Why we are measuring the health of Australian vegetation poorly



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The Victorian mountain ash forest has been severely affected by fires and logging. To determine the actual health of the forest, we need to look at the quality, not just the quantity of what remains.
Graeme/flickr, CC BY-NC

Ayesha Tulloch, University of Sydney; David Lindenmayer, Australian National University, and Hugh Possingham, The University of Queensland

Many of Australia’s ecosystems are in a much worse condition than we think. This is because officials are measuring the health of ecosystems such as forests and woodlands by their size, instead of how damaged they are by disturbances.

A “disturbance” is a short-term change in environmental conditions that leads to a long-term change in an ecosystem. Some habitat disturbances are natural, such as some fires and extreme weather events. Others are created by human activities, such as logging, pollution, intensive grazing, and mining.




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Frequent or intense disturbances generally pose a bigger threat to the health of an ecosystem and it’s not limited to the area of the ecosystem that is lost. This is because the quality of the vegetation that survives a disturbance, such as a fire, may be too low to support the animals that rely on it for food and shelter.

It is much easier simply to measure ecosystem extent rather than ecosystem condition. However, focusing on quantity instead of quality leads to less informed decisions about where and how to conserve native habitats and the wildlife that lives in it.

Disturbances to habitats

Disturbances have grown in frequency and variety. This is one of the major causes of habitat degradation.

Fires are a common and dangerous disturbance to many Australian habitats. The number of bushfires per week in Australia increased by 40% between 2008 and 2013. Increases in the frequency of fires due to human activity have led to the decline or extinction of more than 100 species and declines in at least 29 threatened ecological communities listed in Australia’s Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).

Burnt and unburnt mallee heath in southwest Australia.
Ashley Pearce/Angela Sanders

More attention is now being paid to evaluating the risk of our ecosystems going extinct. But most of the attention is only on the area of vegetation that has been lost, which is easy to map and calculate thanks to images from satellites.

Measuring the disturbances

In a recent study, we found that some Australian ecosystems are more threatened than might be suggested by looking simply at vegetation loss.

We made this discovery by assessing “whole-of-ecosystem degradation”. This calculation is a two-step process. First, we observe the different ages of the vegetation, known as their “age classes”, in an area. Then, we compare how far the current distribution falls short of the ideal distribution of the group of plants that make up that vegetation community.

Some species (such as large trees) require long intervals between disturbances to allow them to have time to mature and reproduce, so their “ideal” age class distribution will have many old plants and fewer young plants. Other species (such as some fast-growing shrubs) prefer short intervals between disturbances, and their ideal age class distribution will have more young plants than old plants.

The “whole-of-ecosystem degradation” approach

We used this approach to look at the dominant plants and animals in two vegetation types: the protea-rich mallee-heath of southwestern Australia, and Victoria’s mountain ash forest.

Banksias are a key component of the ecosystem in the protea-rich mallee-heath forest.
from http://www.shutterstock.com

In the mallee-heath, the ideal distribution was based on the needs of Banksia species (which are in the Proteacea family). These plants provide critical nectar and pollen resources to many animals such as honey possums and honeyeaters. Many Banksias are long-lived and require up to 80 years between fires to maximise reproductive potential.

Our study showed that the banksia age-class distribution in this ecosystem is unbalanced, and therefore much poorer than indicated by information about just quantity. There are more young banksias (up to ten years old) and fewer older ones (more than 40 years old) than might otherwise be expected.

In simpler terms, the frequency of fire is clearly not able to support the flowering of banksia species, resulting in low habitat quality.

In the mountain ash (Eucalyptus regnans) forest, we used the food and shelter needs of the yellow-bellied glider (Petaurus australis) to assess forest health. This animal is already a threatened mammal.

Fire and logging have disturbed almost 50% of the forest in the last 30 years. Fires here are rare but of high intensity and severity, killing the trees in which these mammals live.

Again, our research shows that the remaining forest is in very poor condition. Compared to what would ideally be expected 120 years after a fire, the forest has more vegetation in very young (less than eight years old) and mid-age (up to 75 years old) age classes, and less vegetation in very old (more than 76 years old) age classes.

To sustain food sources and hollows for the yellow-bellied glider, the mountain ash would need to be protected from disturbance between 40 and 160 years.

