Effects of Clipping Frequency and Intensity on Structural Characteristics of Range Grass Ecotypes in a Kenyan Dryland: Implications for Rangeland Management

Abstract

Livestock production is an important economic activity in rangeland environments. Its highly dependent on natural indigenous grasses which are also currently being cultivated and used for restoration of degraded environments. With the challenging biophysical situations in the ASALs, these grasses currently face various challenges including defoliation disturbance and precipitation variability resulting in changes in plant and vegetation structure. A field simulation experiment was used to determine the effects of clipping frequency and intensity on grass ecotypes structural features (plant cover, plant height, spread, tillering) over two growing seasons in southeastern Kenya. 4 grass ecotypes of two common species (Cenchrus ciliaris and Panicum maximum) were subjected to 3 clipping frequencies (High, moderate, low) and 3 clipping intensities (high, low, moderate). Plant responses to these treatments were monitored over two seasons. Panicum maximum TVT was the tallest grass ecotype (64.57 cm) while Cenchrus ciliaris KLF was the shortest (25.18 cm). Canopy spread did not significantly differ among the grass ecotypes (p >0.05) though C. ciliaris MGD had a larger spread (74.82 cm) compared to the other grass ecotypes. C. ciliaris MGD also had a significantly higher number of tillers (282.49) as well as ground cover (45.92%). Infrequent clipping resulted in plants that were taller, had higher canopy spread and had more tillers and enhanced ground cover while frequent and intensively clipping the grass ecotypes had detrimental effects on all the characteristics. Compared to low frequency clipping, high frequency clipping reduced plant height in general by up to 34%, canopy spread by 45%, tillers by 13% and reduced ground cover by 25%. Trends in tillering also varied depending on grass ecotype, frequency and intensity of defoliation in addition to the effects of season. High clipping frequencies and intense clipping, despite being common in rangelands should be avoided as it has demonstrated to reduce some structural features of grasses in this study which is harmful not only to the plant but to the environment in general. This information is relevant to design appropriate utilization strategies and develop varieties that are key to specific semi-arid environments and management objectives.