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Chat Meeting 1 (Kim's idea)
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My stream of consciousness:
What is the biological function of linear habitats in an agricultural setting? First, lets look at on farm. One can think of agricultural landscapes as anthropogenic surrogates for early successional habitat, at least in terms of structure (most crops are sun tolerant, or exist in the herb/shrub layer of a forest, etc.). If this is the case, what would make these areas more ‘natural’, i.e., more able to function like an early successional habitat (i.e. forest gap, post-disturbance, etc.)? Perhaps the most useful species to have nearby would be early successional species, i.e., bees and butterflies and (insectivorous) birds, etc. Species that are edge/scrub/grassland specialists; species that are comfortable foraging/hunting in open habitats. Perhaps this would be more useful than having forest or “climax” organisms nearby, i.e., these species would be more likely to contribute to the functioning of this ecosystem (pollination, predation/pest control, seed dispersal, etc.). And if these habitats are the kind to be most beneficial in terms of “on farm” benefits, what are the implications “off farm”? This will depend on the preponderance of this kind of habitat in the landscape.
Research question: To what extent do hedgerows, fencerows, live fences, ROWs approximate early successional habitats (in terms of species composition and presence of non-natives)? Compare by region/linear type (species comp/functional group in LH vs. species comp/functional group in region-specific early successional/scrub habitat)? How valuable is this kind of habitat in the landscape – look at % area covered by early successional habitat (not forest, not development, not agriculture) for each region. [In Eastern North American, there has been a great reduction in the amount of this habitat type, to the extent that scrub/early successional specialist species are in a well documented declines; but this may not be true elsewhere].
If the goal is to create “the most useful” habitat type in agricultural landscapes (if we decide to use natural scrub as our point of emulation), what recommendations can we make based on the information collected above (in terms of plantings or management)?
Do LH tend to be dominated (or easily invaded) by non-natives just as edge/early successional habitats are? If so, does it matter to the farmer? Does it matter to the surrounding landscape? Why or why not?
Data needed:
1) Species composition in linear habitats of all regions (Europe, North America [perhaps divided into East/Midwest/West?] and central/South America) and paired information on early successional/edge/scrub habitat in those regions (including mention of non-natives).
2) Landscape-level quantification of %early successional/scrub in representative areas in the regions above.
Division of labor (very rough):
Sergio & Adina: Live fence data from CATIE & literature on regional succession [from studies on slash & burn agriculture??]
Jonathan & Kim: focus on Northeast US/ROW industry literature & region-specific studies
Evan: research on what is out there in terms of quantification of habitat by region
Jennifer: Midwestern/prairie grassland, Farm Bill data (CCRP)
Daniel: horticulture/planting aspects. What are the issues involved in plantings (and management) in linear habitats – can we apply what we learn about early successional habitats to better inform what is planted in buffers;
Hi all,
It was great to talk with you all today, and start to get this show on the road! Please use the discussion board liberally to keep ideas moving over this next week or two, in particular. Following is my summary of today's chat. Feel free to add anything I may have missed in a post to the rest of the group.
Have a good week!
--> Our chat discussion on Feb. 26 was centered around Kim’s
proposal for our project. Please see the archives of the chat (Go to the main chat lobby, and then click the "Files, Transcripts, and Searches" tab at the top left, then scroll down until you see our group discussion) for the details
of that proposal. Essentially her idea is to research the extent to which
linear habitats are representative of early/earlier successional habitats in their
broader region, with the assumption that the flora and fauna of such habitats
will best provide the on-farm ecosystem services of pollination, pest control,
and the like (since farm fields are managed for early successional traits).
This has the advantage of applicability to a variety of different biomes,
including our potential data sets from the western, midwestern, and eastern U.S.,
several Central American countries, and Europe.
Otherwise it might be tougher to unify literature from such diverse systems as
hedgerows, live fences, grass waterways, and utility ROWs.
We then spent some time discussing a few other issues related
to the proposal, including:
1) invasive
spp: how their abundance in the LHs might compare to other ruderal habitats in
that region, whether or not their presence would have any detrimental effects
on farm ecosystem functions, and how the LH might act as a reservoir of exotic
species that could expose adjacent unmanaged lands to higher levels of
invasion. There’s still more that needs to be considered here, although it
seems that carefully defining ecosystem services we think the LHs should
promote would be crucial.
2) landscape
dynamics: this is a topic that kept popping up repeatedly, and probably one we’ll
need to keep checking back on. The types of questions we can ask, or at least
their general applicability, need to be constrained a bit by the varied
geography of the various regions, from nearly all land in managed fields (Iowa)
to areas with much more forest cover (eastern states, tropics?). As a result,
the dominant LHs in each area will vary greatly, including the potentially
important distinction between riparian and upland LHs.
