Sadanandan Nambiar, Canberra, Guest editorial Australian...

Sadanandan Nambiar, Canberra, Guest editorial Australian Forestry 2010 Vol. 73 No. 4 pp. 207?208
20.01.11 10:29 am



It took about 130 years to develop pine plantations in Australia from a block planting of 250 ha in South Australia in 1878?1879 to more than one million hectares today. In contrast, about one million hectares of eucalypt plantations have arisen in farmlands in just the last 20 years.

This new resource, dominated by blue gum (Eucalyptus globulus), was largely developed by managed investment
schemes (MIS). Today its future is in a precarious state as several MIS companies have fallen into bankruptcy, mainly because those investments were riding on business models fraught with high risk and in structures that rewarded fast profits?not profit through sustainable forestry.

Australians have invested, in addition to the generous tax support to MIS, hundreds of millions of dollars in eucalypt plantation research through three successive Co-operative Research Centres (CRCs), CSIRO, state
governments, universities and companies. In return, we have substantial knowledge about the opportunity for and risks of eucalypt plantations in our environments, as well as several useful decision-making tools and management prescriptions. There is also a wealth of knowledge from, and well-founded experience of, sustainable management in the softwood sector to draw upon.

Altogether we are well placed to practice sustainable plantation forestry. But what are the realities of blue gum forestry, now and in the immediate future? Is this resource on track to sustainable forestry? I argue, sadly, that three interrelated issues pose serious threats to sustainability.

First, consider the productivity of the first-rotation plantations. The levels of production achieved in the first rotation are, in many cases, at the lower end of the potential, and significantly less than the overzealous ?predicted production? figures in the glossy MIS prospectuses. Moreover, as discussed below, industry may not be sustaining even those low to modest levels of production in subsequent rotations. The low to modest growth rates in the first rotation at many sites were no surprise: those stands were established with stock from genetically unselected seed, and knowledge about prospective sites and silvicultural systems required for good management was in its infancy.

Some plantations grew at an MAI of 20 m3 ha?1, and others even reached 30 m3 ha?1 on a very few sites where the land (site) was fertile (thanks to decades of hard work and investment by farmers in legume-based farming that had enriched the resources of soil nitrogen and phosphorus) and profiles were deep and held adequate supplies of water. The rush to acquire land and inflated land prices pushed plantations to sites unsuitable for short-rotation commercial forestry (where stands are now languishing at an MAI of 10 m3 ha?1 or less), and a dearth of cash limited appropriate silviculture.

The high volumes promised to thousands of grower investors have been and remain on shaky ground. ?Commercial sensitivity? has prevented proper reviews of reality, but not loud whispers of concern in gatherings of foresters.

The second issue is that large areas where growth rates are uneconomic will be deforested in the coming years?and this process has begun. The extent to which this proceeds will be evident only when the fate of troubled MIS plantations is determined. Some industry leaders have suggested, in private, that up to 50% of the land under some MIS groups may go out of forestry.

If such plantations are harvested with eyes set solely on minimising the harvesting costs (as is the case now), we may be left with a legacy of serious adverse impacts on the land and perhaps water.

There is no reason that the land that grew trees cannot be or should not be converted to other sustainable land uses. The question is, will the impending harvesting and site clearing be done in ways that conserve site resources (see below) for the next cycle of land use, or will the whole-stand harvesting practices significantly degrade the land? And where will Australia?s future hardwood supply come from?

The third major issue is about the productivity of plantations that are already in the second rotation and those approaching a second rotation. Blue gum chips have been exported from Western Australia during the last ten years, and most harvested areas have been re-planted. As had been observed in Gippsland, Victoria, earlier (P. Whiteman, pers. comm.), the second-rotation plantations in Western Australia are growing more slowly than those in first rotation (?2R decline?), and such losses in volume may range from 20% to 50%. Despite the critical importance of this rapidly-emerging scenario, the widespread ?sensitivity? of the subject inhibits presentation of reliable data and transparent analysis.

There are of course reasons for this decline. Research in Western Australia has shown that first-rotation plantations may consume all available soil water stored to varying soil depth (having been accumulated when the land was under pasture), and second-rotation stands, in many cases, may start life facing soil-water deficits. In low- to medium-rainfall zones this deficit may be 1000?1500 mm (D. White and D. Mendham, CSIRO,
pers. comm.). Under such conditions, trees grow slowly or die.

The drought prevalent in the past decade has induced endemic water stress. In Australian environments, 50?80% of the variation in productivity can be attributed to site / soil factors that determine soil water availability (D. White, pers. comm.). Deployment of improved germplasm will not overcome the effects of endemic water stress on growth. New silvicultural approaches (e.g. reduced stocking) and / or longer periods of inter-rotation fallow to allow soil water recharge will be essential in the future.

Another cause of the decline in growth is harvesting practices that caused near-complete loss of above-ground pools of organic matter and the nutrients in them. Pressure to reduce costs is driving management decisions, and harvesting operations are a well-known target for cost cutting. Whole trees are dragged by the harvesting machines?often down-slope and baring soil along the way?to the roadside where the slash is piled and burnt.

