| The research of forest carbon sinks on a regional scale and forest ecosystem scale can provide the basis and reference for further study of national and global carbon sequestration functions, while the net increment of carbon storage is an important indicator to measure the carbon sinks of forest ecosystem.In this paper. the dynamic of annual carbon emissions of mortality trees, the carbon storage of ingrowth trees, the residual tree’s net increment of carbon storage, the net increment of carbon storage, and the change trend of carbon storage along with site quality and stand density for natural larch (Larix gmelinii) forest was analyzed by using the data of 602 permanent sample plots (PSPs) from forest resources continues inventory of 4 periods between 1990-2010 in Great Daxing’an Mountains, Heilongjiang Province.The results as follows:l.The tree carbon storage of natural larch (Larix gmelinii) forest have a downward trend on the whole, the tree carbon storage in 1990 is larger(51.3667t·hm-2),and it is samller(39.4503t·hm-2) in 2000,there is a slight increase in 2005 compared with 2000,but the gap is small.2.Overall,the four sample survey data showed that all the carbon storage increase with increasing of aging group(the carbon storage of mature stand is higher than over-mature in 1990 and 1995. The annual carbon emissions and the carbon storage of ingrowth trees for four periods data showed increase first and then decrease and have a rising trend finally, the residual tree’s and the total net increment of carbon storage decreased on the whole;3.The emissions of carbon for all age groups were 0.1337～0.4841 t·hm-2·a and it increased with the increasing of age group. The carbon storage of ingrowth trees is larger (0.1282 t-hm-2·a) in young stand, it is smaller (0.0400 t-hm-2·a) in near-mature stand and there are not significant for other age group. The net increment of carbon storage is inversely proportional with the age group and they are 1.3749,0.9821,0.6499,0.5381, and 0.2407 t·hm-2·a for young, middle-aged, near-mature, mature, and over-mature stand, respectively.4. The emissions of carbon for all age group are positive correlation with stand density under same site quality. The carbon storage of ingrowth trees for young, middle-aged and mature stand decrease with increasing of stand density, and it’s not significant for near-mature stand and over-mature stand. The net increment of carbon storage is the maximum with middle stand density for all age groups except young aged stand. Under the same stand density, the emissions of carbon of all age groups (except near-mature stand and mature stand) are inversely proportional with site quality. For all age groups (except mature stand), the better the site quality, the smaller the carbon storage for ingrowth trees is. Under the similar stand density, the better the site quality, the greater the net increment of carbon storage is.5.The net increment of carbon storage showed a decreasing trend of the approximate hyperbolic form,while the rule between the net increment of carbon storage and the carbon storage of ingrowth trees is not obvious. |
