What does degraded mean?

Logged forest in Perak, Malaysia. But is it degraded?  Photo crid to flickr user Wakx

The Convention on Biological Diversity (CBD) aims to restore 15% of degraded ecosystems by 2020.

This is very ambitious. Even by the CBD’s standards.

But before we get to how we’re going to raise the money to do this, where we’re going to find the manpower to do all this work and what land is a priority we need to work out what we mean by degraded.

A lot of us struggle to define what degraded really means. Don’t worry though, you’re in good company – the CBD don’t know what it means either.

When I searched in google it came up with this:

de·grade

/diˈgrād/

Verb

1. Treat or regard (someone) with contempt or disrespect.

2. Lower the character of quality of

Not very useful right?

Looking at the literature a bit further you see that there have been constant attempts to define degraded forests in particular. The latest of these is a forest which ‘delivers a reduced supply of goods and services from the given site and maintains only limited biological diversity.’ This seems like a reasonable starting point.

However, it is not particularly useful in practice.

The main problems are:

• What do you use as a reference? In some regions it might be relatively easy to find primary forest but other areas don’t really have undisturbed forest any more.

• How much biodiversity/ecosystem service supply do you need to lose in order for the change to count as degradation?

• Where does forest become non-forest? Is there a sensible threshold?

• How can we avoid savannah being classed as degraded forest?

• What ecosystem services are we talking about here? Trade-offs are inherent in any management of ecosystem services so even relatively small changes will reduce supply of one good or another.

That’s all I could come up with at the moment. I’m sure there are more.

All of these problems, and their lack of clarity in the CBD, completely scupper this 2020 goal. Forest biomes should those be for which it is easiest to define degradation, but this hasn’t been done.

Even though I have ranted about it here I realise it is not an easy thing to do. I am not going to solve this with a blog post, which is why I’m going to pursue the topic further in my personal research.

I have a few thoughts on how to push things forward as a starter. We need to be pragmatic and we can’t have woolly definitions in important international agreements if it stops us from balancing the needs of humans with conserving biodiversity.

For what its worth I think we need to:

• Determine reference states for all broad biomes. Only then can we really start to measure degradation.

• Work out thresholds below which ecosystems should be classed as degraded. This will obviously have to be ecosystem specific. It could include things like magnitude of changes in carbon pools, time required to recover from disturbance or some measure of species community similarity to reference states. Species richness should not be used as a biodiversity metric because many disturbed ecosystems have higher richness that neighbouring pristine systems.

• We must develop a means of classifying ecosystem types for use in international agreements. Though this is a difficult task as there are many transition ecosystems, we still need to do it.

• We need to recognise that ‘reduced loss in good and services’ means nothing. If you restore arable farmland to forest you would lose food production. Is this forest then degraded farmland? Obviously not. We must define what ecosystem services we are talking about for each biome and then use these as potential indicators of degradation.

• We need to develop indicators of degradation since we will not be able to measure everything we would like everywhere. Canopy cover and tree height have been suggested for forests, but have rarely been tested.

This list is not exhaustive by any means, but I think its a good start.

I am constantly amazed by the ability of those who come up with CBD goals to forget about how we will actually measure progress towards them. I really think this needs to change in the future. For the moment we should try to develop indicators for the 2020 goals.   Without them we will have little idea whether we’ve achieved them and what we might need to change in the future.