Bog spiders: a serendipitous research project

This is a guest post, written by an Honour’s undergrad student in the lab, Kamil Chatila-Amos. It’s the first of two posts about his work, and the goal of this post is to introduce Kamil and his research project. 

Research can be serendipitous and spontaneous, and that’s certainly the story of how my honour’s project started! I spent last winter working on howler monkeys in Panama (which is a story in itself) and although I adored every second of it, it certainly made me out of touch with the McGill world. When I came back, most of my friends had found themselves a summer research job and even an honours supervisor for the upcoming semester.

So there I was, barely a week after my return, erratically filling out online job applications in the lobby of one of our buildings. I was looking at all kinds of opportunities: herbarium employee in Edmonton, ichthyology assistant in Wisconsin, plant surveying in Vaudreuil, bird surveys in Ontario, insectarium employee in Montreal. I was applying to anything and everything that was still available. Little did I know that the arthropod ecology lab is right next to the lobby… Chris walked by, saw me and stopped to chat. (Well it’s more accurate to say he talked to me while quickly walking to his next meeting)*. Turns out, a student of Terry Wheeler (another entomology Prof. at Macdonald campus), Amélie Grégoire Taillefer, was going to post a job online that very afternoon! She was looking for a field assistant to help her catch flies in bogs in the James Bay area.

A couple days later I was northern-bound! A 15 hour drive north of Montreal is the town of Matagami and about 30 km north of there is Lake Matagami, along which we were staying. In a yurt. A yurt!!! Basically, a large round tent of Mongolian origins. They’re big and this one had a minimal kitchen and shower. But the fact remains that it’s a tent with the isolative properties of canvas. It got pretty cold those first couple weeks and dropped below freezing a few nights. At least it had a fireplace. (It’s actually a great place for people wanting to explore that area of Québec and the owners are wonderful. Go check them out at ecogiteslacmatagami.ca)

Kamil_Yurt

The work itself was great. The first week, we explored the area for suitable bogs to install her pantraps. That’s when I realized how awesome bogs are. There are so many things to eat in bogs! Cattails, cranberries, Labrador tea, cloud berries, chanterelles, boletes, black flies…

For the remainder of the trip two days a week were spent visiting our five sites and harvesting the pantraps filled with flies, dragonflies, crickets, spiders and the occasional putrid mouse. The following two or three days we would sort through the samples, separating the lower flies (Nematocera) from the rest.

Kamil_Sweeping.jpg

Ready for some serious bog-sweeping.

After the first week I couldn’t help but notice just how many spiders we were catching. Mostly out of pity I think, I decided to sort out the spiders as well. I felt bad throwing them out… Fast forward to five weeks later and I’m heading back to Montreal with a bagful of vials filled with dead spiders. (My roommates were not very fond of having them in our freezer).

A few weeks later I set up a meeting with Chris and essentially barged into his office with the spiders to ask to work in his lab. It took a while (and quite a bit of convincing) but here I am, sorting through spiders and writing blog posts!

The research project we structured has two components. The first part will look at how the community composition of spiders varies between the five sampled bogs. Second, I’m lucky enough to have the opportunity to try DNA barcoding using COI markers. This part remains very blurry right now**, but I’m very excited to see where it leads.

Kamil_Microscope

Kamil hard at work in the lab!

If it weren’t for serendipity I would not have gone to James Bay this summer. And if it weren’t for being spontaneous, I would not have sorted out the spiders and would not be working in Chris’ lab right now. But spontaneity does have its down sides. I didn’t plan far enough ahead** and in hindsight, I should have collected some insect orders to be able to do a more in depth ecological analysis.

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* um, yes, I spend a LOT of time in meetings, and often have discussions and chats with student on my way to and from those meetings!

** for what it’s worth, research is often blurry, and planning ahead isn’t always possible!

Summer in the trees: Undergrad research on canopy spiders and beetles

Note: this post is written by undergraduate Honour’s student Jessica Turgeon, who is a member of the arthropod ecology laboratory. This post is part of the requirements for her project, and is an introduction to her research.

I’ve always been interested in nature and the environment but was never a big fan of insects. As time went on and I learned to appreciate all organisms big and small I realized that I didn’t really have a preferred “pet taxon” but rather was interested in ecology and community structure. I found others that my interests were shared with other members of the arthropod ecology lab, and I was able to start an Honour’s project in the lab earlier this fall.

