Studying Invertebrates is a comprehensive guide to designing and carrying out ecological investigations, especially those involving sampling invertebrates. A highly practical guide to fieldwork, statistical testing and interpretation. The book introduces ways of designing and analysing experiments so that complex situations can be described and summarised, comparisons made, and interactions between organisms and their environment examined objectively.
The books in this series are designed to encourage readers to undertake their own studies of natural history. Each one describes some relevant techniques, but they have not enough space to cover the substantial body of more generally applicable ideas and approaches that underlies the design and analysis of such field studies. By describing a selection of these general methods, Studying Invertebrates aims to support those venturing into ecological fieldwork for the first time. The authors have plenty of experience in helping beginners to plan, carry out and interpret ecological surveys and experiments, and hope this handbook will serve as a welcome companion and guide, especially for those who lack confidence in their knowledge of statistical and other methods.
So, you have a plot of land, and you're going to turn it over to Permaculture. You're sure this is going to provide better habitat for wildlife as well as providing food for you and your community.
At some point, someone is going to turn round and ask you to prove it. Actually, one of the ongoing criticisms of Permaculture as it stands is the lack of good scientific evidence informing good practice, or even what might be considered some form of “success”. This is pretty straightforward for a conventional farmer, even many organic ones, but much harder for us, often using different criteria for “success”. To date, we have been pretty poor at demonstrating most of these criteria.
With climate change and the associated extinction event we're now entering it's vitally important that we create as much niche habitat for as many species as possible, and Permaculture is one solution to this problem. We also need to know that our efforts are being effective. Surveying is an important aspect of monitoring and understanding your habitat.
Meanwhile, most research funding is being directed towards maintaining the status quo. There are two possible answers to this: one is to act on faith that we're doing the right thing, and indeed some things, like quality of life, are difficult (but not impossible) to measure. It's possible to compare yields, even add up protein and other energy being harvested from the land (a relatively simple process), measure aboveground, even belowground (more difficult) carbon, and even compare that with control plots. As I've observed elsewhere, it's difficult to compare yields from good farmland with those from someone starting out on a hectare of Irish bog.
Surveying larger fauna, such as birds, is relatively straightforward. You can count them. You can count the number of different species. You can count how many nest in your habitat. You can count how many chicks fledge or even (more difficult) survive to breed. You can watch how much time birds spend foraging in your habitat. You can watch how that changes as your habitat changes.
Hours and hours of fun you can call “work”!
So, let's say the blackbirds are spending a lot of time in your annuals plot. This is good, right? Well, maybe. It may be that they've realised you have a caterpillar problem (which, as far as they're concerned, is an opportunity), which they are in the process of fixing. This is a nice simple case of mutualism between blackbirds and humans. This is the kind of thing that will change over time. One year you have a lot of caterpillars, which means the blackbirds raise more babies, which attract sparrowhawks, which eat some of the blackbirds, so there are not enough blackbirds to feed all the sparrowhawks, so the sparrowhawks move out, but there are now not enough blackbirds left to control the caterpillars, so you end up with happy wasps, which attract bee-eaters, and so on.
On the other hand, without a good grasp of science it can be difficult to tell whether specific changes in your habitat are real or imagined or an artefact of your study method.
To obtain a better picture of what's going on in your habitat it's worth monitoring the life forms you are less likely to notice. Unless you are really nerdy, most of us pay very little attention to the invertebrate life in our habitats. There are others, of course, but surveying bacteria requires access to a good laboratory, and most of us can only identify fungi when they fruit. Particular insect groups (notably ground beetles and hoverflies) have proved to be good indicators of the diversity of a habitat.
There is still a lot of good science to be done, even by the competent amateur, where invertebrates are concerned, and this applies particularly to the novel ecosystems created by Permaculturalists. My own studies have led me to realise that diversity is not just about numbers or organisms, or numbers of species, but about the numbers of functional connections in the ecosystem, because it is that, not the absolute diversity, that provides the resilience in the ecosystem. You can't grasp the functional connections if you don't know what's there. This means you need a hand lens as well as a pair of binoculars. The science of ecology is under constant change itself, http://rstb.royalsocietypublishing.org/content/365/1537/49 and the citizen scientist with access to a novel ecosystem is in a position to contribute to this process.
So, we need a good book that will provide an introduction to studying invertebrates. Short of a college course in ecology, there are few books that will provide you with this introduction.
This volume is one of a series (this is Volume 28) aimed at the beginner naturalist wishing to study a particular group of life forms and undertake research of their own; these books also provide suggestions for useful research. They're aimed at a British market, but the techniques described in all of them will be applicable elsewhere. Many of them provide enough information to identify many or all of the common species likely to be found in Britain, but anyone else may (depending on the depth of identification required) need a companion identification volume for their own ecoregion. For some taxa a good overview from another publisher, such as the Collins New Naturalist series, may be useful. What this book gives is a broader overview of the methods of studying invertebrates from the inception of a study to the presentation of results.
This is not a big volume: it barely tops a hundred pages, but it's incredibly information dense. The authors are (or were) scientists in the Department of Environmental and Geographical Sciences at Manchester Metropolitan University, both have experience in assisting beginners with the design, implementation and interpretation of ecological surveys, and are also joint authors on a book on Practical Field Ecology, which I may get around to reviewing in due course.