3) ecosystem
services: this was discussed, particularly in terms of its link to species
composition (i.e.- if one sp. is particularly efficient at providing a service,
such as break up wind patterns, how important is it to have other species
present in that LH). Again, we’ll have to choose carefully here. Also had some
strong links to the invasive spp. question.
4) riparian
systems: a big question is whether or not to include riparian corridors. There’s
already a lot of literature on them, and it might be difficult to compare with
the more upland LHs. Thoughts?
We closed by discussing a few other ideas that could use
further consideration, namely the question of rare spp. conservation
(especially in intensively managed landscapes) and whether it might be useful
to select out only the most common LHs in each biome to work with.
Is there a lot of data out there that backs up the idea that early successional habitats provide more/better on farm services? Since this seems to be the basis of this whole proposal I think we need to get this clarified first.
Great point, Jenny; it does seem like that's a crucial question. A quick couple of searches on Web of Science ("succession pollination" and "succession pest control") didn't yield a whole lot of hits, although there's a number of interesting ones. Here are a few citations:
Management of field margins to maximize multiple ecological services
JOURNAL OF APPLIED ECOLOGY, 44 (1): 13-21 FEB 2007
Ockinger, E; Smith, HG
Semi-natural grasslands as population sources for pollinating insects in agricultural landscapes
JOURNAL OF APPLIED ECOLOGY, 44 (1): 50-59 FEB 2007- Marino, PC; Landis, DA; Hawkins, BA
Conserving
parasitold assemblages of North American pest Lepidoptera: Does
biological control by native parasitoids depend on landscape complexity?
BIOLOGICAL CONTROL, 37 (2): 173-185 MAY 2006
Carvell, C; Meek, WR; Pywell, RF; et al.
The response of foraging bumblebees to successional change in newly created arable field margins
BIOLOGICAL CONSERVATION, 118 (3): 327-339 JUL 2004
CORBET, SA
INSECTS, PLANTS AND SUCCESSION - ADVANTAGES OF LONG-TERM SET-ASIDE
AGRICULTURE ECOSYSTEMS & ENVIRONMENT, 53 (3): 201-217 MAY 1995
The fact that there aren't a ton of studies explicitly addressing the connection might be a good thing in the sense of indicating a potential gap in the literature. After all, we have several good a priori reasons to think that the relationship should hold. First, active fields are much closer to early successional grasslands than those grasslands are to forests (a wealth of literature on biometrics of succession backs this), and second, a lot of other literature indicates that later successional fauna are often reluctant to enter or use open areas like farm fields, so it's unlikely that they'll be major providers of services like pollination.
Thoughts?
I'm in the process of soliciting some thoughts from the other DGS faculty regarding the validity of the early succession/agricultural landscape link (since Jenny is right that we need to make sure this a useful central idea). I'll let you know what I hear, but also this is something that those of you with more experience working directly in agroecosystems can chime in on as well.
I had a chat with Jonathon this morning and it got me thinking about situation in the midwestern US, an area I am not particularly familiar with. After reading a few more papers on filter strips in this region (thanks, Jenny!) I realized that my perception of what I've been referring to as "riparian buffers" is a bit off the mark. I was thinking of them as mostly areas of remnant natural habitat left uncleared around streams. Whereas based on the papers concerning these buffers in the midwest, many (most?) are actually planted and managed. This makes them less disjunct from the other kinds of linear habitats than I had originally thought. Yes, they are confined to waterways and their position in the landscape is determined/restricted by this, but especially in the midwest, they are THE most important/relevant linear habitats. So I'm thinking now that if we want to do regional comparisons, we will need to include these, at the very least in their midwestern form (CCRP). I'll post the papers that Jenna sent me in the readings folder (I'm still working on uploading some other literature there as well). Of course, everything is still up for discussion, but I thought I'd update my own personal thinking on this.
Finally, I don't feel that I've done a very good job in terms of explaining the way I see ROWs fitting in to this. And as I have admitted, perhaps they don't. But I've put them on the table because they represent (in the Eastern US and Europe and perhaps elsewhere) some examples of extraordinarily successfull management of a linear habitat in terms of providing resources and habitat for wildlife species. What can we learn from these successes that can be applied to linear habitats in agricultural systems? It's like a gigantic experiment (millions of hectares), the data from which no one has sufficiently analyzed. Worth considering, but in no way obligatory!
Finally, I don't want this to be a top-down sort of project, so PLEASE post your ideas/modifications/critiques, etc. They will be taken seriously and are more than welcome....