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The thinning fabric of Earth’s forest cover (commentary)

  • The ever-smaller number of forests that remain truly intact and free from degradation are a precious resource, pivotal in addressing the twin challenges of climate change and biodiversity loss as well as offering many other benefits to people. But are we taking good care of them? Not yet.
  • More and more of the world’s remaining forests are switching from healthy core to degraded, carbon-emitting edges, or isolated patches as intensive human use drives fragmentation, logging, over-hunting, fires, and a host of other pressures large and small.
  • Decision makers mistakenly perceive that forest intactness is not as important or urgent as deforestation, or that it is too difficult to measure and monitor. We must lift these constraints, put better policies in place, and expend far more effort into halting the degradation of forests on the ground, in particular in those 20-30 countries where the most-intact forests are concentrated.
  • This post is a commentary. The views expressed are those of the author, not necessarily Mongabay.

Forests don’t have it easy. Even when they escape being cleared for farmland, pastures, or cities, many of them are battered by a variety of other human pressures. Damage to forests (often termed degradation) is by definition less severe in a given location than outright deforestation, but it affects much larger areas — and so, in aggregate, may be just as big a problem for the global environment.

The ever-smaller number of forests that remain truly intact and free from degradation are a precious resource, pivotal in addressing the twin challenges of climate change and biodiversity loss as well as offering many other benefits to people. But are we taking good care of them? Not yet.

Imagine being parachuted into the heart of one of our last big rainforests and hiking out to a settled area. For the first part of your walk (for many days, if you were lucky) the forest would be in its more or less natural state, and you would see a high, dense canopy; a mostly open, shady understory; and many signs of large-bodied wildlife.

Well before you reached the forest edge, though, huntable animals would become sparser, logging trails more frequent, the canopy more open, trees smaller, and the understory would be more overgrown, hotter, and drier. Approaching the forest edge, you would fight through low, jungly thickets dotted with tree stumps but lacking most larger animals. As you moved into the surrounding farm lands you would notice sad, scattered forest fragments with a few remnant trees, pressured on all sides and dominated by vines.

While all the world’s forests are precious, and we can no longer afford to lose any of them, those tall, shady, undamaged cores of primary forest are where the greatest value is concentrated, whether we think of the tropical, temperate, or boreal ecosystems. Those are the parts that have the highest biodiversity, the largest stores of carbon, and the cleanest rivers. Their multi-tiered foliage pumps abundant moisture back into the air to deliver rainfall to regions far downwind. They are the setting where Indigenous Peoples are best able to pursue their traditional ways of life.

When climates change and other pressures increase, those are also the areas that prove most resilient to fires, droughts, storms, and invasion by alien species. Furthermore, science is showing that these intact forest cores are playing an exceptionally important and poorly publicized role in slowing climate change, by actively absorbing around a quarter of humanity’s carbon emissions each year through incremental growth.

The royal flycatcher is found in forest and woodland throughout most of the Amazon basin. Photo Credit: Mileniusz Spanowicz @WCS.

Despite these exceptional values, more and more of the world’s remaining forests are switching from healthy core to degraded, carbon-emitting edges, or isolated patches as intensive human use drives fragmentation, logging, over-hunting, fires, and a host of other pressures large and small.

More than 9 percent of forests in the most-intact category were degraded in some way during 2000-2016, and the rate is accelerating. In temperate zones and southern parts of the boreal, they are almost completely gone already. Will remaining areas in the tropics and the far north survive the current century intact? Without them or the services they provide, where will we be?

Surprisingly, little attention is given to this issue in the forest policy frameworks that guide finance and action on the ground. Their focus is much more on deforestation and restoration. For example, there are no global targets aimed at keeping the world’s most intact forests in good condition. While degradation sometimes gets name-checked, there are few quantitative targets for halting it, and few countries have yet included it in their national measurement frameworks under REDD+.