Using a beat-sheet in the tree canopy, to collect arthropods

Using a beat-sheet in the tree canopy, to collect arthropods

I was given an opportunity to do an internship at Kenauk Nature, a 65,000-acre plot of land near Montebello, Quebec. This property is primarily used for the hunting and fishing industries, but they are branching into scientific research. Kenauk was keen to support three McGill interns to complete the Black Maple project, the pilot project for Kenauk Institute.

The Black Maple project revolves around black maples, since Kenauk is the only area in Quebec to have a black maple stand. The project consisted of three sub-projects, one for each intern and each project dealing with a different taxon. While the two other students worked on plants and birds, my project was about arthropods and their diversity in Kenauk. We wanted to characterise the community structures of beetles and spiders based on vertical stratification and tree species: this involved tree-climbing!

Jessica - getting ready to climb up!

Jessica – getting ready to climb up!

During the summer, I looked at abundance data and concluded that beetles were more abundant in the upper canopy and that spiders were more abundant in the understorey. This internship transitioned into my Honour’s project, where I plan to look at species richness and functional diversity to answer my questions on community assemblages. To my knowledge, this has never been done at Kenauk Nature and would provide great baseline data for the owners of the property.

We sampled in three sites, each containing three trees. Each site had one sugar maple (Acer saccharum), one black maple (Acer nigrum) and one American basswood (Tilia americana). Within each tree we sampled five times: twice in the understorey, once in the middle canopy and twice in the upper canopy. We also used two different types of traps: beat sheets, an active technique, and Lindgren funnels, a passive technique. Both trap types are specialized, with beating more tailored towards spiders and Lindgren funnels invented to collect beetles. When beating a branch, the arthropods fall on a 1m2 sheet and are then collected whereas Lindgren funnels are hung in a tree and passively collect arthropods that fly into it.

LindgrenFunnel

As part of our job, we learned how to use a single ropes climbing system, a one-person method of using ropes to climb a tree. All three interns caught on quickly and it easily became our favourite part of the job. However, we did have to sort through the samples, a job requirement that wasn’t nearly as fun as climbing trees. But this is what happens in ecology: you romp around in the woods to collect your data then spend time in the lab analysing them. It was nice to experience this first-hand and I must say, I liked it and am looking forward to future projects like this.

Now that the summer is over and collection is completed, I spend all of my free time in the lab identifying beetles and spiders. All of the beetles are identified and about half of the spiders are identified. From this work, Kenauk Nature can proudly say that the property supports 24 families representing 117 species of beetles! Once the Kenauk Institute officially launches, more rigorous research can be done to try and increase these numbers.

Learning Taxonomy... spider drawings (of male palps) help.

Learning Taxonomy… spider drawings (of male palps) help.

All in all, from the sampling in the summer to the identification in the lab, this has been a great experience. Here’s to hoping the second half of my honours project will be as equally fun and challenging as the first half was! Stay tuned for a blog post to be published in the spring of 2016: it will summarize the main results from this Honour’s project.

Heating, cooling, and trying to drown Arctic pseudoscorpions

The Beringian Arctic pseudoscorpion is a charming Arachnid, living under rocks near sub-arctic rivers and streams, in primarily unglaciated parts of the Yukon. It has captured my fascinating for years, and the story of its natural history is starting to unfold. However, some fundamentals about the biology of Wyochernes asiaticus remain unknown: as the most northern pseudoscorpion in North America, how does it survive in such cold climates? How is it adapted to frequent flooding that occurs in its primary habitat, next to streams and rivers?

The Arctic pseudoscorpion, Wyochernes asiaticus

The Arctic pseudoscorpion, Wyochernes asiaticus

Science is a collaborative process, and I teamed up with two thermal biologists to start to answer some of these physiological questions. PhD student Susan Anthony and Prof. Brent Sinclair*, both from Western University in Ontario, came to the Yukon with us last summer, and together we collected pseudoscorpions at Sheep Creek, just north of the Arctic Circle. Part of Susan’s PhD research is about the thermal biology of Arachnids, so Susan and Brent wanted to see what we could learn about Arctic pseudoscorpions. They brought the wee arachnids back to Ontario, and Susan ran a series of experiments, resulting in a recent publication (in Polar Biology).

