Distribution of Parthenium Hysterophorus L. and its Impacts on Biodiversity and Agricultural Productivity in Nyando Sub County, Kisumu County, Kenya
Auma, Murono Dorca
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Parthenium hysterophorus L. has been considered to be one of the worst invasive weed in Asia, Africa and Australia. The weed threatens natural and agro ecosystems in over 30 countries worldwide. In Kenya, the weed was first reported in the early 1970s in coffee plantations in Kiambu County and has since spread to more areas in and around Nairobi, central, western and eastern Kenya. Thus, the aim of this study was to evaluate the extent of invasion and impact of P. hysterophorus on plant species diversity and agricultural productivity in Nyando Sub County of Kisumu County. Distribution was determined as presence of the weed in the sampled areas. Geographical co-ordinates were recorded using a hand held geographical positioning system (GPS) receiver. Fifteen transects were established randomly and vegetation surveys conducted. Soil samples were collected for the seed bank study. A total of 210 respondents were interviewed using semi structured, open ended questionnaires to assess the impact of P. hysterophorus invasion on agricultural production. GPS data on presence of P. hysterophorus was loaded into ArcGPS 9.1 software to develop point distribution map. One-way ANOVA was used to assess difference in mean density of P. hysterophorus and to test difference in size of the seeds among various land use types (p ≤ 0.05). Effect of P. hysterophorus density on species diversity, richness and density of other herbaceous plant species was evaluated by correlation analysis. Data from perception survey was summarized using descriptive statistics. Parthenium hysterophorus was found to be widely distributed. There was a negative correlation between the density of the weed and species diversity (r = -0.075, p = 0.029) and richness (r = -0.924, p = 0.001). This indicated that where P. hysterophorus density was high, species diversity, and richness was low. There was a significant difference in the abundance of seeds in soils from various land use types (F = 3.88, p = 0.017). Most respondents reported a negative effect of P. hysterophorus on livestock and crop production. This study recommends the need for increased awareness of P. hysterophorus, its impacts and possible solutions among the local people, researchers and extension workers. Appropriate control measures should be applied urgently.