Chapter 10. Trees have Already been Invented: Carbon in Woodlands

34 Pages·2016·1.05 MB·English

by  Susanna B. Hecht

Hecht, S B et al 2016 Chapter 10. Trees have Already been Invented: Carbon
in Woodlands. Collabra, 2(1): 24, pp. 1–34, DOI: http://dx.doi.org/10.1525/
collabra.69
ORIGINAL RESEARCH REPORT
Chapter 10. Trees have Already been Invented:
Carbon in Woodlands
Susanna B. Hecht*, Keith Pezzoli† and Sassan Saatchi‡
In the developed world, discussions of climate change mitigation and adaptation tend to focus on tech-
nological solutions such as decarbonizing electric grids and regulating emissions of methane, black car-
bon, and so on. However, an often overlooked strategy for reaching greenhouse gas reduction targets in
much of the developing world is rooted, not in new technologies, but in vegetation management. Trees
and other vegetation absorb carbon as they grow and release carbon when they are burnt, so landscapes
function as carbon sinks and carbon storage sites when forests are growing, on one hand, and as car-
bon sources when forests are cleared, on the other. Since greenhouse gas emissions from such land use
changes rival emissions from the entire transport sector, trees and vegetation are essential to efforts
to slow and adapt to climate change. Under the right circumstances, vegetation recovery and its carbon
uptake occur quickly. Moreover, carbon uptake can be strongly affected by human management of forests;
the right kinds of management can improve rates of recovery and carbon sequestration substantially. This
chapter reviews carbon dynamics in mature forests, secondary forests, agroforests and tree landscapes in
urban areas to point out the variability of these systems and the potential for enhancing carbon uptake
and storage. Furthermore, vegetation systems have many additional benefits in the form of other envi-
ronmental services, such as improving livelihoods, subsistence insurance habitat, microclimates, and water
systems. Finally, by managing forests better, we can also make significant contributions to climate justice
because most global forests and forested landscapes are under the stewardship of small holders.
Keywords: Forest transition; agroforestry; urban heat island; tropical forests; secondary forests;
climate justice; urban forestry
Introduction the curve” of climate change below the projected 2+
Forests, Carbon, and the Additional Benefits of degrees centigrade. However, to achieve the Paris goals,
Woodlands enhancement of forest-based carbon (C) removals to miti-
Global forests store about a trillion tons of carbon [1]. gate emissions in other sectors will be a critical compo-
Forests—whether temperate or tropical, and with closed nent of any collective global strategy for achieving carbon
or open canopy—are the largest terrestrial sink of carbon, neutrality [4, 5]. Any attempt at carbon neutrality must
comprising about 25% of the planetary carbon budget [2]. have significant forest and landscape dimensions. Forests
This is roughly equivalent to the carbon sequestered, or cover a large area of the planet, especially in comparison
kept out of the atmosphere, by the oceans [3]. The 2015 to the 3% of the Earth’s surface occupied by cities. In the
Paris Climate Agreement among 196 countries calls for short term, carbon uptake by vegetation and storage in
achieving a balance between the anthropogenic emissions biotic systems is one of the most rapid and promising
by sources and removal by sinks in the second half of this strategies for addressing emissions.
century. Most temperate zone and developed world strate- In the United States (US), Carbon sequestration in for-
gies focus on cutting carbon emissions through changes ests offsets about 10–15% of emissions from transpor-
in technology and energy consumption in order to “bend tation and energy sources and may help to significantly
reduce the overall costs of achieving emission targets set
by the Paris Agreement [1]. Without improving the extent,
health, and productivity of these forests, the sequestra-
* Luskin School of Public Affairs, UC Los Angeles, and Graduate
tion capacity may reduce because of climate change
Institute for Development
Studies, Geneva, Switzerland and increasing disturbance [6]. Many climate change
† Urban Studies and Planning Program; Department of adaptation enterprises will certainly involve enhancing
Communication, UC San Diego, US tree landscapes at many scales. Such improvements pro-
‡ Jet Propulsion Laboratory, NASA Pasadena, US vide additional “ecosystem services,” or positive impacts
Corresponding author: Susanna B. Hecht ([email protected]) for people, from shading buildings and buffering cities
Art. 24, page 2 of 34 Hecht et al: Chapter 10. Trees have Already been Invented
against storms to making agricultural and grazing land- Forest Multifunctionality
scapes more productive. Woodlands ranging from the high biomass forests of the
With the recent prominence of Reduced Emissions from humid tropics to the peri-urban and urban arborizations,
Deforestation and Degradation (REDD+), more than sixty, especially in the developing world, all provide ecosystem
mostly tropical, countries place forests at the center of services that go well beyond carbon. Many of these are
their climate strategies as part of the 2015 Paris Climate summarized in the Table 1.
