What difference do protected areas make on vegetation extent and condition?

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Logging road in Central Kalimantan, Indonesia. Photo by Roshan Sharma.

Biodiversity is the variety of all life forms on Earth and underpins the health of our planet. It provides important ecosystem services like food and fibre that are the basis of human existence. However, exploitative human activities on Earth have created an unprecedented breakdown of the environment, causing global biodiversity loss at an unprecedented rate and scale. Land cover change, mainly the conversion of vegetation – the state and processes that support biodiversity – is by far the most important driver of biodiversity loss. This conversion is led by the expansion of croplands, urban areas, infrastructure, logging, mining and fire (Curtis et al., 2018). 

The establishment of protected areas (PAs) is one of the most important and globally applicable approaches to reducing these conversions. PAs are clearly defined geographical areas that limit human activities in prescribed areas. Since the campaign to expand PAs in the World’s Park Congress in 1982, nations have strived to increase the extent of land under protection. The global PAs have grown to cover more than 28.4 million square kilometres or around 13 per cent of the Earth’s land surface (UNEP-WDPA, 2019). Further, the Convention on Biological Diversity (CBD) has called to increase the protected area state to 17 per cent of the Earth’s land surface (Aichi Target 11). 

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With the vast areas of land already under protection and calls to increase it, are PAs making a difference? PAs are known to be disproportionately established on marginal lands with least pressure of conversion and places unimportant for biodiversity. This means that PAs may not be having the intended impact – a reason many have criticised them. To understand the difference a PA is making, the outcome after the PA has been implemented needs to be compared with what would have happened without the PA in place (referred to as the counterfactual scenario). Estimating the counterfactual is the crux of finding such a difference or impact. However, estimating counterfactuals can be difficult due to the non-random allocation of PA. Evaluations that fail to accurately estimate the counterfactuals without considering non-random allocation of PAs and other spatial processes will cause bias and result in invalid estimates of impact.

This issue intrigued ICON Science PhD candidate Roshan Sharma, who started searching for literature for impact evaluation studies on PAs. He found that the literature is largely scattered, varied, and in many cases contradicting regarding how much difference PAs were making. There was a clear research gap that needed to be addressed.

Roshan decided to conduct a systematic review to address this research gap. Systematic reviews can be a great approach to synthesising evidence and generating higher quality evidence than individual studies. If done correctly, these reviews can allow researchers to come closer to understanding the true effect of an intervention. 

In an effort to increase the transparency and reproducibility of the review, Roshan developed a protocol with the help of ICON Science peers Ascelin Gordon and Marco Gutierrez, and fellow researchers from the University of Helsinki, the University of Western Australia, the University of Cambridge, and James Cook University. The protocol follows the Collaboration for Environmental Evidence guidelines and ROSES (RepOrting standards for Systematic Evidence Synthesis) reporting framework. Following the standard guidelines and frameworks ensures that the review covers all relevant literature, implements a dual consistency checking in screening and data extraction to remove reviewer bias, has a quality appraisal of all selected studies, and synthesizes only high-quality studies. Publishing the protocol ensures the results of the review will be published regardless of the findings, effectively removing publication bias. The protocol has been recently published in Environmental Evidence and can be found here

Now that the protocol has been published, Roshan and the team will be moving forward to undertake the review. They hope the results of the review will be useful for the larger scientific community and policymakers. There is an ongoing debate on whether the successor of Aichi Target 11 will be on setting higher area targets for PAs or emphasize more on impact measures. Thus, they hope that their findings will be relevant to the development of new post-2020 CBD targets. 

References

Curtis PG, Slay CM, Harris NL, Tyukavina A, Hansen MC. Classifying drivers of forest loss. Science. 2018. http://dx.doi.org/10.1126/science.aau3445

Sharma, R., Eklund, J., Barnes, M. et al. The impact of terrestrial protected areas on vegetation extent and condition: a systematic review protocol. Environ Evid 9, 8 (2020). https://doi.org/10.1186/s13750-020-00191-y

UNDEP-WDPA. The world database on protected areas. 2019.

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