A Study On The Spatial Pattern Of Coniferous And Broad-leaved Mixed Forest At Different Altitude In Taiyue Mountain

Three 100m×100m fixed sample plots were set up at the altitude of 1400m~1800m in the south of Taiyue Mountain,Shanxi Province,and the vertical and horizontal coordinates of the whole forest were recorded.The spatial distribution pattern of the whole forest at different altitudes,point pattern at various altitude and diameter class,distribution pattern of main forest at different altitude,as well as their correlation was operated and analyzed graphically by R language.Furthermore,the change law of the spatial pattern along with the altitude gradient,the formation mechanism and maintaining mechanism of community spatial pattern at various altitude were explored to offer salutary practical basis for future study on the species coexistence mechanism in Taiyue Mountain.And the result shows that:(1)The spatial distribution density is restricted by spatial position at different altitudes,and the individual density distribution has certain randomness.According to point pattern analysis,the spatial distribution of the whole forest varies with different altitudes significantly: in the sample plot at the altitude of 1400 m and a relatively small scale of 0~5m,the distribution of the whole forest is obviously aggregated,and the forest is randomly distributed with the increase of the scale;in the sample plot at the altitude of 1600 m and a scale of 10 m,there is no obvious aggregation distribution,and the other scales are randomly distributed,which indicates that spatial pattern in this plot is restricted by the scale insignificantly.While in the sample plot at the altitude of 1800 m,the pattern of the whole forest is controlled by scale significantly.Within the range of 0-27 m,it shows a aggregated distribution;within the range of 27-34 m,it shows a random distribution,and within the range of 34-50 m,it shows a uniform distribution.(2)The distribution of size-class structure at different altitudes showed a significant "J" type distribution,which indicates that communities at different altitude in the sample plot are growing,and the seedlings grows well.There are significant differences in the point pattern distribution at different altitudes and different diameter class: at the altitude of 1400 m,the diameter I and II are aggregated distributed and are randomly distributed with the scale increase.The diameter III is randomly distributed at small scale(0~4m),while other diameter are aggregated distributed.The distribution of diameter IV is not affected by scale,and it is shown a aggregated distribution.That is to say,interspecific competition and intraspecific competition is more intense within the two diameters.The diameter V is randomly distributed at small scale,and it shows a aggregated distribution when the scale is more than 15 m.And the diameter distribution of the diameter show a intense fluctuation and shows a random distribution.At the altitude of 1600 m,the diameter I and VI are not affected by the scale change,and shows a aggregated distribution.The distribution of the diameter II is aggregated at 0~34m.The diameter III is aggregated distributed at a small scale and randomly distributed at 9~45m.And it increases and then shows a uniform distribution,but is significantly affected by the scale.The diameter IV is randomly distributed at small scale and then aggregates with the increase of scale.And the diameter V is randomly distributed at 15 ~ 50 m,and the pattern show an aggregated distribution at other scales.The diameter I at the altitude of 1800 m is affected significantly,and it show a aggregated distribution with the increase of scale,then a random distribution,and finally a uniform distribution.Diameter II,III,IV are aggregated distributed and then shows a random distribution with the increase of scale.Diameter V,VI are randomly distributed and shows a aggregated distribution within certain scales.(3)The simulation of F,G,J,K at different altitudes of the whole forest is consistent with that of K model.And the degree of dispersion of different altitude is different and the degree of separation reaches its maximum at the altitude of 1600 m.According to the function simulation of plaque space F(r),the plaque space comes to its maximum at the altitude of 1600 m,which indicates that the plant space shows an intense stochastic.And the J function fluctuates greatly,which indicates that it is disturbed by some external elements(such as human factors or grazing).The degree of dispersion is relatively low at the altitude of 1400 m and 1800 m and the simulation of J function is relatively stable,which means the forest habitat is stable.At the altitude of 1800 m,the estimating function in the nearest distance appears an apparent turning point,which indicates that spatial pattern is restricted by the intensity at a small scale.(4)It can come to a natural conclusion by analyzing the point pattern of different species at different altitude that the main species at different altitude show an aggregated distribution and is affected slightly.However,in the sample plot at the altitude of 1400 m,the Pinus tabulaeformis is aggregated distributed at a small scale and is distributed randomly with the increase of the scale.At the altitude of 1600 m,the Betula platyphlla Suk is fluctuated greatly between random distribution and aggregated distribution,which is affected by the scale.While the spatial pattern of Pinus tabulaeformis Carr shows a random distribution with the increase of scale.And the main species are aggregated distributed at the altitude of 1800 m and is affected slightly by scale,which indicates that the community structure is relatively stable.(5)The study on the correlation among the spatial pattern of main species at different altitude was carried out.And the results show that the spatial correlation of the main species at different altitudes is positively correlated or irrelevant in the scale range.At the altitude of 1400 m,the correlation between the main species and the other species of the whole forest was analyzed.And the result shows that there is a positive correlation among the other species,except for Pinus tabulaeformis Carr,which shows a negative correlation.Moreover,it shows a positive correlation or irrelevant correlation with other species,which indicates that it is conducive for the growth of Pinus tabulaeformis Carr.And it show a trend towards Pinus tabulaeformis.In addition,it is negatively correlated or irrelevant between Carpinus cordata and Poulus davidiana and other species.At the altitude of 1600 m,there was a positive correlation among other species,except for Carpinus turzcaniowiii Hance,which show a positive correlation.Moreover,it shows a positive correlation or irrelevant correlation among other species in the large scale.The spatial pattern of Quercus liaotungensis,Betula platyphylla Suk and Pinus tabulaeformis Carr shows a positive correlation or irrelevant correlation between each pair in the whole scale,especially Quercus liaotungensis,which shows a significant positive correlation with other species,because it is more favorable for the growth of Quercus liaotungensis forest.At the altitude of 1800 m,the main species are negatively correlated with other species of the whole forest,and that of Quercus liaotungensis is negatively correlated with other major species,while there is a positive correlation between each pair of Carpinus turzcaniowiii hance,Crataegus cuneata and Pinus tabulaeformis Carr.