The most devastating impact on biodiversity is caused by agriculture. Farming is already the greatest extinction threat to birds, and its adverse impacts look set to increase, especially in developing countries (Green et al. 2005).
Thus one of the global challenges for the next century is the need to develop high-yielding varieties that require minimal inputs, so that impacts on biodiversity can be minimized.
An alternative to the "high-input" approach is to expand the number of organic
farms. Because organic farmers do not use synthetic pesticides, their farms support
higher levels of biodiversity than conventional farms. Some organic farms can yield as much, for some crops, as conventional agriculture (Reganold et al. 2001; Maeder et al., 2002), although in some cases the yields of organic cropping systems is considerably lower than that of conventional or integrated cropping systems (Bruulsema TW et al. 2003;
Maeder et al., 2002)
In cases of low yield, organic practices would require more land be farmed to maintain and increase output levels, thus potentially leading to reduced overall biodiversity. What is the net effect on wildlife when the land being converted to wildlife-friendly farming has a lower yield, and so more land, somewhere, must be farmed to provide the same harvest?
A new study this week published in Ecology Letters seeks to answer this question. The research indicates that when the organic yield per hectare falls below 87% of conventional yield, wildlife does not benefit.
The researchers surveyed Sixteen 10 Ã 10 km landscapes in the Central South West and North Midlands of England. Within each landscape they surveyed one organic farm, one conventional farm, and one grassland SSSI (Site of Special Scientific Interest: a UK conservation designation). They then counted butterflies in each area.
A few of the butterflies surveyed are shown here:
Thymelicus syvestris, Ochlodes venata, Erynnis tages, and Pieris napi (my favorite).
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They found that, for the type of fields and farms investigated, organic farms support a higher density of butterflies than conventional farms, but a lower density than grassland reserves. Organic farms support more butterflies than conventional farms, so if there were no difference in yield it would always be better to farm organically. However, the lower the organic:conventional yield ratio, the more advantageous an alternative land sparing strategy would be.
What this means is that even if we convert ALL of agriculture to organic farms (now only ca. 2% in the United States), we still need to increase yield on these farms if we want to spare land and protect wildlife. The study also suggests that if our goal is a sustainable farming system, we may not be investing wisely. The authors indicate that in the UK alone, £435 m was spent on agri-environment schemes in 2008, as compared to a budget for all other nature conservation of c.£80 m. More interdisciplinary research is urgently needed on how the net benefits of different farming methods compare, so that agricultural policy can be as environmentally sustainable as possible. And, as readers of this blog will not be surprised to hear me say, we need to use the most effective modern genetic methods to increase crop yields on ecologically managed farms.
Hat tip to Stephen Daubert, author of "Threads in the Web of LIfe" for alerting me to this paper.
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But land not used for agriculture, except in areas of natural prairie, doesn't actually convert to grassland reserve in any natural sequence. What it converts to is forested land - I'm not clear on what the advantage of comparing grassland reserves is, since agricultural land is unlikely in the US, at least, to revert to such land use.
Sharon
I only saw the abstract, but I suspect that they used butterflies because they are easier to survey and they are using butterflies as marker species to represent the whole of biodiversity (which would be too difficult to measure).
Completely wild land is much more diverse than any type of farmed land. Comparing diversity of organisms that can fly (birds and butterflies) doesn't count the majority of organisms that can't, plants, other insects, invertebrates, mammals, amphibians, etc. I appreciate that those species are not as charismatic as butterflies and birds, but they are important.
I understand the first calculation, that if organic yields are 87% of conventional yields that conventional farming 87 hectares and 13 hectares of nature reserves yields butterfly populations equivalent to 100 hectares of organic farming.
I am not sure I understand the second calculation. Are they saying that if organic yields are 35% of conventional, then 35 hectares of conventional farming and 65 hectares of field margins are equivalent to 100 hectares of organic farming? I think what that says is that nature reserves are five times better (13 hectares vs 65 hectares) than field margins. I think that shows just how degraded any kind of agricultural land is, even field margins.
So it isn't organic farming techniques, per se, that result in lowered butterfly diversity, it's anything that reduces yield resulting in more land needing to be placed under production. Hence, the title of this blog post is misleading.
Sharon, the reason that abandoned farmland in the American Midwest doesn't revert to grassland is because of fire suppression. Historically, prairie fires, either naturally ignited by lightning or intentionally set by settlers or Native Americans, killed saplings while leaving the roots of perennial grasses unscathed. If fires were allowed to burn abandoned farmland would indeed revert to grassland across the Midwest.
The post did not seem misleading at all. If the organic industry increases, more land will be needed for farming. That will result in a decrease in biodiversity.
Simple math, less human numbers intruding and mutating the environment = natural diversity balance and cycles. Avoid the Stork!
