SUBJECT: RE: Ecological value of ecosystems
AUTHOR: John Hutcheson
DATE: 7th April 2003

KEYWORDS: Unitary system, Coleoptera, trophic links, biosecurity.

SUMMARY: The author repeats his plea for inclusion of recognition of the characteristics of biodiversity at all scales and gives some reasons for doing so. He introduces some scientific heresy, redefines the questions for terrestrial systems as he sees them, provides a practical approach to answering them which is valid for NZ systems, and gives some basic information returned from use of the approach.

In his response to my urging us to include emphasis on the characteristics of biodiversity as a unitary system at the global scale, Martin Sharman focused our attention back onto our present recognition of the characteristics of biodiversity as the separate components we see when wearing our various taxonomic hats. However, we could just as easily (if we could see a reason for it, and psychologically adjust to it) characterize biodiversity as the total unified system, just as we presently characterize both the components and the totality of individual organisms. All organisms are both composites of, and components of, other organisms/systems anyway, to the extent that recognizing an 'individual' requires us to close our minds to everything not defined within the taxonomic group we choose to be seeing. Although the term biodiversity attempts to move us toward a broader appreciation of the biosphere, it has been co-opted by a numericist industry which attempts to understand ecology through eg., 'diversity indices' that ignore the core subject of the biological attributes of the components.

Obviously we will continue to characterize the biosphere in terms of species as these lifestyles represent the various ecological pathways and networks we are attempting to understand. And without such a classification we cannot communicate. We already use the finer scale of genotype in agriculture and conservation, and the larger scale of system level currently drives some policy. But what are the practical gains from an adjustment of our perception to include life at the largest global scale?

Well, it is much simpler to make a strong case that high biodiversity is important when we are contemplating a whole rather than just subsets. Although some natural subsystems function well with apparently low diversity, if we perceive the larger scale we can more easily appreciate the role of diverse genotypes as providing contingency pathways within a variable environment. We can also better appreciate them as functional components of the properties such as global environmental stability, which become emergent at the larger scale. We can thus more easily appreciate that any loss - is a loss of contingency provision. Although this lost potential cannot be experimentally measured, any loss represents a direct threat to the long term, larger scale, environmental stability that our societal structures have become globally dependent upon. The more holistic point of view gets us away from arguments about how much of the patient's body can be surgically removed before death, and better reminds us that we are the patient.

Not emphasizing the whole may also narrow our perception of the tools available for remedial measures. For example, it is quite possible that a spiritual appreciation of biodiversity could better win the hearts and minds of all folk over to the necessary task of conservation of this miracle of life (note that there are no known laws of physics which say that life should arrange itself in this manner (Davies 2002)), than science could ever manage. Every hardnosed, agnostic scientist I know who has worked in natural systems has experienced exalted moments of appreciation of the beauty of life. But this tends to happen when sitting down having lunch and contemplating the whole, rather than when one is busily counting body parts.

If we see life as a complete system we can also better appreciate that biodiversity provides the environment for all species in the system, i.e. the 'environment' of all organisms IS their biotic community. The physical environment that we as scientists measure so assiduously is separated (buffered) from the organisms by the biotic community itself. The loss of any genotype is therefore likely to impinge on the environmental requirements of the remainder of the community, particularly as current understanding suggests that this would lead to less moderation of fluctuations in the physical environment. As we know, when their environmental requirements are not being met, species cannot persist and so the species-loss effect of physical fluctuations within say forest fragments would be expected to accumulate as community change over time, eventually leading to our recognition of system change at the larger scale.

As an aside, this broader perspective also more easily enables us to appreciate that it is the surrounding biotic community that directly selects the fittest subunits - and therefore that evolution is directed by the community (Just to introduce a little heresy into the religion of science).

Once we realize that biodiversity provides both detail and context for our society, the 'better question' becomes 'how does our planetary management affect biodiversity?' This question drives us to seek information at two perceptual levels. The first is local systems as the land manager perceives them, i.e., vegetation. These systems are already being mapped using GIS technology for large areas of the world. The scale and accuracy is continually being refined, but eg., New Zealand already has a mapped conservation hierarchy of ecological regions and districts, and within these, areas of conservation interest. Vegetation systems of the economically productive landscape are also very well documented. However, live vegetation represents current production, while most of biodiversity is involved in retention of past production within the system.

