Evaluation on effect of land consolidation on habitat quality based on InVEST model

Abstract: Land consolidation is a process of re-organization and re-optimization of land resource and its utilization. The change of land resource and its utilization has a profound influence on the circulation process of material flow and energy flow between habitat patches, thus changing the quality and distribution pattern of the regional habitat. Da'an City is located in the Songnen Plain, which is flat, and rich in cultivated land reserve resources and water resources, and is one of the most potential areas of agricultural development in China. This paper took the land consolidation major project area of Da'an City as an example, and analyzed the influence of land consolidation on habitat quality based on the model of InVEST (integrated valuation of ecosystem services and tradeoffs). The data used in the study was the 1:10000 land use map of the land consolidation project area in 2008, 2011 and 2014, which represented the time before, during and after the land consolidation. Based on the ArcGIS 10.0 software, the land use vector data were output as the raster data of 30 m × 30 m, which were used as the evaluation unit of the habitat quality of the project area. The results showed that: 1) Cultivated land, saline alkali land and grassland were the main land use types in the project area. After land consolidation, a large amount of saline alkali land was converted into arable land, and the proportion of arable land area in the total area of the project increased from 14.43% to 71.19%. The degree of landscape fragmentation was significantly decreased after land consolidation. 2) The overall habitat quality of Da'an land consolidation project area was poor. The area of which the habitat quality score was between 0 and 0.1 accounted for 54.62%-72.03% of the land consolidation project area. The main reason for this phenomenon was that for the land use types whose habitat quality was higher, such as woodland and grassland, their areas were small and the distributions were dispersed; the areas of cultivated land and saline alkali land were larger, but the habitat quality of the 2 kinds of land use types was lower. 3) Before land consolidation, the score of habitat quality was 0.194; the score of habitat quality was reduced to 0.189 during land consolidation, and was increased to 0.214 after land consolidation. Before, during and after the land consolidation, the habitat quality showed a trend of first decreasing and then increasing. Saline alkali land is one of the threat factors of habitat quality, and its area in the former project area was large, which has a negative impact on the quality of the whole project area. The disturbance of human during the land consolidation project has reduced the habitat quality of the project area. After land consolidation, the score of habitat quality was increased to 0.214. The main reason was that the land use pattern has been optimized owing to land consolidation. At the same time, a large increase in arable land has made the grain production capacity of the project area increase significantly. 4) Overall, the land consolidation project has improved the habitat quality of the project area, but the habitat quality score has experienced a process of first decrease and then increase. In the 3-4 years after land consolidation, the quality of the habitat was the lowest since land consolidation completed, and it was only 0.06 higher than that before land consolidation. And then the quality of the habitat began to improve gradually. After land consolidation, there would be a small amount of arable land changed to saline land again, so the habitat quality of the project area decreased. However, the maintenance work would improve these saline alkali land and change them to arable land, so the quality of the habitat would rise again.