The book starts with the design of an investigation, and the crucial difference between an experiment and a survey, and the Permaculturalist may be in a position to conduct either or both, and which one you conduct will depend on the kind of information you want to gather. It discusses data types and sampling strategies, and shows you how to ask useful questions. You need to be clear on this before you commence your study. This may be particularly important in a novel ecosystem where microclimates, even variations in abiotic features, may have been designed into the system.
Chapter 2 on Sampling Invertebrates takes up much of the book. You need to understand the vegetation (which may change over the course of a long study, and the methods described here provide a good introduction useful for monitoring changes in vegetation), environmental properties, substrates and, for some studies, water quality. The texts recommended for botanical survey methods will be applicable anywhere, and I will personally recommend several of the texts mentioned for identification purposes for the British Isles, although alternatives will need to be found elsewhere. The book then shows you how to sample invertebrates in water (which may provide useful information about pollutants), substrates such as soils, rocky shores (probably not relevant to most of us, but you never know), species active on the surface and on plants, and species that are found in the air. In other words, it's pretty comprehensive, and ties in with the rest of the series.
There is a discussion on catching and killing invertebrates, but in general this should not be done unless it's essential. My own view is that if your study involves destructive sampling it may be time to review your methods, but some organisms are only identifiable to species through dissection. In general I prefer to redesign the study, or study a different indicator. Sheer laziness should not be used as an excuse to use a methodology that requires killing your research participants. Sometimes this problem can be solved simply by surveying a different taxon, depending on the ecological markers you are interested in. Avoid making your own reference collection (your local museum may have one, and curators are usually enthusiastic about sufficiently interested visitors by appointment to a basement lair).
Some sampling equipment can turn very expensive, and the enthusiast may want to partner with the local university in order to obtain access, but the authors provide useful suggestions for more makeshift designs you can make much more cheaply at home. I really appreciated this touch, because it assists those of us who want to contribute to science on a tight budget.
Sometimes, however, proper surveying for conservation purposes requires identification (Chapter 3) to species. The science of taxonomy is in a constant state of ferment with different groups of organisms being moved from one genus, even one family, to another as better information becomes available. It is far from unusual for even birds (such as the carrion/hooded crow (now Corvus corone and C. cornix respectively)) and mammals (such as the pipistrelle bat (now Pipistrellus pipistrellus and P. pygmaeus) to be separated into two or more different species as a result of research, and this certainly occurs among invertebrate species. It may even be you who discovers that a ground beetle, thought to be one species but with fractionally different morphology prefers one microclimate to another, eventually resulting in taxonomic separation (for which discoverer's naming customs apply, although you may be advised to be cautious when naming a thick-skinned pest species or slimy gastropod after your spouse).
Specialist field guides (some of them in this series) exist for many groups, some of which can be identified in the field, although costs vary depending on the size of the print run: some can be picked up new for under twenty quid; others will annoy the bank manager, and this may well influence the taxa you decide to study. The extended reading list in this chapter is a good one, judging by those taxa I know something about, but it may be worth checking for more recent publications (at least a couple have been updated or there are more recent keys; this is based on a subsample from my own knowledge – I have a preferred reference on bumblebees for example, which was published after this book came out), and will be less use outside this archipelago.
About half the book is taken up by the methods by which you describe data, including examining community diversity and the similarities between communities, statistical testing and presenting and publishing your results. It's thoroughly intimidating (I passed my university statistics course through a great deal of hard work, much informal collaboration and a couple of fraught discussions with the tutor*). Conducting these studies is all very well, but they have limited value unless you publish. This is where good experimental design is critical. At least some of the science linked to various forms of agricultural and horticultural practices associated with Permaculture is of dubious scientific merit, and the field is riddled with overblown claims that do nothing but discredit the movement, some of which is based on nothing but the opinion of a practitioner or a set of circular references leading to little or nothing (did someone mention nutrient accumulators?). Poor interpretation extends as far as lists of papers that purportedly support one field which turn out to largely consist of papers examining one small branch of the subject, and are often badly conducted, not peer reviewed and/or published in predatory journals. http://www.permies.com/t/51968/permaculture/Comprehensive-List-Peer-Reviewed-Articles It's vital we adhere to the highest standards of ecological science, even as amateurs. Poor interpretation and overgeneralisation of inadequate or biased data doesn't help anybody. For instance, a finding of increased functional connections in your polyculture annual vegetable plot may be partially dependent on connections with your contiguous forest garden and may not be replicated by someone without one. An urban system will provide wildly different findings to a rural one, and this will differ from another rural one depending on the diversity of life in the surrounding area.
While comparability is a major problem for Permaculture, with enough of us providing similar results we might be able to better tease out what works under what conditions, but this requires many of us contributing to better science.
This book takes you from beginner to intermediate in the field of invertebrate study, potentially to publishable standard, on a very steep learning curve. I strongly recommend it, and it should be kept handy on your book shelf. Buy it, read it and use it. Studying invertebrates will not only help you understand your own habitat, but will help you to contribute to scientific knowledge on the novel ecosystems key to the development of Permaculture and agroecology, and perhaps also to broader ecological science.
* If you really want to get into this I recommend the now classic How to Lie With Statistics by Darrell Huff (Penguin 1991, but originally published in 1957). It helped get me through my stats course, and will help you evaluate claims by everyone from your local rancher to Monsanto to Pfizer to George Osborne. For real depth I suggest consulting an expert.