A spatial overview of the global importance of Indigenous lands for conservation, Garnett et al. 2018
Indigenous people make up less than 5% of the global population, but their lands encompass 37% of the planet’s remaining natural lands and (partially overlapping with natural lands) 40% of Earth’s protected area, much of this in sparsely inhabited places. Like everyone, indigenous people have multiple interests (economic, political, cultural), which don’t necessarily always support conservation interests. However, “Indigenous Peoples often express deep spiritual and cultural ties to their land and contend that local ecosystems reflect millennia of their stewardship” [Garnett 2018: 369]. Indeed, “Countless Indigenous management institutions have already proven to be remarkably persistent and resilient, suggesting that such governance forms can shape sustainable human landscape relationships in many places” [Garnett 2018: 370].
Thus, the authors argue for indigenous voices to be prominent in land-use decision-making processes at global and local levels. “There is already good evidence that recognition of the practices, institutions and rights of Indigenous Peoples in global environmental governance is essential if we are to develop and achieve the next generation of global biodiversity targets” [Garnett 2018: 372].
In total, Indigenous Peoples influence land management across at least 28.1% of the land area.
About 7.8 million km2 (20.7%) of Indigenous Peoples’ lands are within protected areas, encompassing at least 40% of the global protected area with the proportion of Indigenous land in protected areas significantly higher than the proportion of other lands that are protected. The relationship between Indigenous Peoples and conserved areas varies in nature. While some protected areas (as defined by states and/or the International Union for Conservation of Nature (IUCN)) are under the governance of Indigenous Peoples themselves, others are governed by state authorities with varying degrees of respect for the presence of Indigenous Peoples. This respect ranges from collaborative governance where Indigenous Peoples are consulted on decisions, to de facto management and use of protected areas by Indigenous Peoples despite threats of eviction [Garnett 2018: 370].
Around half of the global terrestrial environment can be classified as human-dominated. Using this as a measure of human influence, we estimated that Indigenous Peoples’ lands account for 37% of all remaining natural lands across the Earth. A higher proportion (67%) of Indigenous Peoples’ lands was classified as natural compared with 44% of other lands. Even though no global data are available on other anthropogenic pressures such as grazing, burning, hunting or fishing, the drivers assessed by the Human Footprint (which range from roads, access, population density and different agricultural land use activity) are suitable surrogates. Consistent with this, most parts of the planet managed and/or owned by Indigenous Peoples have low intensity land uses: less than 3.8 million km2 (10.2%) of the world’s urban areas, villages and non-remote croplands are on Indigenous Peoples’ lands, whereas, in contrast, they encompass 24.9 million km2 (65.7%) of the remotest and least inhabited anthromes. Many of these remote Indigenous areas are nevertheless under pressure from intensive development [Garnett 2018: 370].
Wilderness areas halve the extinction risk of terrestrial biodiversity, DiMarco et al. 2019
We found that wilderness areas act as a buffer against extinction risk. The global probability of species extinction in non-wilderness communities is over twice as high as that of species in wilderness communities. The buffering effect that wilderness has on extinction risk was found in every biogeographical realm, but was higher for realms with larger remaining extents of wilderness such as the Palaearctic [Di Marco 2019: 26].
The remaining intact ecosystems of Earth—which are increasingly seen as essential for providing ecosystem services on which humanity relies and maintaining the bio-cultural connections of indigenous communities—have been neglected in efforts to conserve biodiversity. This is largely due to a belief that these areas are less vulnerable to threatening processes and less rich in threatened biodiversity, thereby having lower conservation value [Di Marco 2019: 585].
These areas are important because they host highly unique biological communities and/or represent the majority of remaining natural habitats for biological communities that have suffered high levels of habitat loss elsewhere [Di Marco 2019: 585].
Ongoing accumulation of plant diversity through habitat connectivity in an 18-year experiment, Damschen et al. 2019
This long-term experiment measured the difference in colonization and extinction rates of connected habitat fragments versus isolated fragments. The connected fragments were linked by a narrow (150m by 25m) strip of habitat. These habitat corridors increased the biodiversity of connected fragments by 14% after 18 years compared to their isolated counterparts.