Susan Anthony and Brent Sinclair, both from Western University.

Susan Anthony and Brent Sinclair, both from Western University.

The experiments may sound a little cruel, but they are the standard approach when studying some of the cold tolerance, thermal biology and physiology of arthropods. Susan heated up and cooled down the critters, and discovered that they can survive up to about 38 degrees Celsius, and down to about -7 degrees Celsius. The upper threshold is relatively low compared to other arthropods, which makes sense since W. asiaticus lives at high latitudes. Because the specimens didn’t survive freezing, we know it’s ‘freeze avoidant’ rather than ‘freeze tolerant’. This is aligns with what we know from many other northern (or southern! i.e, in the Antarctic) arthropods. Presumably the pseudoscorpions adapt to the north by being able to supercool, or perhaps by cryoprotective dehydration,. However, its lower threshold isn’t that low, given the extreme cold winter temperatures in the Yukon. But since our collections were in the mid-summer, this might mean it’s not yet started to adapt, physiologically, for the colder winter conditions.

The next experiments involved immersing the pseudoscorpions in water and seeing how long they survive. This was done because we were very curious to know how these tiny animals might live in habitats that flood frequently. Amazingly, 50 percent of the arachnids survived under water for up to 17 days (!), and after testing with de-oxygenated water, Susan had a similar result: they certainly weren’t relying on oxygen in the water for breathing. Susan did notice, however, that they appeared to have a silvery bubble or ‘film’ around their bodies when immersed so we assume they used this air bubble for breathing during the immersion period, something known from other arachnids.

Sheep Creek, Yukon - a habitat that frequently floods: now we know how the tiny Arachnids survive the flooding!

Sheep Creek, Yukon – a habitat that frequently floods: now we know how the tiny Arachnids survive the flooding!

Putting this in the context of the pseudoscorpion’s habitat in the Yukon: it seems that the sub-arctic rivers in the Yukon typically flood for periods up to 10 days, in the spring. Our little arachnid likely just hunkers down in their habitats under rocks, breathing from air trapped around its body, waiting for floodwaters to recede.

I’m very excited about this paper, in part because of what we have learned that links the ecology of the species to its physiology. I’m also excited because this work represents a major advancement in the fundamental knowledge about Arachnids. Our work is the first to uncover any basic biology related to the physiological adaptations of pseudoscorpions to cold/heat and to immersion tolerance.

This is kind of stunning: the Pseudoscorpiones are an entire Order of Arachnids, yet nobody has ever worked to figure out how they adapt, physiologically, to extreme environmental conditions. AN ENTIRE ORDER! And it’s 2015! An analogy would be figuring out that some butterflies (Order Lepidoptera) bask in the sun, to thermoregulate. Or, like figuring out how ducks (Order: Anseriformes) don’t freeze their feet when standing on ice. These are ‘textbook’ examples of thermal biology and physiology – such facts could be considered common knowledge. Yet looking to the Arachnids, the story of the thermal biology of pseudoscorpions has only just begun. One paper at a time, we will continue to make progress.

The Arctic pseudoscorpion: it has stories to tell. Photo by C. Ernst, reproduced here with permission.

The Arctic pseudoscorpion: it has stories to tell. Photo by C. Ernst, reproduced here with permission.

As Tschinkel & Wilson state, every species has an epic tale to tell. Even tiny arachnids that live under rocks above the Arctic circle are proving interesting for many scientific disciplines: each chapter of its story is starting to unfold, and I’m quite sure there are a lot of very interesting chapters still to come.

Reference:

Anthony, S.E., C.M. Buddle and B.J. Sinclair. 2015. Thermal biology and immersion tolerance of the Beringian pseudoscorpion Wyochernes asiaticus. Polar Biology.

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*A sincere thanks to Brent and Susan for including me on this paper, and for being willing to come to the Yukon with our team, to do collaborative research. I’ve learned a great deal in the process, and am delighted that partnerships between ecologists and physiologists can work out so well.

Monitoring northern biodiversity: picking the right trap for collecting beetles and spiders

Ecological monitoring is an important endeavour as we seek to understand the effects of environmental change on biodiversity. We need to benchmark the status of our fauna, and check-in on that fauna on a regular basis: in this way we can, for example, better understand how climate change might alter our earth systems. That’s kind of important.

