Study On Ecological Effects Of Artificial Scenic Forests And Tree’s Growth Characteristics In North Of Jiangsu Limestone Mountain

In order to research and compare soil physicochemical properties, microclimate effects,vegetation composition, biodiversity, tree photosynthesis and transpiration characteristics as wellas biomass of different forest types in Xuzhou limestone mountain, five experimental samplesincluding four kind mixed plantations of Platycladus orientalis with Ligustrum lucidum, Cotinuscoggygria, Firmiana simplex, Liquidambar and one kind of pure Platycladus orientalis forestwere choosen to investigate, simultaneous determinating an open space as a control. Resultsshowed that:(1) Soil organic matter, available P content in mixed forest of Platycladus orientalis withLigustrum lucidum were highest, their value were68.09g/kg,0.89mg/kg respectively; soilavailable K content was the highest in mixed forest of Platycladus orientalis with Cotinuscoggygria, its value was201.55mg/kg; and content of soil hydrolyzed N in mixed forest ofPlatycladus orientalis with Liquidambar was up to360.31mg/kg. Correlation was extremelysignificant between any two among bulk density, pH and total N, total N and hydrolytic N alsoreached extremely significant level.(2) Afforestation can significantly reduce the light intensity, air temperature and soiltemperature, improve air relative humidity and soil moisture. There was no difference almongfour kinds of mixed forest microclimate index value. In four seasons, light intensity, airtemperature and soil temperature size were ordered by mixed forest <pure forest <open space,air relative humidity and soil moisture were ordered: mixed forest> pure forest> open space.Mixed and pure forest light intensity had significant difference in four seasons, air temperaturehad significant difference in spring and summer, however, in four seasons both air relativehumidity and soil water content were not significantly different, and ability of mixed forest tostabilize air and soil temperature was better than that of the pure forest.(3) Herbaceous layer had more plant species than tree and shrub layers had, Platycladusorientalis, Photinia serrulata Lindl. and Cynodondactylon(Linn.)Pers. were all dominant speciesin limestone mountain, their important value were4.0057,1.8801,1.0739respectively. The shrublayer height of pure forest was the highest,117.8cm, shrub layer biomass of Platycladusorientalis and Cotinus coggygria mixed forest was maximum,209.1kg/hm2. Species of shrub andherb layers were abundance and had uniform distribution in mixed forests, however, the pureforest vegetation diversity was poorer, species was not rich, even without distribution.(4) Average diurnal value of five kind trees’ net photosynthetic rate was ordered byLigustrum lucidum> Liquidambar> Cotinus coggygria> Firmiana simplex> Platycladusorientalis, and average diurnal value of transpiration rate was ordered by Ligustrum lucidum>Liquidambar> Cotinus coggygria> Platycladus orientalis> Firmiana simplex. Maximum average daily stomatal conductance was Ligustrum lucidum, minimum was Firmiana simplex.The average daily water use efficiency proved to be maximum of Ligustrum lucidum, minimumof Platycladus orientalis. In addition, stomatal conductance had obvious influence on netphotosynthetic rate in five tree species, while air relative humidity just affacted netphotosynthetic rate of Ligustrum lucidum, Firmiana simplex and Platycladus orientalis.(5) Both DBH of Firmiana simplex and height of Platycladus orientalis were the highest,their value were0.67cm,0.33m respectively. The stand biomass per unit area was ordered byLigustrum lucidum mixed forest> Firmiana simplex mixed forest> Liquidambar mixed forest>Cotinus coggygria mixed forest> Platycladus orientalis pure forest, tree’ annual growth biomassof Firmiana simplex mixed forest was the highest,3.001t/hm2, and which of Platycladusorientalis pure forest was minimum, only1.092t/hm2, annual growth of Platycladus orientalisbiomass was between1.092~1.906t/hm2, Ligustrum lucidum, Cotinus coggygria, Firmianasimplex and Liquidambar annual biomass growth were0.82t/hm2,0.59t/hm2,1.095t/hm2,0.261t/hm2respectively.(6) The average individual biomass of arbor species had an order of Cotinus coggygriamixed forest> Platycladus orientalis pure forest> Liquidambar mixed forest> Firmianasimplex mixed forest> Ligustrum lucidum mixed forest, annual growth of average individualbiomass from big to small ordered of Firmiana simplex mixed forest> Ligustrum lucidum mixedforest> Cotinus coggygria mixed forest> Platycladus orientalis pure forest> Liquidambarmixed forest. Platycladus orientalis annual biomass growth in Firmiana simplex mixed forestwas0.66kg higher than what in Platycladus orientalis pure forest.