苏南地区景观格局特征与坑塘水质关联关系.

Influences of land use types and landscape pattern indexes on the water quality of ponds were explored here in southern Jiangsu of China, particularly for the environmental protection of rural water under the background of rapid urbanization. Taking 42 rural ponds in Sunan District as the research object, the water sample was collected for the land use data in July 2019 and September 2020. Some parameters were selected as the feature condition for the water quality of ponds, including the potential of hydrogen (pH), electrical conductivity (COND, μs/cm), dissolved oxygen (DO, mg/L), phosphate (TDP, mg/L), and ammonia nitrogen (NH3-N, mg/L). Firstly, Fragstats 4.2 software was used to calculate the landscape pattern indexes. The comprehensive pollution index and pollution load ratio index were then calculated on the basis of the divided watershed. At last, Spearman correction and redundancy analysis (RDA) were thus combined to initially explore the impacts of land use and landscape pattern on the water quality. The results showed: (1) There was a great difference in the water quality of rural ponds in Sunan District. Specifically, there was an increasing trend of COND and NH3-N, a decreasing trend of TDP, while a trend of decreasing first and then increasing for the DO from north to south in the study area. The southern region was more polluted, indicating the most serious DO pollution. The intensity of land use was relatively high in the buffer zones at different scales. The cultivated land and construction land were dominant with an average ratio of 57.34%-73.19%. (2) The water quality varied significantly in the land use types. A positive correlation was obtained on the construction land with NH3-N and DO, whereas, a negative correlation with TDP and COND. A significant positive correlation was observed on the cultivated land with COND and NH3-N, particularly on the 200m and 400m/500m scale with TDP. A certain positive effect was achieved on the woodland and grassland with the water quality purification, where a more obvious correlation was found on the 200m scale. (3) In the correlation analysis, Largest Patch Index (LPI) and Aggregation Index (AI) at 100m scale were significantly negatively correlated with COND and NH3-N, whereas, Landscape Shape Index (LSI) and Patch Division Index (DIVISION) at 100m scale were significantly positively correlated with COND and NH3-N. In the redundancy analysis, the cumulative percentage of the first sort axis (constraint axis) was 94.4% within the 100m buffer zone, and the correlation coefficient was 53.3%, indicating a better relationship between water quality and landscape pattern. (4) LPI, LSI, DIVISION, Patch Cohesion Index (COHESION), and AI presented the most obvious relationship with the water quality characteristics. The findings can provide a sound reference for decision-making in land use planning. [ABSTRACT FROM AUTHOR]

研究不同空间尺度景观类型与景观格局指数对农村坑塘水质的影响程度和机制对于快速城镇化背景下乡村水环 境保护具有重要的现实意义。基于实地水样采集数据及土地利用数据，以苏南地区农村坑塘为研究对象，结合相关分析、 冗余分析等数理统计方法，初步探讨经济发达区农村坑塘水质与土地利用/景观格局之间的特征关系。结果表明：1）苏 南地区农村坑塘水质状况不一，自北向南，电导率（COND）、NH3-N 有增加趋势，磷酸盐（TDP）有减少趋势，溶解氧 （DO）先降后增。平原区坑塘污染较严重，以DO 污染为主，低山丘陵区污染程度较轻，主要为磷元素和DO 污染。不 同尺度缓冲区内土地利用强度较大，耕地、建设用地占主导地位，平均面积比例在57.34%～73.19%；2）不同景观类型 对水质影响存在差异，建设用地与NH3-N、DO 呈正相关，与TDP、COND 呈负相关，耕地在200 m 尺度上与COND、 NH3-N 呈显著正相关，在400～500 m 尺度上与TDP 呈显著正相关，林地和草地对水质净化具有一定正效应，且在200 m 尺度上较明显；3）景观格局指数与水质特征关系较明显且存在尺度差异。相关分析中，100 m 尺度下的最大斑块指数（LPI）、 景观聚集度指数（AI）与COND、NH3-N 呈显著负相关，100 m 尺度下的景观形状指数（LSI）、景观分离度指数（DIVISION） 与COND、NH3-N 呈显著正相关。冗余分析中，100 m 缓冲区内，第一排序轴（约束轴）累积百分比为94.4%，相关系 数为53.3%，较好表达水质指标与景观格局指数的关系；4）LPI、LSI、DIVISION、斑块结合度指数（COHESION）及 AI 与地区水质特征关系最为明显。斑块密度越小，破碎度越低，聚集与连接度越低，分离度越高则越有利于地区坑塘水 质的保护。通过多维度分析，在一定程度上揭示了苏南地区坑塘生态水文过程，有利于经济发达区农村坑塘管理和水质 保护，研究结果可为政府相关部门决策提供一定参考。 [ABSTRACT FROM AUTHOR]