A northern ground beetle, Elaphrus lapponicus. Photo by C. Ernst.

A northern ground beetle, Elaphrus lapponicus. Photo by C. Ernst.

With that backdrop, my lab was involved with a Northern Biodiversity Program a few years ago (a couple of related papers can be found here and here), with a goal of understanding the ecological structure of Arthropods of northern Canada. The project was meant to benchmark where we are now, and one outcome of the work is that we are able to think about a solid framework for ecological monitoring into the future.

A few weeks ago our group published a paper* on how to best monitor ground-dwelling beetles and spiders in northern Canada. The project resulted in over 30,000 beetles and spiders being collected, representing close to 800 species (that’s a LOT of diversity!). My former PhD student Crystal Ernst and MSc student Sarah Loboda looked at the relationship between the different traps we used for collecting these two taxa, to help provide guidelines for future ecological monitoring. For the project, we used both a traditional pitfall trap (essentially a white yogurt container stuck in the ground, with a roof/cover perched above it) and a yellow pan trap (a shallow yellow bowl, also sunk into the ground, but without a cover). Traps were placed in grids, in two different habitats (wet and “more wet”), across 12 sites spanning northern Canada, and in three major biomes (northern boreal, sub-Arctic, and Arctic).

Here’s a video showing pan traps being used in the tundra:

Both of the trap types we used are known to be great at collecting a range of taxa (including beetles and spiders), and since the project was meant to capture a wide array of critters, we used them both. Crystal, Sarah and I were curious whether, in retrospect, both traps were really necessary for beetles and spiders. Practically speaking, it was a lot of work to use multiple traps (and to process the samples afterwards), and we wanted to make recommendations for other researchers looking to monitor beetles and spiders in the north.

The story ends up being a bit complicated… In the high Arctic, if the goal is to best capture the diversity of beetles and spiders, sampling in multiple habitats is more important than using the two trap types. However, the results are different in the northern boreal sites: here, it’s important to have multiple trap types (i.e., the differences among traps were more noticeable) and the differences by habitat were less pronounced. Neither factor (trap type or habitat) was more important than the other when sampling in the subarctic. So, in hindsight, we can be very glad to have used both trap types! It was worth the effort, as characterizing the diversity of beetles and spiders depended on both sampling multiple habitats, and sampling with two trap types. There were enough differences to justify using two trap types, especially when sampling different habitats in different biomes. The interactions between trap types, habitats, and biomes was an unexpected yet important result.

Our results, however, are a little frustrating when thinking about recommendations for future monitoring. Using more than one trap type increases efforts, costs, and time, and these are always limited resources. We therefore recommend that future monitoring in the north, for beetles and spiders, could possibly be done with a trap that’s a mix between the two that we used: a yellow, roof-less pitfall trap. These traps would provide the best of both options: they are deeper than a pan trap (likely a good for collecting some Arthropods), but are yellow and without a cover (other features that are good for capturing many flying insects). These are actually very similar to a design that is already being used with a long-term ecological monitoring program in Greenland. We think they have it right**.

A yellow pitfall trap - the kind used in Greenland, and the one we recommend for future monitoring in Canada's Arctic.

A yellow pitfall trap – the kind used in Greenland, and the one we recommend for future monitoring in Canada’s Arctic.

In sum, this work is really a “methodological” study, which when viewed narrowly may not be that sexy. However, we are optimistic that this work will help guide future ecological monitoring programs in the north. We are faced with increased pressures on our environment, and a pressing need to effectively track these effects on our biodiversity. This requires sound methods that are feasible and provide us with a true picture of faunal diversity and community structure.

It looks to me like we can capture northern beetles and spiders quite efficiently with, um, yellow plastic beer cups. Cheers to that!

Reference

Ernst, C, S. Loboda and CM Buddle. 2015. Capturing Northern Biodiversity: diversity of arctic, subarctic and northern boreal beetles and spiders are affected by trap type and habitat. Insect Conservation and Diversity DOI: 10.1111/icad.12143

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* The paper isn’t open access. One of the goals of this blog post is to share the results of this work even if everyone can’t access the paper directly. If you want a copy of the paper, please let me know and I’ll be happy to send it to you. I’m afraid I can’t publish all of our work in open access journals because I don’t have enough $ to afford high quality OA journals.