Alternatively, slash is windrowed and burnt. I have seen evidence of soil loss in this type of operation recently. In all cases, these practices will degrade the site, depleting it of the organic matter and nutrient reserves significant for long-term productivity. The amount of organic matter (slash + litter) at blue gum sites after harvest may range from 50 to 80 t ha?1. Slash and litter contain large amounts of nutrients including 350?500 kg ha?1 nitrogen, 20?35 kg ha?1 phosphorus, 140?250 kg ha?1 potassium, and appreciable amounts of other elements including calcium, magnesium and micro-nutrients (Nambiar, unpublished). If the operation transported surface soil, losses would be even greater.

The total nitrogen in the slash and litter may account for 30% of the total pool of that nutrient on some Australian sites. These nutrient pools (transferred beyond the planted area and largely lost in fire) were gathered by the trees from the soil profile over their life cycle. The productive capacity of soil inherited by the foresters is the legacy of decades of careful legume-based farming by the farmers. Apart from the direct loss in fire and displacement, windrowing and burning will accelerate nitrogen mineralisation 40-fold (compared to pre-harvest), permitting nitrogen losses via leaching or surface run-off, especially if the soil is exposed by improper harvesting practice.

By deforestation and burning slash and litter at the conclusion of every rotation cycle, plantation forestry would also add to greenhouse gas emissions and forgo some of its carbon neutral or positive credentials.

Despite the seriousness of the issue and some industry-supported research-in-progress, there is neither a quantitative assessment of the extent of these problems nor a concerted approach to address them, even within industry-partnered cooperative research programs.

In stark contrast, when second-rotation decline threatened the pine industry in the 1960s in the Green Triangle of South Australia and Victoria, the foresters in the then SA Woods and Forests Department?followed by those in the then Forests Commission of Victoria?published their evidence of decline based on sound inventory data and encouraged others (e.g. CSIRO) to collaborate to find ways to solve the problem.

This leadership paved the way to positive outcomes.

Advocates of ?efficient harvesting technology? (measured in the narrowest sense of ?productivity? as dollars per unit volume harvested at roadside) and those promoting total biomass harvest (for energy production) tend to hold the view that the losses due to displacement and removal of organic matter and nutrients can be replaced by the application of fertiliser. A detailed discussion on this is beyond the scope of this article, but I emphasise that it is impossible to replace the losses using fertilisers and return the nutrient capital to levels anywhere near the initial levels.

It is not possible for biological, economic, energy and environmental reasons. Plantation harvesting practices in Australia must comply with principles of sustainability. If not, a single harvesting operation (over a few hours) followed by poor site preparation (over a few days) in 15-year-old blue gum plantations can deplete the fertility (built up over decades) of many sites to levels so low as to significantly affect future production in the next and or subsequent rotations.

This is unacceptable but avoidable.

I fear, given the current financial crisis of MIS ventures, that thousands of hectares of plantations may be felled ( deforested) during the next five years with little regard for sustainable land use, and that may penalise the next generation of the forest industry.

There are very few soils in the world, especially in the old land mass that is Australia, which can cope with the loss of critical site resources at every harvest in 15-year plantation cycles and then support sustainable forestry. The most critical single factor that caused the widespread and severe second-rotation decline in pine was the inter-rotation management practices (slash burning, windrowing and repeated cultivation) of that time.

Harvesting, site preparation, planting and early silviculture can pose a high risk to ecosystem processes and functions, but they also provide a window of opportunity to implement science-based best practice. It is a waste of resources to plant genetically-improved seedlings on sites that are progressively depleted of organic matter, nutrients and water. Practices that conserve site resources are used extensively (and profitably) in pine forestry in Australia (but disappointingly not across the whole country) and by pulp-rotation hardwood forestry operations in countries as diverse as Brazil, the Congo and Indonesia.

A sustainable forestry business can only be built on increasing and sustainable wood production, conservation of site resources, maintenance of the properties (and processes) of the natural resource base, due care for the environment and reasonable profit to the investors. These values must be in balance and in harmony.

If Australia?s eucalypt plantations are significantly declining in production after a single short rotation and the soil is degraded because of short-sighted management, what will be the enduring achievements of our science and management?

Apart from the question of sustaining production discussed here, several issues loom for the future of hardwood plantation forestry in Australia. These include the unfulfilled expectation that this resource would provide high-value logs for solid-wood industries and thus help to reduce the economic effect of declining log supply from native forests.

Access to native forests is clearly shrinking year by year, but what are the prospects of supplying quality logs from hardwood plantations in the next decade? The time has come for a prompt and open discussion on sustainable management of eucalypt plantations in Australia?to consider and chart the way forward for the eucalypt plantation estate so that the forest industry can legitimately claim to be sustainable.

The author, now retired, was a Chief Research Scientist in the former CSIRO Division of Forestry and Forest Products.

The article was first published on Tasmanian Times as First published: 2011-01-18 12:29 PM