Presentation is loading. Please wait.

Presentation is loading. Please wait.


Similar presentations

Presentation on theme: "POLICY AND MANAGEMENT ISSUES ARISING FROM SCIENTIFIC SESSIONS."— Presentation transcript:


2 An attempt to distill policy and management implications Some presentations have direct implications - others less so Feedback welcome - especially if we have missed the point! (written please!).

3 1. LAND USE CHANGES: current trends and perspectives There are major use use changes under way in forest areas of humid tropics Many new forested and non-forested landscapes being created Future tropical landscapes a mix of forest fragments, regrowth, agricultural uses, roads, settlements and monoculture plantations

4 These high conversion rates mask considerable variation in each region – possible to identify local “hot spots” This data has heightened the perception that forest loss is a global problem although the causes vary between regions However, this has not contributed to putting water issues on global policy map (?) 1. LAND USE CHANGES: current trends and perspectives (cont.)

5 Suggests need to develop a watershed function classification to identify where water availability and quality are at risk. This could guide investments in research and indicate areas of potential future conflict between stakeholders

6 1. LAND USE CHANGES: current trends and perspectives (cont.) In many humid tropical countries water is regarded as being abundant E.g. in Amazonia - government policies being carried out on the implicit assumption that water is not in short supply – and there are few watershed management problems Consequence: natural resource management often focussed on forest outcomes and not water outcomes However, new external influences (eg. Kyoto CDM, “green” certificates) are beginning to affect policy

7 1. LAND USE CHANGES: current trends and perspectives (cont.) Local people often de facto resource managers – hence a pragmatic reason to involve them in watershed management and policy development Involving local people is necessary - but is not sufficient to achieve sustainable resource management – other key stakeholder groups (e.g. private sector) need to be involved

8 2. HYDROLOGICAL PROCESSES IN UNDISTURBED LANDSCAPES Rare meteorological events (severe storms) often more important than average condition Interestingly, these severe events often clustered in time Possibility that such events will increase in frequency and intensity (greenhouse effect) and affect forests

9 2. HYDROLOGICAL PROCESSES IN UNDISTURBED LANDSCAPES (cont.) Several critical factors determine run-off response to rainfall in tropics (cf. temperate forest regions) rainfall intensity soil permeability surficial (vs. sub-surface) pathways These (+ climatic variables) provide beginnings of a hydrological classification for headwater catchments? But how to deal with larger catchments with mixed land-use and geology?

10 2. HYDROLOGICAL PROCESSES IN UNDISTURBED LANDSCAPES (cont.) Surprisingly small number of tropical field sites in undisturbed forests - and decline in field studies Given conversion rates mentioned earlier - perhaps even more surprising no sites in secondary forests, degraded landscapes or rehabilitated forests

11 3. IMPACTS OF NATURAL AND ANTHROPOGENIC DISTURBANCES There is a background (natural) disturbance/recovery regime, with anthropogenic impacts superimposed on this. Increasingly, forests are becoming fragmented as a result of these man-caused disturbances

12 3. IMPACTS OF NATURAL AND ANTHROPOGENIC DISTURBANCES (cont.) Importance of maintaining minimum low river flows for aquatic life (in light of massive increase in dam building in the humid tropics). Impacts of anthropogenic activities on water yield do not show up in large river basins, whereas impacts on sediment flows do. Extreme events are the main drivers of sediment flows (build risk analysis around these rare events).

13 3. SOIL AND WATER IMPACTS OF FOREST CONVERSION AND RECOVERY Recovery rates vary greatly: Fast recovery (within 5 years) —LAI; albedo; (attributes that determine hydrological functions) Slow recovery—species composition Water yield tends to decline in the early stages of reforestation (20 years) but may then increase during the following period (30 years) to approach that from old growth forests (evidence from temperate S.Africa and Australia). Water yield can be manipulated by management.

14 3. SOIL AND WATER IMPACTS OF FOREST CONVERSION AND RECOVERY (cont.) Impact of afforestation on water yield tends to be a trade-off between improved infiltration (and consequent reduction in overland flow) and increased ET. Evidence is that ET is the dominant factor, but many policies and investment decisions are based on the opposite presumption - thus urgently need clarification of circumstances when the null hypothesis does not apply. The rapid expansion of exotic tree plantations makes clarification of these issues in the tropics urgent (is water use of indigenous species lower?).

15 3. SOIL AND WATER IMPACTS OF FOREST CONVERSION AND RECOVERY (cont.) There is also a need to understand the implications of trading-off tree and crop production in agro-forestry systems in terms of water use efficiency. The use of macro-invertebrates as monitors of water quality has potential, but needs skilled interpretation and much more work.

16 4. NEW METHODOLOGIES  Lumped parameter models are as good as physics-based (process) models for predicting water yields.  Modelling the impact of land use changes requires much more work.  Models should be designed around the data that is (or is likely to be) available.  New developments in remote sensing provide the possibility for process models to become more sensitive to spatial variations.  It is very difficult to detect any greenhouse signature in hydrological data (particularly long term water yields) —CO2 and temperature levels are easier.

17 4. NEW METHODOLOGIES (cont.)  Need to distinguish between research models (for explaining observed regularities) and management models (for using the explanations to predict and manipulate management outcomes).  Models need to be more “client based” and developed in an adaptive and iterative fashion.  Tracer based estimates of residence times of water may provide a way forward for assessing meso-scale land use changes and for testing the internal characterisation of models.

18 Many comments made about the low profile of forest hydrology in the policy arena, particularly internationally. Need strategy to remedy this. A key element would be to identify potential partners who have an interest in enhancing their own policy positions by improving their understanding of: - hydrological processes and - the hydrological impacts of land use changes. Strategic alliances could be developed where there are converging agendas. 5. LINKING SCIENCE WITH INTERNATIONAL POLICY

19 Possible partners could include:  Secretariats of key UN commissions  Development banks and bilateral aid agencies  International NGOs and intergovernmental agencies (FAO, UNDP, UNEP, ITTO, etc)  International research centers (CIFOR, ICRAF, etc  OTHERS ? 5. LINKING SCIENCE WITH INTERNATIONAL POLICY (cont.)

20 Possible “targets” for international policy fora:  World Freshwater Assessment Programme  World Bank water policy  World Bank forest policy  UN Forum on Forests  Convention on Biological Diversity (Technical Committee)  Dams Commission (be quick)  OTHERS ? (Would HELP be a target or the vehicle for carrying the hydrological message?) 5. LINKING SCIENCE WITH INTERNATIONAL POLICY (cont.)


Similar presentations

Ads by Google