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Forest Management of ecosystems plays a fundamental role in providing essential goods and services to rural communities. However, there has been a reduction in the natural forest cover due to resource utilization pressure. The pressure on forest resources is catalyzed by the expansion of markets for forest products, agricultural expansion and escalating poverty levels. An upsurge in the number of users of herbal medicine in urban and rural areas has increased the pressure on the forests, while modernization and change in lifestyle have led to the loss of traditional knowledge associated with medicinal plants utilization and conservation. No detailed economic evaluation of medicinal plants has been undertaken and the current illegal, unregulated and unreported exploitation of medicinal plants has led to overexploitation and loss of biodiversity. A better understanding of the abundance, distribution, uses and economic value of medicinal plants is important for the sustainable exploitation and conservation of forests. The study covered four forest blocks of Kakamega, North Nandi, South Nandi and Kibiri to determine plant species diversity, and their distribution in the disturbed and undisturbed areas of the forest; assess knowledge, utilization and economic estimate by willingness to-pay approach of medicinal plants to communities adjacent to the Kakamega Forest. Value chain analysis had been conducted for medicinal plants and forest user groups from Community Forest Association (CFA) had been trained in product development and access market were used in the study. Experimental Plot techniques were also used to gather ecological data on the frequency, density, diversity and distribution of the plants, whereas key informant interviews, focus group discussions and household interviews were utilized to gather information on ethnobotanical knowledge and household socioeconomic data. Thirty-two key species of medicinal plants were identified and used by local people around the Kakamega forest ecosystem. Forty-seven percent (47%) of these were trees, thirty four percent (34%) were shrubs, sixteen percent (16%) were herbs and climbers three percent (3%). Seventy percent (70%) of the medicinal plants were within the forest and thirty percent (30%) were outside the forest. The three most dominant families were Euphorbiaceae, Piperaceae and Fabaceae with leaves as the most common plant part used constituting 31 % (n=26) of the preparations, followed by roots with 20% (n=17),bark with 14% (n=14), fruits with 11 % (n=9), seeds having 11% (n=9), flowers 2% (n=2) and sap 2 % (n=3). The economic benefits generated from the medicinal plants within the forest ecosystem services in the Kakamega-Nandi landscape in terms of direct use value was about KES 601,918,256 (≈USD 5.19 million) per year, while indirect use value was KES 317,288,046 (≈USD 2.74 million) per year. Indigenous knowledge of the medicinal uses of the plants, their commercial aspects and distribution trends in the forest provision of wide scope for understanding relevant market systems may be tapped for decision support in rural health service planning, policy formulation for conserving the forest, tracking and mitigation of climate change impacts.

Many soils in sub-Saharan Africa, which are farmed by smallholders, are P deficient and highly P fixing. Furthermore, P inputs supplied as farmyard manure (FYM) or inorganic P fertilizer are normally too small to replace P offtakes by crops. Consequently most soils are in a negative P balance, which is reflected in small, and often declining, crop yields. The obvious solution of simply applying adequate P is seldom an option due to shortages of manure, which is usually low in nutrients in any case, and the high cost of inorganic P fertilizer relative to the likely cash value of the harvest. Our aim was to see if we could devise practical methods to increase soil P availability in this situation and to investigate the mechanisms involved. Two approaches were adopted. Firstly, to attempt to saturate the P-fixing sites in the soils by applying a large annual application of P (75 kg P ha−1), which should serve for several seasons. Secondly, to attempt to keep the fertilizer P in biological forms by supplying fertilizer P and cattle manure (FYM) in combination. Here, the aim was to promote the cycling of P through the soil microbial biomass and associated metabolite pools, with the expected result of decreasing P fixation and increased plant availability of this P. These treatments were investigated using two field sites on smallholder farms in Kenya: one, considered a ‘high P fixing’ soil at Malava (Kakamega District) and one considered a ‘low P fixing’ soil at Mau Summit (Nakuru District). The following treatments were applied in 1997 and 1998: nil; 75 kg P ha−1 as super phosphate (P); 25 kg P ha−1; FYM at 1.9 t ha−1 dry matter; FYM+25 kg P ha−1. All treatments also received 100 kg inorganic N ha−1. Maize was the test crop. There was no significant correlation in either year at either site between soil P, measured as NaHCO3-extractable P, resin P or NaOH-extractable P and maize yield. However, the different soil P fractions were closely correlated with each other. Yields at the high P rate (75 kg ha−1y−1) were often little better than the control. There was, however, a significant positive relationship (P

We tested how the incorporation of farmyard manure (FYM) and inorganic phosphorus (P), KH2PO4 fertilizer changed soil microbial biomass phosphorus (biomass Po and inorganic and organic P fractions) in high and low P fixing Kenyan soils. Four soil treatments were compared during 32 weeks of laboratory incubation: (i) Nil; (ii) FYM (10 g kg−1); (iii) KH2PO4 (2.5 g kg−1) (P); and (iv) FYM (10 g kg−1) + KH2PO4 (2.5 g P kg−1). Biomass P was determined by fumigation-extraction followed by resin extraction, and P availability determined using a modified Hedley P fractionation method. The addition of FYM + KH2PO4 only increased biomass P in the high P fixing soil. From a maximum of about 22.5 μg P g−1 soil (week 1), biomass P declined to 4.8 (week 2), increased steadily to week 16 (15.2), and then decreased to 9.7 μg P g−1 soil (week 32). Biomass P in the low P fixing soil, with higher fertility, resin P and organic matter concentrations did not show any significant change. The P fractions that changed the most relative to the control, were the resin, Po–HCO3 and P–OH (week 1 and 16). This difference was enhanced in the high P fixing soil but resin P was the same in that soil at week 16, and the reduction in Po–OH in the FYM + KH2PO4 treatment (162.4 μg P g−1) compared to the control (242.2 μg P g−1) was more pronounced. This indicates an enhancement of microbial activity in the high P fixing soil.