Actually, in the UK, there's a good chance it'll convert to housing... I'm really not convinced that using SSSIs as the baseline is valid. Even if the land in question isn't developed or used for other purposes, it is extremely unlikely to end up as grassland SSSI.
DD, I know that - my point is that at least one of the comparisons in the study seems pointless - the implication is that you'd get more butterflies if you weren't farming the land at all. But if you don't compare the number of butterflies *on the kind of land that follows the abandonment of farmland* then you don't actually know if that's true. Even scrub forests tend to support more life than farmed fields, although it isn't necessarily clear to me that they support more *butterflies.* This strikes me as a methodological problem, if you are using butterflies to stand in for other species, or even if you aren't.
Sharon
SSSIs are typically declared because they're already biodiversity hotspots, or are home to some endangered species... They are, pretty much by definition, small enclaves of unique habitat, and they're also actively managed to maintain and increase that uniqueness.
I'd be interested to see exactly which SSSIs they were using, and the reasons they were originally declared.
Do they talk about the pesticides used on the organic farms? We know that some organic pesticides have lots of off-target effects and might actually be worse than conventional in some ways:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0011…
That would have to impact this data as well. To assume organic = pesticide-free would be incorrect.
My conclusion was that we need to work to increase the yields of the land, quite possibly with more intensive human labour, and also to reduce monoculture expanses that reduce habitats. In either organic or conventional systems, extensive, low-labour-input monocultures are a woefully inefficient way of getting food off acres.
#4:
I didn't say that the post seemed misleading, Mike. I said that the title seemed misleading. It seemed to imply that there was something intrinsic to organic agriculture that reduced butterfly diversity when the text of the post made clear that it was anything that reduced agricultural productivity, and thereby necessitated more land being brought under production, that reduced diversity. If organic agriculture increased yield, as it sometimes can, then butterfly diversity ought to increase accordingly. The title would have been more apt had it read something like "Underproductive Farms Not Always Best for Butterflies."
"Simple math, less human numbers intruding and mutating the environment = natural diversity balance and cycles. Avoid the Stork!"
*Yawn!* Yes, yes, pop those contraceptives! Then promptly piss them down the drain and mess up the bio-diversity of the fish in the streams a la Colorado.
The thing that creeps me out the most is the call for genetically engineering the crops. Yes, we can help nature by messing around with it.
Perhaps we should just let nature be nature, becuase nature takes pretty good care of itself.
@ Christopher Milton
So, for clarity, what exactly are you suggesting when you say "we should just let nature be nature"?
We are already producing more than enough food to feed the world - it's just a matter of distribution. "Less efficient" farming won't ruin that by any means, so arguing that we'd have to farm more land if everybody went organic is false, or at least misguided.
Essentially, an experimental validation of the Borlaug hypothesis (essentially, that one of the best things you can do to help the environment is make farming more efficient, so that less land is used for it). Interesting.
Jammin @14: Yeah, there's enough food produced to feed the world (and our production *capacity* is even higher); world hunger isn't caused by lack of food. Still, if we could grow the same amount of food on half the land, that would spare
This is why I think the objection to GMO crops by some environmental groups is a bad idea. Once that becomes a mature technology, a few decades down the road ... the sky's the limit.
Sharon @1, 7: Yeah, that's another issue; habitats in many places don't actually revert to their natural state due to fire suppression, invasive species etc. It would be an interesting follow-up study to determine if an organic farm has more native grassland species than abandoned land covered in Chinese tallow and the like; it might well.
The study only looked a grain yield - a rather simplistic view.
1. There is also straw as an important yield by-product. Straw grain rations (HI harvest index in technical terms) are different in organic versus conventional farming systems. Conventional farmers use chemicals (CCC) to artificially shorten cereals as they would fall down (lodge) under the heavy nitrogen fertilisation dosage they also get.
In organic farming taller plants are desirable because it helps cereals to compete with beneficial weeds and other plant biodiversity on the field (remember no weed-killers allowed to eradicate all of it). Straw is also a valuable product to sell and it doesn't matter if it contains some weeds. Therefore more yield is in straw rather then grain but lower grain yields are no problem for overall profitability.
2. In addition, organic farmer under-sow their cereals with clover (usually white clover because grows very low). This also competes with water and nutrients to a certain extent and lowers the grain yield, however the same field once harvested has then already a good crop ready to go and use the fertilisers which in conventional production is often lost to the groundwater (pollution with nitrate and phosphate).
In conclusion organic attempts a holistic approach producing not only grain yield rather straw, clover green manure and colourful weed plants (more then some organic farmers aim for) for butterfly and insects biodiversity. They are all plant biomass and non of it is lost to the system.
