DIY and Newbuild Homes - Urban Wildlife's worst nightmare

Urban wildlife has taken a bit of a bashing in recent years. One of my favourite species is the House Sparrow, in the mid 20th century every street in every town in Britain would have a chirpy little flock of these fellas. They are incredibly social birds and have a great character, like little Jack Russell's with wings and beaks!

A House Sparrow on the roof of my garage in Penge, South East London

But since 1967 their numbers have declined by 67%. Ornithologists from the BTO have suggested a couple of reasons for this. Firstly lots of gardens in towns have been either decked, paved, graveled or had a whopping great big trampoline put in them, lawns are obsessively mown and weeds removed with impunity. This removes both habitat for nesting and also a source of seeds and insects. Secondly modern homes don't have the little nooks and crannies that older homes have in abundance, again another important source of nesting habitat for the House Sparrow. The combination of both of these factors is what has silenced that happy little 'churp' from our streets. I am fortunate; I live in the Alexandra Cottages in Penge. These are a series of terraced social housing streets constructed as a bit of a social experiment in the early 19th Century, There are tons of little hidy holes for the sparrows to flit about in, trees and a mature hedge. Consequently there is a relatively large population here.

However conservation of species, particularly in urban settings, is about doing your little bit to help. If we all did so then many of our species (the Hedgehog anyone?) would be in much better shape than they currently are. With that in mind this Spring and Summer I have engaged in a little rewilding project of my own! Braving the passive aggressive distaste of the Alexandra residents association I have left my lawn unmown and my borders relatively weedy. Immediately I noticed more bees, bugs and ants in the garden. I have had a feeder up for the birds for a while but I now also see them feeding in my 'meadow'. A Lapwing will land soon, just you see.

My wildflower meadow, just one of the mosaic of habitats present in the Penge Nature Reserve

There is a little ecosystem in my yard and front garden which is really thriving. The House Sparrows feed from my feeder and lawn, Wood Pigeons and Collared Doves mop up after them and Blue Tits and Goldfinches, although not brash enough to visit my feeder which is very close to the back door, flit among the trees and border picking off insects. I have Blackbirds on my roof and in my garden and even a little mouse (that Inna and I have dubbed Charlie) picks up the husks and bits the birds don't want.  One of the most spectacular sights are the Swifts, feeding hundreds of feet above the houses in long graceful flights. These are the Spitfires of the bird world and are another species that is struggling due to the modernisation of our homes. Although I have no way of knowing it I like to think that some of the insects they are feeding on up there were hatched in my weedy border and long grass!

Penge national nature reserve, free to visit but please leave a donation.

Contributions of sheep farming to the Welsh Economy

If I were to sum up my previous post in a sentence it would be this:

The practice of maintaining large areas of agricultural landscape in Europe through subsidies is misguided. It has lead to the ruin of ecosystems and a warped public view of what the countryside should look like. Rewilding and a return to a more natural state would benefit everyone.

A couple of statistics I have just read in Monbiot (2013) add weight to this assertion; according to the UK national ecosystem assessment farming in Wales contributes £400 million a year to the national economy.  Walking contributes £500 million and wildlife based activity* £1'900 million. 

*includes conservation, wildlife tourism, academic and commercial research and other jobs that would not exist were it not for wildlife.

References

Monbiot, G. (2013) "Feral, rewilding the land, seas and human life". Penguin. London. pp-160

Rewilding in Europe: Lessons for the UK?

The decline of wilderness

Deforestation is an environmental concept that every secondary school student is familiar with. Many scenarios project continuing deforestation in tropical ecosystems however the situation in Europe is in fact the opposite, Pereira et al. (2010). The amount of forest and scrub land in Europe is now increasing.

Before deforestation the pre-neolithic landscape of Europe was a mosaic of forest, grasslands and scrub maintained by herbivorous mega fauna and forest fires. Then Homo sapiens got involved. The rise of classical civilizations accelerated early clearings and this continued into the Middle Ages, with an estimated 50-70% of cover lost in this time-frame, Navarro and Pereira, (2012). During this time species abundance, diversity and range were all significantly reduced. The mosaic of wilderness was replaced with an urbanized, managed, agricultural landscape. However once this stage had been reached, European landscapes have continued to change.

The decline of agriculture

Traditional agricultural landscapes are significant in European environmental policy. The European Habitats Directive lists 231 habitat types, 41 of which are associated with low intensity agricultural management e.g. hay meadows, Halada et al. (2011). However since the mid 20th century the agricultural landscape of Europe has been in flux. Since 1961 there has been a 17% reduction in the rural population of Europe and the number of livestock declined by 25% between 1990 and 2010.

Marginal agricultural areas have been subject to a spiral of decline throughout the 20th century and arguably longer. Land of low productivity, competition from foreign markets and better opportunities in urban areas cause depopulation. With this comes a dereliction of services and ultimately deprivation. As long as the young continue to migrate to cities the populations of marginal agricultural areas will continue to age and decline, Keenleyside and Tucker, (2010).

European policy has been to try and maintain these landscapes and reverse or halt the decline in population through subsidies. The common agricultural policy designates these marginal areas as 'less favourable areas' (LFAs). In 1975 33% of agricultural land in the EU was categorised as an LFA. In 2005 this had increased to 50%. 12.6 billion euros of payments were made to farmers in LFAs between 2007-2013, propping up an unprofitable industry with the goal of maintaining the cultural landscape. The question I wish to address is could this money be better spent?

Rewilding, an alternative...

