Research On Natural Regeneration Characteristics And Influencing Factors Of Larix Principis-rupprechtii In Guandi Mountain

In order to explore the reasons why the Larix principis-rupprechtii forest cannot be regenerated naturally in the natural state,this study takes the natural Larix principis-rupprechtii forest in the Chailu Valley of Guandi Mountain as the research object.Through field sample surveys and laboratory experimental analysis methods,The basic characteristics of natural regeneration of Larix principis-rupprechtii,the influence of environmental factors on the natural regeneration of Larix principis-rupprechtii,and the spatial distribution pattern of Larix principis-rupprechtii seed trees and their regeneration seedlings are analyzed.The redundancy analysis method was used to find out the main factors restricting the natural regeneration of Larix principis-rupprechtii.The research conclusions are as follows:(1)The slope of the study area has a significant impact on the sapling density,and the altitude has a significant impact on the seedling density of Larix principis-rupprechtii.(2)When the forest density in the study area is 225 plant/hm2,the density of saplings and seedlings of Larix principis-rupprechtii reaches the maximum,and the regeneration state is the best;The regeneration density of Larix principis-rupprechtii reaches the maximum when the canopy closure is 0.2 and 0.3,indicating that the canopy closure of natural secondary forest of Larix principis-rupprechtii in this area is in favor of promoting the natural regeneration of Larix principis-rupprechtii.(3)There was a significant positive correlation between the herb Shannon-wiener index and the density of sapling and treelings of Larix principis-rupprechtii.The herbaceous Simpson diversity index is significantly positively correlated with the density of Larix principisrupprechtii treelings.The thickness of the litter decomposition layer is significantly positively correlated with the seedling density of Larix principis-rupprechtii,The thickness of the undecomposed layer of litter has a very significant positive correlation with the sapling density of Larix principis-rupprechtii,and a significant positive correlation with the treeling density.(4)As the soil moisture content increases,the seedlings of Larix principis-rupprechtii show an increasing trend,while the treelings show a decreasing trend.The density of Larix principisrupprechtii saplings is significantly negatively correlated with the soil total phosphorus content of 0-10 cm and 20-40 cm soil layers,and is significantly negatively correlated with the soil total nitrogen content of 0-10 cm soil layers,and is Significantly positively correlated with the content of available potassium in the soil layer of 20-40 cm.The density of Larix principisrupprechtii treelings is significantly negatively correlated with the soil available phosphorus content of 0-10 cm,10-20 cm,and 20-40 cm soil layers,and is significantly negatively correlated with the soil total phosphorus content of 20-40 cm,40-60 cm soil layers.0-10 cm,10-20 cm,and40-60 cm soil layers have a significant negative effect on the density of treelings through other nutrient factors.(5)The regeneration seedlings of Larix principis-rupprechtii are mainly distributed in the true north and northwest directions which are closer to the seed tree,and there is little seedling regeneration in the south direction.The distribution pattern of Larix principis-rupprechtii at different growth stages in the study area showed a low degree of clustering distribution.(6)In the study area,the seed trees of Larix principis-rupprechtii showed an extremely strong mixed state,the treelings showed a strong mixed state,and the saplings and seedlings showed a weakly mixed state as a whole.(7)In the study area,Larix principis-rupprechtii seed tree is in a dominant state as a whole,seedlings are in a disadvantaged state as a whole,saplings are in a moderate state as a whole,and treelings are in a sub-dominant state as a whole.This shows that the average size ratio of Larix principis-rupprechtii at different growth stages in the study area is Useed tree <Utreeling<Usapling <Useedling.(8)Through redundancy analysis,stand density and litter thickness are the most critical factors affecting the natural regeneration of Larix principis-rupprechtii,followed by herbaceous Pielou uniformity and soil alkaline nitrogen.To a certain extent,soil available phosphorus has obvious influence on the natural regeneration of Larix principis-rupprechtii.