It doesn't stop with deforestation: Highlighting degradation

When we think of the Amazon and anthropogenic impact, we often have this image in our heads:

However, after reading on environmental and climatic impacts of land cover change in the rain forest (in coming blog posts) I became aware that we need to highlight forest degradation as well as deforestation. Both have significant effects, and the fact that land still “looks green” in satellite pictures does take into account the forest productivity nor species diversity.

Therefore let me outline the two differing phenomena in the context of the Amazon rainforest area. Using the FAO definitions:

Deforestation: this involves a decrease in the area covered by forest, with no guarantee of continuity in maintaining the forest cover (by e.g. regrowth)

Forest degradation: this does not involve a reduction of the forest area, but rather a quality decrease in its condition, this being related to one or a number of different forest ecosystem components (vegetation layer, fauna, soil, ...), to the interactions between these components, and more generally to its functioning.

To illustrate this, I’d like give a few examples that would reduce forest “quality” or productivity: selective logging for specific timber wood and other extraction practices (and the infrastructure and transport associated with this), fires, infrastructural projects (roads, the Belo Monte Dam) and variable edge effects (of forests adjacent to clear-cut land).

Forest degradation is a more subtle process and (opposed to the picture above) not as easily identifiable. It therefore poses significant challenges to controlling its continued occurrence. Deforestation figures have occasionally slowed due to (variably effective)  environmental policies limiting the clear-cutting of rainforests.  According to Imazon, the percentage of land degradation is on the constant rise – the increase in total rainforest area degraded between Aug 2013-14 and Aug 14-15 being 207%. Additionally, the total area degraded in the considered time period (July14-15) is greater than total area under deforestation.

I hope I have shown how forest degradation cannot be neglected from the picture – and highlighted that if the functionings of the rainforest and all its ecosystem services are to be preserved, we need to tackle this issue along with clear-cut deforestation.

Clear-cutting the Amazon

Roughly 40% of the South American continent is covered by the Amazon basin, with the Amazon rainforest representing the largest tropical rainforests on Earth. It is located within rapidly developing nations with booming industries and thus its conservation has been difficult. Over the past 30 years, 15% of the natural ancient forest has been completely destroyed. The diagram below shows the reported annual clear-cut deforestation figures, supplied by the Bazilian Government.

As when dealing with any metrics, we should be aware of the limitations of these. What I find most important to note here, is that these figures represent deforestation within the “Legal Amazon”. While logging regulations have become stricter over time, and thousands of control agents employed by the IBAMA (Brazils ‘environmental police’), there is still a large proportion expected to be cleared illegally. “Heating” wood has recently become a grand issue – making illegally felled logs look legal with falsified papers by bribing (or death-threatening!) landowners to sign it off. 

The latest figures by Brazils National Institute for Space Research have shown a clear surge in deforestation rates in 2013 and mid-2014, after a previously decreasing trend had given some hope to forest conservation. To blame here are mostly the continued poorly-enforced regulations* (a cut of 72% in government expenditure on environmental law-enforcement) and a government dominated by those in favour of agribusiness expansion. The future of the tropical forest seems to swing in between the two extremes: natural forest preservation (e.g. creating natural reserves) and forest clearance to create farmland for large-scale producers. Arguments exist on both sides, with the sustainable solution most likely occupying some area in between.

* The country's forestry code requires landowners in the Amazon to devote 80 per cent to native forests.

A timelapse of Amazonian deforestation 2000-2010

This timelapse shows how dramatic the land cover changes are that South American regions such as Rondonia in Brazil (area of video) undergo.  The rapid deforestation experienced in the western state of Rondonia is mainly driven by the needs of small farmers, cattle ranchers, miners and loggers. An astonishing 25% of natural forests was already cleared by 1993.

Setting the scene: Land cover in South America

 Hello and welcome to my blog!

Remotely sensed data, photography and population statistics all point to the interesting changes the South American continent is undergoing. Rapid urbanization, rising prosperty and growing agribusinesses drive the anthropogenically induced land cover changes and the global changes in climate exacerbate local climate variability to top things up.

South America was the world region with the highest net forest loss 1990-2005.

My blog for the next few weeks will focus on the land cover changes of the recent past, present and predicted future under climate change scienarios. What I am most interested in, is how these differently caused changes affect an even wider set of phenomena. These can range from the global climate system to populations' livelihoods, local biodiveristy and anexed biomes.

To introduce the topic, a detailed land-cover map of South America shows the current spread of 10 identified ecological groups in Eva et.al. (2004).

Natural climate variability (e.g. intensified, more frequent ENSO events) affect the continent's vegetation cover over time. However, the observed unprecedented rate of land cover change calls for a close examination of the influence of human activities.

Land use change = change in the use or management of land by humans, which may (or may not!) lead to a change in land cover.

This diagram below by Foley et. al. (2005) shows (very generalised) how a transitions in land use may affect land cover of a developing area.

Some of these changes have been observed in South America. The advancement of the agricultural 'frontier' into the humid tropical forest domain both from the west along the Andes and from the southeast has led to continuously high rates of forest clearance, and resulted in higher proportion of agricultural/pasture land cover. However, Amazonia has experienced the appearance of "deforestation hotspots" and the high rates of urbanisation in major cities have often meant a jump from natural land use to fully urban build-up environments. These examples highlight the diversity of rates and types of change observable on the continent.

With this introductory post, I hoped to highlight the varied land cover of South America, and give an overview of drivers and rates of change. My blog will explore these issues together with an examination of the wider environmental, climatic and societal consequences.