Tag Archives: ecosystem dynamics

Two Visions of Ecological Research

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Let us assume for the moment that the goal of scientific ecology is to understand the reasons for changes in the distribution and abundance of animals, plants, and microbes. If you do not think this is our main agenda, perhaps you should not read further.

The conventional, old paradigm to achieve this goal is to obtain a good description of the natural history of the organisms of interest in a population or community, define the food web they operate within, and then determine by observations or manipulations the parameters that limit its distribution and abundance. This can be difficult to achieve in rich food webs with many species, and in systems in which the species are not yet taxonomically described, and particularly in microbe communities. Consequently a prerequisite of this paradigm is to have good taxonomy and to be able to recognize species X versus species Y. A whole variety of techniques can be used for this taxonomy, including morphology (the traditional approach) and genetics. Using this approach ecologists over the past 90 years have made much progress in deriving some tentative explanations for the changes that occur in populations and communities. If there has been a problem with this approach, it is largely because of disagreements about what data are sufficient to test hypothesis X, and whether the results of manipulation Y are convincing. A great deal of the accumulated data obtained with this approach has been useful to fisheries management, wildlife management, pest control, and agricultural production.

The new metagenomics paradigm, to use one label, suggests that this old approach is not getting us anywhere fast enough for microbial communities, and we need to forget most of this nonsense and get into sequencing, particularly for microbial communities. New improvements in the speed of doing this work makes it feasible. The question I wish to address here is not the validity or the great improvements in genetic analysis, but rather whether or not this approach can replace the conventional old paradigm. I appreciate that if we grab a sample of mud, water, or the bugs in an insect trap and grind it all up, and run it through these amazing sequencing machines, we get a very great amount of data. We then might try to associate some of these kinds of data with particular ‘species’ and this may well work in groups for which the morphological species are well described. But what do we do about the undescribed sequences? We know that microbial diversity is much higher than what we can currently culture in the laboratory. We can make rules about what to call unknown unit A, unknown unit B, and so on. That is fine, but now what? We are in some sense back where Linnaeus was in 1753 in giving names to plants.

Now comes the difficult bit. Do we just take the metagenomics approach and tack it on to the conventional approach, using unknown A, unknown B, etc. instead of Pseudomonas flavescens or Bacillus licheniformis? We cannot get very far this way because the first thing we need to decide is does unknown A a primary producer or unknown B a decomposer of complex organic molecules? So perhaps this leads us to invent a whole new taxonomy to replace the old one. But perhaps we will go another way to say we will answer questions with the new system like is this pond ecosystem changing in response to global warming or nutrient additions? We can describe many system shifts in DNA-terminology but will we have any knowledge of what they mean or how management might change these trends? We could work all this out in the long term I presume. So I guess my confusion is largely exactly which set of hypotheses are you going to test with the new metagenomics paradigm? I can see a great deal of alpha-descriptive information being captured but I am not sure where to go from there. My challenge to the developers of the new paradigm is to list a set of problems in the Earth’s ecosystems for which this new paradigm could provide better answers more quickly than the old approach.

Microbial ecology is certainly much more difficult to carry out than traditional ecology on macroscopic animals and plants. As such it should be able to use new technology that can improve understanding of the structure and function of microbe communities. All new advances in technology are helpful for solving some ecological problems and should be so used. The suggestion that the conventional approach is out of date should certainly be entertained but in the last 70 years the development of air photos, of radio telemetry, of satellite imagery, of electrophoresis, of simplified chemical analyses, of automated weather stations, and the new possibilities of genetic analysis have been most valuable to solving ecological questions for many of our larger species. But in every case, at every step we should be more careful to ask exactly what questions the new technology can answer. Piling up terabytes of data is not science and could in fact hinder science. We do not wish to validate the Rutherford prediction that our ecological science is “stamp collecting”.

On Understanding the Boreal Forest Ecosystem

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I have spent the last 40 years studying the Yukon boreal forest. When I tell this to my associates I get two quite different reactions. First, on the positive side they are impressed with the continuity of effort and the fact that we have learned a great deal about the interactions of species in the Canadian boreal forest (Krebs, Boutin, and Boonstra 2001). Alternatively, on the negative side, I am told I am at fault for doing something of no practical management importance for so long when there are critical conservation problems in our Canadian backyard. Clearly I prefer the positive view, but everyone can decide these issues for themself. What I would like to do here is to lay out what I think are the critical issues in the Canadian boreal forest that have not been addressed so far. I do this in the hope that someone will pick up the torch and look into some of them.

