Spatial Distribution Patterns Of Tree Species And Their Correlation With Habitat In Secondary Cold-warm Picea Forest In Guandi Mountain

Spatial distribution pattern of trees was the result of interaction of multiple ecological mechanisms in forest ecosystems,which was closely related to the ecological processes of trees.Driving forces from habitat heterogeneity had an important influence on the formation of tree distribution patterns.Quantitative analysis of the spatial distribution pattern of trees and their correlation with habitat is of great significance in exploring the process of tree pattern formation and in-depth understanding of populations,community structures,and their ecological mechanisms,as well as of scientifically explaining the mechanisms for the formation and maintenance of biodiversity in forest ecosystems.Using the platform of 4 ha(200 m X 200 m)secondary Picea forest in Guandi Mountain,based on the background survey of the sample plot community,combined with sample continuous review and laboratory determination,we mainly studied the composition and structure of tree species,spatial distribution pattern of tree species and their correlation with habitat.The study consisted of 4 parts,and in the first part we completed analysis of the composition and structure of species,including species abundance,dominance and diameter distribution,etc.using classical statistical methods;A paired correlation g(r)function of O-ring statistics was used in the second part to analyze the spatial distribution patterns and correlations of the main tree and shrub species,the purpose is to detect the influence of habitat heterogeneity on the spatial distribution pattern of trees.In the third part,based on the analysis of spatial heterogeneity of soil and its correlation with topography using variogram of geostatistics?RDA ordering and variance decomposition,we further analyzed the correlation between distribution of different life form species and habitat using PCA and GAM methods.As a supplementary study,in the fourth part we selected three satellite sample plots(Picea forest,poplar birch forest,larch forest)in Guandi Mountain and two large sample plots respectively in Changbai Mountain(broad-leaved Pinus koraiensis mixed forest)and Heishiding(subtropical evergreen broadleaf forest),and conducted comparative studies on the spatial distribution pattern of typical forest species within and between regions.The main conclusions are as follows:(1)Species composition and structure of secondary cold-warm Picea forest:a total of 30 woody plant species existed in the sample area,which belonged to 11 families,22 genera.The total individual number(including branches)was 26218(independent individual number was 10266).Big differences of individual number,average diameter at breast height(DBH)and basal area among different species caused significant community layering effect,and the dominant species in each layer was obvious.Trees showed bimodal skewed normal size class structure at the canopy layer(including Picea wilsonii and Larix principis-rupprechtii),approximate normal distribution at the subtree layer(dominated by Betula albo-sinensis,Betula platyphylla,Quercus wutaishansea and Sorbus pohuashanensis)and "L" type distribution at the shrub layer(dominated by Lonicera chrysantha,Corylus mandshurica,Rosa davurica,Cotoneaster acutifolius,Spiraea pubescens and Lonicera szechuanica).The community structure was stable,and the plants in the forest were updated well.(2)Spatial distribution patterns of the main tree species:under the condition of completely random,Picea wilsonii,Larix principis-rupprechtii and Betula albo-sinensis were mainly aggregated at 0-50 m scales;Betula platyphylla and Quercus wutaishansea were aggregated at 0-40 m and 0-40 m scales,respectively;Sorbus pohuashanensis was aggregated at 0-13 m scale;Shrub tree species were clustered in a scale larger than 28 m.These were consistent with the clustering distributions of dominant population or major population at a certain scale in most forest communities.After eliminating habitat heterogeneity,the aggregation distribution scale of the main trees and shrubs became relatively small,while the random or uniform distribution was shown on the larger scale,so it can be speculated that habitat heterogeneity has obvious influence on the distribution pattern of tree species.(3)Interspecies correlation of the main tree species:Picea wilsonii and Larix principis-rupprechtii were negatively associated respectively with Betula albo-sinensis,Betula platyphylla,Quercus wutaishansea,Sorbus pohuashanensis,Lonicera chrysantha,Corylus mandshurica,Spiraea pubescens at almost the whole scale,which is conducive to species renewal and the formation of species diversity.But a positive correlation respectively between Larix principis-rupprechtii and Picea wilsonii,Betula albo-sinensis and Betula platyphylla,Sorbus pohuashanensis and Lonicera chrysantha,Picea wilsonii and Lonicera szechuanica,Quercus wutaishansea and Rosa davurica,Cotoneaster acutifolius and Lonicera szechuanica was shown at a relative large scale in the plot,which is in favor of mutual promotion and full utilization of resources so as to maintain stable coexistence of species(4)Correlation between different life-form species and habitat:we determined 190 soil samples and elevation,slope and convexity,soil pH,organic matter,available nitrogen,phosphorus and potassium showed significant spatial self-correlation variation and spatial plaque distribution pattern.Elevation had the strongest effects on the soil pH,available nitrogen and phosphorus(elevation had positive correlation with soil pH and available phosphorus,but negative correlation with available nitrogen).Convexity had the strongest negative effects on available potassium and organic matter.The total interpretation of topography for soil spatial variation was 44.79%,and the topography became an important factor in soil spatial variationTerrain and soil totally explained 53.34%of trees,55.65%of small trees and 45.83%of shrubs distribution,including an independent explanation by terrain(8.36%,5.06%and 5.48%,respectively)and an independent explanation by soil(31.12%,44.22%and 32.04%,respectively),the joint part explained by the two factors account for 13.86%,6.37%and 8.31%;Altitude,aspect,available K,N,Mg play an important role in species distribution.The result showed that the effect of habitat factors such as terrain and soil on the different life-form species distribution was different,this difference promoted the coexistence and biodiversity maintaining of species in secondary Picea forest on Guandi Mountain.(5)Comparative study of the spatial distribution pattern of typical forest tree species:analysis at intra-region species level showed that,trees of Picea forest presented different spatial distribution pattern compared with those of the other two forests in Guandi mountain,Picea wilsonii and Picea meyeri were obviously aggregated as the dominant population,Betula Albo-sinensis and Betula-platyphylla showed a completely random distribution as the associated tree species;In poplar birch forest,Picea wilsonii and Picea meyeri mainly distributed randomly as the associated population,but Betula Albo-sinensis and Betula-platyphylla showed strong aggregation distribution as the dominant species;Larix principis-rupprechtii existed mainly as middle or small size class individuals and showed aggregation distribution in Picea forest,but existed mostly as large size class individuals and showed even and random distribution in larch forest.The analysis at inter-region level showed that large size class individuals of Pinaceae family evenly distributed in GDS plot but aggregated in HSD plot;The Fagaceae family existed mainly as middle or small size class individuals in GDS plot and showed aggregation distribution,but existed mainly as large size class individuals in CBS plot and showed approximately random distribution;Fagaceae family with middle or small size class individuals was negatively correlated with Pinaceae family in GDS plot but positively correlated with it in HSD plotIn conclusion,spatial distribution pattern and interspecific relationship of trees in secondary cold-warm Picea forest closely related to habitat,and changed with the structure of community and diameter class,as well as varied with supply-demand balance of environment-tree growth on regional scale.