After looking at the general principles of ecosystem services and the distribution of water resources in Africa, I aim to explore in detail hydrologic services with particular attention paid to lakes and floodplain wetlands.
Wetlands
Characterized as 'natural assets' (Barbier 2012), wetlands are some of the most hydro-ecological productive and diverse ecosystem. Wetlands can be characterized by unique characteristics (Maltby and Acreman 2011):
- Presence of surface water or within root zone
- Unique soil/sediment characteristics compared with adjacent non-wetlands
- Presence of adaptive vegetation to varying degree of wetness
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| Source |
Wetlands are widely distributed across the floodplains of Sub-saharan Africa within all major river basins (Rebelo 2010). Hydrological processes initiates ecosystem functions which drives biogeochemical interactions and subsequently modulates the performance of ecosystem services beneficial to human well-being. Due to high connectivity in the hydrological cycle, ecosystem system delivery and beneficiaries extend well beyond the boundaries of wetlands/lakes, supporting the livelihoods of rural and urban citizens alike and ensuring food and water security while having substantial impacts on poverty alleviation and international development. Irrespective of size/catchment area, wetlands of all sizes are capable of delivering pivotal ecosystem services (from water quality regulation to recreation) along hydrological pathways and trade-offs can only be fully understood if all scales are consulted (Blackwell and Pilgrim 2011).
Schuyt (2005) identifies 4 categories of ecosystem functions:
- Regulating functions - climate regulation, water regulation, nutrient regulations
- Carrier functions - space for human settlement, energy production, agricultural production
- Production functions - food production, water supply, support for raw materials (eg. timber)
- Informal functions - recreation, tourism, spiritual health, scientific studies
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| Interdisciplinary involvement in research between wetland and ecosystem services delivery (Source) |
Closed water bodies of fresh/brackish water also provides an entire suite of ecosystem services beneficial to human well-being (Schallenberg et.al. 2013). Wetlands, lakes and rivers are integral and interrelated parts of the hydrologic cycle. Ecosystem delivery or dis-service in a lake/river will no doubt influence the ecosystem services delivery in wetlands. Similarly, reduced services by wetlands will have knock-on impacts to services in lakes.
Threats
Threats to ecosystem services often arises from the inherent trade-offs after alteration of the natural environmental conditions. Trade-offs arise from distributional effects after the wetland/lake ecosystem is altered and the natural hydrological state changed. Freshwater ecosystem services are determined by geographic location, timing of flow, quantity of flow and water quality. Modulated by regional climate, any changes to the hydrological conditions, whether anthropogenic or not, will risk compromising the integrity of the wetland/lake. Although wetlands only cover less than 3% of global land mass, they deliver over 40% of renewable ecosystem services each year (Zedler and Kercher 2005). Despite the variety of ecosystem services provided, wetlands has been subjected to increasing anthropogenic development with little consideration of service trade-offs. Hard engineering approaches for irrigation/agricultural expansion is the main threat to wetlands ecosystem services in Africa. Decision-makers often favour short term economic gains rather than long term benefits of human well-being from ecosystem services (Shuyt 2005).
Hey Wilson!
ReplyDeleteI was wondering what your opinion on this question would be:
If a development plan is proposed for an area like a wetland that would see economic returns (and resultant poverty reduction) far greater than what the area currently offers (assessed via the ecosystems services method), do you think it would still be worth protecting the ecosystem in question?
Hi Baljeet! Thank you for commenting, sorry for taking so long to reply! The situation you illustrated is definitely a common dilemma water managers find themselves in. Trade-offs are an inherent characteristic of practically applying the ecosystem services approach. Your question also gets into the complex philosophical and ethical debate over whether or not we should value nature economically and put a price on 'nature' (which was discussed in a later post 'Valuing Ecosystem Services I').
DeleteHowever, I think it would be beneficial to understand that the ecosystem services approach does not only value one particular service (eg. fisheries/fertile soil for agriculture), but instead recognizes the interconnections and interrelations between multiple ecosystem functions and services (regulatory, provisioning, cultural, recreational). Some services may depend on others to operate and other services may expanded after anthropogenic intervention. The high economic returns from wetlands would therefore be derived from one suite of services (eg. fisheries) being prioritized over others, risking the possibility of causing the collapse of other services and the supporting services which depends on the integrity and interconnectedness of multiple services. These are often forgotten by economics and monetary valuation of ecosystem services.
This can be perfectly illustrated by the case study I blogged about at Lake Victoria where human intervention of introducing new species of Nile Perch encouraged an economic boom and led to population increase near the lake and thus increased wetland conversion to agriculture. Combined, these may have a high economic return but it eventually caused a fundamental regime shift in the lake when Nile Perch dominated and caused native fish species to nearly go extinct, losing the regulatory services provided by them. Adding on to that, wetland conversion eliminated the regulatory services provided by the wetlands on water quality and filtration, eventually resulting in the near collapse of the fisheries industry and a dramatic deterioration in water quality of the lake. It is therefore far too often for economics to neglect the connectivity between services and the 'hidden' services provided by ecosystems if they are protected which may not be easily quantifiable or economically valued.