Purpose of this paper and approach taken

4 One might question why the popular narrative, with its myths and misunderstandings, continues to persist in the face of scientific consensus on key aspects of forest–water relationships. There are many reasons for this see Hamilton, 1985; Calder, 2000; Calder 2005; and FAO, 2005 for detailed discussions. Calder 2000 postulated that there are seven main reasons for the persistence of the popular narrative: •฀ Researchers have not made their results available to a broad community of people operating in disciplines related to environmental research and decision-making and to the general public. •฀ Research grant-making bodies tend to promote single disciplinary research where impacts are not linked to policy and decision-making in the real world. •฀ Managers and decision-makers do not take the trouble to make themselves aware of contemporary scientific developments. •฀ The media are generally content to repeat conventional wisdom and pseudoscience rather than check authenticity. •฀ The scientific community has a vested interest in assuring that no questions are finally answered so that research funding can continue. •฀ Structural inadequacies within and among large organizations hinder information flows. •฀ Inappropriate systems of economic incentives, penalties and regulations governing land management and production practices persist. Even though the science of forest hydrology in temperate regions is no longer young, it is only since the late 1980s that sufficient research has been carried out in humid tropical regions to enable a science-based explanation of forest–water interactions to be formulated that is applicable to these regions. Cassells et al. 1987 noted that the evolving knowledge of tropical forest hydrology was not always applied in forest management and forest policy development. Indeed, where it was applied, it was often against strong resistance from forest bureaucracies and the forest industry. Many of the ideas that prevailed prior to the 1980s still persist and have influenced university teaching in some countries as well as popular attitudes. In addition to the seven reasons previously cited for sustaining the popular narrative, part of the rationale is undoubtedly a desire by many people and groups, including the popular media, for simple and easily understood cause–effect relationships. Thus, they tend to generalize and oversimplify the complex and overlapping processes involved. This is exacerbated by the well-intentioned desire of many foresters and agroforesters to promote the use of forests as being good for the environment in all situations.

1.4 Purpose of this paper and approach taken

The purpose of this paper is threefold: i summarize the scientific consensus on the hydrological impacts of forest management; ii propose recommendations to community forestry policy-makers and practitioners to plan for and manage hydrological aspects of community forestry and iii propose recommendations to RECOFTC – The Center for People and Forests on the incorporation of contemporary scientific knowledge on hydrological aspects of community forestry into its strategies and programme. As noted, interest by policy-makers and forest managers in forest–water interactions has been high for many decades, if not centuries. Partly because of this general interest but particularly driven by the disconnect between the popular narrative and science-based understandings, numerous attempts have been made over the past 30 years to review comprehensively the results of forest hydrology research around the world and summarize the state of knowledge. The most important of these reviews are listed in table 2. Table 2: Selection of important reviews of forest–water relations since 1983 1983 L.S. Hamilton, with P.N. King. Tropical forest watersheds: hydrological and soils response to major uses or conversions. Boulder, Colorado: Westview Press. Tropical 203 Year of review Title of review in chronological order Geographic focus of review Number of references cited 5 Year of review Title of review in chronological order Geographic focus of review Number of references cited L.S. Hamilton. Overcoming myths about soil and water impacts of tropical forest land uses. In: S.A. El-Swaify, W.C. Moldenhauer and A. Lo, eds. Soil erosion and conservation. Ankeny, IA: Soil Conservation Society of America. pp.680-690. D.S. Cassells, M. Bonell, L.S. Hamilton and D.A. Gilmour. The protective role of tropical forests: A state of knowledge review. In N.T. Vergara and N.D. Brianes, eds. Agroforestry in the humid tropics. Honolulu: Environment and Policy Institute, East-West Center. pp.31-58. L.A. Bruijnzeel, with C.N. Bremmer. Highland-lowland interactions in the Ganges Brahmaputra River Basin: a review of published literature. Occasional Paper No. 11. Kathmandu: International Centre for Integrated Mountain Development. L.A. Bruijnzeel. Hydrology of moist tropical forests and effects of conversion: a state of knowledge review. Paris and Amsterdam: UNESCO and Free University Amsterdam. L.M. Reid. Research and cumulative watershed effects. Pacific Southwest Research Station, General Technical Report PSW- GTR-141. Washington, DC: US Department of Agriculture, Forest Service. FAO. Land-water linkages in rural watersheds. FAO Land and Water Bulletin 9. Rome: Food and Agriculture Organization of the United Nations. Forestry Agency of Japan. International expert meeting on forests and water, Shiga, Japan, 20–22 Nov. 2002. Tokyo: Ministry of Agriculture, Forestry and Fisheries. L.A. Bruijnzeel. Hydrological functions of tropical forests: not seeing the soil for the trees. Agriculture, Ecosystems and Environment, 104. pp.185-228. V. Andreassian. Waters and forests: from historical controversy to scientific debate. Journal of Hydrology, 291. pp.1-27. M. Bonell and L.A. Bruijnzeel, eds. Forests, water and people in the humid tropics: past, present and future hydrological research for integrated land and water management. International Hydrology Series. Paris and Cambridge: UNESCO and Cambridge University Press. I.R. Calder. Blue revolution: integrated land and water resources management. Oxford: Earthscan. FAO. Forests and floods: drowning in fiction or thriving on facts? RAP Publication 200503. Bangkok: Food and Agriculture Organization of the United Nations. 1985 1987 1989 1990 1993 2002 2002 2004 2004 2005 2005 2005 Tropical Tropical Ganges Brahmaputra River Basins Humid tropics US Global Global Tropical Global Humid tropics Global Global 34 73 278 659 918 332 88 243 51 6 The book edited by Bonell and Bruijnzeel 2005 is worthy of special mention. It is a 925-page volume that is a state-of-the-art overview of current knowledge on the hydrological functioning of tropical forests, the environmental impacts of forest disturbance and conversion and the best ways to minimize the adverse impacts. This paper draws heavily on the results of the reviews listed in table 2, supplemented by additional studies and reports. Where possible, original research papers were perused, particularly those that have had an important influence on the scientific views of contentious issues. While there is a large body of literature on forest–water interactions in general, very little of it relates specifically to community forestry. Year of review Title of review in chronological order Geographic focus of review Number of references cited 2005 2007 2008 A.E. Brown, A.E., L. Zhang, T.A. McMahon, A.W. Western and R.A. Vertessy. A review of paired catchment studies for determining changes in water yield resulting from alterations in vegetation. Journal of Hydrology, 310. pp. 28-61. I.R. Calder, T. Hofer, S. Vermont and D. Warren. Towards a new understanding of forests and water. Unasylva, No. 229, 584. Rome: Food and Agriculture Organization of the United Nations. pp.3-10. FAO. Forests and water. FAO Forestry Paper 155, Rome: Food and Agriculture Organization of the United Nations. Global Global Global 106 15 151 7 An understanding of the hydrological cycle is necessary for any informed discussion of forest–water interactions. Before moving into the summary of the hydrological impacts of forest management, the following describes the basic hydrological processes that operate in forested catchments. The hydrological cycle Water moves in a continuous cycle from the atmosphere to the earth by precipitation and eventually back to the atmosphere by evaporation, with the process driven by energy from the sun. This is referred to as the “hydrological cycle” figure 1. The amount and type of streamflow coming from a catchment the water yield is a measure of the interaction among many factors, including rainfall, geology, geomorphology, soil and vegetation. Figure 1: The hydrological cycle Components of the hydrological cycle

1. Evaporation from open water surfaces,