| Masson pine (Pinus massoniana Lamb.) is a main coniferous tree species in subtropical area. It is the major industrial timber species in China. Forestry practice has been proved that pure pine forest couse series of problems such as decline in forest productivity, weak ecological function, rampant of pine moth, soil fertility decline, and weak fire prevention ability. Mixedwood can effectively utilize light energy and soil, to improve forest productivity. ZongYang County, Anhui province belongs to subtropical monsoon climate zone and the four season’s climate changes obviously. The mixedwood of conifer with deciduous broad leaved tree is the main vegetation types in the area. This paper researched different proportion of Masson pine mixed forest since2007. The forest biomass, plant carbon, soil organic carbon, biodiversity, undergrowth, root and soil had been studied. The results showed as follows:1. Tree layer(1) The main arbor tree trunk analytical results show that Masson pine aerial parts of each organ and whole plant biomass and growth indicators and the relationship between model for Wtrunk=53.69704+0.01025×(D2H)、lnW skin=-16.24899+9.89795·lnD-0.58846·D、 lnWbranch=6.18119-1.60294·lnD-0.75932·ln(H/D)、Waboveground=-14.63286+40.72698·lnD、 Wplant=6.1435+39.05153·lnD; And each organ and aboveground part and whole plant biomass model for lnWtrunk=0.55883+0.70839·lnD-1.98923·ln(H/D)、Wsin=1.6635·D0.07566、 lnWbranch==6.87613-0.703524·lnD+3.40175·ln(H/D)、lnWleaf=4.58771+0.20155·lnD+5.19331·ln(H/D)、 lnWaboveground=9.99853-3.73503·lnD+0.28907·D、lnWplant=10.48087-3.85889·lnD+0.29122·D. Tree species for biomass and forest carbon measurement provide shortcuts.(2) With the increase of Masson pine mixed proportion, the stand total above ground biomass changes unceasingly. The stand total above ground biomass gradient and mixed proportion relations as follows:40-60%>20-40%>60-80%>80-100%>0-20%.When the proportion of Massion pine is40-60%, the total above ground biomass is biggest with about123.36t-hm-2. While pine mixing proportion is80-100%, the total above ground biomass is lowest with only81.79t·hm-2. Tree layer biomass to a certain extent determines the distribution trend of the total stand above ground biomass.2. Herbs and shrubs layer(3) With the change of Masson pine mixed proportion, the shrub layer biomass is significant different (P<0.01). The biggest is0.97t.hm-2in the forest with Masson pine60-80%, followes by40-60%,20-40%,80-100%and0-20%successively. The mixed ratio of60-80%has lowest shrub biomass of0.98t. hm-2. The mixed ratio of20-40%has highest shrub biomass of1.36t.hm-2.(4) Different mixed proportion leads to different shrub and herb structures. The study showes a trend of decrease after the first increase that the shrub layer species richness increased with the increase of proportion of Masson pine; herb layer species richness almost not change along with the change of proportion of Masson pine; the shrub layer coverage showed a trend of gradually reduce; herb layer’s height down slowly, shrub layer’s hight volatility changes. Mixed proportion significantly effect on undergrowth biodiversity index. The Shannon-Wiener index and Margalef index of shrub layer plants is:80-100%<0-20%<20-40%<60-80%<40-60%successively.(5) Total biomass with shrub layer biomass and shrub layer diversity index with richness index has significant positive correlation, partial reached extremely significant positive correlation. Shrub layer biomass has significant negative correlation with herb layer biomass. Herb layer biomass is significantly positive correlation with plant diversity and richness. In different proportions of mixed forests, shrub layer biomass of understory biomass proportion is higher, the herb layer only accounts for less, with the increase of mix ratio, undergrowth biomass showed a trend of decrease after increase. In different proportion of forest, shrub layer biomass take up of the total biomass of the understory order as:60-80%<80-100%<0-20%<20-40%<40-60%, with80-100%and60-80%of the very significant (P<0.01) lower than other three kinds of proportion.3. Underground(6) The average fine root (d<10mm) biomas of Masson pine mixed is1.693t·hm-2.With the changing of mixed ratio, fine root biomass changes unceasingly. The order of fine root biomass is60-80%<80-100%<0-20%<20-40%<40-60%. The ratio of fine root biomass with total root biomass is in the order:40-60%>20-40%>0-20%>80-100%>60-80%. The highest fine root ratio is in the stand with Masson pine40-60%. Fine root has the function of improve forest soil structure, increasing soil organic matter content, improves the community species richness, also increased the fine root biomass.