Energy Structure Characteristics Of The Dominant Plant Species On The Southern Slope Of Middle Qinling Mountains

Pinus armandii community, Pinus tabulaeformis community and Quercus alienacommunity in centra south Qinling Mountains were studied by sample-plot survey andlaboratory tests. In this research, standing crop of energy and carbon storage of Pinusarmandii community was researched to explore characteristic of vertical spatial distribution,and the biomass, caloric value, ash caontent and standing crop of Pinus tabulaeformiscommunity and Quercus aliena community in different regions and site conditions weremeasured to anlysis spatial distribution characteristics. The results are as followed:1. Total biomass and standing crops of energy, ash storage and carbon storage ofP.armandii community were81.39t/hm~2,1539.04GJ/hm~2,3765.86kg/hm~2and33.70t/hm~2.The biomass, standing crops of energy, ash storage and carbon storage in tree layer were79.45t/hm~2,1494.89GJ/hm~2,1950.41kg/hm~2and32.95t/hm~2, accounting in all layers for97.62%,97.13%,51.79%and97.78%. Gross caloric value, ash-free caloric value and carborncontent reduced from tree layer to herb layer, and ash content opposited. Gross caloric valueand ash-free caloric value of P.armandii in different organs were in order of branch＞leaf＞root＞bark＞stem and branch＞bark＞leaf＞root＞stem, respectively; ash content was inorder of bark＞branch＞root＞leaf＞stem; carbon content was in order of branch＞leaf＞bark＞root＞stem.2. The biomass of P. tabulaeformis community and Q. aliena community displaedinverse “U”-shape from west to east along survey aere. The biomass of P. tabulaeformiscommunity in Caizipin forest farm and Q. aliena community in Huoditang forest farm werehighest, and P.tabulaeformis community in Huangbaiyuan region and Q. aliena community inShagou forest center were lowest, respectively. The good P. tabulaeformis community and Q.aliena community were located between the elevation of1400—1500m and1500—1600m.Both of their total boamss decreased with the increase of slope; both of them in upper slopewere better than those of other slope positions; biomass of P. tabulaeformis in shady slopewas higher than sunny slope, however Q. aliena community showed opposite tendency.3. Gross caloric value of P. tabulaeformis and Q. aliena in Huoditong forest farm washigher, and both of them in Huangbaiyuan forest farm were lowest. From west to east, ashcontent of P. tabulaeformis along survey aere first increased and then decreased, and ash content of Q. aliena along survey aere displayed “U”-shape. Ash content of them were2.81%～3.54%and6.10～7.63%in different regions, respectively.Slope position was main factor to impact on the biomass of P. tabulaeformis, effects ofsite factors on the biomass of Q. aliena was insignificant. The biggest average caloric value ofP. tabulaeformis was in elevation1600—1700m, caloric value of Q. aliena increased withelevation, and both of them on the upper slope were higher than those of other slope positions.Their average gross caloric value reduced with increasing of slope, and located sunny slopewere higher than shady slope.Site factors showed influence on ash content of P. tabulaeformis, and reached maximumbetween the elevation of1400and1600m, but ash conten of Q. aliena had no regular withelevation. Both of their ash content reduced with the increase of slope, and were nicresingwith slope position. Ash content of P. tabulaeformis shady slope was higher than sunny slope,however Q. aliena community showed the opposite tendency.4. Standing crop of energy of P. tabulaeformis community displaed inverse “U”-shapefrom west to east along survey aere, were in order of Huoditang forest farm＞Caizipin forestfarm＞Xunyangba forest farm＞Huangbaiyuan forest farm; standing crop of energy of Q.aliena community decreased along survey aere, and were in order of Huangbaiyuan region＞Fopin region＞Huoditang region＞Shagou region. Both of their energy were increasingfirst and then decreasing along elevation, and reached the maximum at1500—1600m, andreduced with the increase of slope. Energy of P.tabulaeformis on the upper slope was higherthan other slope positions, but Quercus aliena showed the opposite tendency.