The link below is to an article that looks at deforestation of the Amazon in Peru for more gold mining.
Tens of millions of wild animals are killed each year by land clearing across Australia, according to our research on the harm done to animals when native vegetation is removed for agricultural, urban and industrial development.
As my colleague Nahiid Stephens and I point out in our study, this harm to animals is largely invisible, unlike the obvious effects of clearing on trees and other plants. But just because something is invisible, that does not mean it should be ignored.
We argue that reforms are necessary to ensure that decision-makers take wild animals’ welfare into account when assessing development proposals and land clearing applications.
How does land clearing harm animals?
Land clearing harms animals in two basic ways. First, they may be killed or injured when native vegetation is removed, typically through the use of earth-moving machinery. For example, animals may suffer traumatic injuries or be smothered when vegetation is cut or soil and debris are shifted.
Second, the removal of native vegetation puts animals in harm’s way. Those that survive the clearing process will be left in an environment that is typically hostile, unfamiliar or unsuitable. Animals are likely to find themselves in landscapes that are devoid of food and shelter but filled with predators, disease, and increased aggression from members of their own species as they struggle to make a living.
Land clearing causes animals to die in ways that are physically painful and psychologically distressing. Animals will also suffer physical injuries and other pathological conditions that may persist for days or months as they try to survive in cleared areas or other environments to which they are displaced.
Many reptiles and mammals are territorial or have small home ranges, and thus have strong associations with small areas of habitat. Koalas in urban areas, for example, tend to rely on particular food trees. Likewise, lizards and snakes often rely on particular microhabitat features such as logs, rocks, and leaf litter to provide the combination of temperature and humidity that they need to survive.
Laws are not protecting animals
Land clearing remains a fundamental pressure on the Australian environment. While the regulatory frameworks for land clearing vary greatly across the Australian states and territories, the principal statutes that govern native vegetation clearance in most jurisdictions typically contain some sort of express recognition of the harm that land clearing causes, such as the loss or fragmentation of habitat, land degradation, and salinity.
Yet these regulations are uniformly silent on the issue of how land clearing harms animals. No state or territory has developed a clear framework to evaluate this harm, let alone minimise it in future development proposals.
This failure to recognise animal welfare as a significant issue for decision-making about land clearing is troubling, especially given the scale of current land clearing. In Queensland, for example, an estimated 296,000 hectares of woody vegetation was cleared in 2014-15, nearly all of which was for the purpose of converting native vegetation to pasture. In our study we estimate that, on the basis of previous studies and current estimates of clearing rates, land clearing in Queensland and New South Wales combined kills more than 50 million birds, mammals and reptiles each year.
What reforms are necessary?
We suggest that two basic reforms are required. First, state and territory parliaments should amend the laws that govern environmental impact assessments and native vegetation clearance, to require decision-makers to take animal welfare into account when assessing land clearing applications.
Second, we urgently need accurate ways to evaluate the harm that proposed clearing actions may cause to individual animals. Animal welfare is broadly recognised as an important social concern, so it makes sense that in a situation where we know animals are being harmed, we should take steps to measure and prevent that harm.
The basic aim of any reform should be to ensure that the harm that land clearing causes to individual wild animals is appropriately considered in all forms of environmental decision-making and that such evaluations are based on clear and objective criteria for animal welfare.
At a minimum, those who apply to clear native vegetation should be required to provide an estimate of the number and type of native animals that will be killed by the proposed land clearing. This would ensure that all parties – applicants, decision-makers, and the community – understand the harm that the clearing would cause. These estimates could be made by using population density information for species that are likely to be affected – an approach that has been already been used.
We also need to revise our perceptions about the usefulness and necessity of land clearing in Australia. A better idea of what is “acceptable” would include not only the environmental costs of clearing an area of native vegetation, but also the individual suffering that animals will experience.
Issues of causation and responsibility are critical here. While it’s unlikely that someone who wants to clear land actually wants native animals to suffer, such suffering will nevertheless be an inevitable consequence. The relevant question is not whether animals will be killed and harmed when land is cleared, but how much of that harm will occur, how severe it will be, and whether it ought to be avoided.
If such harm is deemed necessary – based on an accepted system for weighing the potential benefits and harms – the next question is how the harm to animals can be minimised by, for example, keeping the amount of vegetation to be cleared to a minimum.
When you cut and burn a tropical forest, you’re left with a barren plain of cracked red mud, incapable of supporting life – the opposite of the teeming, hyperdiverse array of life that was destroyed. Once the trees are gone, the nutrients wash away and the soil degrades into a dense, brick-like layer so hardened that plant roots can’t get through it.
This was the vision of tropical deforestation held in the popular imagination for many years, but the reality is more complex – and more hopeful.
In recent decades, researchers have found that tropical forests are remarkably resilient. As long as some remnants are left when the forest is cleared to provide seeds and refuges for seed dispersers, tropical forests can grow back with astonishing speed.
In a paper published this week in Nature, lead author Lourens Poorter and a team of international collaborators, including me, found that forests in Central and South America can quickly rebound without human intervention on land that has been cleared for cattle grazing or growing crops.