Accords, which make special provision “to conserve This impressive list of additional benefits provided by
and enhance sinks and reservoirs of greenhouse gases tree systems helps explain why between 800,000 and
through results based payments”—which is more gener- 1.4 billion people on the planet are at least periodically
ally known as REDD+. While many discussions of climate dependent on forest resources for their livelihoods, labor
solutions focus on technological change, energy demand, markets, agricultural inputs, building and artisanal mate-
and reactivating energy resources such as nuclear power, rials, subsistence, and survival “insurance” in difficult
there are significant and rapid carbon uptake gains to be times [20, 21, 22, 23, 24, 25, 26]. North American main-
made through managing landscape systems. Changes in stream views of the environment that strongly segment
landscape management are generally more decentralized land uses have difficulty “seeing” such heterogeneous sys-
than changes in technology and energy, especially in the tems in part because of the conceptual construction (and
tropics where most of this sequestration and storage takes constriction) of “types” of nature into wild, agricultural,
place [7, 8, 9]. We also emphasize that there are gains to be and urban systems which are assumed to have little over-
made “at the margins” through improvement of second- lap. This perception is far less prevalent in the develop-
ary, agricultural, and urban forests with positive mitiga- ing world, but these separations, which have a venerable
tion and adaptation outcomes. history, have led to many policy distortions [27]. The fact
Many technological solutions to climate change define that human use of woodlands can be periodic, seasonal,
the benefits by human gains and goals. These approaches dispersed, or indirect further obscures the importance of
usually require rarified knowledge systems and complex forested landscapes.
technologies such as electric cars and solar panels; they Forests reflect biotic, social, and symbolic systems.
have narrowly specified outcomes and are often highly Forests occur in wild landscapes, in inhabited and working
monetized. In contrast, forest and landscape improve- landscapes of varying forms and intensities, and in highly
ment provides many additional benefits for humans, non- “unnatural landscapes” like cities. The ubiquity and extent
humans, and biophysical processes with relatively low of forests also contributes to their invisibility. Woodlands
entry and management costs. These co-benefits—or envi- are culturally complex; they have rich social and eco-
ronmental services—improve the health of the biosphere logical capacities as well as social and ecological vulner-
as well as the hydrological and microclimatic systems that abilities. Forests embody ideologies, knowledge regimes,
play an important role in the maintaining the carbon institutional approaches to land control and land access,
sequestration capacity of the Earth. This “broad spectrum” human symbolic meaning, sensitivity to economic signals,
quite direct enhancement, in addition to GHG uptake and and diverse power relations among local, national, and
storage, is unmatched by any other intervention to avoid international stakeholders. While woodlands and pastures
climate disruption. are generally viewed as parts of wild or distant nature, in
We frame this paper by exploring the multifunctional- this chapter we emphasize the pervasive arboreal nature
ity of arboreal systems, including their carbon uptake (or of even urban areas as critical sites of woody and other
sequestration) and storage. We emphasize the importance biota-based “carbon plus” environmental services. Just as
not only of dense tropical forests, but also of inhabited an example, in a survey of over a thousand urban house-
landscapes shaped by people—such as secondary for- holds in South Africa, non-timber forests products con-
ests, mixed agricultural systems, and cities and their tributed 20% of household income [28, 29, 30], a finding
environs—and discuss where such landscapes fit in cli- hardly unique to South Africa [25, 31, 32, 33]. Animal
mate policy and practices. We begin by introducing the production is also often a considerable part of urban food
ideas of multifunctionality and climate justice, but then production in cities, both in the developing world and the
move to specific contributions to carbon uptake in a range US [34, 35, 36].
of forest types, including “agroforests,” or forests people Peri-urban areas—or areas surrounding cities—are also
use to grow food, as well as urban and peri-urban forests. increasingly important in this regard as intersections
We conclude with the question of GHG uptake in urban between wildlands, agricultural lands, and cities. Peri-
areas and how researchers are rethinking the greenhouse urban areas often host complex agronomic systems with
gas footprint of cities, including urban waste. We empha- tree components on the urban fringes, in landscapes
size that “bending the curve” of climate change below through which people migrate to the city [35, 37, 38, 39,
2+ degrees centigrade is not simply a technical issue of 40, 41, 42, 43].
planting more trees, although that is part of it. “Bending Far more than any other climate mitigation or adapta-
the curve” also involves reassessing our relationship to tion “technology,” forest systems of multiple types engage
nature and creating political economies, institutions, and large portions of the planet’s residents. People of many
practices that support biotic processes as one of the cen- cultures, backgrounds, and material capacities are, in
tral responses to climate change. fact, already taking part in global woodland dynamics
Hecht et al: Chapter 10. Trees have Already been Invented Art. 24, page 3 of 34
Forests have many functions, and the practices of preserving forests and planting trees have many benefits besides carbon uptake
and storage. Forests and other tree landscapes provide:
1) Biodiversity benefits, including
a) habitat for many species;
b) ecological architecture;
c) ecological and habitat connectivity;
d) ecological services such as pollination, commensal support, predation, seed distribution, and food supply.
