Species'ism

Is it ok to be species'ist - to advance one species or retard another just because of its species?

We seem to have concluded that racism and sexism - advancing or retarding individuals just because of their race or gender - is not ok. But what about whole species?

Species'ism seems to happen a lot in nature. In fact, a colleague and I recently found that one species of tree has been comprehensively retarded over 2,000 square kilometres of the Cooma-Monaro plains of southern NSW. Every individual Eucalyptus viminalis - Ribbon Gum - is either dead or dying in this extensive area. The Ribbon Gum was an iconic tree of this region, common on the rocky knolls and hills around fertile grazing and farming land. You can still see healthy trees in the region ...but if it is healthy it is not a Ribbon Gum.

We don't know why this one species is dying while the snow gums and other trees around are not. We do know insects are involved, but they are not the sole or even primary cause. We suspect that drought or changes to the rainfall patterns or to minimum and maximum temperature regimes might be affecting this one species to a much greater extent than others. There may even be some impact on this one species caused by changes in the local fire regime - too few, or too hot, or just too different to the pre-European fires. We do know that the once extensive stands of Ribbon Gum are all dead. We know this species won't be coming back at least for quite some time if ever. Nature, or the heavens, or even climate change has practiced species'ism to a fatal extent here.

We also know that something else will take over the place these trees previously occupied - something else will use the sun, the water and the nutrients that those Ribbon Gums used to use. Do we care what takes over? Do we want to promote one species over another? Should we actively intervene by planting our preferred species or be passive and just let any local "disturbance adapted" species win this 2,000 square kilometre home?

If a species that we do not want takes over this land, we define it as a "weed" and happily practice species'ism. But why should we choose not to want a species that can grow where Ribbon Gum clearly can no longer survive? The reasons for species'ism vary from the new species not providing the ecological services we are used to, through to aesthetics, and even that the new species are just "not from around here".

All trees provide a range of ecological services to different extents. They all produce oxygen, they all sequester carbon, they all slow and filter water. Some trees are more preferred as the habitat of birds or aerborial mammals while others are better at sheltering ground and bark dwelling insects. Some do more while some do less, but none will do exactly what a stand of Ribbon Gum used to do.

Aesthetics too are confusing. Humans tend to like what they are used to, and they have been used to Ribbon Gums in these lands. Although these trees have been dying for a decade now, so maybe the humans travelling through this region think dead trees are attractive!

Like racism, the argument that species are just "not from around here" is very often the only reason given for Species'ism. Often passionate arguments are made that only local species, grown from locally collected seeds should be planted in any restoration or revegetation project. But, the local Ribbon Gum will no longer survive. So, do we plant Ribbon Gum from areas far away that might cope with whatever killed the current trees - the natural range for Ribbon Gum is extensive and goes from Tasmania through Victoria and up the coast of NSW and someone could probably trial a huge selection if there was time. Does that violate the "not from around here" bias? But if we don't really know what killed the current Ribbon Gum, how could we really risk planting more Ribbon Gums? Is a Ribbon Gum grown from a seed collected in Tasmania more "local" than seed from another species of Eucalyptus grown only 10's or 100's of kilometres away from the dead Monaro plains? How important is it that the species remains "pure"?

How do we value the trees and their ecosystems services and aesthetics? How do we balance our understanding of the history or iconic nature of one species with the risk its time has come! How do we choose between species? These are not simple questions and they can't be answered by by scientists or economists or conservationists or engineers or community activists or even artists working alone.

 

Three Trillion Trees

A new report out of Yale University and published in Nature concludes that, globally, there are over 3 trillion trees alive today! This figure, they say, is substantially greater than the previous estimates of only 400 billion trees. However, the study also concludes that the world is loosing 15 million of these trees every year. Some really big numbers there, and given that measuring forests is actually one of my areas of research, I have had my 5 minutes of "fame" on national radio and TV talking about these numbers.

Is the beauty or the value of this scene related to the number of trees?

"How did previous researchers get it so wrong?" is the question I get asked, often with the follow up of "does this new information change anything?" Well, I am not entirely positive that the new estimate of 3 trillion trees is totally right either, but don't think details about non-normal error distributions and back-transformations would make anybody other than statisticians, biometricians or mensurationists sit up and listen - so I won't talk about that here. But if the differences between the estimates are real, it is probably more likely to be due to previous studies not being interested in the number of trees - they simply estimated that for completeness. "But why wouldn't we be interested in the number of trees?" I sense you asking. The number of trees is only useful when you know the size and distribution of those trees, so most previous studies have concentrated on estimating total biomass, carbon or volume of the trees and mapping that. These total values essentially are the result of multiplying number and average size together and so total biomass or volume give you both number and average size in the one figure. A forest with 10,000 small trees may have the same biomass as another with only 800 large trees, so loosing 800 trees may be important in one forest but not in another. However, a forest with a large biomass will tend to have greater biodiversity, stored (sequestered) carbon and other ecosystem services than a forest with low biomass. Studies of isolated trees in farm paddocks and urban areas demonstrate that even a single tree of the right size and in the right place may have substantially greater value to ecosystem services, birds, animals and even aesthetics than hundreds of trees elsewhere. With trees, it is not always the case that one plus one equals two!

