| Upland meadow plays an irreplaceable role in mitigating global warming.The increase and decrease of area,vegetation composition and quality status,distribution pattern and changes in soil carbon storage capacity will have a great impact on regional environment and global changes.Therefore,it is of great theoretical and practical significance to study the landscape pattern change of upland meadow and its impact on soil organic carbon storage(SOCR).This study took the upland meadow of Wugong Mountain in Jiangxi Province as the research area,based on the landscape ecology and soil ecology theory,and based on the data of the TM remote sensing image data of 1995,2002,2010and 2015 and the plot test data.With the support of“3S”,the landscape dynamics of Wugong Mountain meadow in the past 20 years was studied,and the influencing factors of upland meadow degradation were analyzed.Based on the landscape pattern analysis,the soil carbon storage of different types of upland meadow was studied,and the in-depth analysis of SOCR process in the degradation process of upland meadow.The research conclusions are as follows:(1)Temporal and spatial dynamics study of landscape pattern in the meadow area:the area of upland meadow decreased,the area of non-meadow increased,the landscape types changed frequently,and the conversion area accounted for 36.60%of the total area of the meadow;the dynamics of each landscape type and the trend of area change were consistent,and the center of mass changed.The upland meadow landscape was shifted to the southeast by 70.96°and about 394m.The topographic factors had significant effects on the landscape pattern of the meadow area(P<0.05).The area of the landscape type and the proportion of the landscape showed different distribution patterns with elevation,slope and aspect.The analysis of the landscape pattern index reflects the increasing interference of upland meadow and the increasing dominance of non-meadow types.At the landscape scale,the study area was fragmented and diversified,but the trend of increased landscape heterogeneity has slowed down.(2)Analysis of dynamic change of vegetation coverage in upland meadow:from the two dimensions of landscape and scenic area respectively,the area of upland meadow decreased in 20 years,and the vegetation coverage generally showed an upward trend,showing the distribution characteristics of southeast and northwest which spatial degradation and improvement coexist.The area of meadows in Jinding Scenic Area was the largest,and the vegetation coverage was the best.The vegetation coverage in 20 years has improved.The vegetation coverage of Jiulong Mountain Scenic Area has changed drastically,and the overall situation was rising.The vegetation coverage of the Fayunjie Scenic Area was low,showing a slight improvement trend.There was a high correlation between the distribution pattern and topographic factors of upland meadow(P<0.05),and the vegetation coverage changed regularly with the change of aspect,slope and altitude.The influencing factors of the dynamic change of vegetation coverage in upland meadow were analyzed by using climatic factors and human factors.The results showed that precipitation and temperature in climatic factors had significant effects on the growth of Wugong Mountain meadow(P<0.05),and the influences of annual precipitation was greater than the annual average temperature;the increase of tourists was not conducive to the growth of meadows and vegetation patches.It has promoted the diversification and fragmentation of the landscape;human disturbance such as overgrazing and agricultural reclamation was also an important reason for the growth of the meadow.However,the standardized management and ecological restoration of the scenic area contributed to the restoration of vegetation and soil.(3)Distribution law of soil organic carbon density in upland meadow:From the profile,the upper layer soil was significantly higher than the lower layer soil(P<0.05).The density of organic carbon in the whole soil layer(0-40cm)was between 2.07-13.17kg/?,which was much lower than the organic carbon density of alpine meadow soil.The soil organic carbon density of different coverage types in upland meadow was significantly different(P<0.05),the highest coverage area was the highest,the middle coverage area was the second,and the low coverage area was the lowest.The comparison between different scenic spots shows that the Jinding Scenic Area was higher than the Jiulong Mountain Scenic Area,and the Fayunjie Scenic Area was the lowest.The results showed that there was a high correlation between ground vegetation cover and soil carbon storage capacity in upland meadow.(4)SOCR and its interannual variation characteristics in response to changes in upland meadow landscape:The SOCR in 1995 was 294.66×10~3t.The overall soil organic carbon storage in upland meadow landscape decreased during the past 20 years,and was reduced by 17.27×10~3t in 2015,showing a weak carbon source phenomenon.In the past 20years,there have been different carbon source carbon sink conversions with the change of landscape pattern.Based on the measured carbon sequestration capacity of high-coverage meadow soils in three scenic areas,and those three scenarios were set to estimate the soil carbon sequestration potential.In the Jiulong Mountain Scenic Area,the grazing prohibition was carried out.The Wugong Mountain meadow will increase the soil organic carbon storage by 3.64×10~3t;the disturbance of tourism,animal husbandry and ecological agriculture will be reduced to 50%,and the whole mountain meadow soil organic carbon will increase by 11.56×10~3t;the most ideal ecological restoration mode was to completely ban the tourism,animal husbandry and agriculture in the study area.The soil carbon fixed potential of the mountain meadow in the whole study area was 23.11×10~3t. |
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