The hilly areas of central Sichuan Basin are located in the upper reaches of the Yangtze River.The stand in these areas is an important component of the ecological barrier for the upper reaches of the Yangtze River.The Shrub and grass layers as an indispensable part of forest ecosystems have a great function on improving the interception of runoff and maintenance of biological diversity and conserving water and soil.In this paper,the main stand types(mixed alder and cypress plantation and pure cypress forest developed from mixed alder and cypress plantation) are used as the study objects,and researches are conducted on the species diversity of shrub and grass layers under the mixed alder and cypress plantation.These results will provide a theoretical basis for the species diversity conservation and the healthy management of artificial cypress plantations in these regions and similar areas.
Based on the remote sensing data of Landsat TM (1985, 1995, and 2000) and CBERS (2006), and by using landscape pattern method and index model of regional land use change in combining with eco-function regionalization, this paper analyzed the dynamic characteristics of forest landscape in Chengdu City in 1985-2006. In the study period, over 17,000 hm2 of forest land lost, and the number and area of small- and medium-size patches changed significantly, indicating the apparent conversion and fragmentation of forest land. Forest land was mainly distributed in mountainous area, accounting for 70% of the total. In contrast, more number of patches was found in plain region, amounting to 70% of the total. The most rapid change of forest land area occurred in 1985-1995, especially in mountainous region. The relative change rate of forest land area in different eco-function regions also varied in different periods. Forest land, converted to or converted from, was mainly related to cropland and grassland. In 2000-2006, forest land was quite stable. Survival-oriented economic welfare, environmental security, and fast urbanization process were the main driving forces of the temporal dynamic change of forest landscape, whereas geographical division and socio-economic layout were the main constraints to the spatial dynamic change of forest landscape.
Water supply is one of the core ecosystem services functions for wetland. Due to the important status of Zoige wetland, assessment of water supply in Zoige wetland is significant for ecological security all over the world. In this paper, Heihe and Baihe basins in Zoige wetland were taken as research objects, the water yield module of the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model was used to spatially quantify water supply, with the aims of revealing the driving mechanism of water supply under different basins and spatial scale. We observed the spatial pattern change of water yield under baseline and eleven future scenarios and used the ANOVA of repeated measures and multiple linear regression model to explore the patterns and driving factors of water supply in Heihe and Baihe rivers basins. The research results were as follow. (1) The precipitation is main factor to improve water yield, but this intensity is different in different basins and spatial scale. Topography, climate, vegetation, and percentage of wetland conditions have important impacts on water yield services. However, the impacts of these conditions on water yield were various significantly across different watersheds and spatial scales (excluding factors such as precipitation, slope, and percentage of swamp wetland). (2) The spatial pattern of water yield main was affected by land use change and the amount of water yield main was affected by future climate change. (3) Water yield in the Baihe basin was more sensitive to climate change, while the Heihe basin is more sensitive to land use changes. Wetland ecological restoration strategies can effectively improve regional water yield, especially in the Heihe basin. (4) In all scenarios, the southeast regions of the study region were both the main hot spots of water yield. Wetland ecological restoration strategies have added hot spots in the north regions of the Baihe river basin, reduced hot spots in the middle-south regions of the Heihe basin.
Litter production and nutrient return studies in three plantations of Pinus eliottii Engelm,Robinia pseudoacacia,mixed stand of Pinus eliottii and Robinia pseudoacacia in the low hills rainstorm district of Guangyuan City have shown that the annual amount of litter of the three plantations ranges from 3 609.6 kg·hm-2·a-1 to 4 917.6 kg·hm-2·a-1,and in addition to Robinia pseudoacacia stand,the leaf litter production of the Robinia pseudoacacia stand and Pinus eliottii and Robinia pseudoacacia stand is the most,with respective 87.45% and 55% shares of their total volume.The litter production of the Pinus eliottii stand displays three peak values,and the Robinia pseudoacacia stand and the mixed stand of Pinus eliottii and Robinia pseudoacacia have two peak values in a year.Annual return production of N and P of the Robinia pseudoacacia stand is the largest,and that of the Pinus eliottii stand is the least.The nutrient return of leaves is the most in each component.Comparison is made among three kinds of forest,which exhibits that the total amount of litter in Pinus eliottii stand and mixed stand of Pinus eliottii and Robinia pseudoacacia is obviously larger than that in Robinia pseudoacacia stand,but their nutrient return amounts are different.Robinia pseudoacacia plantation and mixed stand of Pinus eliottii and Robinia pseudoacacia are significantly higher than that of Pinus eliottii stand,thus indicating that broad-leaved forest has a good the ability of maintaining soil fertility,and needle-leaved and broad-leaved mixed forests have a bigger ability to improve soil fertility.