Comparing organic and conventional only on grain yield is possible however rather simplistic as intensity also comes with other negative impacts (leaching to groundwater, pesticide accumulation, chemicals to artificially shorten plants let alone the fossil fuel energy embedded in those high inputs).
This article is grasping for straws.
First of all, to lable industrial agriculture as "conventional agriculture" is misleading considering we have only used industrial methods for three quarters of a century. Second, its is entirely inaccurate to reduce the situation to a simple equation of Organic= reduced production= more land= less biodiversity. Because the destruction to biodiversity that industrial agriculture inflicts far exceeds the amount of land it uses. Industrial agriculture puts herbicides and pesticides into our soil and water, killing micro organisms and stripping the soil of life system that creates nutrients for plants. Therefore requiring industrial fertilizers which leaches into the water table and threatens our water supply. Also industrial agriculture only uses land for one purpose at a time, therefore using more land than organic or permaculture farms which create an agriculture system of multiple layered production relationships and build biodiversity, especially for micro-organisms and insects.(note that I am not talking about industrial organic systems)
I realize this article is not attacking the methods of organic production but it is also not taking them into account. This article is focused on biodiversity but then reduces its measure to amount of land used to construct a "simple math equation" that is just plane false and aimed at convincing the uneducated.
Essentially, an experimental validation of the Borlaug hypothesis (essentially, that one of the best things you can do to help the environment is make farming more efficient, so that less land is used for it). Interesting.
Posts #16 & #17: Perhaps so but the issues you address are beyond the scope of this study. It's unreasonable to criticize a study over issues it was not designed to explore.
I wonder how much money the author receives in grants, lab equipment, etc, from the GM community?
foodfreedom.wordpress.com/2010/07/18/new-study-gm-wheat-yields-48-56-percent-less-in-field-experiments/
New study: GM wheat yields 48-56 percent less in field experiments
A new study out of Switzerland reveals that the performance of GM crops in the glasshouse differed significantly from their performance in the fields. GM field plants had significantly fewer seeds and lower yield than control plants, and were more susceptible to infestation, summarizes Devinder Sharma.
Better link for comment #20 is
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011405
which links to the actual article rather than just commentary on the article.
It's not overly surprising to see a GM variety perform poorly in the field compared to conventional - this happens all the time - one of the big challenges in agronomic traits is to get events with efficacy (in the case of the wheat experiment efficacy = mildew resistance, which they apparently got in spades) and yield parity (which the greenhouse suggests should be the case, but which the field trials suggest probably isn't the case) - you categorically cannot take the yield results of one GMO and apply this across all GMOs (just as you can't take any set of data for GMOs and apply it across all GMOs - a case by case basis is required) - I have a feeling that this finding illustrates another issue with public funded research producing viable GM lines - not only is the regulatory hurdle massive, but in order to demonstrate yield parity large scale trials are an absolute necessity (I can't go into detail on the size of trials industry uses, but suffice to say the trial size in the paper is absolutely pitiful by the standards I am used to)
The paper shows a single location (ouch) 4 rep (not bad for 1 location, but not awesome) relatively small plot (1mx1m) field experiment which was vandalized (which to me suggests the data isn't that viable - the paper argues otherwise however) - also they claim to have repeated the experiment the enxt year sans damage - which if this is the case why use the data from a bad year?
(sorry for messy formatting - Pam's twitter box is in the way! Bad twitter box!)
is the final line from the conclusion of the report - this paints an inaccurate picture of selection of transgenics in industry - multi location multi rep field trials categorically are what is utilized at the proof of concept level for literally hundreds of genes - other supporting data is also gathered, but it is acknowledged in the industry (at least in Monsanto - I think Pioneer is more heavily invested in greenhouse results in their fast growing corn, although this is possibly just a rumour) that without powerful multi-loc multi-rep (and preferably multi-year) data that advancement of any gene or set of genes quite frankly doesn't make sense commercially (whereas academically the issues of non-yield parity are something that you'd want to deal with later on after you prove efficacy of the trait in question - which apparently was a resounding success in all cases for the wheat in question)
Anyway, that's my bit on that... apologies for continuing to take the discussion completely off track - that's what happens when an interesting article is cited I guess
Piney @#17
Yes, conventional farming (called "conventional" not because it has been used the most throughout history, but because it is the convention in 2010) releases a lot of nasty pesticides and herbicides. Guess what, organic farms also use them, they just use "natural" poisons. For example, look up rotenone.
The paper shows a single location (ouch) 4 rep (not bad for 1 location, but not awesome) relatively small plot (1mx1m) field experiment which was vandalized (which to me suggests the data isn't that viable - the paper argues otherwise however) - also they claim to have repeated the experiment the enxt year sans damage - which if this is the case why use the data from a bad year?
I totaly agree to expand the number of organic farms, but are people willing to pay the price?