Tit for tat on habitat

As we make our way on planet earth these days more and more pressure is exerted on the resources we use. Farming is a major resource consuming activity and frequently lands in the sights of ecologists and conservationists motivated to preserve and protect resources both for our own future and for the present and future wellbeing of earth’s other inhabitants.

Conversations around biodiversity and habitat loss push back and forth depending on one’s value proposition for wildlife, air and water quality, soil conservation, food security, and a host of other concerns where planetary resources are used or consumed for our benefit.

In a recent comment exchange at Jeff Ollerton’s fine blog on biodiversity there was a smallish difference of opinion over farming and habitat loss, wherein Jeff pointed to “loss of habitat due to more intensive farming” (in the UK) as a major reason for pollinator losses. Quibbler that I am I wondered whether he actually meant ‘intensive’ or rather ‘extensive’. And I also wanted to take a more nuanced approach to habitat change… suggesting that even more extensive agriculture use of the landscape is not necessarily habitat loss but more habitat conversion or change.

Loss vs. Modification

I may be off base here, but if one blows the top off a mountain and then strip mines the exposed coal seam… this is habitat loss. If one plants a grass crop such as corn in one season and then plants a legume crop such as soybean in a following season the habitat does change – but only for some members of the ecosystem. All sorts of critters great and small can still take advantage of resources in such and agricultural system. Indeed the success of the system is often very dependent upon how friendly the system is to the non-crop biodiversity. Further, a properly husbanded agricultural field is very easily converted to other biodiverse habitats. Forest restoration will naturally take a longer time than a mixed species meadow, but compared to our topless mountain or tearing up a parking lot… not so much.

Intensive vs. Extensive

Agricultural landscape use comes in many flavors, but let’s focus on intensification vs. expansion. Cutting down a forest to plant crops is an expansion, it is extending the footprint… it is extensive. Choosing and implementing a higher yielding form of agriculture (more food from the same space) is intensive. If the goal is to produce a given yield of crop then an intensive strategy can spare other land to remain wild or perhaps even be converted to other use. Conversations around ‘land sparing’ and ‘land sharing’ come down in this venue (more on this later). Where the conservation conversation often goes sideways is when intensive landscape use is expanded. Here the goal is even greater food production, a fine objective, but the goalpost has been moved. We’re no longer comparing one to the other… we’re using both. It hardly seems appropriate to blame a good land use for our overblown appetites.

Sparing vs. Sharing

Joern Fischer’s Ideas for Sustainability Blog has an interesting piece on this. In the comments there a point is made about landscape aspects and the relative value of lands being spared or shared. An excellent point too, but let’s backup a touch and define these terms. Land sparing occurs when sufficient food is produced on a given plot such that no further expansion onto unfarmed space is required. Land sharing occurs when the plot of land under consideration is farmed in a manner that mixes uses on a finer scale. Instead of a square mile block of all corn the square mile block would be broken up with hedge rows and/or other features that allow cover (habitat) for critters less likely to inhabit the corn monoculture (or a corn/soybean rotation). A common feature of agricultural landscapes here where slopes will affect water movement are grass waterways. A grass waterway is typically a permanent feature and offers different habitat, but because of its landscape position it is not equally productive or comparable to adjacent land for which it might be compared in sparing/sharing discussion. Perhaps a finer distinction… but appreciating that our agricultural footprint is gargantuan does tend to make even fine distinctions worth some trouble.

In-situ vs Ex-situ

Conserving biodiversity has to occur over time as well as space. Land sparing and sharing are frequently considered on a space dimension and if time is considered at all it is typically on a relatively short frame. I mentioned forest restoration above. Let’s consider the recovery from a burn for a second. Outside our agricultural use there are ‘natural’ ecosystems that experience severe perturbation without any participation on our part. Is a forest fire a case of habitat loss? Depends upon your definitions and value propositions. Native prairie depended upon fire for protection against encroachment of timber species. The biodiversity maintained within ecosystems disturbed by such extreme perturbation evolved to tolerate the same. Conserving biodiversity on this type of landscape is more problematic than mere sharing and/or sparing. But let’s get our definitions in place: In-situ is ‘in place’; Ex-situ is ‘out of place’. A museum specimen or a zoo is ex-situ, a wildlife park or protected wilderness area is in-situ. A plant germplasm collection is analogous to a zoo. Less space is needed and professional attention can be brought to bear for preserving diversity in a collection or a zoo. But the continuing forces of evolution are not experienced within the controlled environment of the collection or zoo. Interactions with commensals are very difficult to maintain in artificial environments as well.

However we wish to participate with our fellow travelers on this planet it will serve us well to consider the available options carefully. And the language we choose to employ in the conversation will be critical.

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I have to add here that on a recent trip trough Chicago on the EL the Bucket observed the Art Institute out the window as we rushed by.  He had to mention in too loud a whisper: “Now museum, now you don’t”.

Tags: agricultural intensification, biodiversity, conservation, corn, Mother Nature, resource allocation, soybean