Study On Growth And Herbaceous Diversity Of Larix Principis-rupprechtii Plantation At Different Altitudes

The purpose of this study was to investigate the forest growth and herb diversity of Larix principis-rupprechtii plantation at different altitudes in mountainous area of northern Hebei province.In this study,Larix principis-rupprechtii plantation with different altitudes in Wudaogou forest farm of Hebei Mulan Paddock State Forest Farm was selected as the research object.The sample site about 1400 m in the study area was set as low-altitude areas,the sample site about 1600 m is set as medium-altitude areas,and the sample site about 1800 m is set as high-altitude areas.There are 3 standard plots in different altitudes,and a total of 9 plots.The growth process of DBH,tree height and per tree volume of Larix principis-rupprechtii plantation at different altitudes was studied,and the growth model of Larix principis-rupprechtii plantation was established.One-way analysis of variance was used to analyze the significance of the differences.At the same time,the understory herb structure and herb species diversity index of Larix principis-rupprechtii plantation at different altitudes were analyzed.It provides theoretical basis for the management of Larix principis-rupprechtii plantation at different altitudes in the mountainous area of northern Hebei Province.The results show that:(1)The total growth process of DBH,tree height and per tree volume of Larix principis-rupprechtii plantation was basically the same at different altitudes.The growth law of forest is more appropriate to Logistic growth model.Although there were some differences in the growth process of trees at different altitudes,they did not attain statistical significance difference.(2)There are differences in understory vegetation richness at different altitudes.A total of 35 herbaceous species belonging to 18 families were found in Larix principis-rupprechtii plantation at low altitude.A total of 25 herbaceous species belonging to 14 families were found in Larix principis-rupprechtii plantation at the middle altitude.A total of 23 herbaceous species belonging to 14 families were found in Larix principis-rupprechtii plantation at high altitude.The understory vegetation richness of low altitude forest is obviously higher than that of middle altitude and high altitude.The richness of herbaceous species in low-altitude understory forests was significantly higher than that in middle-altitude and high-altitude forest stands.(3)The herb species diversity index of Larix principis-rupprechtii plantation at different altitudes showed obvious regularity.The a diversity of Margalef index,Simpson diversity index,Shannon-Wiener index and Pielou evenness index of understory herbaceous species decreased with the increase of altitude.In the Whittaker index of P diversity of understory herbaceous vegetation in Larix principis-rupprechtii plantation at three different altitudes,βW low altitude-middle altitude(3.070)>βW middle altitude-high altitude(2.632)>βW low altitude-high altitude(2.556).In terms of the Cody index of the β diversity of understory herbaceous vegetation of Larix principis-rupprechtii plantation under three different altitudes,βC low altitude-middle altitude(17.000)<βC middle altitude-high altitude(18.000)<βC low altitude-high altitude(20.000).According to the Routledge index of β diversity of understory herbaceous vegetation in Larix principis-rupprechtii plantation under three different altitudes,βR low altitude-middle altitude(30.681)<βR middle altitude-high altitude(33.283)<βR low altitude-high altitude(36.379).Both the Cody index and the Routledge index showed the largest trend in the low-altitude-high-altitude group,indicating that the herbaceous species were quite different between low-altitude and high-altitude.(4)The association of herbaceous vegetation in Larix principis-rupprechtii plantation is different at different altitudes.In the χ2 test of 190 species pairs of 20 dominant species in the understory of low altitude Larix principis-rupprechtii plantation,45.79%of the total species pairs are positively correlated.The number of species pairs with negative correlation accounted for 54.21%of the total species pairs.The number of species pairs with no significant correlation is 115,accounting for 60.53%of the total species pairs.In the χ2 test among 153 species pairs of 18 dominant species under the middle altitude Larix principis-rupprechtii plantation,75.16%of the total species pairs are positively correlated.The number of species pairs with negative correlation accounted for 24.84%of the total species pairs.The number of species pairs with insignificant correlation accounted for 63.40%of the total species pairs.In the χ2 test among 136 species pairs of 17 dominant species in the understory of Larix principis-rupprechtii plantation at high altitude,77.21%of the total species pairs are positively correlated.The number of species pairs with negative correlation accounted for 22.79%of the total species pairs.The number of species pairs with insignificant correlation accounted for 63.24%of the total species pairs.The proportion of species pairs showing positive correlation was the largest in high altitude.