So what we are sadly lacking are the links between the systems we see, and the characteristics of the biodiversity they are comprised of. Because different species have different environmental requirements, no taxonomic group of limited membership and system presence can be used to infer the characteristics of biodiversity in the broader community (Eg. you can't learn much from shark communities in a desert). This directs us toward the largest section of biodiversity (and the total dominants of terrestrial biodiversity), the insects. Not just as taxonomic lists, but as lifestyle networks to illustrate the linkages between biodiversity as 'characterized' at the scales of communities of species and individuals, and the systems recognized by the land managers.

Within the insects, beetles appear to provide about half the species. Therefore any indicator (such as vegetation), which has not first been 'calibrated' against beetle communities cannot claim to represent biodiversity. The extremely diverse range of lifestyles within Coleoptera communities can provide us with functional (eg. trophic) summaries of what each vegetation system type and dynamic represents in terms of its biodiversity 'characteristics'. These may then guide us in our management of the vast areas of the globe that are currently managed as though land was a simple physical commodity rather than a global biological entity.

The message from NZ beetle community samples is that biodiversity represents the jobs needing to be done in the system. Thus beetle biodiversity is vital for forest carbon recycling, and wood to recycle is vital for beetle biodiversity. It is instructive that use of vegetation alone as an indicator would exclude our rapidly growing exotic (for NZ) pine plantations from consideration of endemic biodiversity. However beetle community samples show they contribute a vast amount to the retention of indigenous NZ biodiversity (Hutcheson and Jones 1999). The extremely rapid carbon acquisition and turnover in these systems is reflected in much higher species richness and abundance of (almost all endemic) species at the local site level than found with native vegetation systems on similar (pumice) soils (Hutcheson and Kimberley 1999). However, over the larger spatial scale (in terms of both area and structure), sample composition reflects the much greater homogeneity within plantations. This accords with the obvious fact that landscape diversity is necessary for the retention of associated biodiversity as characterized at the species level.

Samples from sustainably managed private indigenous forest, reveal beetle biodiversity to be enhanced by limited forest disturbance (as this provides the recycling resource), and thus that a policy of judicious utilization is therefore not anathema to biodiversity (Brooks 2001). This latter finding is to be welcomed because in order to attempt to slow the loss of global climatic buffering, we need to radically and rapidly enlarge natural forested areas. Because humans are everywhere, to do so we will need to live amongst them and utilize them.

NZ has locally endemic species wherever sufficiently skilled people have looked (e.g. Kuschel 1990). However there is still separation of the conservation and utilization lobbies in this country. Neither lobby seems yet to comprehend that we cannot afford such separation, that conservation must be global or human society loses - probably in the short to medium, rather than the long term. This therefore means that while we must extend and utilize natural systems, all our utilization processes and systems must be scrutinized for their relative destructiveness (or otherwise) to the components of biodiversity. The only way to do this is to examine the heart of biodiversity (the beetles) within our land management systems using a standardized sampling system. A national (or international) coordinated approach to such work would have major positive spinoff for ecological understanding, biodiversity conservation and biosecurity (in the agricultural sense rather than the paranoid American one).

References

Brooks, D.F. 2001. Selective Logging in Silver Beech Forest (Nothofagus menziesii): Monitoring with Beetles. B Sc (Hons) Thesis. University of Canterbury, New Zealand.

Davies, P. 2002. Seven Wonders. The seven biggest questions in physics. New Scientist, 21 Sept. pp 28-33.

Hutcheson, J.; Jones, D. 1999. Spatial variability of insect communities in a homogenous system: Measuring biodiversity using Malaise trapped beetles in a Pinus radiata plantation in New Zealand. Forest Ecology and Management 118: 93-105.

Hutcheson J.A.; Kimberley, M.O. 1999: A pragmatic approach to insect community characterisation: Malaise trapped beetles. New Zealand Journal of Ecology 23(1): 69-79.

Kuschel, G. 1990. Beetles in a suburban environment: a New Zealand case study. DSIR Plant Protection report no. 3.

A contribution by:

John Hutcheson
Biological systems Ltd.
Forest Research Associates
POBox 1031, Rotorua, New Zealand