Quantifying the Hydrology, Carbon Dynamics, and Nutrient Cycles in Forest and Forest Transitions in South-West Mau, Kenya

Background Forest Ecosystem services Mau Forest Complex water storage, January 1995 January 2010 Forest Ecosystem services water storage, river flow regulation, flood mitigation, soil erosion control, water purification, conservation of biodiversity. Mau Forest Complex 416,542 ha (GoK 2009) >107,000 ha destructed “Water tower” KEFRI and UNEP: worth $1.3 billion/yr (KFS 2010) Its forests provide critical ecological services: water storage, river flow regulation, flood mitigation, recharge of groundwater, reduced soil erosion, water purification, conservation of biodiversity, and micro‐climate regulation. Thus the Mau Complex is fundamental to support key economic sectors including energy, tourism, agriculture and livestock, and to provide water supply to urban centres and conservation areas.

Introduction|Background Smallholder agriculture Tea/tree plantations Natural forest Smallholder tea

Catchment hydrology|Background Modelling studies in Mara and Nyoro basins: Decrease in discharge when forest is converted to agriculture (Mango et al. 2011) Increase in runoff and soil erosion (Baker and Miller 2013; Baldyga et al. 2004; Defersha and Melesse 2012; Mati et al. 2008) Field study in South-West Mau: No significant effect of conversion of natural forest to tea on water quality or quantity, but increased water yield during the process (Blackie and Robinson 2007)

Main Objective To quantify the effect of land use and Land cover change on hydrology and biogeochemistry in the Mau Forest, based on field measurements Quantity Quality Timing

Study area Name Land use Area (km²) Elevation (m) Slope (%) Main Mixed 1020 1719 – 2931 10.3 TTP Tea/tree plantations 27.3 1789 – 2139 9.8 NF Natural forest 37.3 1965 – 2382 12.4 SHA Smallholder agriculture 34.0 2391 – 2693 9.2

Instrumentation

Instrumentation Solar panels and lightning protection spectro::lyser Water level sensor spectro::lyser condu::lyser Data logger Sensor cleaning system Batteries and solar charger

Methods|Automatic system

HYDROLOGY, CARBON DYNAMICS AND NUTRIENT CYCLES IN FOREST AND FOREST TRANSITIONS Water quality and sediment loading. Streams from (a) forest (b) smallholder agric and (c) Commercial tea plantation

Outputs and outcomes Datasets of continuous discharge and water quality measurements. Quantitative evidence of forest ecosystem services provisioning. Increased understanding of stream flow patterns and hydrogeological dynamics and how this is affected by land use change. Scientific basis for Informed decisions on Forest resource.

UNEP 2013, Africa Environment Outlook “Making promising policies work” Adequate and reliable data and information: Evidence-based decision making, which is more compelling than that based on intuition, is only possible if adequate and reliable data exist on the issues at stake. Strengthening the data and information bases on environment and health linkages would therefore enable adequate assessment and subsequent use of the findings to inform planning, budgeting, reviewing policy performance and evaluating progress towards the desired environment and health outcomes.

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