Modern Agriculture and Biodiversity Conservation

I came across a publication by the EuropeanCrop Protection Association (ECPA), which is an organisation representing the pest control industry and promoting modern agricultural technology in the context of sustainable development. Maybe the source of this publication is slightly biased because of the publisher, but I thought it raised a few interesting points in relation to my previous post about farms as supporters of biodiversity.

Agriculture Benefitting Biodiversity

ECPA suggest that the evolution of European agriculture has actually enriched biodiversity, through the conversion of relatively homogeneous woodland vegetation into a heterogeneous ‘mosaic’ of cultivated fields with boundaries that provide a range of different ecosystems and habitats. As a result, they claim that many plant and animal species are now dependent on agriculture.

These may seem quite rash claims, but there is evidence to support some of these assertions. For example, floral diversity in grasslands and alpine meadows are maintained by stock (sheep and cattle) pasturage, and without this agricultural input these areas would revert to scrub vegetation that is less biodiverse. There are a number of bird and plant species that are promoted by agriculture, with the skylark and yellow wagtail two prominent examples as well as cornflower and corncockle.

The Skylark can be seen in fields in the UK (Source: birdforum.net)

As long as landscape heterogeneity is maintained, agriculture will continue to support biodiversity.

Modern Agriculture and Biodiversity Conservation

An increase in land used for agriculture is a major threat to biodiversity. However, as ECPA suggest, the intensive practices of modern farming can play a role in minimizing land conversion and hence aid the conservation of biodiversity. The proportional growth in global cropland is far smaller than the growth of the human population (10 times smaller between 1961 and 2005!).

By increasing yields on existing agricultural land, modern agriculture has contributed to biodiversity conservation by leaving more land for conservation purposes than there would otherwise be in the absence of such intensive technologies and practices. This issue has been highlighted by the European Commission on debates relating to deforestation, raising the point of a need to invest in increasing yields on existing farmland to halt further habitat conversion.

What this publication summarises is the role of agriculture in promoting and supporting biodiversity, both within the agricultural landscape and externally to it. Agriculture, if practiced appropriately, can help in biodiversity conservation. Of course, if poorly managed and practiced, farming presents a real threat to biodiversity. The key is to find a balance between production and environmental protection, so that both systems can continue to prosper in the face of climatic change and increasing demand from growing global populations.

Farms as Supporters of Diversity

Debates through the lenses of an environmental change perspective tend to portray agriculture in a bad light. Well, as someone from an agricultural background I would challenge those that assume agriculture is a wholly damaging practice that is causing losses of biodiversity.

The agrarian landscape, which has come to define the British countryside, can provide a space for certain species to thrive. If you think about the iconic animals of our countryside – Fox? Hare? Rabbit? – they all spend a great deal of time on land managed for agricultural production. Birds, like pheasants, buzzards, and the barn owl (notice the word barn…!), all love the rural landscape too. It is important that we don’t forget the importance of farmland as a wildlife and plant habitat.

Hares can be seen boxing in the Spring (source: robertefuller.blogspot.co.uk)

A Reliance on Farmland?

I came across an interesting article recently that presents the findings of a research study conducted in Africa and Asia, which suggested some threatened species needed farmland for survival. The study found at least 30 bird species that would have been driven to extinction without the existence of farmland. The species under particular threat were dependent on farming for all of their primary needs (land for nesting, breeding, and food). A comment I found particularly interesting was that of Dr Wright, who pointed out that most conservation efforts in the developing world focus their attention on forest species and pristine habitats, to the detriment of those that rely on farmland. Is this because of a general assumption that farming practices are damaging diversity, not supporting it? I think this is a real possibility.

The Danger of Intensification

Of course, as was pointed out in this study, the intensification of agriculture is a threat to many species. Agricultural practices must look to promote biodiversity and ecological functions, with habitats managed sensitively. Indeed, if agricultural intensification continues, those species currently reliant on farmland may suffer. Organic farming practices and new forms of management such as eco-agriculture provide possible strategies for ensuring these landscapes remain important wildlife habitats. At the very least, the maintenance of traditional and mixed farming should be actively encouraged.

But, taking everything into consideration, we should recognise farmers as important managers of our landscape, as farmland does indeed support many species.

Intercontinental Biotic Connectivity and Tipping Points

It is perhaps fairly clear that agricultural expansion and/or intensification is very likely to have an impact (and more so a detrimental one) on the surrounding habitats and environment. The conversion of terrestrial biomes into agricultural landscapes has reduced habitat areas available to species and can have many negative impacts for globally important ecological processes (Foley et al., 2005). As Sanderson and colleagues (2002) quantify, 'Human Footprints' can be identified across 83% of Earth's land surface, influenced by high population density, agriculture, or infrastructure. Therefore, a considerable proportion of Earth's natural environment has experienced change as a direct result of local agricultural changes.