2) Agricultural benefits, including
a) pollination;
b) pest predation;
c) alternative hosts [10, 11, 12, 13, 14, 15];
d) soil fertility improvements in some cases;
e) erosion control.
3) Soil benefits, including
a) enhanced soil drainage;
b) soil moisture storage;
c) increasing organic matter in the soil and improving soil structure.
4) Water benefits, such as
a) buffering the impacts of rainfall;
b) transpiration (taking up moisture through the roots and releasing it through the leaves);
c) recharging the moisture in the soil;
d) moderating the flow of streams;
e) erosion control.
5) Microclimate improvements, especially for
a) moderating urban heat island effects [16, 17, 18];
b) reduction of heat stress in agroforestry and silvo-pastoral systems [16, 19];
c) evaporative cooling;
d) wind breaks.
6) Local weather defense, including
a) windbreaks;
b) shoreline protection via mangroves;
c) shade.
7) Economic benefits, such as
a) producing food;
b) producing timber and posts;
c) producing non-timber products, such as resins, latexes, medicines, oil seeds, and stimulants like coffee and teas;
d) producing commercial commodities, such as coffee, tea, cacao, and so on;
e) artisanal inputs;
f) potential REDD derivatives or other offset initiatives pertaining to carbon.
8) Subsistence benefits, such as
a) providing food to people who live in or near forests;
b) providing fuel;
c) artisanal inputs;
d) providing fodder for livestock;
e) providing construction materials;
f) providing medicinals.
9) Survival benefits and complex livelihood “insurance,” such as
a) medicinals,
b) “hunger crops”;
c) bush meat;
d) periodic extraction.
10) Human symbolic meaning, including
a) demarcation;
b) place making;
c) totems;
d) sacred groves;
e) aesthetics.
Table 1: The Multifunctionality and Co-Benefits of Woodlands.
as part of formal and informal systems of management forms of intervention for “bending the curve” of climate
and access, as well as through consumption of forest change below 2+ degrees centrigrade. This helps explain
products, economic activity, and aesthetic and symbolic why wooded landscapes from wildlands to urban regions
practices. Landscape systems are by far the most inclusive produce faster results for GHG uptake and at larger scales
Art. 24, page 4 of 34 Hecht et al: Chapter 10. Trees have Already been Invented
than most other technological interventions in carbon regions and populations most at risk from climate change.
mitigation, as we will show later in this paper. Economic support for carbon absorptive production sys-
Our own Western enchantment with technology blinds tems like agroforestry, urban community arborization,
us to the importance of living landscapes and the con- conservation investments within inhabited landscapes,
tributions of their “soft technologies.” In part, this is and new institutions and ideologies that support such
because the management and stewardship of woodlands approaches can enact a wide number of interventions,
is imbricated in a vast set of social relations, institutions, seeking input from local populations and capitalizing on
socio-political forces, economic imperatives, and global local innovations [52, 53,54, 55].
pressures that are not especially amenable to reductionist REDD might usefully focus on secondary and agro-
analysis, uniform scales, or even necessarily classic forms forests, but so far most carbon offsets have emphasized
of scientific inquiry. Further, these systems are ubiquitous, standing old growth forests with conservation support,
although very under-appreciated, and for this reason, such as Noel Kempff Mercado National Park in Bolivia and
some of the urban and peri-urban dynamics of woodlands the Juma Reserve in Amazonas [53, 55, 56, 57, 58]. Brazil’s
and their “footprints” remain almost invisible [23, 42, 44, “Bolsa Florestal” program and Ecuador’s “Socio-Bosque”
45, 46, 47]. These kinds of “invisibilities” have occluded program provide a modest subsidy to forest dwellers to
attention to secondary forests and extensive home gar- conserve forests and alleviate poverty. Such REDD+ pro-
dens for decades [48]. grams have raised many questions about tenurial arrange-
ments (who owns and who has rights to occupy and use
Climate Justice the land and other resources), distribution of economic
The term climate justice, when used in a restricted sense benefits, inclusion, competition among governance strat-
for policy purposes, means addressing the economic dis- egies and institutions, and compliance and monitoring.
