Size does not matter, but the species specific habitat needs in planning protected areas

  • 14/05/2004

You rightly suggest that the Protected Areas (PAs) at present do not cover much of the biodiversity that survives around the tropics. Yet, would the area that needs to be brought under the PA regime be disproportionately high to cover the species with small ranges sizes or high degree of endemism? Does that make the simple percentage-based target too naïve a method to afford protection?
Ana S. L. Rodrigues: The high levels of biodiversity and endemism in the tropics have two consequences for PA planning: In general, it is expected that a higher percentage of area will be needed to cover all species than in a species-poor country, and therefore a single percentage-based target cannot be generalised; and most importantly, rather than simply defining a higher percentage-based target to countries of higher diversity, what is needed is a strategic expansion of the PA network in these regions. That is, more than the number of protected areas, what is important is the quality of the protected area, to ensure that the species that most need it are adequately covered.

Mohamed I Bakarr: It is prudent to assume that the PA regime needed to cover species with small ranges or areas of high endemism will be disproportionately higher, but definitely represent only a small increment relative to the existing coverage. The analysis we have presented will allow us to be both "strategic" in defining the areas - at least in a global context - and also "opportunistic" in pursuing options to bring those areas under protection.

The problem with the simple percentage-based target is that it undermines the need to be strategic in creating protected areas. But it will no doubt remain a very effective way for countries to account for progress in achieving protection of their natural areas; if in addition they can indicate that all biodiversity-based targets, or documented species, are reasonably well covered in the system.

What pitfalls would one need to be careful of while contextualising the study"s recommendations to a particular region, say like in the eco-regions of India? Here the creation of PAs is an entirely political and social exercise with ecological parameters rarely being vital in the final implementation of the parks.
Ana S. L. Rodrigues: The global gap analysis is not adequate for defining priorities within a given region, only to highlight which regions come out as priorities for action, for the species analysed, of course, at the global scale. At the regional scale, a finer analysis is needed, one which also incorporates political and socio-economic factors. However, conservation planning can only be strategic and effective in halting biodiversity loss if guided by biodiversity information. Otherwise, the tendency will always be to put parks in the most remote lands that have little value for human use, and which frequently have little biodiversity value as well.

Mohamed I Bakarr: Because the analysis was done at the global scale, we have acknowledged the need for caution in extrapolating the results at finer scales. Clearly, some countries will have gap species within their national system that do not necessarily occur as gap species at the global scale. What we have demonstrated in this paper is the need to fully use existing data and knowledge about species distribution in "defining" new priorities for creating protected areas. The "process" for actually creating those protected areas will undoubtedly need to take into account the social, cultural, economic and political context of each country or region. Past experiences have hardly recognized the need for maximizing representation of species based on their distribution and status. Now, even in India, there is more data available on this than ever before, and therefore gives good reason to have such analysis as a crucial first step in defining national systems.

You also mention that the gaps species number is highly correlated with endemism and not as strongly with the size of Pas. What implications would that have on PA sizes and designs in your view? How challenging would it be to create PAs that serve to protect small range species?
Ana S. L. Rodrigues: Our point in the paper is not on "PA sizes" but on "the size of the protected area network". That is, we are not talking about the size of individual reserves, but on the size of the protected area network, which is measured as per cent of area protected in a country or biome. But your question is interesting. Everything being equal, large protected areas are most effective in protecting species over time as they have larger populations and are more buffered against human disturbance and ecological disasters.

However, in many of the places that came out as high priorities for expanding the global network, for example the Western Ghats in India, the remaining natural habitat is highly fragmented, and some of the small fragments are highly valuable. A strategic conservation planning strategy in these regions requires not only protected areas but most likely a set of smaller PAs as well, in order to prevent many species from going extinct. Many of these smaller areas however, may not be viable in the long-term and their protection needs to be seen as a method for buying time rather than solving the problem. In the long-term, they may need connection to other fragments and expansion through restoration of habitat around them.

Mohamed I Bakarr: The issue of shapes and sizes of PAs has been a long-standing area of debate in the subject of conservation biology. The debate was on whether PAs should be "Single Large or Several Small - the debate was dubbed "SLOSS" - which never really got us anywhere. Clearly, by increasing our understanding of species-specific needs for habitats, whether for food, reproduction, or migration, we are beginning to acknowledge that size does not matter. What matters is that we must design PAs that maximize representation and persistence of species based on their habitat requirements.

Furthermore, the extent to which the designated protected areas are integrated in surrounding landscapes is also crucial, because for many small range species, their survival will still depend on maintenance of gene flow between populations. There is therefore an increasing shift toward "landscape approaches" to conservation, as opposed to the single site focus that only leads to the isolation of PAs.

