Structural attribute and optimization of farmland and non-cropped green-land patches of agricultural landscape: A case study of Fengqiu County, Henan Province

Agricultural landscape is one of the most important landscape types on the Earth. It is a composite mosaic made up of natural and human-managed patches, providing basic production and living conditions for humans. In agricultural landscape, non-cropped green-land patches or habitats are vital for maintaining biodiversity, functionalities and services of agro- ecosystems. However, these contributions of non-cropped green-land patches are not been fully recognized and understood even up to now. Plenty of evidence show that accelerated development of modern agriculture in the world has led to the disappearance of a large number of non-agricultural green-land patches. Moreover, the structure of agricultural landscape has become increasingly simple, severely damaging the functions and services of agro-ecosystems. Thus the sustainable development of agriculture and even the whole world require an increasing emphasis on the study and examination of the relationships between agricultural productivity and biodiversity, landscape heterogeneity and ecosystem functions and services. The middle and lower reaches of the Yellow River plain is an important grain-producing area in China. The plain has typical agricultural landscape features and provides the conditions for ideal case studies. Fengqiu County is located in the lower reaches of Yellow River in Henan Province, which was selected as case-study area for this research. To analyze the landscape structure, we firstly extracted and classified green-land patches by ArcGIS10.0 based on 2013 remote sensing images. Secondly, we derived vector diagrams of green-land patches to get basic and useful information on non-cropped green-lands in the study area. Then by referencing to the national green space classification standard, non-cropped green-land patches were divided into 3 types — residential green-land, hedge/ditch green-land and artificial forest. In this study, we specifically analyzed the structural attributes of non-cropped green-land patches using Fragstats package. The study results showed that both of the total rates and areas of non-cropped green-lands had low values in the Fengqiu County. The dominant type of non-cropped green-land patches was artificial forests with single structure and sparse vegetation, which was well distributed around residential areas. Residential green space was relatively scattered and broken whereas the connection degree of hedge/ditch green-land was low. The diversity index of non-cropped green-land patches was lower. All these suggested the fragmentation distribution characteristics in the study area. In order to increase the quantity and quality of non-cropped green-land patches in agricultural landscape, it was suggested to build new types and increase the ratio of non-cropped green-lands by adjusting the spatial structure and strengthening the configuration of different landscape elements. The detailed optimization methods of this strategy were given as follows: 1) enhancing landscape heterogeneity by increasing non-cropped green-land patch types; 2) increasing complexity of green-land patch structure by adjusting the proportion of non-cropped green-land patches; and 3) accomplishing rational distribution of landscape structure by optimizing the configuration of non-cropped green-land patches. The results of the study provided scientific bases for further exploration of landscape pattern arrangements and final construction of multifunctional landscapes in the future.