parity between those societies that now generate and have All of these questions have significant climate justice
historically generated most GHGs, on one hand, and those implications [58, 59, 60]. While many actors are trying to
that have borne the brunt of the effects of climate change, build flexibility into the programs, REDD runs the risk of
on the other. Climate justice involves not only compensat- being excessively overarching and falling prey to the vice
ing those who suffer the consequences of climate instabil- of becoming a “development fad,” abandoned and reviled
ities [49, 50], but also, some argue, allowing them to par- a few years later. Given the problems that currently plague
ticipate in developing policies with climate consequences the carbon cap and trade markets, this is a real risk for
that affect them (such as policies about mining, REDD, REDD programs specifically and to addressing problems
the siting of pipelines and processing plants, and so on). A at the “transnational level” in general. Global policies may
definition of climate justice that goes beyond economics be unable to deal with resistance on the ground; in part,
(including a normative call for intergenerational equity, this results from the importance of forest goods in peo-
resources transfers, and sustainable development) can be ple’s livelihoods and to their wellbeing. Article Five of the
found in chapter 8 of this report. Paris Accords helped draw global attention to forests, but
The decentralized nature of the problem of climate jus- most of the language revolves around “wildlands,” rather
tice, the question of intentionality, and the difficulty of than working landscapes, and many complexities remain
taking collective action to address climate injustice pre- [58, 61, 62]. Such working woodland areas are crucial for
sent serious ethical and practical challenges. These chal- livelihoods and livelihood supplements in rural and urban
lenges involve problems of scale, unforeseen impacts, economies throughout the world, where an estimated
interactive outcomes among agents, power relations, and billion people are forest-dependent to some degree [33,
diffuse consequences that dramatically transform the 63, 64, 65, 66]. In a recent transnational set of studies in
vulnerabilities of populations whose carbon footprint rural areas, about 30% of the livelihood products—includ-
and historic responsibility for planetary carbon loads and ing food, forage, fuel, building materials, and so on—were
other GHGs are minimal. These indirect effects are com- derived from forest ecosystems [67, 68, 69, 70].
pounded by globally divergent consumption patterns,
limited capacities for resilience of states and communi- Smaller Scale, Bigger Impact?
ties, and augmented vulnerabilities [51]. The current Many subnational approaches, such as the 100 Resilient
explosive fires in the American west, continuing “record” Cities initiative, seem to have more traction on climate
flooding in the Mississippi and Missouri valleys, and hyper justice concerns. As international REDD programs wait
severe tornedo seasons highlight that climate justice and to get off the ground, national governments increasingly
climate vulnerability is a class issue in environmental jus- look to regional forests to offset their own emissions. This
tice in developed countries as well. actually puts forest questions at the heart of climate jus-
The means of compensation so far have mainly taken tice issues, since most rural development policy increas-
the form of fiscal transfers, provisioning of social services, ingly focuses on a few global and regional markets and
and in some cases infrastructure improvement. Broader high-input commodities. While forest policy has garnered
approaches could include support for rural livelihoods, increased visibility, attention to it has revolved strongly
improvement of urban and peri-urban biotic amenities, around conservation and climate. Development policies
jobs, compensation for environmental services (such focused on forest-based rural livelihoods have received
as but not limited to REDD), adaptation investments less attention, in spite of the best efforts of international
and programs that focus on reducing vulnerabilities of organizations such as the Center for International Forestry
Hecht et al: Chapter 10. Trees have Already been Invented Art. 24, page 5 of 34
Research (CIFOR) and La Via Campesina, the international about 32% in soils. Boreal forests more or less reverse this
peasant movement for small-scale sustainable agriculture storage pattern with some 20% of the C in biomass and
[71, 72, 73, 74]. 60% in soils (Pan et al 2011). As Table 2 reveals, there
Access to forests and their products are changing, and is a large consistent uptake of C of about 2.5 –2,3 Pg C
traditional uses may be criminalized in some GHG offset year from 1990 to 2007. When secondary forest uptake
regimes [9, 53, 75, 76, 77]. Insecure tenure regimes may is reviewed and added to the totals, there is a consistent
precipitate land grabs and forest conversion. For this rea- gross forest sink of some 4.05 Pg C per year and a net sink
son, it is essential to work with local communities and of some 111 ± .82 Pg per year. The biomass of more or
with multiple forms of local knowledge in order to design less intact tropical forests is roughly two-thirds of the total
effective systems. We must make sure that carbon offsets global forest carbon sink. Thus what happens in tropical
do not become a new form of expropriation, assuaging forests of critical importance for the global climate and
the guilt of GHG gluttons while marginalizing and crimi- not some tropical fetish of scientists. Some of this pro-
nalizing those whose livelihoods depend on functioning ductivity is explained by the processes of C fertilization in
forests. This is a critique that is regularly leveled at REDD. mature forest biomes, which remains controversial. But,
Woody systems have the potential to both sequester car- significantly, a great deal of sequestration is occurring via
bon and help alleviate poverty through subsistence and secondary forest recovery over the last century of changes
market goods, although the magnitude remains contro- and land abandonment in the tropics.