This finding has important implications for climate change because these so-called secondary forests soak up large amounts of carbon from the atmosphere, even without costly reforestation efforts. These regenerating forests are also crucial for protecting biodiversity and all the ecological and social benefits it provides.
Tropical secondary forests – that is, forests that grow after a major clearing, such as a fire, farming or logging – cover an increasing part of the globe. And as their extent expands, so does their potential to shape conservation strategies, both at the local and global scales.
At the U.N. Climate Summit in 2014, 30 nations and a host of NGOs and private companies endorsed the New York Declaration on Forests, a document that advocates halving deforestation by 2020 and ending it completely by 2030.
One of the key points of the declaration calls for the restoration of 150 million hectares (about 375 million acres) of degraded forest land by 2020 and additional restoration in the following decade.
But active forest restoration can be an expensive process, and it may not be cost-effective or even necessary in every case. In landscapes with low levels of degradation, simply protecting young forests and allowing them to develop may be the best strategy.
In our research, my colleagues and I present the largest data set yet assembled to investigate forest regrowth in the New World tropics. The data set spans 45 sites in the lowland tropics from wet forest to dry forest, with a total of 1,478 plots and more than 168,000 individual trees.
It offers an unprecedented, and more hopeful, view of forest recovery.
According to this analysis, tropical secondary forests have enormous potential for removing carbon from the atmosphere. The net carbon uptake for these secondary forests is 11 times that of old-growth forests in the region we studied.
The rate of biomass recovery varies widely across the region, with the fastest regrowth in areas with high rainfall. The median time for a forest to reach 90 percent of old-growth biomass levels was 66 years, but recovery can be much faster in some areas.
Big win for biodiversity
It shouldn’t come as a surprise that tropical forests can grow back after major disturbances. Tropical forests can be affected by a number of different large-scale natural disasters like floods, fires, landslides, major storms and volcanic eruptions.
Even old-growth tropical forests are highly dynamic systems, marked by cycles of tree death and regrowth. The mortality rates for trees larger than 10 centimeters in diameter have been estimated at one percent to two percent per year for forests in the Amazon and Central America. In other words, at the upper end, one in every 50 large trees will fall in the course of a given year.
The gaps in the forest that result from treefalls are rapidly colonized by a riot of vines and fast-growing tree saplings. The heterogeneity of habitats produced by this cycle is a major driver of tropical diversity.
In addition, the history of human-induced disturbances in tropical forests is longer and more complex than we often acknowledge.
Legacies of ancient human use, stretching back for millennia, have been detected in nearly every “pristine” tropical forest on earth: massive earthworks in the Amazon and modern-day Cambodia; charcoal and pottery fragments in the Congo Basin; and evidence of forest clearing going back nearly 50,000 years in Papua New Guinea.
Indeed, various forms of slash-and-burn cultivation have been practiced for millennia throughout the tropics.
As long as the cleared areas are modest in size and the period between cycles of cultivation is sufficient for recovery, diverse forests can persist for thousands of years.
Local and global benefits
Tropical secondary forests can – and should – form a substantive part of the long-term global strategy to combat carbon emissions and preserve biodiversity for the future.
Our recent research shows, for example, that in areas where biomass recovery is slow – like the tropical dry forest – we should prevent further forest loss. Where recovery is rapid, we can combine old-growth forest conservation with policies that promote secondary forest formation.
Shifting focus to the conservation of regenerating forests should not take away from the urgent imperative to conserve the remaining uncut tropical forest.
The clearing of old-growth tropical forests is a major source of human-induced greenhouse gas emissions, second only to fossil fuel combustion. Clearly, keeping the carbon that’s currently stored in intact tropical forests from being released to the atmosphere should be a priority.
Old-growth tropical forests also harbor immense biological diversity – including genetic diversity – and if all of the remaining old-growth forests in a landscape are cut, there will be no seed source to promote regeneration.
Conserving secondary forests offers a different, and complementary, set of benefits.
As well as their massive potential for taking up carbon as they grow, secondary forests provide resources and livelihoods for the people who inhabit them.
Secondary forests can harbor a high diversity of ethnobotanically important species that can be used for medicines. They can serve as extractive reserves, where limited harvesting of timber, game animals and other forest products will prevent the exploitation of resources in vulnerable protected areas. They protect watersheds and prevent erosion.
As secondary forests grow back, they eventually come to resemble the forest that was cut, and in the meantime, they knit together the remaining fragments of forest into a more contiguous landscape.
As David Quammen wrote in “Song of the Dodo (1997),” isolated populations of organisms in forests lose connections to the resource base that supports them. Over generations they lose their genetic diversity, making them more vulnerable to inbreeding, disease, and eventual extinction.
Secondary forests offer the hope of reconnecting habitats and creating a more resilient landscape for the future.
So harnessing the power of forest regeneration in the tropics will have benefits both locally – providing resources and restoring ecosystem services – and globally, by sequestering carbon from the atmosphere.
At the Paris Climate Summit, leaders took important steps toward halting deforestation. Promoting forest regrowth is another vital piece of the equation. It’s time for policymakers to recognize the benefits that tropical secondary forests provide, and to shape policies that take advantage of this enormous potential.