Buffer Zones - Their Processes and Potential in Water Protection
We decided to organise this conference for a number of reasons. Most importantly, there had not been an opportunity for all those engaged in research and implementation of buffer zones to meet formally and exchange ideas, problems and hopefully some solutions. Research into how and why buffer zones work was reaching a critical stage. Over 10 years of detailed research had been conducted (see Correll, this volume) and it was over 20 years since the merits of buffer zones for water quality were first discussed in western literature (e.g., Waikato Valley Authority, 1973). It is against this backdrop of scientific interest and a rising level of concern from land managers and government agencies that the conference was called. In the words of The Earl of Cranbrook, Chairman of English Nature and the opening speaker for the conference:
"English Nature believe that buffers must be an important element of any overall strategy... Perhaps the most important challenge, which we must not lose sight of, is to develop an overall strategy for land use. Such a strategy will identify in which Iandscapes buffer zones are best suited. Only then can we achieve the level of protection and enhancement of our river systems that is needed."
We were overwhelmed by how positive the response was to the conference. All our first-choice speakers accepted the invitation to give papers and over 70 poster presentations were made, bringing together the best in the field. Overall, 21 nationalities were represented, a truly "international" conference.
The principal aim of the conference was to further our understanding of the value of buffer zone landscapes by examining the processes occurring within buffer zones in relation to their potential to conserve, enhance and protect the water environment. The use of natural buffer zones to protect freshwater from pollution has attracted considerable interest within the European Union and elsewhere. However, the factors accounting for the pollution retention capacity of buffer zones are diverse and, therefore, the performance of a buffer zone within a catchment is difficult to predict.
In recent years there has been a drive to integrate the results from research into management solutions that control diffuse pollution and protect the water environment. Some politically-driven initiatives have, thankfully, accelerated the debate on buffer zones but have, at the same time, stretched us to the limits of our knowledge on buffer zones. This drive for "solutions" has culminated in recent years in a number of major reviews. The first was a synthesis of Swedish research published in a special issue of Ambio (1994, volume 23, number 6) which documented the potential of a range of wetland habitats to trap nitrogen (also see Fleischer et al., this volume). The second major review was the result of work within the Chesapeake Bay Program, Eastern USA (Lowrance et al., 1995; Lowrance, this volume). Key summaries of the hydrogeological framework of riparian buffer zone investigations were developed as well as statements on the competence of riparian zones in these various hydrogeological settings. The third major publication, a combination of review paper and management document, was from the National Institute Of Water and Atmospheric Research (NIWA), New Zealand (Collier et al., 1995). This document included a svnthesis of scientific data as well as management implications for farmers and agencies responsible for river and stream protection. The combination of scientific and practical advice should be central to any implementation policy and we were delighted when members of the Nevv Zealand group accepted the invitation to present their work at the conference (Cooper, this volume; Downes et al., this volume).
STRUCTURE OF THE BOOK
The proceedings consist of three parts: Part I, the processing of target chemicals within buffer zones; Part II, the potential of habitat types to act as buffer zones; Part III the creation, restoration and longterm sustainability of buffer zones. We have drawn together in the book most of the spoken papers together with a small selection of the poster presentations. The titles of all the posters presented at the conference can be found in Appendix I.
Part I, the processing of target chemicals within buffer zones
This section seeks to review the key processes that account for the retention, transformation and ultimate fate of waterborne pollutants within buffer zones. Speakers were asked to focus on a key water quality parameter and review how this parameter is controlled within a range of habitats. Of key concern was the effect of buffer zone structure on its ability to function and what habitats are best for sediment, nitrogen, phosphorus or pesticide retention? Speakers were asked to comment on the optimal design or attributes required of a buffer zone, in order to achieve a particular function and also to comment on the limits of our current knowledge with suggestions of topics that need to be explored.
There were also special concerns about how the ecology and microbiology would react to nutrient inputs. Groffman focuses on the microbiological aspects and Dr. Chris Newbold (English Nature, Peterborough) spoke at the conference on the response of the vegetation complex (this paper is likely to be published elsewhere later this year).
Part II, the potential of habitat types to act as buffer zones
Here the focus is on specific habitats: in-stream, riparian, ponds, wetlands etc.; their potential to act as buffer zones is examined. Authors were asked to describe the principal features, hydrological regime and vegetation complexes of a particular habitat and comment on how these factors influence the dynamics of nutrient uptake. The authors were then asked to consider where in the catchment these habitats could be located to achieve their optimum potential and whether they need to be managed to sustain the key processes? Finally, we asked authors to discuss whether we know enough to make firm recommendations on how to preserve or restore these environments and, if so, what their outline suggestions would be for their chosen habitat.
The concluding papers in Part II develop similar themes but were asked to take a more global perspective; namely, to what extent can we model buffer zones (Gold and Kellogg) and the interactions between buffer zones and their catchment (Merot and Durand).
Part III, the creation, restoration and long-term sustainability of buffer zones
Part III sought to examine the strategies required to preserve or create buffer zones and the implications of buffer zone creation. The creation of buffer zones to control pollution is a change of land use which has a direct and multiple impact on the farmer. Dickson and Schaeffer and also Cook looked at the consequences of establishing buffer zones in the context of a farm. Tytherleigh discusses the lessons learnt from MAFF's Habitat Scheme Water Fringe Option, a pilot project which seeks to establish set-aside land along selected rivers in England. At the conference Dr. Terry Tooby (Pesticide Safety Directorate, UK) discussed in detail the problems of developing concepts of buffer zones in relation to the regulations on the use of pesticides. Tooby was unable to provide a written paper, but readers are directed to papers by Harris and Gril et al. (both in Part I) for a review of work on pesticide impacts and their fate within buffer zones. Downes et al. sought to examine the practical implications of restoring nitrogen buffers, while Addiscott was asked to take a critical look at whether buffer zones are a serious tool for the control of diffuse pollution. The final papers in this section sought to take a more strategic overview of the whole process. Gardiner and Perala-Gardiner discuss the role of integrated planning frameworks, particularly the role of catchment management plans, whilst Baudry looks at farm and landscape interactions. The section is concluded with a paper by Cooper who offers an insight into the New Zealand experience of encouraging implementation of buffer zones.
The editors have the final word and we present a concluding summary of the current concerns, as well as our own overview of what work needs to be done for the future development of the buffer zone concept. We believe there is now a sufficient basis in the literature to develop ideas and practices for buffer zone restoration. These proceedings give an insight into that foundation of knowledge.
Ambio (1994) Special Edition: Wetlands as Nitrogen Traps. Ambio 23(6), 320-386.
Collier, K.J., Cooper, A.B., Davies-Colley, R.J., Rutherford, J.C., Smith, C.M. and Williamson, R.B. (1995) Managing Riparian Zones: A contribution to protecting New Zealand s rivers and streams. Volumes 1911. NIWA, Department of Conservation, Science Publications, P.O. Box 10, 420 Wellington, New Zealand.
Lowrance, R., Altier, L.S., Newbold, J.D., Schnabel, R.R., Groffman, P.M., Denver, J.M., Correll, D.L., Gilliam, J.W.,
Robinson, J.L., Brinsfield, R.B., Staver, K.W., Lucas, W.C. and Todd, A.H. (1995) Water quality functions of riparian forest buffer systems in the Chesapeake Bay Watersheds. U.S. Environmental Protection Agency, Chesapeake Bay
Program Report. EPA 903-R-95-004.
Waikato Valley Authority (1973) Lake Taupo - cntchment control scheme. Final Report. Published by WVA Hamilton, New Zealand.