Evaluation On Carbon Sink Of Cunninghamia Lanceolata-Vernicia Montana Mixed Forest And Its Relationship With Nutrient Characteristics

With the rapid development of morden social economy, people need more andmore wood.But the original forest has been cleared.So a large area of artificial pureforest appeared.However, because of the long-term operation of artificial pure forestand people did not take effective measures,a series of problems such as thedegradation of pure forest soil,soil acidification,the productivity of the forest declineand so on appeared.These problems seriously threatened the sustainable developmentof forest land,and has caused domestic and international wide attention in manycountries.In such a case, in order to improve forest economic, social and ecologicalbenefits, building mixed forest is the inevitable choice.Chinese fir which was one of the fast growing tree species in our country andwas the most important afforestat tree in Southern China was large-scale planting.However, the malpractice which was led to by the large area of pure Chinese firplantation which was continuously planting becomed more and more prominent.Scholars began to study the way to alleviate the stress. One was to build mixed forestwhich was formed by Chinese fir and other broadleaf tree.This paper made12years Chinese fir plantation, Aleurites Montana pure forestand mixed forest of Chinese fir and Aleurites Montana (mixed ratio of about1:1) asthe research objects. The paper mainly studied stand biomass,organic carbon andnutrient content's characteristics, carbon and nutrients storage of forest ecosystemabout soil and plant in three kinds of forest. The main results were as follows:The results of the study about biomass showed that the total biomass of arberlayer, shrub layer, herbaceous layer and litter respectively was63.374t/hm~2,33.376t/hm~2and62.420t/hm~2,most of which was from arbor layer, respectively was60.771t/hm~2,30.432t/hm~2and60.259t/hm~2.And the remaining was from shrub, herb andlitter. Either the total biomass or arbor layer's biomass, Chinese fir plantations wasslightly higher than that of mixed forest, which was related to many factors such asdensity, habitat and so on.The biomass of trunk of the arbor and shrub layers washighest. While the biomass of root was the highest in the herb layer. Litter's biomass was relatively high in every stands, especially in Aleurites Montana pure forest. Themaximum of root 's biomass existed Chinese fir plantation.The results on organic carbon of forest ecological system showed that, in general,the content of soil organic matter presented upper> middle> lower,and it was higherin March and lower in September, and it was slightly higher in mixed forest than thatin pure forest. Organic carbon content of botany performenced litter layer> arborlayer> shrub layer> herb layer, the maximum of organic carbon content in pureforest wais in September, the lowest in December. The maximum of organic carboncontent in mixed forest was in March, the lowest in September.When it comes to theseason, the month in which average content of soil organic matter was high was lowerin organic carbon content. The varieties of organic carbon in mixed forest wereconsistent with that of the soil organic matter content. As for average content of soilorganic matter,it presented mixed forest> Chinese fir plantation> Aleurites Montanapure forest. The average content of plant organic carbon performenced Chinese firplantation> Aleurites Montana pure forest>mixed forest.The results on nutrition content of forest ecological system showed that nutritioncontent presented different variety regularity with the season and stands differing. Theseasonal variety about soil nutrient contents in pure forest was very complex.On thewhole, it was higher in March and June in pure forest, while it was higher inMarchmixed forest. The seasonal variety about plant nutrition contents was alsocomplex, and the plant nutrition contents was highest in December. Soil nutritioncontent was higher in mixed forest, while plant nutrition content was higher inChinese fir plantation. The relationship between plant nutrition content and soilorganic matter content was complex, not showing certain regularity. The content ofpotassium and iron was higher while magnesium and manganese was lower.The total carbon storage of three types of forests performanced that it was higherin soil than that in plant, explaining tnat nutrient elements mainly existed thesoil,which was consistent with the previous research results. But the soil organiccarbon and nutrition storage of three types of forest presented pure forest>mixedforest> Aleurites Montana pure forest, which was not consistent with the previous research results. While the carbon and nutrition storage of plant performanced formixed forest>Chinese fir plantation> Aleurites Montana pure forest.The main reasonwas that forest density was higher in mixed forest than that in pure forest.It had moreplant in mixed forest,so the carbon and nutrition storage was naturally higher in mixedforest. But the forest density was an important factor for tree's growth. Proper forestdensity can make full use of forest land resources and make forest grow well.However,unreasonable forest density may inhibit the growth of forest trees.In general, the above conclusions were less consistent with previous researchresults.About forest ecosystem biomass,it was higher in mixed forest than that in pureforest. The organic carbon and nutrition content of forest ecological system, in general,was higher in mixed forest than that in pure forest, too. They proved that the mixedforest wais superior to pure forest.But the results of this article was that Chinese firplantation was better.It was related to many facors such as forest density, environment,management process and so on.