Deforestation for conversion to agricultural land in South America (Source: plant-talk.org)

However, whilst reading a thought-provoking paper by Barry Brook and colleagues exploring the concept of tipping points within the terrestrial biosphere, I unearthed an interesting concept of 'direct intercontinental biotic connectivity' and the coupled regime shifts. Essentially, the interconnectivity of ecosystem responses translates on a global scale to biotic connections between both biomes and continents, which facilitate the diffusion of localised changes across the terrestrial biosphere. Moreover, if these teleconnections permit changes to be felt fast enough, a global tipping-point response could be created. (In case you're not 100% sure about tipping points, they are where systems shift radically to a different state, potentially irreversibly.)

So, how could agriculture play a role?

Well, I'll start with an example. Intensive agriculture in the western USA resulted in habitat change, which in turn appears to have caused abrupt losses of Arctic ecosystem structure and biogeochemical cycling, essentially meaning biodiversity and functional loss. It is suggested by Robert Jefferies and colleagues that this stems from the increased populations of migrating snow geese through their subsidisation by agricultural food supplies. Here we see that agriculture has the capability to play a role in environmental change through teleconnections.

Snow geese in Missouri, USA (Source: dailymail.co.uk)

Not all changes have a teleconnection to another part of the globe. Limiting these direct biotic linkages could be physical barriers to species movement (oceans and mountain ranges spring to mind) as well as species niches (so the range of climatic conditions specific species are adapted). Thus, not all changes caused by agriculture will contribute to a change elsewhere. But certainly, agriculture has the ability to be a direct cause of change felt in separate regions due to 'intercontinental biotic connectivity'.

Irrigation circles in Colorado (Source: ecolibrary.org)

The number and magnitude of these connections will determine the chances of a tipping-point pattern. So, if environmental changes continue globally, we could see a tipping point within the terrestrial biosphere in the future. Naturally, as it is practiced worldwide and is identified as a significant infringer on habitats and environments, agriculture (through its expansion and intensification) could play a very real role.

Agriculture: A Thirsty Industry

Agriculture uses 70% of the Earth’s surface freshwater, which makes it comfortably the greatest consumer of freshwater. Because of this great thirst, it has a central control on the health and sustainability of freshwater ecosystems, and the biodiversity such systems support.

The world’s freshwaters support up to a third of all vertebrates and at least 40% of global fish diversity, and when considering that they only make up 2.5% of the world’s surface water, freshwater ecosystems are a vital source of global biodiversity. What concerns many scientists is the increasing threats facing freshwater biodiversity, of which agriculture is a significant one.

Continuing intensification, with greater applications of artificial fertilisers and pesticides, and expansion in response to growing global populations, as well as inefficiency in freshwater usage (60-80% is lost via evaporation and seepage), mean that agriculture is threatening freshwater biodiversity. As the graph below demonstrates, sourced from Martin Jenkins’ journal article for Science, over the last 30 years freshwaters have suffered most in terms of biodiversity degradation. This coincides with an intensification of agriculture worldwide.

Species population indices for forest, marine, and freshwater ecosystems, as included in the 2002 WWF Living Planet Index (Source: Jenkins, M. (2003) in Science, 302)

David Dudgeon andcolleagues go as far to say that ‘freshwaters may well be the most endangered ecosystems in the world’ (2006: 164), and I would be inclined to agree in face of the evidence. The Aral Sea and Lake Victoria provide two definitive examples of how human interference, and in particular the contributions of agriculture within the catchment, have decimated freshwater biodiversity. Inefficient and unsustainable freshwater use and immensely excessive chemical applications led to the demise of the Aral Sea and the biodiversity it supported. Similarly, the contribution of agricultural intensification in the catchment of Lake Victoria exacerbated aquatic biodiversity degradation.

Satellite imagery showing the shrinking of the Aral Sea, Central Asia (Source: www.fansshare.com/aralseadesertification)

Agriculture –in particular intensification and unsustainable water usage – has severely damaged freshwater ecosystems in the recent past, and with the trend of intensification and expansion expected to continue, the threats to freshwater biodiversity currently posed by agriculture will only increase. There is a real need for agriculture to become more sustainable and efficient globally, and to specifically recognise how intensification or expansion in a particular region will impact freshwater ecosystems. The ignorance of the Soviet Union, in regard to implications on the Aral Sea of cotton production in Uzbekistan, is a real example of how damaging a lack of awareness can be for freshwater biodiversity. If the world’s current freshwater biodiversity decline is to be curtailed, such mistakes cannot be repeated.

If we can quench agriculture's great thirst for freshwater globally, or certainly reduce how much it spills from its glass, then that will be a real step in the right direction for freshwater biodiversity.

Agricultural Expansion: Still a Cause for Concern

Recently I have been reading some interesting articles on global biodiversity scenarios for my ‘Global Environmental Change’ module (the module for which I started this blog). As I have been discussing fairly specific topics in my last few posts I thought this was a perfect opportunity to get my head out of the hives (see previous posts if you’re struggling with that pun…) and talk more generally about environmental change.

