Fire is an extensively used wetland management tool in both tropical and temperate areas, but its effects on wetlands are not well understood. The purpose of this paper is to review the effects of fire on wetland hydrology, biogeochemical cycling and vegetation composition, including primary effects that take place during the fire such as combustion of plant material, loss of volatile substances to the atmosphere and deposition of ash on the soil surface, and secondary effects such as alteration of soil pH as a result of ash deposition, exposure of the soil surface to solar radiation, and increased availability of nutrients. Several of the secondary effects are most dramatic immediately after a fire, but become progressively modulated by newly stimulated vegetation growth. The findings suggest that the effects of fire depend upon a wetland's characteristics, including its climatic and hydrological context, as well as upon interactions with other disturbances such as grazing. Thus, similar fire regimes may have dramatically different outcomes. Where knowledge gaps were identified, some general predictions are offered, drawing from comparable ecosystems such as mesic grasslands. These predictions provide potential hypotheses for further research.
Wetland rehabilitation planning needs to take into account many different aspects of the wetland and its context. In South Africa, much emphasis is placed on the delivery of ecosystem services, poverty relief and skills development for those involved in labour-intensive rehabilitation measures. A framework is presented that facilitates decision-making with regards to wetland rehabilitation planning. This starts with prioritizing which wetlands need attention within a catchment. This is followed by decisions regarding which rehabilitation measures would be effective in improving certain ecosystem services based upon the aims of rehabilitation and the social context of the surrounding catchment. The functional unit that is most suitable to work with for rehabilitation is the Hydrogeomorphic (HGM) Unit, defined as a section of a wetland with more or less uniform hydrological and geomorphological characteristics. An individual wetland may comprise several HGM units, and a HGM Unit itself can be sub-divided into several smaller habitat or vegetation units. Different rehabilitation measures have been identified which are appropriate for the different scales in this spatial framework. Two case studies are presented as examples of how this spatial framework impacts upon the decisions made by the rehabilitation practitioner.
Assessing the ecological outcomes of wetland rehabilitation activities is an important need recognised by the 'Working for Wetlands' programme in South Africa. An assessment of ecological response was conducted in the Killarney and Kruisfontein wetlands, KwaZulu-Natal, in 2005 prior to rehabilitation in 2006, and again in 2011 and 2012, respectively, following rehabilitation. The assessment criteria included an evaluation of changes in ecological integrity, the supply of ecosystem services, and vegetation composition. Improvements in hydrological and geomorphic integrity were recorded in both wetlands, resulting in improved ecosystem delivery. However, investigation of vegetation composition using the wetland index value and floristic quality assessment index indices showed that, seven years after rehabilitation, Killarney's vegetation composition had improved, but Kruisfontein's vegetation was still largely dominated by pioneer species and appeared to be stable, but in a severely transformed state. The response of these wetlands has shown that sites for rehabilitation should be screened before work begins, and wetlands requiring intensive management of vegetation recovery should be assessed in terms of the objectives and the anticipated benefits of the project.
A rapid assessment technique, termed WET-EcoServices, was developed 10 years ago to help assess the ecosystem services that individual wetland hydrogeomorphic units supply. The technique requires the assessor to consider and score a suite of indicators (e.g., hydraulic roughness of the vegetation) which are then used to rate the ability of the wetland to provide 16 different ecosystem services. WET-EcoServices has become well entrenched in the South African context, with wetland specialists routinely using the technique to inform development planning, whilst it has also been used extensively in the wetland rehabilitation context. The technique has recently been revised, including the following key changes: (i) the technique is now more explicit in terms of distinguishing both ecosystem services’ supply and the demand for all ecosystem services assessed; (ii) the technique has been expanded to include non-wetland riparian areas; (iii) several of the indicators have been refined or replaced with indicators more relevant or appropriate for informing the rating of the ecosystem service or for which information is more readily available at a national level; and (iv) the algorithms used to integrate scores for the relevant indicators have been comprehensively refined so as to better account for the relative importance of the respective indicators. The aim of this paper is to present an overview of Version 2 of the technique and its underlying approach and then to demonstrate its application to 6 selected cases representing contrasting contexts, with a particular focus on the graphical representation of ecosystem service supply and demand for each case. Some of the key emphases and approaches applied by WET-EcoServices are then discussed in relation to other published techniques widely used for assessing wetland ecosystem services. After reflecting on some key limitations of WET-EcoServices, the paper concludes with recommendations on the technique’s potential contributions to operationalizing key broad imperatives of government.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.