** The big caveat here is that a proper quantitative study that compares pan and and pitfall traps to the “yellow roof-less pitfall” traps is required. We believe it will be the best design, but belief does need to be backed up with data. Unfortunately these kind of trap-comparison papers aren’t usually high on the priority list.

Vouchers? What vouchers? Revealing a crisis in arthropod-based research

Here’s a hypothetical scenario:

Q: “Hey I see you published a paper that shows the wolf spider Trochosa ruricola occurs up in the Ottawa Valley – I didn’t realize it had reached that far. It’s an invasive species, so tracking its distribution is quite important

A: “Yeah, we too were surprised it was up that far: to our knowledge, only Trochosa terricola was in that part of Ontario

Q: “It is tricky to tell apart those two species! What museum did you deposit specimens in? I’d like to take a look at them to verify the identification.

A: “Um, we didn’t get around to depositing specimens in the museum. There might still be some in the lab. I’ll have to get back to you...”

Not cool.  And also much too common.

Bottom line: when specimen-based research is done with arthropods, whether it is a biodiversity inventory, a community ecology study, or a taxonomic revision, the researchers must deposit voucher specimens in a research museum or institutional collection. This is only way to truly verify that the work is accurate, that people are calling things by the same name, and it puts a stamp in time for the research. Without deposition of these voucher specimens (somewhere that is publicly accessible and curated, and along with data about time, place and collector) the research cannot be verified, and this goes against the principle of repeatability in science.

Beetles in drawers: a great example of specimens in a curated museum, and shows how such specimens can be used for all kind of research!

Beetles in drawers: a great example of specimens in a curated museum, and shows how such specimens can be used for all kind of research!

This is a no-brainer, right? It’s time to test whether or not scientists actually bother to deposit voucher specimens…. As part of a graduate-level* class in Entomology last winter, we surveyed the literature to find out the frequency of voucher deposition with arthropod-based research. We looked at papers to see what percentage actually report on vouchers, assessed whether the frequency of voucher deposition varied by research type, study organisms, institution (of researcher), and whether voucher deposition has changed over time.

We published the results a few weeks ago, in the Open Access journal PeerJ, and our work has revealed a crisis in arthropod-based research. Overall, rates of voucher specimen deposition were very low, as only 25% of papers report on the deposition of voucher specimens. This is horrible, and essentially means that the specimens from the majority of papers published cannot be traced to a collection, and cannot be verified.

Some disciplines were worse than others, as crustacean researchers deposited vouchers only 6% of the time, as compared to the relatively higher rate of voucher deposition by entomologists, at 46%. Here is a summary of the main findings:

The main findings of our research: the asterisk illustrates a significant difference relative to a global mean.

The main findings of our research: the asterisk illustrates a significant difference relative to a global mean. Figure from our paper, published here.

Is there any good news? Perhaps so… when looking at rate of voucher deposition over time, more papers are reporting about vouchers in 2014 (35%) compared to 1989 (below 5%).

At the end of our paper we provide some conclusions and recommendations, and these are repeated here:

  1. PIs must be responsible and proactive on the process of voucher specimen deposition, from the start of any project.
  2. Graduate students need to be mentored appropriately about the importance of voucher specimen deposition.
  3. It needs to be recognized that voucher specimens are important for all branches of arthropod research – there is no reason that entomologists should do better than, say, crustacean biologists.
  4. Close collaboration between Universities/Research Centres and Museums is required, so that there is an agreed up, and easy process for all researchers to deposit vouchers.
  5. Everyone involved with arthropod-based research needs to work together to push for long-term, sustainable funding for institutional collections/museums so that proper curation of vouchers can be done.
  6. Publishers and editorial boards need to have clear policies about voucher specimens, so that any papers published are required to report on vouchers.

I recognize that the title of this post is provocative. Is it *really* a crisis?

I think it is: I think that even the best rate of voucher deposition that we report on is too low. We must aim to be closer to 100%. It’s important as we work to describe the world’s biodiversity, understand what is happening to our species in the face of climate change, or track the distribution of invasive species. It’s important that our hard work is more than a publication: our hard work is often a specimen, and that specimen needs to be accessible for future generations.