versial [78, 79, 80, 81, 82]. Tropical land use changes have caused net C releases that
In the next sections we outline several dynamics that are second only to fossil fuel emissions and are estimated
we suggest have important effects for bending the curve. at about 60% of fossil fuel emissions. These large addi-
We look at six processes in terms of both how they can tions to atmospheric GHG are significantly offset by about
mitigate climate change and how they can help people 50%—by secondary growth, and other forms of forest land
and ecosystems adapt to it. These processes are: 1) slow- recuperation. We discuss secondary forests in more detail
ing deforestation; 2) forest resurgence; 3) agroforestry and further on, because they are among the most dynamic sys-
matrix systems; 4) urban and peri-urban forests in carbon tems in the global carbon cycle, but also involve social and
dynamics; and finally 5) the urban waste system and meth- biotic processes that are among the most complex [83, 84,
ane management. All these strategies occur within highly 85, 86, 87, 88]. The significance of these intact and recov-
conjunctural social, market, institutional, cultural, and ering tropical forests—summing about 2.7 ± 0.7 Pg C per
environmental conditions of possibility, and all are highly year—is that they account for about 70% of the gross C sink
interactive and reactive to economic, environmental, and of the world’s forests, and, at the same time, C releases
political volatilities. History, economics, politics, culture, from deforestation in the tropics are equivalent to 60%
institutions, and questions of epistemology shape these of global fossil fuel emissions. Tropical areas are the focus
dynamics far more than we imagine. of vast new development programs which are changing
land uses, even as climate change is also strongly affecting
Forests and Forests by Other Names: The these forests and thus threatening their carbon seques-
Biotic Dynamics and Social Lives of Woodlands tration and storage patterns [89, 90, 91]. As Pan et al [1]
The Global Forest Carbon Sink: Magnitude and point out, “tropical forests have the world’s largest forest
Dynamics area, the most intense contemporary land use change,
Forest lands store about a trillion tons of carbon, roughly the highest C uptake, but also the most uncertainty.” It
25% of global carbon, about as much as the oceans. Tropi- is important to control deforestation but on the optimis-
cal rainforests convert more carbon into biomass than tic side of the story, substantive changes in clearing can
any other terrestrial system, and so their dynamics have occur relatively quickly, in decades [39, 92, 93, 94, 95, 96].
been most widely studied and are especially important to Although deforestation still continues, there are signifi-
carbon neutral development strategies anywhere on the cant declines in deforestation in some areas, which reflect
planet. Wooded ecosystems of varying biomass and cover unusual constellations of socio-economic, institutional,
have already been invented, they are readily accessible in and political factors.
most biomes, and they can be manipulated to capture What does this mean? First, temperate forests overall
and store even more carbon in most cases. There are also are doing well through dynamics of suburbanization,
vast local and scientific knowledge systems about their shifts in agricultural lands from agrarian to other uses, for-
management and reproduction. Table 2 outlines carbon est regrowth, and, in the case of China, intensive reforesta-
sequestration by forests across the major forest biomes. tion which enhanced its forest C sink by some 34% [97].
Current global carbon (C) stocks of about 861 ± 66 Pg C Even in the US, there are ample opportunities to augment
are found in world forests, with about 44% in soil C stor- forest sequestration through more carbon-based manage-
age, 42% in living biomass below and above ground, about ment and enhancing forests in less wooded landscapes
8% in deadwood, and another 5% in litter (Pan et al 2011). [98].
Tropical forests store about 55% of this C (471 ± 93 PgC), This positive trend is countered by the reality that US
with slightly less than a third in boreal ecosystems (32%, western forests and some boreal forests are suffering
or 272 plus or minus 23 Pg C), and temperate forests hold- from high tree mortality from combinations of drought,
ing about 19% of forests stocks (119 ± 6 Pg C). Tropical climate change, and related insect predation [99]. US
forests store most of their carbon in biomass (56%), with Forest Service data, released in June 2016, provide
Art. 24, page 6 of 34 Hecht et al: Chapter 10. Trees have Already been Invented
e 9 1 4 5 4 4 8 2 9 6 4 5 8 3 0 4 3 1 9
ock changper area –1 Mg C ha–1year) 0.3 1.2 0.0 0.4 0.4 0.9 1.6 1.2 1.5 2.8 0.3 1.0 0.1 1.0 0.9 0.9 0.5 0.7 0.6
t (
S
y 6 0 3 7 3 5 0 5 9 5 3 2 2 9 0 4 6 4 9
t 6 5 8 4 6 4 1 8 3 7 8 7 8