Decision makers mistakenly perceive that forest intactness is not as important or urgent as deforestation, or that it is too difficult to measure and monitor. We must lift these constraints, put better policies in place, and expend far more effort into halting the degradation of forests on the ground, in particular in those 20-30 countries where the most-intact forests are concentrated.

The coming months offer an exceptional chance to bring these ideas into the new ten-year Global Framework for Biodiversity that will be agreed in Kunming, China at the end of 2020, and into mechanisms for financing implementation of newly-enhanced national commitments under the Paris Climate Agreement.

Climate and biodiversity values converge in intact forests, forming a great opportunity for the two conventions to move out of their silos and truly cooperate. With this recognition, there is still hope that the last great forests on Earth have a prospect of surviving and thriving into the next century.

Amazon rainforest. Photo Credit: Eleanor briggs @WCS.

CITATIONS

• Aragão, L. E. (2012). Environmental science: The rainforest’s water pump. Nature, 489(7415), 217. doi.org/10.1038/nature11485

• Baker, J., & Spracklen, D. (2019). Climate benefits of intact Amazon forests and the biophysical consequences of disturbance. Frontiers in Forests and Global Change, 2, 47. doi:10.3389/ffgc.2019.00047

• Benítez-López, A., Santini, L., Schipper, A. M., Busana, M., & Huijbregts, M. A. (2019). Intact but empty forests? Patterns of hunting-induced mammal defaunation in the tropics. PLoS biology, 17(5), e3000247. doi:10.1371/journal.pbio.3000247

• Chaplin-Kramer, R., Ramler, I., Sharp, R., Haddad, N. M., Gerber, J. S., West, P. C., … & Mueller, C. (2015). Degradation in carbon stocks near tropical forest edges. Nature communications, 6, 10158. doi.org/10.1038/ncomms10158

• Funk, J. M., Aguilar-Amuchastegui, N., Baldwin-Cantello, W., Busch, J., Chuvasov, E., Evans, T., … & Phillips, O. (2019). Securing the climate benefits of stable forests. Climate Policy, 1-16. doi:10.1080/14693062.2019.1598838

• Haddad, N. M., Brudvig, L. A., Clobert, J., Davies, K. F., Gonzalez, A., Holt, R. D., … & Cook, W. M. (2015). Habitat fragmentation and its lasting impact on Earth’s ecosystems. Science advances, 1(2), e1500052. doi:10.1126/sciadv.1500052

• Hughes, A. C. (2018). Have Indo-Malaysian forests reached the end of the road?. Biological conservation, 223, 129-137. doi:10.1016/j.biocon.2018.04.029

• Mackey, B., DellaSala, D. A., Kormos, C., Lindenmayer, D., Kumpel, N., Zimmerman, B., … & Watson, J. E. (2015). Policy options for the world’s primary forests in multilateral environmental agreements. Conservation Letters, 8(2), 139-147. doi:10.1111/conl.12120

• Pan, Y., Birdsey, R. A., Fang, J., Houghton, R., Kauppi, P. E., Kurz, W. A., … & Ciais, P. (2011). A large and persistent carbon sink in the world’s forests. Science, 333(6045), 988-993. doi:10.1126/science.1201609

• Peres, C. A., Emilio, T., Schietti, J., Desmoulière, S. J., & Levi, T. (2016). Dispersal limitation induces long-term biomass collapse in overhunted Amazonian forests. Proceedings of the National Academy of Sciences, 113(4), 892-897. doi:10.1073/pnas.1516525113

• Taubert, F., Fischer, R., Groeneveld, J., Lehmann, S., Müller, M. S., Rödig, E., … & Huth, A. (2018). Global patterns of tropical forest fragmentation. Nature, 554(7693), 519. doi:10.1038/nature25508

• Watson, J. E., Evans, T., Venter, O., Williams, B., Tulloch, A., Stewart, C., … & McAlpine, C. (2018). The exceptional value of intact forest ecosystems. Nature ecology & evolution, 2(4), 599. doi:10.1038/s41559-018-0490-x

Tom Evans is Forests and Climate Change Lead for WCS (Wildlife Conservation Society).

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