In a large and well-replicated habitat fragmentation experiment, we find that annual colonization rates for 239 plant species in connected fragments are 5% higher and annual extinction rates 2% lower than in unconnected fragments. This has resulted in a steady, non-asymptotic increase in diversity, with nearly 14% more species in connected fragments after almost two decades. Our results show that the full biodiversity value of connectivity is much greater than previously estimated, cannot be effectively evaluated at short time scales, and can be maximized by connecting habitat sooner rather than later [Damschen 2019: 1479].
The authors note that 70% of the world’s forest area is within 1 km of an edge – meaning Earth’s forests are very fragmented. They stress that connecting habitat fragments is critical to the success of habitat and biodiversity conservation.
Conservation plans that ignore connectivity, such as plans that focus solely on habitat area, will leave unrealized the substantial, complementary, and persistent gains in biodiversity attributable specifically to landscape connectivity [Damschen 2019: 1480].
Plant phylogenetic diversity stabilizes large‐scale ecosystem productivity, Mazzochini et al. 2019
Phylogenetic measures of diversity contain information on evolutionary divergences amongst species, thus representing the diversity of phylogenetically conserved traits related to resource use, acquisition and storage. Thereby, distantly related species are expected to respond differently to changing environmental conditions. These functional traits can be general traits related to the fast–slow growth rate spectrum, such as specific leaf area and wood density, and also physiological traits triggering plant responses to climatic fluctuations, such as flowering and leafing phenologies. [Mazzochini 2019: 1431].
This study shows that (phylogenetic) plant diversity helps to stabilize ecosystem productivity – even at the landscape scale. Previous experiments have shown that plant diversity increases the stability of ecosystem productivity in small patches of vegetation where plant interaction boosts overall productivity, as does difference in response to environmental fluctuations among different species. The present study increases the scale of observation to the landscape level, and finds that biodiversity increases ecosystem stability due to varied or “asynchronous responses of distantly related species during environmental fluctuations” [Mazzochini 2019: 1431].
Our results expand by several orders of magnitude the spatial scale of evidence that high biodiversity strengthens the resistance of key ecosystem features to climatic fluctuations. Specifically, we show that the positive relationship between phylogenetic diversity and stability reported in local experiments can also be observed at larger spatial extents and grain sizes using available biodiversity databases and modelling techniques. As we expected, in the analyses at the landscape resolution, phylogenetic diversity correlates with vegetation productivity stability mainly due to a reduction in productivity variability across the years, and not by increasing average productivity, which was mostly driven by climatic variables [Mazzochini 2019: 1435].
Rate of tree carbon accumulation increases continuously with tree size, Stephenson et al. 2014
The growth rate of trees – and thus their accumulation of carbon – increases continuously with tree size. Even though the leaves of smaller, younger trees are more efficient (more productive per unit area of leaf surface), larger trees have more total leaf surface area and thereby grow at a faster rate than their smaller counterparts. “For example, in our western USA old-growth forest plots, trees > 100cm in diameter comprised 6% of trees, yet contributed 33% of the annual forest mass growth” [Stephenson 2014: 92].
Since trees use atmospheric carbon to grow, the more they grow, the more carbon they sequester. “Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees” [Stephenson 2014: 90].
Europe’s forest management did not mitigate climate warming, Naudts et al. 2016
Despite their total area having increased by 10% since 1750, European forests have failed to achieve a net removal of CO2 from the atmosphere because of how they’ve been managed over that time. Eighty-five percent of Europe’s once largely unmanaged forest has been subjected to tree species conversion, wood extraction via thinning and harvesting, and litter raking, resulting in a large overall loss of carbon from biomass and soil.
Putting 417,000 km2 of previously unmanaged forest into production is estimated to have released 3.5 Pg of carbon to the atmosphere, because the carbon stock in living biomass, coarse woody debris, litter, and soil was simulated to be, respectively, 24, 43, 8, and 6% lower in managed forests compared with unmanaged forests [Naudts 2016: 598].
The sweeping change in Europe’s forest species from broad leaf trees to conifers represents a shift to a production-oriented approach to forestry undertaken to satisfy demands of a population that quadrupled between 1750 and 2010.