There is a social cost to the creation of PAs that would naturally increase if the bias were towards the tropics. For one, would you think the developing countries are under greater pressure to change land allocations rather than say, Alaska, although there the oil lobby has its own games to play?
Ana S. L. Rodrigues: Perhaps not by chance, people and biodiversity tend to favour similar ecological conditions. The result is that some places in the world with highest levels of biodiversity are also among the most densely populated. These are therefore regions of potentially high conflict between conservation and human activities. Addressing this conflict cannot happen through an "either-or" approach. The idea is not to either declare a region lost for biodiversity or else off-limits for people, but to look for approaches at a finer spatial scale such that both conservation and human activities can happen within the region. These regions are those where strategic conservation planning is most needed, to create a network of protected areas that maximises biodiversity protection with the available resources. In many cases, ensuring that such resources are sufficient requires investment from external sources, which alleviate the pressure on land by providing local populations with economic alternatives. Our recommendation is that, at the global scale, the burden of conservation on many of these regions rich in biodiversity but poor in economic resources, is shared by the global community.

Mohamed I Bakarr: The opportunity cost for creating PAs is undoubtedly higher in the tropics than in temperate areas because of the huge concentration of biodiversity. But there is no reason why developing countries in the tropics cannot take advantage of the high opportunity costs to balance the scale of global investment in protection of biodiversity. The amount of money involved is affordable by the global community, provided the commitment and political will in developing countries is forthcoming.

You do mention that the efficacy of the PAs to actually provide protection is itself debatable. I would presume that the efficacy of the PAs is less in regions where human population and its dependence on resources is higher, say in the tropics. If that be the case, would it be wise to recommend an increasing PA network in these regions where the effectiveness of the PAs is not determined at best, and low, at worst?
Ana S. L. Rodrigues: Many protected areas have little existence beyond paper, and many which do are still losing species because they were too small to start with or because they suffer high pressure. Despite this, protected areas are still the best conservation tool available, because they tackle the most important threat to biodiversity, which is habitat loss. Our aim therefore should not be to give up on PAs but to improve their effectiveness. For many parts of the world, giving up on PAs is in practice equivalent to irreversibly giving up on their biodiversity.

In the Nature paper, our main premise is that PAs cannot be expected to protect what they do not contain in the first place, hence we focus on identifying species which fall completely out of the current PA network, even though we recognise that many species which seem to be protected are probably not. But our concept of PAs in this paper is quite broad; it does not mean strict no-go areas. It includes a diversity of models such as indigenous and forest reserves, many of them allowing for multiple use. The recommendation for the expansion of the PA network is equally broad. What our data tells us is that the regions highlighted have species which need protection. The best "format" for this protection will vary from one region to another, depending on the ecological requirements of the species as well as the socio-economic constrains of the region.

Mohamed I Bakarr: Although the efficacy of PAs remains a problem in many parts of the developing world, previous research has also shown that just having an area designated for protection is still far better than not having one at all. So in as much as we should continue to strive for effective management of PAs, it is important that the effectiveness issue per se does not preempt the designation or expansion of new areas. The problems of effectiveness can be characterised in many different ways, including the social, cultural, economic and political context for creation of PAs. If we can navigate these complexities during the designation of PAs, then management will most likely be very effective.

Are there any particular taxa or groups where you may have overestimated the gap species, and from your data, would the errors of omission and commission be higher in some particular geographical regions?
Ana S. L. Rodrigues: The taxa and regions for which an overestimation of the numbers of gap species is most likely are those with the worst knowledge. This could happen in regions for which the PA database is most incomplete, but we can"t predict this precisely because the PA data available is the best we have access to! It may also happen that for some regions the species maps are less complete, that is, that they exclude parts where the species truly exists, which can be a source of omission errors, or overestimating the number of gap species. This would particularly be the case with amphibians, in some regions of Africa and Asia. On the other hand, these regions are so little known that the odds are that they contain yet many undescribed species, which underestimates the number of gap species. As you may know, many new species of amphibians were just recently described from Sri Lanka and the Western Ghats. This means that it is difficult to predict what the overall net effect would be for these poorly-known regions. Overall, we believe that the commission errors are the dominant effect, with many species apparently covered by PAs when they are not.

Mohamed I Bakarr: Because our definition of gap species was fairly strict enough to just include those species whose natural ranges were not touched by any protected area, it is unlikely that there was an overestimate for any particular taxa or groups. We did not report on geographical patterns of omission and commission, but I"ll encourage you to read a much more detailed report that was presented at the recent World Parks Congress in Durban.