Tag Archives: Biodiversity

Species distribution modelling is not as simple as you think

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One of the most fruitful sub-fields in ecology is using climate variables to predict species’ geographic distributions. For the uninitiated, species distribution modelling assumes that species are limited in their distributions to suitable climate zones. By studying the environmental conditions where species are known to occur, you can infer the total geographic distribution by calculating the suitability of unsampled regions based on the environmental. Furthermore, using the same principle, species distribution modelling can forecast the effect of future climate change of the distribution of life on earth.

Unfortunately, studies have shown that these fancy climate-based techniques cannot consistently outperform much simpler ones based on spatial phenomena. For instance, spatial interpolation between point occurrences outperforms sophisticated climate-based predictions. Similarly, elaborate climate-based predictions perform no better than expected from random chance.

The trouble lies in the spatially-structured world we live in. Species distributions, especially at large spatial scales, are spatially-autocorrelated due to constrained dispersal. Similarly, climate variables are also spatially structured because the meteorological processes at proximal regions are generally more similar than those at distant sites.

When trying to link species distributions to climate conditions, the challenge lies is separating spatial and environmental correlations in species distributions. Specifically, we should identify three patterns in the geographical species distributions.

  • We must first identify ‘true’ correlations with the environment, which are independent of spatial patterns (E|S).
  • Next, we must identify the environmental-associations that also have a strong spatial structure (E∩S). This is known as exogenous spatial autocorrelation because it is due to autocorrelation is the underlying variables.
  • Finally, we need to identify spatial patterns that are completely independent of environmental conditions (S|E). This is called endogenous spatial autocorrelation because it supposedly stems from spatial processes, such as dispersal.

In our latest study just published online at Ecography, we set out to quantify the degree of environmental correlation, exogenous and endogenous spatial autocorrelation in the distributions of 4 423 species of amphibians, reptiles, birds and mammals in Africa. Continue reading →

Conservation and poverty alleviation: the case of Golden Gate Highlands National Park, South Africa

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Biodiversity conservation and poverty alleviation often walk hand-in-hand. At the global scale, most species and the majority of poor people are concentrated in a narrow band near the tropics. This is also true at smaller scales, where formal protected areas for conservation are regularly situated away from urban centres and, therefore, often coincide with poor communities deprived of basic infrastructure. As a consequence, any conservation strategy that hopes to be sustainable in the long-term should pay careful attention to local socio-economic conditions.

Regular readers of this blog might know that I have a soft spot for Golden Gate Highlands National Park (GGHNP) in South Africa (e.g. the history of the park and the guide to the hiking trails). This national park happens to be in one of South Africa’s poorest regions: the Maluti a Phufong local municipality.

Consider these scary statistics for the region:

  • Only 1 in every 4 people (26.8%) has successfully complete secondary school education.
  • Approximately 75 % (155 429 out of 208 296) of people aged between 15 and 64 are unemployed.
  • 80% of households earn less than ZAR 40 000 per annum (that’s roughly US$10 per day shared among 3.35 people per household).

There is no doubt that the region surrounding GGHNP is in dire need of rejuvenation. I suppose it’s unsurprising then that the South African Journal of Science published a commentary in December last year criticising the recently approved 10 year management plan for GGHNP. In short, the authors argued that the management plan failed to highlight the need for conservation strategies that address the harsh socio-economic realities of the region and they suggested that tourism in the region be fast-tracked to generate revenue.

Here are some snippets from their essay:

“The GGHNP management plan can only succeed in promoting biodiversity and heritage conservation if it provides livelihood opportunities that safeguard continued socio-economic benefits.”

“Park resources, if managed properly, can provide long-term sustainable benefit to individuals, communities and institutions.”

“There must be speedy documentation of cultural heritage sites to promote route tourism development.“

“The GGHNP has rich cultural and heritage resources, yet is unable to effectively preserve them and to turn these assets into tourist attractions that earn revenue and provide opportunities for local economic development.”

At first inspection, this all sounds good. They use all the right buzzwords and seem to tick all the boxes. But I couldn’t help being annoyed when reading this commentary. Along with disagreeing with its general argument, I also had other misgivings, mostly due to the misrepresentation of the current situation at GGHNP.  I pointed out these errors to the editor at South African Journal of Science and these views were published last week (open access). Continue reading →

Handling cumulative impacts during the environmental decision-making process

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Although ecology doesn’t have many general laws, one most likely to qualify is the species-area relationship. If you walk through a field in a straight line and count all the different species you come across, you’ll notice that the total number of species increases as you progress along your straight path. After a while, however, you’ll start seeing the same species over and over again until you eventually find that you’re no longer spotting any new ones. This is the asymptotic species-area curve. While the exact mathematical form of the relationship is still hotly debated, it is safe to assume that it is an increasing function that reaches a plateau once all the species have been encountered.

Continue reading →

Classical camera trap critter compilation

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Two years ago, I treated myself with a Bushnell 8MP camera trap. I bought this bit of kit purely for my own amusement – without any scientific intentions – but even I can’t believe how much fun I’ve had using it during the last two summers spent at home in South Africa. Below is a little video showcasing some of the cool animals I’ve managed capture on film.

The are some things to consider: I only have one camera so I needed 6 weeks of trapping (over two summers) for this 2 minute compilation. Not that I am complaining; I loved crawling on my belly to set up the camera in a rocky cave. Furthermore, this was all filmed on our family farm – not a nature reserve – so  I am sorry to disappoint if you were expecting the big five (Try the BBC, perhaps David Attenborough can provide that?). Lastly, please excuse my amateurish efforts because I know very little about video editing and even less about classical music.

How many species can you identify?

Crush the economy for the sake of conservation? Why not, we’ve done it before…

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Should we conserve nature at the expense of the economy? Specifically, should we risk the collapse of major industrial sectors to save species?

We’ve created modern buzzwords like “sustainable development” and “new conservation” to explain multiple-objective conservation programs because many argue that conservation is only sustainable when it aligns with other economic, social and political goals. I’ve even argued this point-of-view in the past. Society is petrified of putting an end to the exploitation of nature because we worry about the terrible consequences of dismantling the modern-day economy. Should we worry about the impending threat of unemployment, debt and unpaid mortgages if we were to choose conservation instead of consumption?

The short answer: No! Well, at least not if the past is any predictor of the future. Continue reading →

Passion is not enough to reverse the biodiversity crisis

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If you’re reading this, then it’s safe to assume that you love nature. Your passion for all creatures great and small might even have pushed you to pursue a career in ecology or conservation biology. But is passion enough?

I don’t think so, and here’s why.

Continue reading →