n 2 3 4 4
ertai()±
c
n
U
7 Total stock hange 264 199 10 27 499 239 239 182 37 18 51 9 3 777 117 482 418 1017 2294
0 c
0
2 d 3 6 1 3 3 8 7 7 2 0 0 6 0 0 6 8 3 6 9
2000– arvestewood product –1ear) 1 2 2 1 7 2 2 1 8 2 3 18
H y
C
Soil (Tg 42 35 7 –10 74 37 65 28 8 4 14 1 0 156 ND ND ND ND 230
r 3 5 9 4 1 8 9 8 D D 0 0 0 5 2 6 5 3 8
tte 4 3 1 10 1 N N 1 4 1 15
Li
ead ood 97 19 16 0 132 9 2 24 5 2 ND 0 0 42 10 43 45 98 273
Dw
s 9 4 3 1 0 7 7 5 3 2 7 1 2 4 0 5 5 0 4
s 6 8 5 2 2 4 3 1 2 1 1 5 0 2 4 7 4
a – 1 1 1 1 4 1 4 3 8 4
m 1
o
Bi
Stock change per area –1 (Mg C ha–1year) Boreal* 0.39 0.93 0.11 1.12 0.45 Temperate* 0.72 1.71 0.96 2.28 2.14 0.33 0.91 0.07 0.91 Tropical intact 0.88 0.94 0.77 0.84 0.73
y 4 7 7 6 6 4 8 4 4 4 3 2 1 8 8 2 6 7 3
t 6 3 1 7 3 5 3 1 1 7 3 0 6 4 6
n 3 1 3 3
ertai()±
c
n
U
99 Total stock change 255 146 26 65 493 179 232 135 54 14 50 7 1 673 144 532 652 1328 2494
9
1990–1 arvested wood product 19 41 23 11 94 33 24 7 2 0 8 5 0 80 5 9 22 35 209
H
Soil –1ar) 45 36 6 38 125 9 81 31 19 5 15 1 ND 160 ND ND ND ND 286
e
y
Litter (Tg C 63 22 14 3 103 13 8 15 ND ND 10 0 ND 46 2 7 9 17 166
ead ood 66 10 –24 0 53 6 2 22 9 2 ND 0 ND 42 13 48 48 109 204
Dw
s 1 7 6 3 7 8 7 0 4 6 7 1 1 5 5 9 3 7 0
s 6 3 1 1 1 1 6 2 1 4 2 6 7 6 3
a 1 1 1 3 1 4 5 1 6
m 1 1
o
Bi
s
Biome and country/ region Asian Russia European Russia Canada European †boreal Subtotal ‡United States Europe China Japan South Korea Australia New Zealand Other countrie Subtotal Asia Africa Americas Subtotal Global §subtotal
Hecht et al: Chapter 10. Trees have Already been Invented Art. 24, page 7 of 34
Uncertainty Stock change ()per area± –1 (Mg C ha–1year) 2973.53 1351.47 4294.56 5393.19 2982.38 3051.08 5771.30 7181.38 7281.04 me periods of 1990 to 1999 alculation refers to the sup- oreal and temperate forests. ood and Agriculture Organi-
2000–2007 Harvested Total Dead wood stock woodLitterSoilproductchange –1(Tg C year) ND[1]30ND593 ND[1]83ND271 ND[1]113ND858 ND[1]226ND1723 102306711 436838753 455113231276 9813226362740 2731584561894017 by biomes by country or region for the tiand” (afforested land). The uncertainty c ctices) are included in the estimates in b nd “other wooded land” reported to the F
Biomass 564 188 745 1497 664 613 1090 2367 2941 –1g C year) ew forest l ement pra n 2007), a
1990–1999 Biome and Harvested Total country/ Dead wood stock Uncertainty Stock change regionBiomasswoodLitterSoilproductchange()per area± –1 (Mg C ha–1–1(Tg C year)year) Tropical regrowth Asia498ND[1]27ND5262633.52 Africa169ND[1]73ND2421211.48 Americas694ND[1]113ND8074034.67 Subtotal1361ND[1]213ND15744963.24 ||All tropics Asia6231322756702662.14 Africa6384877397743251.06 Americas12674891132214584361.42 Subtotal2529109172133529036051.40 ¶Global total299120416649820940686151.04 Carbon Sequestration by Forests Across Major Biomes. Estimated annual change in C stock (TTable 2: and 2000 to 2007. Estimates include C stock changes on “forest land remaining forest land” and “nporting online material. ND, data not available; [1], litter is included in soils. Source: Pan et al. [10].* Carbon outcomes of forest land-use changes (deforestation, reforestation, afforestation, and manag† Estimates for the area that includes Norway, Sweden, and Finland.‡ Estimates for the continental U.S. and a small area in southeast Alaska.§ Estimates for global established forests.|| Estimates for all tropical forests including tropical intact and regrowth forests. ¶ Areas excluded from this table include interior Alaska (51 Mha in 2007), northern Canada (118 Mha ization.
Art. 24, page 8 of 34 Hecht et al: Chapter 10. Trees have Already been Invented
alarming statistics: extreme drought, warming weather, intensifying agriculture reduced forest clearing in the Bra-
and bark beetle infestation have killed 66 million trees in zilian case. But while many other soybean-growing areas
California’s Southern Sierra Nevada since 2010. 26 million of Latin America adopted the same new technology, there
of those trees died over just an eight month period at the the result was expanded forest clearing in a classic case of
end of 2015 and beginning of 2016 [100]. We know the the Jevons paradox by which more efficient technologies
southwestern US has had decadal droughts and the region do not reduce resource use because they also increase
may be on a cusp of a biome change [101, 102, 103]. The demand.
large-scale death of trees in California and elsewhere In Brazil, social dynamics were able to decouple agri-
has radically changed fire behavior, in tandem with the cultural intensification and economic expansion from
increase in fire suppression practices that disrupted his- forest clearing. This runs counter to the usual explana-
toric fire management regimes in which more frequent, tions of deforestation drivers; neither Malthusian pres-
smaller fires prevented large conflagrations. sures or nor market insertion could explain the outcome.
