decomposition level.The reserves of woody residues are not only affected by altitude,but also by a combination of factors such as annual average precipitation.(2)The organic carbon(C)content of wood residues in Saihanwula Reserve decreased first and then increased with the increase of decomposition level;the C content of Hanshan Reserve increased first and then decreased with the increase of decomposition level;The C content of Qingshan Nature Reserve increases with the increase of the decomposition grade;the nitrogen(N)element has no obvious change law;the phosphorus(P)content of different decomposition grades in the three study areas increases with the increase of the study area As the decomposition level of Beihe increases,the released content is larger;the P element in Saihanwula Reserve shows a downward trend with the increase of decomposition level,and the content of P tends to be stable when it reaches the decomposition level of III;The content of P element in the area first decreased and then increased with the increase of the decomposition level;the content of P element in Qingshan Reserve increased with the increase of the decomposition level;the potassium(K),calcium and(Ca),sodium(Na),magnesium(Mg),iron(Fe)elements are less in content,and there is no obvious release law.The research on C/N,C/P and N/P of woody residues found that the decomposition rate of woody residues in Qingshan Reserve was the slowest,and the woody residues had the slowest rate in the middle stage of decomposition.(3)The water storage capacity of the woody residues in the three study areas increases with the increase of the decomposition level.The body has the functions of maintaining soil and water and conserving water sources.Wood residues are used as nutrient reservoirs.The three study areas have abundant C element reserves,N reserves,and P reserves.Although the reserves of Mg,Na,K,Ca,and Fe are small,they also have the ability to regulate nutrients in forest ecosystems.Features.The research on forest regeneration found that with the distribution of the study area from south to north,the number of new seedlings increased,but the diameter of the living seedlings decreased accordingly,and the number of new seedlings in the fallen wood plots was the most,indicating that the fallen trees can promote regeneration.effect.Fallen trees in different study areas of Hanshan secondary forest area are mainly broken by "dry base breaking".A large number of fallen trees accumulate in the forest,which hinders,intercepts,and shades the regeneration of seeds,seedlings,and saplings.After a long period of time,it will cause serious crushing,smashing and other negative effects on the renewed seedlings and other plants under the forest.