The ideal time interval between fire disturbances to provide food and shelter to yellow-bellied gliders in mountain ash forest is more than 120 years, to allow new trees to grow after burning kills old trees. Photos show progression from newly burnt to old growth forest.
David Blair/Tabitha Boyer

Understanding the effect of disturbances

Our research shows that measuring an ecosystem’s health by its size alone can be misleading, especially when the area is large but severely degraded.

It is therefore crucial to consider disturbances when evaluating ecosystems. This is especially so when forest health is being assessed for listing through the IUCN Red List of Ecosystems, or for conservation planning and management.




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We recommend that decision-makers be more aware of the role of disturbances in degrading ecosystems. This requires two crucial elements of information.

First, we need good maps that tell us when the last disturbance in an area was. This kind of mapping is carried out within our protected reserve system, but is not currently available at a national scale.

Second, we need a better understanding of ideal benchmarks of ecosystems to compare with the current conditions. Benchmarks may be linked to the needs of dominant plant species (such as banksia in mallee-heath) or the needs of dependent species of concern (such as yellow-bellied glider in mountain ash).

The ConversationWe propose that our method be applied to evaluate the condition of different ecosystems. This will ensure that ecosystem declines are identified before systems cannot be recovered.

Ayesha Tulloch, DECRA Research Fellow, University of Sydney; David Lindenmayer, Professor, The Fenner School of Environment and Society, Australian National University, and Hugh Possingham, Professor, The University of Queensland

This article was originally published on The Conversation. Read the original article.

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The NSW government is choosing to undermine native vegetation and biodiversity


Neil Perry, Western Sydney University

While everyone’s eyes were turned to the Federal budget last Tuesday, the NSW government released a very controversial piece of draft legislation that will remove restrictions on land clearance and, despite their claims, threaten biodiversity.

The new reforms implement the recommendations made in the NSW Biodiversity Legislation Review but the economic assumptions underlying both documents are not accurate or acceptable.

The reforms aim to “conserve biodiversity” and “facilitate ecologically sustainable development”. However, they will only do so in a perfect world where farmers have complete knowledge about the value of native vegetation, where there are no spillover effects from land clearance, and where landowners care about the long-run condition of the land as much as they care about current income. Outside of this world, the Baird government’s reforms will lead to large increases in land clearance, increased carbon emissions and more threats to endangered species.

While some aspects of the new legislation are informed by ecological science, the main approach derives from economic theory. Essentially, the government will repeal the Native Vegetation Act, 2003 (NVA), which restricted land clearance on farms, and replace it with a market-based approach that provides flexibility for farmers to clear land.

While the NVA had certain exemptions where land clearance was allowed, the new Biodiversity Conservation Act has many more and applies a risk-based approach. The risk is loosely framed around threats to endangered species or communities. For example, low-risk vegetation includes land that has been cleared at some point in the last 25 years, and grasslands assessed as being of low conservation value.

Based on a farmer’s self-assessment of risk, land clearance is allowed at the lower risk levels while it requires approval at higher risk levels from Local Land Services – administrative bodies that can include other farmers as members (itself a possible conflict of interest). A biodiversity market can be used to offset land clearance impacts at these high-risk levels. That is, landowners who clear land can either buy credits in the Biobanking scheme or pay money into a biodiversity trust fund.

In contrast, under the NVA, any approved land clearance had to be offset by improving the environmental condition of other areas on the property. This ensured protection for biodiversity at the local level.

Thus, the new approach will “broaden and deepen” the use of biodiversity markets and it will apply offsetting at the regional and State level rather than the local level, which means that local biodiversity will be lost.

The government’s argument for taking this approach is that the current system “doesn’t deliver”. This is simply not true. Since the NVA was implemented in 2004/5, land clearance for agriculture has reduced from an average of 21,500 hectares to 16,000 hectares per year. A 2009 review of the NVA stated that from 2006-2008 the legislation led directly to the conservation or rehabilitation of 250,000 hectares.

Thus, if the aim is to conserve biodiversity and deliver ecologically sustainable development, the NVA certainly has delivered. Of course, the NVA may not be delivering maximum short-term economic gains for some farmers and large agribusiness firms, but that is another matter.

The underlying economic assumptions don’t stack up to reality

The government claims that the new legislation will both facilitate economic development and protect the environment. By giving farmers more freedom, they say, native vegetation will be preserved and protected. The old legislation creates perverse outcomes, they argue, and limits the actions of responsible farmers. If we put trust in the farmers, they state, the environment will be conserved.