El Niño weather patterns dry tropical forests and enor- Conventional wisdom and typical modeling would
mously increase their flammability. The influence of these have predicted increased deforestation. Population was
climate stresses is persistent [90, 104, 105, 106, 107, 108]. increasing and the landscape was deeply integrated
We must avoid dynamics that produce downward spirals, into global markets, and yet deforestation was slowing.
which now means paying a lot more attention to broader The shop-worn, familiar explanations could not account
landscape scales and human interventions that result in for the effects of unforeseen socioeconomic and politi-
forest clearing. Even short-term tropical deforestation cal dynamics, new policies, regulations, monitoring,
pulses can rapidly exceed the emissions of industrial and changing cultural norms. Trees did not have to be
economies, as occurred in 2015 when forest clearing in invented. But new social relations around environment
Indonesia resulted in C releases that exceeded the emis- and development did.
sions of the US economy. All of these factors point to the While soy production, one of the central drivers of
importance of both avoided and zero net deforestation as deforestation, continues to have “leakage” into other
a central climate change mitigation strategy. biomes in South America [114], in the Brazilian Amazon,
forest clearing has undergone a shift that was almost
Slowing Deforestation unimaginable slightly more than a decade ago. The only
Global tropical deforestation, at roughly 12% of total comparable decline in Amazonian deforestation processes
global emissions, is equivalent in its carbon release to was probably that associated with the massive die off of
the entire global transportation system. At the same time, native populations in the colonial period [115, 116, 117].
deforestation in the Amazon has declined dramatically Figure 1 shows the dramatic recent decline in deforesta-
(going down 80% since 2004) due to a complex of new tion in the Brazilian Amazon.
institutions, regulations, political will, and monitoring. In a different way, deforestation and deforestation pres-
Social pacts, social transformations at broader scales, and sure have declined significantly in El Salvador, a place that
structural change in the regional economies were critical was the poster child for deforestation in the 1970s and
in producing this astounding result [95, 109, 110]. Brazil’s 1980s. Due to a number of factors outlined elsewhere
reduction in Amazonian deforestation—largely from con- [83, 118], out-migration and remittances slowed regional
trol over the soy-cattle complex in the southern Amazon forest clearing. Remittances (monies that migrants earn
arc of deforestation—represents the single biggest emis- abroad and send home to their families) were positively
sions cut in the past decade. Brazil’s reduction in defor- correlated with declines in deforestation, as these funds
estation amounted to offsetting 3.2 billion tons of carbon rather than the results of agricultural sales provided
dioxide emissions, equal to the savings that would have income for food and other household needs. Such land-
been achieved by taking all cars off American roads for scapes reflect both a decline in woodland loss and increas-
three years. This decline dropped Brazil’s total emissions ing secondary forests. Figure 2 shows that increasing
by 40%, making this country one of the global leaders remittances are correlated with both a decrease in forest
in climate mitigation. This was achieved quickly—within clearing and with forest resurgence.
a decade—and reflected a local decoupling, or unlink- In other contexts, conservation areas have helped slow
ing, of economic growth from forest clearing in southern regional forest clearing to some degree, as parks and
Amazonia. (Such decoupling of economic health from reserves inhibited speculative and acquisitive clearing [93,
GHG emissions is perhaps more widespread that realized: 119, 120, 121]. Indigenous and traditional peoples have
California, the world’s eighth-largest economy, produces blocked forest clearing in many cases, which has shown
only 1% of global emissions.) Unlike many technology- that inhabitation can protect forests and underscored the
based mitigation efforts that focus on a single innova- value of the social movements that produced inhabited
tion, in Brazil a confluence of social dynamics, scientific forests [92, 122, 123, 124, 125]. For this reason, tradi-
analysis, global market configurations, commodity chain tional peoples’ movements and the ratification of their
pressures, regional politics, social movements, careful land rights are considered central in climate justice and
monitoring, institutional development, and activism climate mitigation debates in the tropics. The effects of
across multiple scales produced what is now being hailed such populations on forest clearing highlights the com-
as the country’s “low carbon” development track [48, 94, plexity of rural development politics, including controver-
111, 112, 113]. In part, technological gains associated with sies about rights-based claims to land, carbon dynamics,
Hecht et al: Chapter 10. Trees have Already been Invented Art. 24, page 9 of 34
Figure 1: Deforestation patterns in the Brazilian Amazon, 1988 to 2015.
Figure 2: An increase in remittances from out-migrants who send money home correlates with reduced deforestation
and forest regrowth. Source: Hecht and Saatchi [118].
Art. 24, page 10 of 34 Hecht et al: Chapter 10. Trees have Already been Invented
and the distribution of economic and subsistence benefits is significant “rewilding” [144]. Europe also is undergoing
[126, 127, 128, 129, 130, 131, 132]. such processes [145, 146, 147].