Voucher for critters than need to be stored in liquids looks something like this.

Voucher for critters than need to be stored in liquids looks something like this.

Reference:

Turney S, Cameron ER, Cloutier CA, Buddle CM. (2015) Non-repeatable science: assessing the frequency of voucher specimen deposition reveals that most arthropod research cannot be verified. PeerJ 3:e1168 https://dx.doi.org/10.7717/peerj.1168

* A most sincere thanks to my graduate students Shaun, Elyssa and Chris – these students did the lion’s share of this project, and took on this graduate class with great enthusiasm, maturity and motivation. You all inspire me!

Yukon field work: Arachnids, landscapes, and the inspiring North

It’s a dream for an arthropod ecologist: a dramatic biome transition from boreal forest to subarctic tundra, a beringian landscape, and diverse and abundant insects and spiders. I have just returned from field work along the Yukon’s Dempster Highway, Canada’s only road to cross the Arctic circle. And again, I was not disappointed!

A stretch of the Dempster Highway

A stretch of the Dempster Highway

This year’s expedition was focused on three projects:

1) Tiny, wonderful arachnids:

On this trip, I continued to document the distribution of an arctic Pseudoscorpion, Wyochernes asiaticus. This is a beringian arachnid, known from the old world, and known in North America from almost exclusively unglaciated parts of the Yukon and Alaska. Like wooly mammoths and giant short-faced bears, these tiny arachnids roamed North America while the rest of the top half of the continent was buried under ice. But unlike the mammoths and giant short-faced bears, the Arctic Pseudoscorpion is not extinct! It’s a relict of the past, thriving today under rocks near beringian rivers and streams. I have been working on this species for many years (and a life history paper about this arachnid will appear in the Canadian Field-Naturalist sometime this month), and each time I visit the Yukon, I leave with more questions, and more specimens. This time, I collected some animals to hopefully work on their population genetics: I am curious about the relatedness among the populations from different watersheds along the Dempster Highway (by the way, I am seeking collaborators [phylogeographers!] for this work… If interested, let me know!)

The Arctic pseudoscorpion, Wyochernes asiaticus

The Arctic pseudoscorpion, Wyochernes asiaticus

2) Northern food webs:

I have left my PhD student Shaun Turney up in the Yukon (along with his field assistant) where he is working on characterizing the arthropod-based food webs along the latitudinal gradient of the Dempster Highway. Past research has given some hints that northern food webs may be atypical, but to fully test this we decided to characterize the entire fauna from 1 x 1 m patches of the tundra. This involved placing tents over the tundra, and Shaun collected critters within those tents, and even “vacuumed” the tundra within the square metre. Shaun started this work near the stunning Richardson mountains above the arctic circle, and over the month of July, will repeat the sampling at different locations along the Dempster Highway.

Shaun Turney, vacuuming the Tundra.

Shaun Turney, vacuuming the Tundra.

3) Thermal biology of wolf spiders

Colleagues from Western University joined me in the Yukon to start some projects related to the thermal biology of the extremely abundant Pardosa wolf spiders which inhabit the tundra. There are several species that occur along the Dempster Highway, and when the weather is good, it’s quite possible to collect hundreds of individuals over the span of several hours. Past work has suggested the density of these spiders is about 0.5 per square metre, and those past estimates certainly seemed accurate on this trip also! The spiders will be taken back to their lab, and I am eager to find out how northern Pardosa may be adapted to Yukon conditions.

Searching for wolf spiders on the Tundra

Searching for wolf spiders on the Tundra

All the sciency parts of our field work were exciting and gratifying, but there are other reasons why the Yukon is special*: it is a breathtakingly beautiful place. From stubby black spruce trees to tufts of tundra-dwelling cotton grass, every turn of the highway or footstep over a hummock is a treat. It’s not all easy (hordes of mosquitoes at some of the campgrounds, or being driven off the tundra by cold rains and strong winds), but it is all inspiring.

The lines between science and passion are blurred on the tundra, and that is a good thing. Searching for spiders is work that is fun; seeing a northern shrike or watching two lonely caribou dart up a river valley is fun that comes with the field work. I am immensely grateful for being able to hike under midnight sun, and be a northern researcher during the day. I am delighted to be able to discover some of hidden secrets of the Yukon.

