基于典范对应分析的滨海滩涂围垦区景观格局与土壤盐渍化关系

Relationship between landscape patterns and soil salinity based on canonical correspondence analysis in coastal reclamation area

以江苏中部如东滩涂围垦区为研究区,利用典范对应分析探讨不同空间尺度景观格局对土壤盐渍化程度的影响和贡献度。结果表明:(1)研究区斑块密度、边缘密度、景观形状指数、聚集度指数、散布与并列指数较高,说明景观破碎化程度较高,景观结构复杂,景观分布受人为干扰的程度较大。(2)土壤中Na+和Cl-分别占阳离子总量和阴离子总量的87.4%和90.1%,土壤盐渍化指标的变异系数为53.49%~129.03%,反映了土壤盐分的非均匀分布。(3)研究区景观格局指数在100 m和200 m缓冲区尺度分别能累积解释土壤盐渍化程度变化的66.6%和80.1%,土壤盐渍化程度与农建地和水浇地面积比例呈正相关关系,与旱地面积比例呈负相关关系。(4)景观水平上的土壤盐渍化程度与最大斑块指数、蔓延度指数呈正相关关系,与斑块密度、边缘密度、景观形状指数、香农多样性指数呈负相关关系;斑块类型水平上,最大斑块面积指数、边缘密度、景观形状指数是影响研究区土壤盐渍化程度的共性指标。研究对于优化滩涂围垦区土地利用格局,降低土壤盐渍化程度具有重要意义。

Coastal zone is an important land reserve resources. Its improvement and development has become a hot topic in many countries. Rudong coastal reclamation area was selected as the study area in this study. The canonical correspondence analysis was applied to analyze the relationship between soil salinization and landscape pattern at different scales, and to determine the contribution of the landscape index to the degree of soil salinization. The results showed that the patch density （PD）, edge density （ED）, landscape shape index （LSI）, aggregation index （AI） and interspersion and juxtaposition index （IJI） of the study area were higher and varied in land use types that indicated the higher level of landscape fragmentation and more complex of landscape structure; The landscape structure was dominantly affected by anthropogenic activities. Soil Na~ and CF was the main component of soil salinity, accounting for 87.4% and 90.1% of the total cations and anions, respectively. The coefficient of variation of soil salinization index varied from 53.49% to 129.03%, which reflected the nonhomogeneous distribution of soil salinity caused by anthropogenic activities. The result of canonical correspondence analysis showed that, landscape pattern variables in 100 m and 200 m buffer zones could explain 66.6% and 80.1% variations of soil salinization, respectively. The positive relationship was observed among the ratio of agricultural construction land, irrigated land and the level of soil salinity, while that of dry land was negatively correlated with the level of soil salinity. Soil salinization had a positive correlation with largest patch index （LPI） and contagion index （CONTAG）, while as it had a negative correlation with PD, ED, LSI and Shannon＇s diversity index （SHDI） on landscape level. On patch class level, LPI, ED and LSI were the Colinear indicators affecting the soil salinization. Finally, the study on the relationship between landscape patterns and soil salinization may be of great significance to optimize the land use pattern and to reduce the degree of soil salinization.