Pondering the effects of habitat fragmentation

Are the negative effects of habitat fragmentation a zombie idea? Do we see positive or negative effects of habitat fragmentation more often? And even before we do that, can we make broad generalisations about the effects of habitat fragmentations; if we can, should we be? What would be the potential effects on conservation policy and actions?

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Journal club joy

This week we had our first EdGE meeting, under the theme of a Biodiversity Journal Club, and we pondered all of those questions and more in a lovely thought-provoking and stimulating atmosphere! We focused on the following paper:

Fahrig, L. (2017). Ecological responses to habitat fragmentation per se. Annual Review of Ecology, Evolution, and Systematics48(1).

Check out the full blog post summarising our thoughts on the EdEN website!

Qikiqtaruk Book Club based on Mark Vellend’s “The Theory of Ecological Communities”

This series of blog posts was written on Qikiqtaruk-Herschel Island in the Western Canadian Arctic as part of Team Shrub’s island book club, aiming to read and discuss Mark Vellend’s 2016 book “The Theory of Ecological Communities” while we are out in the field, right next to the communities we study.  

Qikiqtaruk is a beautiful and inspirational place – science chats are particularly special when you can see, feel, hear and even smell your study system change as the growing season progresses. Out during phenology data collection yesterday, we saw that the spring flowers are fading and seed dispersal is beginning… summer is well under way. And this year, in addition spotting awesome wildlife, admiring magnificent sunsets and informally chatting about science in our remote Arctic field site, we have also started a book club!

Plant communities on Qikiqtaruk

Our book club discussions are summarised in four blog posts:

Qikiqtaruk Book Club Part I: Ecological communities in the Arctic

Qikiqtaruk Book Club Part II: Selection in the Arctic

Qikiqtaruk Book Club Part III: Speciation, drift and dispersal in the Arctic

Qikiqtaruk Book Club Part IV: Theory and high-level processes in the Arctic

We thoroughly enjoyed reading “The Theory of Ecological Communities” whilst on fieldwork at our remote field site in the Canadian Arctic. There is particular charm in reading about a certain ecological process, be it high- or low-level, and then observing it in action moments later in the field. We look forward to continued discussions of the synthesis of ecological theory, but definitely agree with Mark that four high-level processes do shape community composition – selection, speciation, dispersal and drift.

Meta-analyses, theory and stylised facts in ecology

What is a theory? Is ecology theory-poor and if yes, why? What are the paths to theory development in ecology? Meta-analyses? Data syntheses? Big data? Stylised facts? These are the questions we set out to discuss during  this week’s lab meeting. We extended an invitation to EdGE (the EdEN discussion Group for Ecology) to get more diverse perspectives, and shared our thoughts on these topics, largely inspired by Dynamic Ecology’s posts about stylised facts in ecology and why meta-analyses in ecology often don’t lead to theoretical insight. We also added in Marquet et al.’s 2014 paper “On Theory in Ecology” into our discussion, bringing forward many thoughts on the different types of theory in ecology, and whether theory in ecology is possible to begin with.

We defined theory as a hierarchical framework of postulates, based on a number of assumptions, and leading to a set of predictions. As we set out to do our research, we can use theory as the base on which you build your hypotheses – and if you find enough support for your hypotheses, in time they might grow into a theory, thus prompting more hypotheses – a self-propelling cycle of gathering empirical evidence and developing theory. But is the cycle broken, with empirical evidence (or its synthesis) becoming an endpoint that prompts little theoretical insight?


We had a mix of undergraduates, PhD students and PIs in the room, and it was interesting to see how our thoughts varied based on our career stage. We started off with a quick quiz on 1) whether we had heard of the theories covered in the paper before, and 2) whether we had thought deeply about them. Here are the results!

Continue reading “Meta-analyses, theory and stylised facts in ecology”

The role of β-diversity in conservation

What indicators should we use in conservation? Why do different biodiversity indicators seem to disagree? What is the role of beta-diversity in conservation? This week we extended our usual TeamShrub lab meeting to hold a discussion on two recent biodiversity papers, as part of the EdEN (Edinburgh Ecology Network) EdGE (EdEN Discussion Group for Ecology) meetings. We talked about what are the best indicators to assess biodiversity change, whether there is a place for β-diversity metrics in guiding conservation actions, and why do different indicators of biodiversity change seem to disagree with one another.

We all had an interesting and jolly discussion, inspired by the following papers:

Socolar, Jacob B., et al. “How should beta-diversity inform biodiversity conservation?.” Trends in ecology & evolution 31.1 (2016): 67-80.

Hill, S. L.L., Harfoot, M., Purvis, A., Purves, D. W., Collen, B., Newbold, T., Burgess, N. D. and Mace, G. M. (2016), Reconciling Biodiversity Indicators to Guide Understanding and Action. CONSERVATION LETTERS, 9: 405–412. doi:10.1111/conl.12291


As we work in the Arctic, we appreciated how the papers recognised the fact that regions which are not particularly rich in biodiversity still deserve to be on the conservation radar.

We started off by identifying what β-diversity is and how we measure it – we discussed temporal β-diversity (how has species composition changed through time) and spatial β-diversity (commonly known as just beta-diversity, how do communities differ across space – i.e. measures of similarities, etc.) and what are the implications of using β-diversity metrics in conservation. We can mostly agree that one of the goals of conservation is to maximise biodiversity, but what diversity? Alpha, beta, gamma?

Unlike α-diversity (diversity at the local scale) and γ-diversity (diversity at the global scale), β-diversity does not refer to a spatial extent, but to the comparison between communities, and as such is is often used as an indicator of biotic homogenisation.

Calculating β-diversity allows us to understand biodiversity loss from a different perspective – we can look beyond species richness increasing or decreasing, and think about whether communities are becoming more similar, and what the implications of that might be for ecosystem functionality and the provision of ecosystem services. Nevertheless, β-diversity has to be used carefully – if two communities are both changing, β-diversity might stay the same (i.e. they might still have the same amount of species in common), but their current species composition might have changed. We also discussed how increasing the spatial extent of agri-environment management (or other conservation measures) might not always have the desired outcomes – such actions might decrease β-diversity by favouring the same set of species over large spatial extents. Communities can shift in many ways, which don’t necessarily fit in the biodiversity loss toolbox we most often use.

Can we use beta-diversity to link local scale observations to global scale inferences on biodiversity trends?

We thought that this is theoretically a great idea, but logistically, there are difficulties in going from the local scale observations to inferences on γ-diversity – gaps in the data, understudied regions, etc. We also pondered the dangers of promoting rare species at the expense of common species, and also what about disturbance-tolerating species? It is easy to say that e.g. Plot1 has lost/gained one species, but hard to have confidence in how the world has changed over time. Perhaps it is β-diversity that will help us link our local-scale observations to inferences on the global scale.