The northern landscape, near the Yukon-Northwest Territory border.

The northern landscape, near the Yukon-Northwest Territory border.

For more photos of the recent trip, check out my Flickr page.

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* my colleague Terry Wheeler shares a passion for the Yukon – here is his post which outlines why he keeps returning to the region.

Landscape structure, insect herbivory, and ecosystem services

I’m pleased to announce a new publication to come out of the lab, with lead author Dorothy Maguire and co-authored by Elena Bennett and Patrick James. In this work, Dorothy ponders and writes about the broader implications of insect herbivory. More specifically, how insect herbivory is affected by landscape connectivity (i.e., the degree to which habitats are linked to each other), and how plant-feeding insects may relate to ecosystem services (i.e., the values and services that humans get from our natural systems).

Female (l) and male (r) Gypsy moth, caught in the act.

Important insects when, as caterpillars, eat a lot of foliate: Female (l) and male (r) Gypsy moth, caught in the act.

We certainly know that insects can do all kinds of damage to plants in ecosystems, but do insects in more (or less) connected habitats do more damage? To address this question Dorothy scoured the literature and got the relatively unsatisfactory answer of “sometimes”: 49% of the papers suggest increased connectivity relates to more insect herbivory and 28% of the papers show less herbivory in more connected patches. The lack of a clear answer actually makes quite a bit of sense since every context can be quite different, and not all insects are equal. It is hard to generalize since effects in forests will not be the same as in fields, and insects that are out-breaking (i.e., with major population explosions) may be affected differently than non out-breaking species. Dorothy certainly found these contexts were important. The results were important to illustrate how we need to adapt any management options with close attention to both landscape feature and their interaction with the life-history of the herbivore.

The second part of Dorothy’s work delved deeper into the literature to ask about the effects of out-breaking versus non out-breaking herbivore species on a select suite of forest ecosystem services: effects on timber production, aesthetics, soil formation and Carbon sequestration. There were some interesting results of this and again, any particular effect of herbivory on an ecosystem service was highly sensitive to the outbreak status of the herbivore. For example, the aesthetics of a forest can be positively affected by low levels of herbivory since this may help create pleasant conditions for light infiltration to the forest floor. However, an out-breaking species may defoliate a tree more completely, thus reducing the aesthetic value. Another example is that low levels of herbivory may positively affect timber production because trees may show “compensatory” growth after light feeding by an insect. In contrast, timber production will be negatively affected by high levels of defoliation as this may reduce a tree’s ability to grow. Although some of these results may seem rather logical, Dorothy’s work was unique as it showed how the scientific literature supports the connections between a herbivore’s life-history and key ecosystem services.

Screen Shot 2015-06-11 at 6.55.21 AM

Visual representations of the hypothesized relationships between insect herbivory and ecosystem services. Specifically (a) timber production, (b) aesthetic value of forests. Graphs are divided into four sections representing positive and negative effects of herbivory on ES, during non-outbreak (low) vs. outbreak (high) levels of herbivory. Quadrants are coloured differently based on the hypothesized strength of the effect of herbivory on ES: weak (light grey), moderate (dark grey) and strong (black). Proposed relationships are derived from synthesis of the available literature. From Maguire et al.

The last part of the work was focused on building a conceptual framework – a framework that ties together landscape structure, the process of herbivory, and ecosystem services. This is meant to be a road map for any stakeholders with an interest in any or all of those factors. For example, should a forest manager be tasked with understanding how to increase or support a particular ecosystem service, she or he needs also to recognize how that service is tied to important processes such as herbivory, and the related connections to the broader landscape.

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This work is novel and important because it links the well known process of insect herbivory to concepts of ecosystem services and to the discipline of landscape ecology. The marrying of these areas is critically important as we face increasing pressures on our natural systems, and the complexity of the systems can be overwhelming. We hope this work piques more interest in this topic, and that the framework Dorothy provides is useful to all the stakeholders.

Reference:

Maguire, DY, PMA James, CM Buddle & EM Bennett Landscape connectivity and insect herbivory: A framework for understanding tradeoffs among ecosystem services. Global Ecology and Conservation. doi:10.1016/j.gecco.2015.05.006