Rewilding is the passive management of ecological succession. Succession on abandoned farmland will lead to scrub and in most cases, when left long enough, woodland. The map below is from Navarro and Pereira (2012) and shows the hotspots of abandonment and rewilding (areas that are projected to rewild or become aforested by 2030). A saddening lack of green on the UK.

But what are the benefits of rewilding and can the significant challenges be overcome? As discussed in a previous post one argument against rewilding is based on the IDH, however I feel that this hypothesis is flawed and empirical evidence supports this view. There is also significant opposition from farmers who worry about predation of their livestock by large carnivores, between 1992 and 1998 an average 2 million euros a year was spent compensating farmers. This figure will be higher now and will likely increase as more areas rewild. Also since the 1960s the abundance and distribution of large European carnivores has increased, Enserink and Vogel (2006), good news for some but not all.

I think the best argument for rewilding and the best chance of convincing sceptics is based on considering the ecosystem services such a process will provide. The supporting service of biodiversity will increase, allowing for a range of benefits in regulating and cultural services. I have already highlighted the increase in large carnivores but re-vegetation also increases soil moisture and biomass content increasing the numbers of worms and insects. This has positive impacts on bird abundance and diversity, Russo (2006). Carbon sequestration is provided by the increase in vegetation helping mitigate climate change and soil nutrients are restored. Re-vegetated land provides better protection against flooding and the reintroduction of keystone species has ecosystem wide benefits (see the example of the wolf here).

The rewilded landscapes will provide opportunities for recreation and tourism, reinvigorating deprived areas and providing sustainable, meaningful employment. I am convinced as a species we have lost our fundamental connection to, and appreciation of, nature and believe that the restoration of large areas to 'wild' land will go a long way to reconnecting us. Also because rewilding is so passive, once the initial recovery has begun, the tangible and more spiritual benefits can be attained for limited levels of investment.

The UK is a crowded little island and rewilding on the scale expected in parts of Europe will never be realistic, but it should seriously be considered for large parts of our landscape. Imagine a return of the Caledonian forest across huge areas of the Highlands or Oak and mixed woodland carpeting the moors and heaths of South West England and the North. I wholeheartedly believe our country would be a better place for it.

References

Enserink, M. and Vogel, G. (2006) "The carnivore comeback." Science. 314: 746-749

Halada, L. Evans, D. Romao, C. and Petersen, J-E. (2011) "Which habitats of European importance depend on agricultural practices?". Biodiversity and Conservation. 20 (11): 2365-78.

Keenleyside C. and Tucker G. (2010) "Farmland abandonment in the EU: an assessment of trends and prospects. London. WWF and IEEP. 97pp.

Navarro, L. and Pereira, M. (2012) "Rewilding Abandoned Landscapes in Europe". Ecosystems. 15 900-912

Pereira, HM., Leadley, PW., Proenca, V., Alkemade, R., Scharlemann, JPW., Fernandez-Manjarres, FP., Araujo, MB., Balvanera, P., Biggs, R., Cheung, WWL., Chini, L., Cooper, HD., Gilman, E., Guenette, S., Hurtt GC., Huntingdon, HP., Mace, GM., Oberdorff, T., Revenga, C., Rodrigues, P., Scholes, R., Sumaila, UR. and Walpole, M. (2010) "Scenarios for global biodiversity in the 21st century" Science. 330 1496-501. 

Russo, D. (2006) "Effects of land abandonment on animal species in Europe: conservation and management implications" Integrated assessment of vulnerable ecosystems under global change in the EU. Project report.

The Intermediate Disturbance Hypothesis (IDH)

I have made a start on some reading ahead of starting my MSc in September. I am interested in rewilding as an approach to conservation ecology. A paradigm I am currently exploring is the potential for rewilding to successfully manage abandoned farmland in Europe (blog to follow soon) and a concept that crops up in this reading is the intermediate disturbance hypothesis (IDH). I felt this interesting concept deserved its own post to discuss it ahead of a longer post on rewilding in Europe to follow.

Policy makers and researchers who argue that rewilding will have negative impacts on biodiversity cite the IDH in support of their arguments, Navarro and Pereira, (2012). The theory states that biological diversity is highest in extensively managed ecosystems where disturbance factors are moderate, Wilkinson (1999).

Essentially ecosystems are prevented from reaching communities at both ends of their succession scale (plagioclimax) therefore limiting interspecific competition and promoting biodiversity. The organisms that outcompete at the start and end of succession; pioneers and climax species, cannot dominate the system so diversity is higher. Ecologists who have supported IDH and carried out empirical tests predicted a humped relationship between species diversity and disturbance factors (Figure 1). In some studies such a relationship was indeed observed.

Figure 1 - Humped relationship between diversity and disturbance

However there is criticism of IDH. Fox (2013) states that in the vast majority of empirical cases the relationship predicted in figure 1 is not observed. It is argued that abundance of species will be impacted by moderate disturbance but not the mechanisms of interaction between species. If anything the levels of competition required between species in order to impact their populations will be reduced as a result of smaller populations and less genetic diversity, ultimately impacting communities capacity to adapt.


References

Fox, J. (2013) "The intermediate disturbance hypothesis should be abandoned". Trends in Ecology & Evolution. 28 (2) 86-92

Navarro, L. and Pereira, M. (2012) "Rewilding Abandoned Landscapes in Europe". Ecosystems. 15 900-912

Wilkinson, DM. (1999) "The disturbing history of intermediate disturbance". Oikos. 84 145-147.