Based on the translated data from remote sensing images(IKONOS4) in 2005,the survey data of sub-compartments in 2007 and data from the runoff plots in Xinqiao positioning research station,the landscape structure and ecological function of protection forests in Guansi river watershed were analyzed.The results have shown that the area of mixed Pinus-Cupressus forest is the largest one,occupying 27.37%,the Pinus massoniana forest was the second,accounting for 25.41%,while mixed Quercus-Cupressus forest is the least,occupying 0.96% only.The area of pure forest is obviously large,which is 45.31% higher than mixed forests.The LPI(largest patch index),ED(edge density and PD(patch density) of mixed Quercus-Cupressus forest and mixed Pinus-Cupressus-Quercus forest is smaller,which mean that the distribution is fragmentized;while the Pinus massoniana forest,mixed Pinus-Cupressus-Quercus forest and Cupressus forest is centralized.The IJI(interspersion juxtaposition index)of mixed Alnus-Cupressus forest and mixed Pinus-Cupressus forest is bigger,which implies that the spatial relationship is the more complicated.The AI(aggregation index) of mixed Quercus-Cupressus forest and Cupressus forest is smaller,which means that the patch dispersion degree is bigger and connection is worse,while mixed Alnus-Cupressus forest and mixed Pinus-Cupressus-Quercus forest is opposite.The LSI of mixed Alnus-Cupressus forest mixed Pinus-Cupressus-Quercus forest is smaller,which indicates that the shape distribution is more regular,while Pinus massoniana forest and Cupressus forest is opposite.The diversity of shrub and herb of mixed Pinus-Cupressus-Quercus forest and mixed Quercus-Cupressus forest is bigger,while Pinus massoniana forest and Cupressus forest is opposite.From the function of water and soil conservation,the effectiveness of mixed Alnus-Cupressus forest and mixed Pinus-Cupressus-Quercus forest is better than Cupressus forest and Pinus massoniana forest,the effectiveness of mixed Alnus-Cupressus forest is better than mixed Pinus-Cupressus-Quercus forest.Thus,in the process of restructuring the protection forests in the upper reach of Changjiang river,more mixed forest models,especially with combination of trees,shrubs and grasses would be applied;besides,dense stands should be regulated in order to exert sound ecological function.
Taking the three kinds of inefficient protection forest of pure cypress forest,pure pine forest and mixed pine-cypress forest in hilly area of central Sichuan as research objects,the experiment of open window was done and the four broad-leaf species,Robinia pseudoacacia,Alnus formosana,Cinnamomum japonicum and Cinnamomum camphora,were planted.By using three factors: different types of fertilizer(compound fertilizer-A1,nitrogenous fertilizer-A2,decaying cake fertilizer-A3),different fertilizing methods(hole fertilization-B1,radial canal-B2,control treatment-B3) and different number of fertilizer(50 g-C1,100 g-C2,150 g-C3),the broad-leaf species(L9(34)) were fertilized with manurs by orthogonal test and then a survey was made of their growth of tree height and ground diameter after a year.The results showed that:(1)To four broad-leaf species,the annual average of tree height growth of Cinnamomum camphora was the biggest among them,which was more 52%,77% and 75% than Robinia pseudoacacia,Alnus formosana,Cinnamomum japonicum,while the annual average growth of its ground diameter was more 44%,74% and 56%.(2) The growth of the four broad-leaf species in the mixed pine-cypress forest was the best among the three different transformation patterns,the next was pure pine forest,the last was pure cypress forest.The annual average growth of tree height was mixed pine-cypress forest(0.83 m)pure pine fores(0.71 m) pure cypress forest(0.32 m),while the ground diameter was mixed pine-cypress forest(0.90 cm)pure cypress forest(0.83 cm) pure pine fores(0.82 cm).(3)The optimal combination of every factor level was A1B1C3,the next was A1B1C1.The influence to both the growth of tree height and ground diameter of every factor level was A→C→B.(4)Not only using different active carbon but also using different kinds of fertilizer had a remarkable impact upon the growth of trees,while using different combinations of fertilizations had not obvious influence.
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