Avoiding deforestation and slowing deforestation New forms of capital—from remittances to state
remain central policy goals, but these complex dynamics transfers—are major elements of rural poverty alleviation,
require an array of legislative, institutional, social move- and these have had an impact on forests. Tropical areas
ment, technical, monitoring, ideological, and political tac- are notable for their remittance economies: they receive
tics. Forests must be able to hold their own in the face of monies from migrants who send funds home [39, 40, 148,
emergent frontier land markets, “post frontier” commod- 149, 150, 151]. About a billion people are migrating, and
ity markets, and corrupt land agencies. Historical land remittance economies as well as social subsidies like con-
claimants who have supported forests and lived in them ditional cash transfers (subsidies to poor households for
have typically been overrun or expropriated through com- child health and education), pensions, and even proceeds
plex forms of state investment, state expropriation for from clandestine economies are shaping land uses. As a
mineral resources, private appropriation, and, often, vio- result, people are doing less labor-intensive agriculture
lence [133, 134, 135, 136, 137]. and closely-timed annual cropping; instead, households
In places such as Amazonia, El Salvador, and also engaged in all kinds of migration substitute more flexible
Panama, the transformation of deforestation processes assets, such as livestock and forest investments [23, 118,
reflects the more general dynamics of their multi-actor 152, 153, 154, 155]. Transnational communities—such
character. Multiscalar processes including global envi- as the “hometown associations” that Mexican migrants
ronmental financing and markets, an interested nation in the US organize to support their communities of ori-
state, civil society, engaged local government organiza- gin in Mexico—often involve environmental activities,
tions, regional investments in trees or tree crops, local including reforestation, forest management, and some
livelihoods, and local environmental politics all played Mexican REDD projects. Such initiatives represent “social
important roles in slowing deforestation. In the Brazilian remittances” in the form of environmental ideologies
case, forests benefitted from new forms of globalization, that migrants send back home [149, 156, 157]. Secondary
such as international environmental politics around cli- forest systems reflect enormous variability in the social
mate change, increased pressure on commodity chains, processes that produce them, but unfortunately their
boycotts, and social movements. In El Salvador the impact complexity also acts as barrier to their inclusion in con-
of war, remittances, agricultural retraction, and struc- ventional economic policies aimed at reducing carbon
tural change in the economy were significant drivers. In emissions.
Panama, government reforestation investment, declining
agro-industrial dynamics, regional migration to smaller Forest Transitions
urban areas, and social movements inhibited deforesta- The forest transition represents an important opportu-
tion and contributed to an overall forest gain [88, 118, nity to enhance carbon uptake in changing landscapes
138, 139, 140]. The point here is that many agents across through policy support, the manipulation and choice of
varying scales and significant globalized processes slowed tree species, and engagement in landscape recuperation
deforestation. Controlling deforestation is a significant in already inhabited places. While increasing attention
part of the picture, but helping forests that are growing focuses on constructing institutions and policies for sec-
back is also an important strategy, and the one to which ondary forest landscapes, how these translate into carbon
we turn next. dynamics remains largely unstudied [158, 159, 160, 161,
162]. Further, these systems are socially complex and the
Secondary Forests: From Abandoned Landscapes to array of property and use regimes that surround them
Carbon Heroes differ greatly among regions. The sheer heterogeneity of
Significant areas of secondary forests—or forests that drivers and processes is an active research area [27, 48, 88,
have grown back after clearing—can be found throughout 141, 163, 164, 165].
the world. Forest regrowth is the result of many factors, This relative lack of knowledge partly reflects the “low
including land use change, migration, urbanization, the status” of secondary forests as an area of study among trop-
impact of remittances from migrants, reforestation poli- ical ecologists and as a focus of domestic and international
cies, emerging markets for environmental services, mar- policymakers. It could also reflect a certain political indif-
kets for tree crops, slope stabilization, energy and timber ference to the social matrix—migrants, peasantries, and
markets, and agricultural retraction as a consequence of absentee owners—that shapes such woodlands. At another
poor prices for annual crops usually grown by peasants level, landscape analysts and political ecologists note the
[26, 141, 142, 143]. In Latin America, secondary forests difficulty in understanding the value and the cultural val-
account for almost a third of the land that has thus far ues that inhere in such secondary forests because their use
been cleared. While socially complex and difficult to moni- may be sporadic or clandestine and the institutions that
tor, the dynamics of forest recovery in the tropics are wide- mediate their access may also be contested. Wood, fruit,
spread. Regardless of the diversity of proximate or struc- and forage collection (and sometimes theft) are classic
tural causes, from the carbon perspective forest regrowth examples of periodic and often invisible uses. Thus these
is a positive outcome because young forests are much secondary forests—among the most common, yet most
more active in terms of GHG uptake. Even within the US, variable forest formations on the globe—are in many ways
especially in the northeast and parts of the south, there ciphers because their socio-cultural characteristics and the