Whereas deforestation between 1750 and 1850 mainly replaced broadleaved forests with agricultural land, afforestation from 1850 onward was often with coniferous species. Broadleaved forests were also directly converted to coniferous forests, resulting in a total increase of 633,000 km2 in conifers at the expense of broadleaved forests (decreasing by 436,000 km2). For centuries, foresters have favored a handful of commercially successful tree species (Scots pine, Norway spruce, and beech) and, in doing so, are largely responsible for the current distribution of conifers and broadleaved species in Europe [Naudts 2016: 598].
The authors note that many other parts of the world have followed a similar path,
Wood extraction occurs in 64 to 72% of the 26.5 to 29.4 million km2 of global forest area, and substantial species changes have occurred in China (216,000 km2), Brazil (71,000 km2), Chile (24,000 km2), New Zealand (18,000 km2), and South Africa (17,000 km2) [Naudts 2016: 599].
This global trend has resulted in limiting the ability of many managed forests to sequester carbon, compared to their wild or better-managed counterparts.
Hence, any climate framework that includes land management as a pathway for climate mitigation should not only account for land-cover changes but also should equally address changes in forest management, because not all forest management contributes to climate change mitigation [Naudts 2016: 599].
The exceptional value of intact forest ecosystems, Watson et al. 2018
Forests currently cover a quarter of Earth’s terrestrial surface, although at least 82% of that remaining forest is degraded by human activity. While a handful of international accords rightly encourage forest conservation and reforestation to limit global warming, these agreements fail to prioritize protection specifically of intact forests, or forests that are free from human activities “known to cause physical changes in a forest that lead to declines in ecological function” [Watson 2018: 1].
The authors argue for the protection of all forests, including degraded ones, as well as reforestation, to stem global ecological collapse, while here they particularly emphasize the exceptional value of intact forests. They present these key arguments:
- Carbon sequestration and storage. “Intact forests store more carbon than logged, degraded or planted forests in ecologically comparable locations. Industrial logging and conversion of forest to cropland causes heavy erosion and contributes to the loss of belowground carbon” [Watson 2018: 3].
- Local climate. “Intact tropical forests are critical for rain generation because air that passes over these forests produces at least twice as much rain as air that passes over degraded or non-forest areas” [Watson 2018: 4]. By contrast, deforestation and forest degradation can increase the frequency of hot, dry days, leading to drought.
- Biodiversity. Forested ecosystems support the majority of global terrestrial biodiversity, and “beyond outright forest clearance, forest degradation from logging is the most pervasive threat facing species inhabiting intact forests” [Watson 2018: 4]. “For example, a recent global analysis of nearly 20,000 vertebrate species showed that even minimal initial deforestation within an intact landscape had severe consequences for vertebrate biodiversity in a given region, emphasizing the special value of intact forests in minimizing extinction risk” [Watson 2018: 5].
- Indigenous peoples. “Industrial-scale degradation of intact forest erodes the material basis for the livelihoods of indigenous forest peoples, depleting wildlife and other resources. It also renders traditional resource management strategies ineffective, and undermines the value of traditional knowledge and authority” [Watson 2018: 5], ultimately driving indigenous peoples off their land.
- Human health. “Forested ecosystems are major sources of many medicinal compounds that supply millions of people with medicines worldwide” [Watson 2018: 6]. Forest degradation results in the decline or loss of medically relevant species, while also directly harming human health through increased wildfire severity and spread of disease.
- Forest resilience. Forest degradation reduces the resilience of forests to climate change, leading to even greater ultimate loss of ecosystem function.
The authors warn that intact forests could soon disappear unless action is taken to protect them, which must necessarily start with greater recognition of their value compared to degraded forests.