The number of trees also changes substantially in any patch of forest over time. In eucalyptus forests after a major fire, thousands or even tens of thousands of trees may germinate and race towards the heavens. However, as early as three years of age, these trees will start to compete and many will die so by about 80 years, there may only be about 300 - 800 trees left living. Then however, other types of trees (shade tolerant ones) might get involved and start growing underneath these surviving eucalyptus giants, so the number of trees start increasing again. Given enough time, those original eucalypts will die of old age or wind and fire damage (number goes down again) which might allow a whole new race of young trees for the heavens (increasing the number). While the number of trees goes up and down through this natural sequence, the total biomass and even the total biodiversity tends to always increase. So, it is better to measure biomass than number of trees because it is more closely related to what we really want to know about, and it is also easier because we don't have to worry about the noisy increases and deceases in number through time.

So, was there any advantage in undertaking and publishing this study on the number of trees? It may be simply that people have a better understanding for numbers of a count of trees rather than the area in hectares of forest or the biomass in tonnes. People might be able to connect better with the idea of 15 million trees being lost each year to agriculture whereas they cannot come to terms with thousands of hectares undergoing land use change. People in general are not too good at estimating area once it gets beyond, say, a football field (do you know how big a football field is?). We may be even worse when estimating weights - how many tonnes is a Blue Whale, so how many equivalent Blue Whales are cleared for agriculture this year? On the other hand, do you really appreciate how many zeros there are in a Trillion?

The Nature article itself stated that civil societies resonate with programs like the "Billion Tree" or even "Million Tree" urban planting goals, so putting a count of the number of trees might help civil society to comprehend the size and importance of the forest. This is probably the greatest benefit of the study - and certainly the reason I was invited to the TV and Radio for my bit of fame. Fame and civic awareness of forests are certainly good things even if forest ecologists, scientists and foresters wont really care about the final big number.

Me at the Canberra studio, waiting for the Prime Minister of Australia to finish so I can have my say on trees.

 

 

Reserving a big new National Park

If the current reserve system in Victoria - both formal and informal - cannot save Leadbeater's Possum, why would just adding area to the formal reserve system will make a positive difference?

A substantial increase in the formal area of reserve in Victoria, by itself, would not "save" the possum. At the very least, such an increase would need to occur in conjunction with an even more substantial increase in funding and resources to offer a chance of success. It is myth that National Parks can simply be locked up and left to follow healthy and sustainable trends. In cases where reserves have been simply fenced in, the ecosystems often drift off to something unexpected and undesirable as the result of altered fire or flood regimes, or invasive species, or a combination of factors. Active management, resource intensive management, will be increasingly needed for our existing reserves to "save" species in the face of ecological change wrought by climate change and other human impacts. Extension of the reserve boundaries will have to consider active management and substantial increases in funding. No doubt this will be an uncomfortable debate for many people, but one that is needed.

These extra resources won't be just for an extension of the track system, or better maintenance of fire trails, or better rubbish removal, or even more research that describes the current populations. In the specific case of Leadbetter's possum, if the lack of habitat hollows is already a population threatening problem, and hollows are not being formed naturally at a sufficiently fast rate, then active management will be necessary to correct this imbalance - just waiting another 70 years and hoping everything survives that long is not a recipe for success. The predominant factor relating to hollow development is tree size, and Foresters especially trained in silviculture and forest ecology, know how to manipulate population pressures within a forest to ensure a minimum number of trees can grow to reach the size to support hollow development in the minimum amount of time. Further, they can appropriately "damage" the crown of appropriate trees to speed up hollow development. The wait for hollows to home the possum can be substantially reduced from 70 years with active management. But such an exercise is expensive, labour intensive and will require some trees to be felled.

An even greater problem for under-resourced reserves is that weeds will take natural advantage of increased stress caused by changes in fire regimes or climate. Similarly, pest populations will boom as natural control mechanisms falter under already observed changes. How will the existing reserve system cope if Australia suffers a pest outbreak like the mountain pine beetle experienced in Canada? What happens to the potential for control or mitigation if the reserve system is twice as large due to an under funded increase in area? Active management was seen as an essential part of coping with this pine beetle outbreak with the Canadian Government providing substantial funding to First Nations, communities and school districts for fuel management and hazard tree removal in post-infested areas, as well as recovering some costs by selling the killed timber.

Changed fire regimes in the US have changed the species composition and structure of the forests leading to more mega fires than ever before. Active management is being pursued in the U.S., and products are being sold to offset some of the costs of management. United States taxpayers are fully funding their program but American Professor Scott Stephens said about 40 per cent of the cost of implementing the program is covered by repurposing the cleared timber (i.e. selling it as garden mulch, woodchip, fence posts of even sawn lumber).