The first issue is that ecological studies of the boreal ecosystem are completely fractionated. The most obvious division is that we have studied the boreal forest in the southwest Yukon with few concurrent studies of the alpine tundra that rises above the forest in every range of mountains. The ecotone between the forest and the tundra is not a strict boundary for many plant species or for many of the vertebrate species we have studied. On a broader scale, there are few studies of aquatic ecosystems within the boreal zone, either in lakes or streams, another disconnect. The wildlife management authorities are concerned with the large vertebrates – moose, bears, caribou, mountain sheep – and this work tends not to tie in with other work on the smaller species in the food web. Interests in the carbon dynamics of the boreal zone have greatly increased but these studies in Canada are also completely disconnected from all other ecological studies that consider population and community dynamics. I think it is fair to say that carbon dynamics in the boreal forest could turn out to be a very local affair, and too much generalization has already been made with too little spatial and temporal data.

One could consider the ecology of the boreal zone like a puzzle, with bits of the puzzle being put together well by researches in one particular area, but with no view of the major dimensions of the total puzzle. This is readily understood when much of the research is done as part of graduate thesis work that has a limit of 4-5 years before researchers move on to another position. It is also a reflection of the low funding that ecology receives.

Within the Yukon boreal forest there are several areas of research that we have not been able to address in the time I and my many colleagues have worked there. Mushroom crops come and go in apparent response to rainfall (Krebs et al. 2008) but we do not know the species of above ground mushrooms and consequently do not know if their fluctuations are uniform or if some species have specialized requirements. Since fungi are probably the main decomposers in this ecosystem, knowing which species will do what as climate changes could be important. On a practical level, foresters are determined to begin logging more and more in the boreal zone but we have no clear understanding of tree regeneration or indeed any good studies of forest succession after fire or logging. Since logging in northern climates is more of a mining operation than a sustainable exercise, such information might be useful before we proceed too far. If the turnaround for a logged forest is of the order of 300 years, any kind of logging is unsustainable in the human time frame.

The list goes on. Snowshoe hare cycles vary greatly in amplitude and we suspect that this is due to predator abundance at the start of any 10 year cycle (Krebs et al. 2013).  The means to test this idea are readily available – satellite telemetry – but it would require a lot of money because these collars are expensive and need to be deployed on lynx, coyotes, and great-horned owls at least. And it needs to be done on a landscape scale with cooperating groups in Alaska, the Yukon, the Northwest Territories, and British Columbia at least. Large-scale ecology to be sure, but the results would be amazing. Radio-telemetry has the ability to interest the public, and each school in the region could have their tagged animals to follow every week. Physicists manage to convince the public that they need lots of money to do large experiments, but ecologists with down to earth questions are loath to ask for a lot of money to find out how the world works on a large scale.

Migratory songbirds have been largely ignored in the boreal forest, partly because they leave Canada after the summer breeding period but at least some of these songbirds appear to be declining in numbers with no clear reason. Yet studies on them are virtually absent, and we monitor numbers in imprecise ways, and continue to mark the position of the deck chairs on the Titanic with no understanding of why it is sinking.

Insect populations in the boreal forest are rarely studied unless they are causing immediate damage to trees, and consequently we have little information on their roles in ecosystem changes.

At the end of this list we can say in the best manner of the investigative reporter why did you not do these things already? The answer to that is also informative. It is because almost all this completed research has been done by university professors and their graduate students and postdocs. What has been done by all my colleagues is amazing because they are not in charge of the boreal forest. The people are, via their governments, provincial and federal. The main job of all of us when this research in the Yukon boreal forest was being done has been education –to teach and do research that will train students in the best methods available. So if you wish to be an investigative reporter, it is best to ask why governments across the board have not funded the federal and provincial research groups that had as their mandate to understand how this ecosystem operates. Because all these questions are about long-term changes, the research group must be stable in funding and person-power in the long term. There is nothing I have seen in my lifetime that comes close to this in government for environmental work except for weather stations. In the short term our governments work to the minute with re-election in sight, and long term vision is suppressed. The environment is seen as a source of dollars and as a convenient garbage can and science only gets in the way of exploitation. And in the end Mother Nature will take care of herself, so they hope. Perhaps we need a few Bill Gates’ types to get interested in funding long-term research.

But there remain for ecologists many interesting questions that are at present not answered, and will help us complete the picture of how this large ecosystem operates.

Krebs, C.J., S. Boutin, and R. Boonstra, editors. 2001. Ecosystem Dynamics of the Boreal Forest: the Kluane Project. Oxford University Press, New York.

Krebs, C.J., P. Carrier, S. Boutin, R. Boonstra, and E.J. Hofer. 2008. Mushroom crops in relation to weather in the southwestern Yukon. Botany 86:1497-1502.

Krebs, C.J., K. Kielland, J. Bryant, M. O’Donoghue, F. Doyle, C. McIntyre, D. DiFolco, N. Berg, S. Carrier, R. Boonstra, S. Boutin, A.J. Kenney, D.G. Reid, K. Bodony, J. Putera, and T. Burke. 2013. Synchrony in the snowshoe hare cycle in northwestern North America, 1970-2012. Canadian Journal of Zoology 91:562-572.