| Pinus kesiya(Pinus kesiya var. Langbianensis) plantation is an important main timber tree species in Yunnan province and it is a kind of high carbon sink tree species. It can provide basic data of soil carbon stock in yunnan province by the study of Pinus kesiya plantation carbon storage. Fine root, as the key factor of the underground ecological processes of forest, plays a important role in carbon cycling in the forest ecosystem. It is necessary to study the fine root biomass, carbon stocks, degradation and the soil carbon storage of Pinus kesiya plantation. In this paper, Pinus kesiya plantation which has different age and different density were conducted at the region of Si Mao and Jing Gu county in Puer City,Yunnan Provice. The main results of this study are as follows:(1) In the 0-30 cm soil layer, 15 years old plantion owns the largest fine root biomass(14.44±3.55 t.hm-2). and natural Pinus kesiya forest has the lowest Pinus kesiya fine root biomass(6.78±0.71 t.hm-2). The other fine root biomass increased with the increase of forest age, and Natural Pinus kesiya forest has the largest other fine root biomass. Fine root biomass has obvious vertical distribution characteristics. Fine root biomass increases with the plantion age. Pinus kesiya live fine root biomass is significantly higher than the death; Pinus kesiya fine root biomass decreases with the decreasing of density and when come to 2m×2m the fine root biomass become increasing; Planting density and other fine root has a significantly negative correlation relationship between root biomass. The plantion age and total fine root has a significantly negative correlation relationship. The plantion age with live fine root biomass and the death all have negative correlation relationship.(2) In the 0-30 cm soil layer, fine root biomass in 30 years old Pinus kesiya plantion and Natural Pinus kesiya forest significantly large than other aged plantion, and the carbon content of fine root is increased with the increase of forest age; Fine root biomass of 30 years old Pinus kesiya plantion and the natural Pinus kesiya forest are lowest; The fine root carbon storage are reducing with the soil depth deepening; In 0-20 cm soil layer, fine root carbon storage has contributed more than 70%.(3) Fine root and needle in natural forest has the minimum dry weight residual rate. Dry weight residual rate of fine root and needle in different density plantion is the 2m×3m plantion; Decomposition coefficient of Pinus kesiya fine root is 0.1125 to 0.2248. Fine roots and needle’s decompose relatively quickly in the first two months and September.(4) The length and SRL of coarse root, large root, medium root and small root increased with the increase of diameter class, the SRL of fine root are decreased with the increase of diameter class; The poprotion of biomass on medium root, small root and fine root decreases first then increases with increase of diameter class, coarse root and large root increases first then decreases with increase of diameter class. On same diameter class, SRL of fine root are much higher than other roots. Biomass of various organ was following stem>branch>root>needle>cone, and the stem biomass accounted for over 50% of the total biomass. Each organ biomass increases with the increase of diameter class, and aboveground biomass was significantly positively related with underground biomass. Individual aboveground biomass range between 2.23~324.95 kg and belowground biomass range between 0.52-41.80 kg. Biomass of root collar, taproot and lateral root increase with the increase of diameter class. collar/taproot, collar/total root and lateral root/taproot was significantly positively related with DBH and H and taproot/total root as significantly negative related with DBH and H. Adding height in the LR biomass equations(W=a DbHc) except con biomass equations could significantly improve model fitting performance and predicting precision. Taproot dominated over total root and the ratio of lateral root biomass is relatively small on total root. Taproot/total root decreases, lateral root/total root increase with increase of DBH and H. Root morphology is influenced by many factors and fine root root has higher nutrient absorption rate than others. Tree layercarbon stocks of Pinus kesiya var. langbiannesis plantation of three stand age-class(immature forest, near-mature forest and over-mature forest) are 47.52±2.27 t·hm-2,116.88±9.19 t·hm-2,242.71±17.20 t·hm-2 and increased with stand age development. Layercarbon stocks between three stand age-class have sigenificant differences.(5) SOC content, nitrogen content and C:N decrease with soil depth, and bulk density increases with soil depth. Different aspect and slope significantly affect the SOC stocks, SOC stocks of sunny slop was significantly higher than shady slope, SOC stocks of slope 20-30° significantly lower than 10-20° and 0-10°, slope position was no significant effect on SOC stocks. On 0-100 cm soil, with the increase of soil depth, SOC stocks showed a decreasing trend at different site conditions of middle-aged Pinus kesiya var. langbianensis forest. SOC stocks are significantly higher than other 0-20 cm soil on different aspect, slope position and slope. Aspect and slope significantly affect the SOC stocks of 0-20cm(P <0.05). On 0-20 cm, SOC stocks and soil bulk density was significantly negatively correlated, and aspect, slope were significantly negatively correlated. SOC stocks and total nitrogen were significantly positive correlation on other soil levels, besides 20-40 cm. SOC stocks and slopes, SOC stocks and C: N have no significant correlation in the either soil level.(6) Base diameter, plant height, total biomass and numbers of branches of Pinus kesiya seedling between different fertilizer treatments and each organ biomass distribution had no significant differences. The carbon content of stems and branches are the highest, and the lowest are roots. Nitrogen, phosphorus and N: P on needles was the highest in all organs between different fertilizer treatments; N:P on roots is the smallest and C:N on roots is the biggest, followed by branches and stems, and needles is the smallest. |
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