Changes of local agricultural landscape patterns induced by land consolidation in hilly and mountainous Southwestern China

Land consolidation (LC), as a type of human disturbance, improves land production efficiency and changes landscape distribution through land parcel reallocation. The objective of this study was to comparatively analyze the changes of landscape patches before and after a land consolidation project (LCP) and the effects of land levelling, irrigation and drainage work and road engineering on the landscape structure. FRAGSTAT3.3 and buffer zone analysis were used to investigate those changes. The results suggest that the heterogeneity of landscape depressed, and tended to simplification after LC. Dry land was the most highly variable land use pattern, and the change of forestland was least due to its locations at a gradient larger than 25°. LC resulted in a more rational use of land, and could be an important step in promoting rural development in depressed and fragmented agricultural areas through unused land exploitation, small-patch combination, irrigation and water conservancy, and road construction. Land levelling leveled off the gradient field surface and decreased the slope. The fragmentized patches were much more incorporated with increasing slope. On the other hand, the ridge of a field became longer so that the length of field surface and area of patch were increased. Land levelling regulated, simplified and combined patches, so that the complexity degree was reduced. It is found that the buffer distance of 35 m was a turning point of human disturbance by irrigation and drainage systems, and patches presented flaky distribution when the buffer distance was smaller than 35 m. Meanwhile, the distance range between 25 m to 50 m was an impressible area for road engineering, which was sensitive to human actions, and the changes of all landscape metrics were larger than those in other buffer zones. In general, LC not only reallocated fragmented parcels, but also improved agricultural conditions.

Dynamic changes and transitions of agricultural landscape patterns in mountainous areas:A case study from the hinterland of the Three Gorges Reservoir Area

Analyzing the agricultural landscape patterns in mountainous areas is critical to clarify the dynamic changes and development direction of agricultural landscapes.This also plays a significant role in the rational planning and management of agricultural land.A theoretical framework for agricultural landscape pattern transitions in mountainous areas is proposed to fill the gap of current research with an empirical study in the Caotangxi Watershed,Three Gorges Reservoir Area(TGRA),China.The transition characteristics of agricultural landscape patterns from 2000 to 2018 as represented by sloping farmland,abandoned land,and orchards are analyzed from a holistic-local perspective.The results indicate that the orchards expanded along river valleys,and abandoned land expanded at high elevations,which led to reduced sloping farmland.This phenomenon gives regional landscape differences at the holistic and local levels.Namely,it enhances the region’s holistic landscape diversity but causes fragmentation and aggregation of landscape patches in local areas.The agricultural landscape pattern transitions within the farming range in the study area are manifested primarily in four modes:sloping farmland-orchard conversion type(FOCT),comprehensive conversion type(CCT),partially abandoned type(PAT),and wholly abandoned type(WAT).Each transition mode reveals different development stages of the mountainous agricultural landscape patterns.In general,the agricultural landscape pattern transition is driven by socioeconomic factors in mountainous areas of the TGRA and is bidirectional.This attribute is expressed as the transition from the traditional grain-planting landscape with an even distribution to the eco-economic win-win orchard in valleys and transitions from sloping farmland to abandoned land in high-elevation areas.Overall,the results of this study reveal the uniqueness of agricultural landscape pattern evolutions in China’s mountainous areas in recent decades,which has enlightened the in-depth understandings of rural land use and agricultural ecosystems in mountainous areas of the TGRA,as well as improvements in rural developments and ecological environments.