I’ve gone a bit quiet on both blogs recently, and not just because I’ve retreated to lick my post-election wounds. It’s the start of another field season, and I’ve been busily helping some of our MSc students get started with their projects as well as launching into another phase of data collection for my PhD. With the aid of two of the aforementioned students (who, I am grateful to say, are doing the lion’s share of the work!) we’ve been setting up three pairs of insect traps in each of a number of different woods in and around Reading. All the sites are within 15km of the town centre but incorporate a variety of wood sizes, habitat structures, and situations; from plantation to copse, beech to oak wood, and urban (like McIlroy Park, below) to rural.
In each pair of traps, we are setting one pitfall — very simply, a plastic cup buried in the ground to catch any invertebrates that happen to stumble in — and a flight intercept trap, pegged to the ground, which will catch anything that happens to fly through the trap door. In other words, we have one trap to catch walking creatures and one to catch those on the wing, but both set in the same place for a direct comparison.
The pitfall traps should catch a good range of invertebrates, but chiefly beetles from the families Carabidae (ground beetles) and Staphylinidae (rove beetles). One of my PhD colleagues at Reading, Jess Neumann, has been studying woodland ground beetles for a number of years now, using them as an indicator group for the effects of landscape structure and composition on woodland biodiversity. Her study sites are almost entirely rural in setting, so it will be interesting to see whether similar patterns emerge in the urban set of woods where we’re collecting in this summer. I’m particularly keen to explore her findings about the influence of the historic landscape on contemporary invertebrate distributions, and the idea that woodland carabids owe a substantial extinction-debt, persisting as they do in landscapes which no longer meet their ecological requirements.
Then we have the flight traps. These will capture mostly small flies and parasitic wasps, as well as a few small bugs and beetles. I foresee more of a challenge identifying some of these, to say the least, but eventually we should have some really interesting data that will enable us to compare change, across wooded landscapes, of a number of different invertebrate communities. Will small flies — fungus gnats, for example — prove as sensitive to habitat fragmentation and the composition of the surrounding landscape as the relatively big, flightless woodland specialist ground beetles? If ground beetles are indeed an indicator of wider biodiversity, what exactly is it that they indicate? Watch this space!
In the meantime, I am fortunate enough to have the excuse to get up early* and head for some rather special places. Between digging pitfalls and setting traps, I’m able to enjoy some fantastic scenery and usually happen upon some pretty great wildlife, too. It’s tiring work, but I can hardly complain when the rewards are this lovely.
*Digging holes in woods, even when you have permission to do it, always looks a bit suspicious, so I prefer to get fieldwork done before most people are up and about!