By now most of us realise that with environmental changes come changes to biodiversity levels. In a paper written by Henrique Pereira and his colleagues habitat loss is picked out as a key metric for biodiversity change, with land-use a dominant driver of change in terrestrial systems. Straight away my ears pricked up and the light bulb appeared over my head…agricultural expansion!

Agriculture is a key land-use across the globe, and throughout history it has expanded to enable growing world populations to meet their food production demands. Quantitative scenarios still hold the conversion of natural and semi-natural habitats into agricultural landscapes as a substantial contributor to future global biodiversity changes. As conversion can often lead to habitat loss and degradation it is hardly surprising agriculture plays such a large role in global environmental change.

Pereira and his colleagues highlighted conversion of forest to agricultural systems as the most important habitat change affecting global biodiversity levels, with particular losses occurring in the tropics. In the western world such conversions are no longer extensive, and are in fact in reverse due to overall gains in forest. However, these gains cannot directly compensate for forest losses in temperate regions in terms of biodiversity, as the forest habitats of the northern hemisphere support comparatively lower levels of biodiversity than those in tropical and subtropical regions. This is reflected in the fact that models of global biodiversity scenarios still suggest species declines in terrestrial systems.

Deforestation, to make space for agriculture, in Brazil (source: forestjustice.org)

One issue I am taking from this is that no matter what regulation changes are taken in the developed world to improve agricultural practices in terms of environmental sensitivity, or even those to restrict agricultural intensification and expansion, global biodiversity levels are still facing a future of decline. Agriculture is a global phenomenon, with global impacts, and hence any attempts to drive improvements in the health (and future) of the natural environment through changes to agriculture must be implemented on a global scale. This is where geopolitics becomes hugely relevant, but that is more the realm of a human geographer!

The World Continues to Buzz About Colony Collapses

Whilst doing some hunting around the topic of bee declines for my last post, I came across this (very) informal video that summarises what’s been going on in the world of bees and suggests what actions we need to be taking.

I think the main points to pick up on are:

• If bees disappear, a lot of our ecosystems will follow
• A loss of bees will not only have direct effects for crops we consume, but also knock-on effects for livestock industries
• The ban on neonicotinoids in the EU (commencing in December) isn’t likely to make a (significant) difference in reducing bee declines
• The loss of our bees is most likely a combination of a variety of factors, all contributing to their demise. Hence, multiple actions need to be taken

Hopefully any skeptics left out there after my last post will be convinced by this video!

Bee Aware!

I briefly mentioned in my last post that there has been a recent degradation of pollination services, which has severe consequences for agriculture in the future.  Bees are the greatest pollinating machines in agriculture, and without our little bumbling friends plants would be unable to reproduce and crop-bearing plants would not be sufficiently fertilised. Resulting from their pollination of 70% of the 90% of crops that the world population relies on for food, the commercial value of pollination services provided by bees has been estimated at as much as $153bn worldwide every year. In the UK alone, Friends of the Earth have estimated that bees are worth £510 million a year to the UK economy.

Bees are the ideal pollinator, with 'flower fidelity' making them incredibly efficient (Source: pdphoto.org)

Some of us may think that a decline in bees could be a blessing – we all know that anything that can sting isn’t welcome at a picnic – but the scientific and agricultural communities are expressing real concern over recent declines, with the 4 million colonies in the USA of the 1970s dropping to around 2.5 million today. Colony losses in Europe could have reached up to 35% between 2002 and 2010.

So, what’s caused this worrying decline?

Well, here lies another big issue…nobody really knows! The scientific community is yet to agree on a single coherent theory explaining current bee population trends, and this makes combatting the issue much more challenging. Agricultural intensification has been identified as a key cause of bee declines globally, and it is hard to argue against this being at the very least a significant contributing factor. Pesticides are toxic by design, leaving bees more vulnerable to disease and poor nutrition. Greenpeace have their own strong opinions, but not everyone shares such aggressive views against intensive farming. The National Farmers Union argues that the blame attributed to farmers and pesticide overuse is an unfair attack on the industry, failing to consider the good work farmers do to increase farmland biodiversity.

I am inclined to agree with Dr Chris Hartfield  – a leading NFU scientist on bee health – and say that this is a “multi-factorial” issue. A combination of habitat loss, pesticide use, fungal diseases, and mite infestations has contributed to such widespread losses. Moreover, climate change should be considered as a factor, as harsher winters and wetter springs in Europe reduce winter survival rates and suppress re-emergence in the spring.

Worker bees and honeycomb (Source: blogs.discovermagazine.com)

What can we do?

Agriculture has a key role to play in helping to reverse recent declines in bee populations. Measures taken to promote biodiversity on farmland and increase landscape diversity could provide new habitats for bee populations, and a conscious effort to avoid excessive chemical use could go some way to aiding bee recovery. We, the general public, can drive this process through increased consumer demand for ecological and organic farming products. So if we all start buying organic then maybe we can keep the world buzzing.