(7) Soil bulk density is negatively correlated with total biomass, shrub layer biomass of undergrowth and herb layer biomass, soil porosity were positively correlated with them, which places in total biomass has significant negative correlation with soil bulk density and the significant positive correlation with soil porosity. Bulk density has a weak negative effect with the shrub layer’s and herb layer’s biomass; moisture content has certain positive effect with the shrub layer biomass, but did not reach significant level. The index, which content Margalef and Shannon, of understory shrub layer and herb layer showed different degrees of positive correlation with soil water content, pH, organic matter, total nitrogen, total phosphorus, total potassium and available phosphorus and available potassium, but none of them reach significant level. Margalef index and Shannon Wiener index of shrub layer showed a hegher negative correlation with soil bulk density, at0.456and0.432respectively.(8) The fine root biomass is extremely significant positive correlation (P<0.01) with porosity, organic materior. Total phosphorus and available phosphorus are significantly positive correlation (P<0.05) with water content in the0-10cm soil layer. Specific root length is significantly negative correlation (P<0.05) with soil total potassium and total nitrogen. The density of fine root is significantly positively related to density and soil porosity (P<0.05). In10-20cm soil layer, the fine root biomass is very significant positive correlation (P<0.01) with porosity, moisture content, organic matter and total phosphorus, and is significantly positive correlation (P<0.05) with available k. Specific root length was significantly negative correlated (P<0.05) with available potassium and total potassium. In20-30cm soil layer, the fine root biomass is very significant positive correlation (P<0.01) with porosity, water content, available potassium and organic matter are significantly positively related (P<0.05) to total potassium. Root length negatively correlated with total phosphorus. And the root density is significantly positive correlation (P<0.05) with total potassium.4. Forest colosystem(9) The biomass in dirrefent organ difference. The distribution of biomass in the tree is the trunk>root> branch>skin>leaf. Standard of Masson pine wood maximum per plant, and trunk biomass above ground were114.69kg,98.48kg,77.83kg, have appeared in the Masson pine mixed proportion of40-60%of the forest; Minimum value in0-20%mixed in the proportion of forest, respectively is102.8kg,86.01kg,63.57kg. The relationship between biomass of vegetative organs and diameter at breast height and tree height present positive correlation is same as under the tree with diameter at breast height and tree height increases. Masson pine root biomass per plant biomass accounted for about15%, is each organ biomass accounted for the proportion of the total plant biomass change in the smallest. As for Platycarya strobilacea, the relationship between biomass and diameter at breast height and tree height is positively correlated. And the maximum biomass above ground is82.56kg per plant, and appeared in the mixed ratio of20-40%of the forest. The minimum value is65.21kg, and appeared in the mixed ratio of60-80%of the forest. The proportion of trunk biomass is the largest too, followed by the branch and stem.(10) The mixwood with different proportion of Masson pine has different capacity of carbon. Gradient of forest carbon is40-60%>60-80%>0-20%>20-40%>80-100%. The maximum of the litter and coarse wood carbon reserves is2.15t.hm-2, and appeared in the mixed ratio of40-60%of the forest, it is far higher than many other proportion of mixed forest. The mixed proportion of forest litter and coarse wood carbon carbon capacity is far greater than the shrub layer, thus it can be seen, and litter and coarse wood is an important part of carbon sinks. Experimental shows that with the increase of the mixed proportion the0-30cm soil carbon reserves in the study area as follows:40-60%>60-80%>20-40%>80-100%>0-20%. |
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