LUCID’s Land Use Change Analysis as an Approach for Investigating Biodiversity Loss and Land Degradation Project

Forage Diversity and Impact of Grazing Management on Rangeland Ecosystems in Mbeere District, Kenya LUCID Working Paper Series Number: 36

By Peris Kamau National Museum of Kenya P.O. Box 45166 Nairobi, Kenya E-mail: [email protected]

January 2004

Address Correspondence to: LUCID Project International Livestock Research Institute P.O. Box 30709 Nairobi, Kenya E-mail: [email protected] Tel. +254-20-630743 Fax. +254-20-631481/ 631499

Forage Diversity and Impact of Grazing Management on Rangeland Ecosystems In Mbeere District, Kenya LUCID Working Paper Number 36

By Peris Kamau National Museum of Kenya P.O. Box 45166 Nairobi, Kenya E-mail: [email protected] January 2004

Address Correspondence to: LUCID Project International Livestock Research Institute P.O. Box 30709 Nairobi, Kenya E-mail: [email protected] Tel. +254-20-630743 Fax. +254-20-631481/ 631499

Copyright 2004 by the: International Livestock Reaserch Institute, and United Nations Environment Programme/Division of Global Environment Facility Coordination. All rights reserved. Reproduction of LUCID Working Papers for non-commercial purposes is encouraged. Working papers may be quoted or reproduced free of charge provided the source is acknowledged and cited. Cite working paper as follows: Author. Year. Title. Land Use Change Impacts and Dynamics (LUCID) Project Working Paper #. Nairobi, Kenya: International Livestock Research Institute. Working papers are available on www.lucideastafrica.org or by emailing [email protected].

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TABLE OF CONTENTS LIST OF FIGURES................................................................................................................. iv APPENDIX .............................................................................................................................. iv Abstract ..................................................................................................................................... 1 INTRODUCTION .................................................................................................................... 1 1.1 Rangeland resources.................................................................................................................... 2 1.2 Herbivory and plant diversity .................................................................................................... 2 1.3 Grazing management systems ................................................................................................... 3 1.4 Objectives ..................................................................................................................................... 4 1.5 Research hypotheses ................................................................................................................... 4 2. MATERIALS AND METHODS......................................................................................... 5 2.1 Study Area .................................................................................................................................... 5 2.1.2 Climate ....................................................................................................................... 5 2.1.1 Location and description ............................................................................................ 5 2.1.3 Topography ................................................................................................................ 5 2.1.4 Soils............................................................................................................................ 5 2.1.5 Land use ..................................................................................................................... 7 2.1.6 Vegetation .................................................................................................................. 7 2.3 Vegetation data ............................................................................................................................ 7 2.3.1 Herbaceous biomass production................................................................................. 7 2.3.2 Trees and shrubs biomass........................................................................................... 7 2.3.3 Canopy cover.............................................................................................................. 8 2.4 Forage Preferences by Cattle and Goats................................................................................... 8 2.5 Soil analyses methods ................................................................................................................. 8 2.6 Data analyses ................................................................................................................................ 8 3. RESULTS.............................................................................................................................. 8 3.1 Biomass ......................................................................................................................................... 8 3.2 Species diversity .......................................................................................................................... 9 Open .................................................................................................................................. 10 Enclosure........................................................................................................................... 10 Total species richness........................................................................................................ 10 3.3 Herbaceous species richness and biomass ............................................................................. 10 Dry-open................................................................................................................................... 10 3.4 Canopy cover ............................................................................................................................. 10 3.5 Forage preference and acceptance........................................................................................... 10 3.6 Effect of grazing on soil properties ......................................................................................... 10 4. DISCUSSION..................................................................................................................... 11 4.1 Biomass ....................................................................................................................................... 11 4.2 Plant species diversity ............................................................................................................... 11 4.3 Herbaceous species richness .................................................................................................... 11 4.4 Canopy cover ............................................................................................................................. 12 4.5 Forage Preference and acceptability ....................................................................................... 12 4.6 Impact of grazing on soil properties ....................................................................................... 12 4.7. Management implications ....................................................................................................... 14 5. CONCLUSION AND RECOMMENDATIONS............................................................. 15 Acknowledgements .......................................................................................................................... 16 6. REFERENCES ................................................................................................................... 17

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LIST OF TABLES Table 1a. Comparisons (t-test) between total and herbaceous species richness, biomass (gm-2) between the enclosure and open site. ..................................................................................... 10 Table 1b. Comparisons of plant species richness, diversity and evenness between four treatments ................................................................................................................................... 10 Table 2. Comparisons of % cover of growth form in enclosed and open sites. ......................... 10 Table 3. Comparisons (t-test) of physical and chemical variables of soil between open and enclosed sites ............................................................................................................................. 11

LIST OF FIGURES Figure 1. Map of the study area showing Machang’a field station............................................. 6 Figure 2. Climate diagram of Machang’a field station............................................................... 6 Figure 3. Log normal plot of species biomass for dry season in enclosed site ..................................... 8 Figure 4. Log normal plot of species biomass for wet season in enclosed site .......................... 9 Figure 5. Log normal plot of species biomass for dry season in open site................................. 9 Figure 6 Log normal plot of species biomass for wet season in open site ................................. 9

APPENDIX Appendix 1. Raw data for environmental variables ...................................................................... 20

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Abstract Composition, biomass and vegetation cover in Mbeere rangeland was assessed for comparison of the effect of grazing and other human interference in open and enclosed sites. A total of 245 plant species were recorded. Clipping and preference unit technique were used to estimate herbaceous and trees and shrub biomass respectively. Canopy cover was done by visual estimation for three growth forms while forage preference was through direct observation. Grazing reduces above ground biomass in communal lands mainly through overgrazing and elimination of palatable species. Forage productivity on the other hand largely depends on availability of rainfall and disturbance. Grazing management systems used in this particular rangeland have a direct impact on forage diversity. T-test results shows that total species richness and herbaceous richness in the open site were significantly different (p