Recent Shrinkage and Fragmentation of Bluegrass Landscape in Kentucky

Jia Yang,Ray Smith,Wei Ren,Bo Tao,Jinze Liu,James Fox,Alex C Ruane,Yanjun Yang

doi:10.3390/rs12111815

Abstract

The Bluegrass Region is an area in north-central Kentucky with unique natural and cultural significance, which possesses some of the most fertile soils in the world. Over recent decades, land use and land cover changes have threatened the protection of the unique natural, scenic, and historic resources in this region. In this study, we applied a fragmentation model and a set of landscape metrics together with the satellite-derived USDA Cropland Data Layer to examine the shrinkage and fragmentation of grassland in the Bluegrass Region, Kentucky during 2008–2018. Our results showed that recent land use change across the Bluegrass Region is characterized by grassland decline, cropland expansion, forest spread, and suburban sprawl. The grassland area decreased by 14.4%, with an interior (or intact) grassland shrinkage of 5%, during the study period. Land conversion from grassland to other land cover types has been widespread, with major grassland shrinkage occurring in the west and northeast of the Outer Bluegrass Region and relatively minor grassland conversion in the Inner Bluegrass Region. The number of patches increased from 108,338 to 126,874. The effective mesh size, which represents the degree of landscape fragmentation in a system, decreased from 6629.84 to 1816.58 for the entire Bluegrass Region. This study is the first attempt to quantify recent grassland shrinkage and fragmentation in the Bluegrass Region. Therefore, we call for more intensive monitoring and further conservation efforts to preserve the ecosystem services provided by the Bluegrass Region, which has both local and regional implications for climate mitigation, carbon sequestration, diversity conservation, and culture protection.

Highlights

Land use and land cover changes have reshaped the landscape and substantially altered the capacity of ecosystems to provide various services, such as food and water production, soil fertility, nutrient cycling, biodiversity, socioeconomic and cultural benefits, etc. [1,2]
Forests are mainly distributed in the north and west of the study area, while the built-up areas are mainly concentrated in the center of the Inner Bluegrass Region, the northernmost and the far west of the study area, the metro areas within Kentucky of Lexington, Cincinnati, and Louisville
This study shows that the grassland ecosystem in the Bluegrass Region, Kentucky, has experienced significant shrinkage and has become more fragmented over the past decade

Summary

Introduction

Land use and land cover changes have reshaped the landscape and substantially altered the capacity of ecosystems to provide various services, such as food and water production, soil fertility, nutrient cycling, biodiversity, socioeconomic and cultural benefits, etc. [1,2]. In the U.S, substantial land use change occurred in the late 19th century and the first half of the 20th century and was characterized by agricultural expansion in the Midwestern U.S and secondary forest regrowth in the Eastern and Central regions [3]. Some studies have argued that this decline could be a result of the changes in the definition of cropland in the USDA census of 1945 and subsequent years [3]. There are significant geographic and temporal variations in land-cover change across the U.S characterized by a mix of expanding, contracting, and stable land use and land cover types across regions [5]. Prior studies have put more emphasis on agriculture and forest-dominated regions such as the Midwest and Southeast U.S, where dramatic land use changes have occurred over the past decades. Recent land use changes in the Central U.S have received relatively less attention, especially at local scales

Methods

Results

Conclusion