Determination Of Effect Of Land Use On Distribution And Abundance Of Ground Dwelling Macro Invertebrates In Kirimiri Forest In Embu County, Kenya

Abstract

Ground dwelling macro invertebrates are essential for soil functions and other significant ecological process such as nutrient cycling. The distribution and ecological role of crawling macro invertebrates may be influenced by anthropogenic factors. Human factors such as deforestation and agricultural activities that destroy the habitat pose great threat for the survival of macro invertebrates. Most of the natural ecosystems including forests in Kenya have been encroached, segmented and reduced in size by the rapidly growing population. However, studies on the impact of such destructive activities on the abundance and distribution of ground dwelling macro invertebrates are limited. Thus, there exist information gap on macro invertebrate composition and their distribution in different ecosystem and habitat segments in Kenya. Such studies are necessary in generating knowledge and creating wholesome understanding to facilitate policy making, habitat management and conservation of crawling macro invertebrates. Based on the above highlights, this study was conducted to determine the effect of land use on the distribution and abundance of ground dwelling macro invertebrate in Kirimiri forest in Embu County, Kenya between January and April 2016. The Napier grass plantation, Tea plantation and indigenous intact forest were evaluated for their macro invertebrates. In every habitat studied, crawling macro invertebrates were caught using the pit fall traps set in 50 m by 50 m grid subdivided into six rows at equidistance gap of 8 m. The pit holes comprised of 60 (250 ml capacity) clear plastic containers filled with 30 ml mixture of ethanol and liquid soap. Macro invertebrates were identified using their morphometric features and then stored in 70 % Ethanol for further laboratory identification at the National museums of Kenya headquarter in Nairobi, Kenya. The data collected was analyzed using Scientific Analysis System (SAS) version 9.4 and significance means separated using Least Significance Difference (SLD). The indigenous intact forest recorded the highest mean of macro invertebrates with family of Polydesmidae being the most abundant (mean=17.33). Tea plantation had the second largest mean (4.59) of macro invertebrates, and the family Gryllidae was the most abundant group with mean of 12.667. Napier grass plantation had a mean of 3.94 and the family Platydesmidae was the most abundant group (mean=12.833). The disparity in abundance and distribution of terrestrial macro invertebrate observed in this study may have resulted from micro climate and microenvironment shift influenced by human activity along and within the forest.