An increasing concern is that Eucalypts have particularly poor dispersal capabilities, so natural stands will be generally be unable to track changing climatic conditions. (Booth et al, 2015). Will active management be needed to translocate species to new environments? Species like the "pioneer" Eucalyptus that dominate after a fire, need bare ground at least 80 m from standing dominant trees for their seeds to germinate and grow well. However, if the climate warms and the rainfall patterns change as predicted in many reputable Australian climate models, will these large gaps of bare earth may become too hot and dry for successful natural regeneration? Will reserve workers need to manually plant and water seedlings to avoid a species change?

More money and resources need to be allocated to the existing Reserves and National Parks to give a chance to "save" what humans hold precious. Substantially more funding will be required if the area of reserves increases - there is little opportunity for "economies of scale" in the reserve system management because each additional hectare added is unique. Without a substantial increase in general tax payer funding the reserve managers need opportunities to co-fund their own maintenance and safe keeping. Payments for ecosystem services have long been held out as a way of generating these sorts of funds, but the mechanisms for such funding are far from developed and active. Sale of products extracted from the reserves, especially when the mass of those products may themselves be contributing to the problem, is a much more immediate source for funding.

 

How much is enough?

Everyone knew that Prime Minister Abbot would create headlines when his speech to a major Forest Industries dinner included  a suggestion that we had "enough", or even too much, protected forest.  The suggestion of enough or too much begs the question "...for what?"

There are some famous thresholds in science where "enough is enough" is measured. LD50 - the level of drug dosage that results in the death of 50% of a target population is one such measure. Significance levels, eg p=0.05 which is where you accept there is a 0.05 or 1 in 20 chance that the important difference you think you can see is simply a bit of random luck. But even these thresholds are arbitrary and indefensible except through claims that "we have always used them". Significance levels in fact vary between disciplines as well as countries and levels of p might be as high as 0.3 in wildlife ecological studies or as small as 0.0001 in medicine where you really want to be quite sure your drugs have the effect you want. 

Similarly, thresholds of the fraction of land in reserves exist but are largely arbitrary. Early discussions about "CAR" reserves - Comprehensive, Adequate and Representative - in the late 20th century started with suggestions that adequate meant 5% of the area pre-European conversion for each major forest type. This percentage has progressively climbed to 10%, 12%, 15% and currently sits around 17%, with each increase due to temporal arguments to balance economic, political, social and ecological values. Simultaneously, the forests are being more finely classified and divided and restrictions placed on what can be done near the boundaries of the reserves. This fine sub-division and restricted activity means that reserves can impact a significantly larger area that just that within their boundaries. Imagine, for example, that you had to reserve 10% of your home, say to let your aged parents move in, and you could not walk within 1m of the reserve boundary. You might loose a bedroom or your study. But if to had to reserve 10% of each room and not come within 1 m of those boundaries you would loose access to the toilet and any room less than 2-3 m in length. In fact, your hallway would probably be cut and you would loose access to half your house. So, how much really is being reserved by a 10% reserve? 

But why a nominal 10% area even if it results in substantially more than a 10%  reservation? Why not 11%, and if 11% why not 12% and so on? Must you stop before 50% while you can say the reserves are a minority use. In contemporary news, the difference between 49% and 51% is massive for QANTAS - the right to call yourself the Australian carrier and the need to employ Australians and manage for Australian good apparently revolves around whether 49% or 51% can be in foreign ownership. The difference between 49 and 51 may have great importance in business and in democratic elections, but it has no real significance in ecology. 

If a scientist looks in sufficient detail, any hectare that could be added to a reserve will be uniquely different to all the others already in the reserve. Nature is full of diversity at a variety of scales and although two areas may look to be the same to a human with their poor senses, they in fact will be different. So if you want to reserve a bit of every different environment you have to reserve all the hectares. If the Department of Heritage wanted to reserve one of every unique house, you would have yours, wherever it is, reserved. 

So obviously we do not reserve everything - we need to keep somewhere for ourselves to live and to produce the things we need to live. In the past, the majority of forest was converted to agriculture and urban development. When people say that 85% of our forests have been lost, it is to agriculture and cities that they have been lost. And these land uses must actively continue to keep the forests at bay - if you abandoned Sydney or Melbourne or the Queensland cattle farms, the forests would return. Should we try? Let's take 10% of Sydney and remove the offices and houses to allow the forests to return - they will return, and those forests will be unique and therefore worthy of being reserved. That would return more than twice as much forest as the area being disputed in Tasmania now. Why stop at 10% ...or 15% ...or 50%? 

But of course we could not reserve and return 10% of Sydney to its pre-European forest nature. Where would the people live and work? There has to be a balance between people being able to live and work against reserving arbitrary percentages of land.