# Climate Effects on Tallgrass Prairie Responses to Continuous and Rotational Grazing
## 1 Introduction  
Tallgrass prairie systems are important forage sources for beef cattle in the Great Plains of the United States [1] where cattle production is a major revenue for farmers in the region [2]. Cattlegrazing also acts as an effective way to maintain the prairie landscape [3; 4]. There are two main grazing management systems nowadays: continuous grazing and rotational grazing. The cattle herd remains in the same pasture in continuous grazing management, while the herd is alternately moved to different paddocks in rotational grazing management. In contrast to year-long (or growing season) continuous grazing, rotational grazing has been recommended as an effective tool to maximize livestock production and maintain sustainability of the operations since the mid-20 th century [5; 6; 7; 8; 9]. However, there has been a long history of debate over continuous versus rotational grazing by both rangeland managers and research scientists across the world that is yet not resolved [10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23]. The overall assumption behind multi-paddock rotational grazing is that it can reduce selective grazing (spatially uneven distribution of livestock grazing) [24] and allow rest to vegetation in the paddocks, during different periods of the year, to help improve species composition and/or productivity [12; 25; 21]. The disadvantages of the rotational grazing system include trampling damage in high intensity grazing paddocks and waste of feed values in the rested pastures because forage quality decreases after plant maturity [12; 26; 27]. In comparison, continuous grazing has lower stocking rate and can promote biodiversity for conservation goals [28]. However, selective grazing and underutilization of forage production in the peak growing season can occur in continuous grazing [18; 25]. The long-lasting grazing management debate indicates the complexity of direct comparison between continuous and rotational grazing. A wide range of variation exists in vegetation structure, composition, productivity, prior condition, and climate. Climate interacts with multiple objectives (e.g., production, wildlife, soil, and water conservation) and capabilities among ranchers to make responses of grassland to grazing management variable in time and space. Studies that compare continuous and rotational grazing in the Great Plains have not generated consistent conclusions due to varied landscape types, experimental settings, and rancher objectives. Several of them found no statistically significant differences in vegetation responses to continuous and rotational grazing [7; 8; 15; 29; 30; 31], while some studies favored rotational grazing [25; 32]. Thus, it is still not clear how vegetation will respond to different grazing management strategies in the tallgrass prairie systems of the Great Plains over years under variable climate conditions. The responses of vegetation to continuous and rotational grazing are usually examined from the perspectives of vegetation canopy structure, species composition, primary productivity, and forage quality using field survey data [14; 15; 16; 18; 23; 29; 30; 32; 33; 34]. Field data collection is time-consuming and labor intensive. Little work has been done using periodic and long-term satellite remote sensing data to examine the responses of vegetation to different grazing management systems [35; 36]. The major difficulty of utilizing satellite remote sensing in grazing studies lies in the relatively coarse spatial resolution satellite data compared to the size of paddocks. For example, the widely used Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance product has a spatial resolution of ~500 m, which might be larger than a single paddock in a rotational grazing system. Landsat has a spatial resolution of 30 m in visible and near infrared (NIR) bands, which makes it more suitable to study the impacts of different grazing management on vegetation phenology.