However, for these environmental benefits to be realised under the looser, market-based approach, the following three conditions need to apply. First, farmers would need to have perfect knowledge about the impact of native vegetation on their current and future incomes. For example, farmers would need to understand the value of native vegetation in halting erosion and salinity, providing wind breaks, harbouring bird diversity, restricting pest invasions and supporting current and future agricultural productivity. Only then can farmers accurately value the conservation of native vegetation.

The second condition that the draft legislation assumes to be true is that land clearance creates no spillover effects. However, native vegetation does not simply provide benefits on a farmer’s own property. It provides spillover benefits such as pest resistance, flood control, wind protection and pollination services to other properties in the local area. Native vegetation also provides regional benefits, such as climate and water regulatory functions, and it houses threatened and endangered species and biodiversity valued by other citizens.

Unless farmers are forced to consider these spillover effects, as they were forced to do under the NVA, they will make decisions on the basis of private benefits and costs only. Thus, they will clear too much relative to the desires and needs of society and other local land users. The legislation does require offsetting of high-risk land clearance which in some way internalises the spillover cost, but the market-based offset price is not equal to the social impact and spillover costs occur when low and medium-risk vegetation is cleared as well.

The third unrealistic assumption of the draft legislation is that the ‘discount rate’ of landowners is identical to society’s. That is, it is assumed that the rate at which farmers discount future income compared to current income is the same as society’s rate of discount. In contrast, if landowner’s rate of discount is greater than society’s, too much land will be cleared relative to the needs and desires of society and future generations.

The impact of high discount rates can be seen in the extreme in the clear cutting of tropical forests where farmers are poor and desperate. NSW farmers may not be as poor and desperate as landowners bordering the Amazon, but as they frequently tell us, they are highly indebted and being squeezed from all sides between multinational input suppliers and highly-concentrated domestic food wholesalers and retailers. Thus, according to their own evaluation, farmers have high discount rates and as such a focus on short-term economic interests rather than environmental sustainability will drive decisions under the proposed legislation.

The Baird government is undermining the long-run condition of the land

The theory underlying the government’s reforms assumes that farmers know best. That is, farmers know how to best manage their land (perfect knowledge), they will incorporate their neighbour’s needs and the broader public interest (zero or internalised spillover effects), and they will act in the long-run interest of the land (discount rate equal to society’s). Because these assumptions are untrue in reality, the new legislation will lead to a vast increase in land clearance and loss of biodiversity. This exact result occurred in Queensland when similar changes were made to land clearance laws.

Aware of the devastating effects of the Queensland legislation on land clearance, the government has claimed that NSW is “not Queensland” and that more checks and balances are in place. But these checks and balances are still designed for a world with perfect knowledge, no spillover effects and perfectly forward-thinking landowners. Thus, the checks and balances will not “deliver”.

Ultimately, the major impact of the reforms is to free up land clearance, to make it easier to clear and to reduce regulation. As all environmental problems stem from unrestrained economic activity, the removal of regulation can only be seen as a decision to accept a lower land condition – a land with more erosion and salinity, less species and biodiversity, and eventually less economic productivity as well.

The Baird government seems to believe that we exist within an unrealistic, textbook version of a free-market economy and is setting policy on the basis of free-market ideology and in response to the demands of large agribusiness firms and food retailers who want still lower farm-gate prices. In setting policy this way, the Baird government is promoting a less sustainable land condition and undermining the prosperity of future generations. This is no way to manage the commons.

The Conversation

Neil Perry, Research Lecturer, Western Sydney University

This article was originally published on The Conversation. Read the original article.

Blackbutt Reserve


Kevin's Daily Photo, Video, Quote or Link

Since I was unable to visit Gap Creek Falls the other day, I decided I might pop in to have a look at the new animal enclosures at Blackbutt Reserve near Newcastle. I will say straight off the bat that I do have something of a prejudice against Blackbutt Reserve, as I see the place as nothing like a natural bush setting, it being far too ‘corrupted’ by human activity, weeds and the like. Having said that it is a good place for a family or group outing/event. It certainly has its place, but it is not a true nature reserve (in my opinion).

Visitor Centre

ABOVE: Visitor Centre

I do think that some well designed animal and bird enclosures at Blackbutt could lift the value of the reserve dramatically and make it a really great place for families, especially young families. There are opportunities for educational visits for kids, possible environmental…

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