Boasting about backyard biodiversity

The easiest way for an aspiring naturalist to explore wildlife is by stepping out into their own backyard. Try it yourself. As I write this, I can look through my window at a Karoo Thrush hopping about my garden. But this post is not about the tiny garden surrounding my current apartment, but rather about my childhood home. I was tremendously fortunate to grow up on a 60 hectare farm, where  first discovered my love for nature.

Between wrapping up my PhD and starting my current lecturing position, I spent a few months of unemployment back in the house I grew up in. During that time, I discovered the thrill of recording unobtrusive nocturnal critters using a camera trap. Every afternoon, I set up the camera trap and eagerly explored the footage the following morning. It was so much fun.

After enough time, even I was amazed by the variety of species that lived on this relatively small farm. Perhaps, I should rephrase that last sentence. You see, calling it a farm is not accurate because it hasn’t been used for agricultural in more than ten years. The last cows were removed back in 2004 and since then the land was left dormant and only managed to minimise the risk of wild fire.

Still, I captured footage of 18 different mammal species, which is remarkably high for such a small area. Moreover, the camera trap is unlikely to capture any footage of bats and small rodents, so the total mammal diversity is probably even higher. I decided to write up these observations and the results have just been published online in the African Journal of Ecology. Continue reading

Conservationists must realise that farmers are central to conserving nature

The patchwork of farmland near my childhood home

The patchwork of farmland near my childhood home

Between finishing my PhD and starting my current job, I spent several months of unemployment on the family farm near Bethlehem in the Free State Province, South Africa. Rather than actively searching for a real job, I procrastinated by watching birds and tracking mammals with a camera trap.

The experience was like re-reading a really good book; I kept seeing things I hadn’t noticed before. Despite spending my childhood in the area, it wasn’t until I actually started paying close attention that I realised the amazing nature around me.

Although it is an agricultural heartland, the region is teeming with life. For example, the sampling quadrat for the South African Bird Atlas Project near my house contains 257 different bird species. To put that in perspective, the entire Island of Madagascar supposedly only hosts 265 species (give or take 10 species depending on the source).

No wonder the area is part of the Rooiberge-Riemland Important Bird and Biodiversity Area.

If I, as a professional ecologist, took so long to realise the amazing biodiversity of the area, then surely others are also oblivious to it? As conservationists, we should be concerned by this.

Most of the half-a-million hectares of the Rooiberge-Riemland Important Bird and Biodiversity Area is on commercial farmland. How can we expect to conserve this area without the buy-in from the local farmers? They are, after all, the owners of the land and are solely responsible for what happens on the ground.

As a consequence, I am trying to realign my own career trajectory. The idea now is to make it as easy as possible for farmers to conserve nature. To this end, I wrote an essay for pilot African version of the The Conversation.

If you’re interested please click through: Farmers hold the key to nature conservation: let’s treat them that way.

We’re used to hearing great tales of conservation in faraway tropical forests and coral reefs, but I am incredibly excited about the opportunity to conserve nature in my own backyard. Hopefully, this is just the first in a long-line of things I have planned. Watch this space.

How do correlations between climate and biodiversity arise? UPDATED

Anyone who as ever watched a David Attenborough documentary knows that biodiversity differs in areas with different climates. Only a few species an survive in hot and dry deserts whereas warm and wet tropical forests are teeming with life. But have you every stopped to wonder why this is so?

Why are certain climate conditions able to support many species and others not? More specifically, how does this work mechanistically?

This was the question my co-authors and I set out to answer in our most recent paper just published online at Global Ecology and Biogeography.

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The scalability of macroecology

Russian Dolls

No matter at which scale you look at it, nature is remarkable.

Like many others, I was taught ecology in a very hierarchical way: individual organisms are part of a wider populations of species, collections of species form communities and communities come together to make up ecosystems. Similarly, single trees are nested within forests, which aggregate to form biomes. I’m sure you can come up with many comparable examples.

The trouble with such neat spatial hierarchies is that they lure us into believing that if patterns appear similar at several different spatial scales, then the processes leading to these patterns should also be similar. It’s so easy to assume that nature is like a set of Russian Dolls: each daughter exactly the same as its mother, only slightly smaller. But this is not necessarily the case.

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Species distribution modelling is not as simple as you think

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