There are still significant tracts of forest that are free from the damaging impacts of large-scale human activities. These intact forests typically provide more environmental and social values than forests that have been degraded by human activities. Despite these values, it is possible to envisage, within the current century, a world with few or no significant remaining intact forests. Humanity may be left with only degraded, damaged forests, in need of costly and sometimes unfeasible restoration, open to a cascade of further threats and lacking the resilience needed to weather the stresses of climate change. The practical tools required to address this challenge are generally well understood and include well-located and managed protected areas, indigenous territories that exemplify sound stewardship, regulatory controls and responsible behavior by logging, mining, and agricultural companies and consumers, and targeted restoration. Currently these tools are insufficiently applied, and inadequately supported by governance, policy and financial arrangements designed to incentivize conservation. Losing the remaining intact forests would exacerbate climate change effects through huge carbon emissions and the decline of a crucial, under-appreciated carbon sink. It would also result in the extinction of many species, harm communities worldwide by disrupting regional weather and hydrology, and devastate the cultures of many indigenous communities. Increased awareness of the scale and urgency of this problem is a necessary precondition for more effective conservation efforts across a wide range of spatial scales [Watson 2018: 8].
Addressing change mitigation and adaptation together: a global assessment of agriculture and forestry projects, Kongsager, Locatelli & Chazarin 2019
In climate policy and financing, the goals of adaptation (helping communities and ecosystems adapt to the effects of climate change) and mitigation (reducing carbon emissions and increasing carbon sinks) are often separate. This is because “adaptation and mitigation are driven by different interests and political economies, with distinct international donors and national institutions. These differences are reﬂected in the guidelines and requirements that climate change project developers have to follow” [Kongsager 2019: 279].
This present study, however, found that many climate change projects do or could address adaptation and mitigation jointly.
PDDs [Project Design Documents] integrating adaptation and mitigation shared several common features. They recognized ecosystems as providers of multiple services for both mitigation (carbon) and adaptation (watershed protection, forest products for livelihood diversiﬁcation or safety nets, mangrove protection against storms and waves, microclimate regulation in agricultural ﬁelds) [Kongsager 2019: 278].
Ninety percent of mitigation projects mentioned adaptation goals while 30% of adaptation projects had mitigation goals. The authors speculate on the reason for this discrepancy:
There appears to be an intrinsic value in integrating adaptation into mitigation projects even without incentives provided by funders, because of reduced climatic risks and increased sustainability, as mentioned by a few project developers … By contrast, there is no clear rationale for a project developer to integrate mitigation into adaptation projects, beyond the perspective of receiving additional support from mitigation funding by selling carbon credits [Kongsager 2019: 279].
The authors recommend adjusting the institutional framework to encourage deeper, better coordinated integration of mitigation and adaptation goals into climate-related projects.
With a synergetic approach, AFOLU [agriculture, forests, and other land use] projects would be designed to combine adaptation and mitigation in a way that project components interact with each other to generate additional climate beneﬁts compared to projects in which adaptation and mitigation are separated. Mainstreaming climate compatible development (i.e., adaptation, mitigation, and development) may avoid that projects respond to adaptation and mitigation urgencies separately. Scarce resources could be more efﬁciently spent, for instance, by not establishing separate institutions and processes to support adaptation and mitigation, and by avoiding conﬂicting policies, because a current major challenge in integrating adaptation and mitigation is the institutional complexity [Kongsager 2019: 279].
Damschen, Ellen I., et al., 2019, Ongoing accumulation of plant diversity through habitat connectivity in an 18-year experiment, Science 365, https://science.sciencemag.org/content/365/6460/1478.abstract.
Di Marco, Moreno, et al., 2019, Wilderness areas halve the extinction risk of terrestrial biodiversity, Nature 573, https://www.nature.com/articles/s41586-019-1567-7%C2%A0.
Garnett, Stephen T., et al., 2018, A spatial overview of the global importance of indigenous lands for conservation, Nature Sustainability 1.
Mazzochini, Guilherme G., et al., 2019, Plant phylogenetic diversity stabilizes large‐scale ecosystem productivity, Global Ecology and Biogeography 28, https://onlinelibrary.wiley.com/doi/abs/10.1111/geb.12963.
Naudts, Kim, et al., 2016, Europe’s forest management did not mitigate climate warming, Science 351, https://science.sciencemag.org/content/351/6273/597.
Stephenson, N.L., et al., 2014, Rate of tree carbon accumulation increases continuously with tree size, Nature 507, https://www.nature.com/articles/nature12914/.
Watson, James E. M., et al. 2018, The exceptional value of intact forest ecosystems, Nature Ecology & Evolution, https://www.nature.com/articles/s41559-018-0490-x?source=post_page---------------------------.