ArticlePDF Available
Old-growth forests as global carbon sinks
Sebastiaan Luyssaert
, E. -Detlef Schulze
, Annett Bo
, Alexander Knohl
, Dominik Hessenmo
Beverly E. Law
, Philippe Ciais
& John Grace
Old-growth forests remove carbon dioxide from the atmosphere
at rates that vary with climate and nitrogen deposition
. The seques-
tered carbon dioxide is stored in live woody tissues and slowly
decomposing organic matter in litter and soil
therefore serve as a global carbon dioxide sink, but they are not
protected by international treaties, because it is generally thought
that ageing forests cease to accumulate carbon
search of literature and databases for forest carbon-flux estimates.
We find that in forests between 15 and 800 years of age, net ecosys-
tem productivity (the net carbon balance of the forest including
soils) is usually positive. Our results demonstrate that old-growth
forests can continue to accumulate carbon, contrary to the long-
standing view that they are carbon neutral. Over 30 per cent of the
global forest area is unmanaged primary forest, and this area con-
tains the remaining old-growth forests
. Half of the primary forests
(6 3 10
hectares) are located in the boreal and temperate regions of
the Northern Hemisphere. On the basis of our analysis, these forests
alone sequester about 1.36 0.5 gigatonnes of carbon per year. Thus,
our findings suggest that 15 per cent of the global forest area, which
is currently not considered when offsetting increasing atmospheric
carbon dioxide concentrations, provides at least 10 per cent of the
global net ecosystem productivity
. Old-growth forests accumulate
carbon for centuries and contain large quantities of it. We expect,
however, that much of this carbon, even soil carbon
, will move back
to the atmosphere if these forests are disturbed.
We conducted a literature search to test the hypothesis that old-
growth forests continue to accumulate atmospheric carbon dioxide
). Site-level estimates of the annual sums of carbon-cycle com-
ponents were compiled, including those of biometry-based net prim-
ary production (NPP), eddy-covariance or biometry-based net
ecosystem production (NEP) and chamber-based heterotrophic res-
piration. The data set was completed with site information related to
stand characteristics, standing biomass and stand age. Data were com-
piled from 519 plot studies that reported one or more components of
the carbon cycle. The studies involved boreal (,30%) and temperate
(,70%) forests and represented the full range of conditions of such
forests, excluding those subjected to experimental treatments such as
fertilization and irrigation (Supplementary Information, section 1.1).
Tropical forests were excluded from the analysis because only 12 sites
were found for which NEP and age estimates are available.
The NEP is the net carbon balance of the forest as a whole, and is
the difference between CO
uptake by assimilation and losses
through plant and soil respiration. On the basis of our global data
set we find that in forests between 15 and 800 years old, the NEP is
usually positive; that is, the forests are CO
sinks (Fig. 1a). The
maximum probabilities of finding a single forest to be a source of
carbon at 60, 180 and 300 years of age are 0.20, 0.25 and 0.35,
respectively. However, the probability of finding an ensemble of
ten old-growth forests that are carbon neutral is negligible
(Supplementary Fig. 1). In the small number of case studies on the
effect of age on the carbon balance of forests, several have demon-
strated some age-related decline in NEP but very few have shown old
forests to be sources
. Our NEP estimates suggest that forests
200 years old and above sequester on average 2.4 6 0.8 tC ha
(tC, tonnes of carbon; Fig. 1a). In our model (Supplementary
Information, section 1.3), we find that old-growth forests accumulate
0.4 6 0.1 tC ha
in their stem biomass and 0.7 6
0.2 tC ha
in coarse woody debris, which implies that about
1.3 6 0.8 tC ha
of the sequestered carbon is contained in roots
and soil organic matter.
The commonly accepted and long-standing view that old-growth
forests are carbon neutral (that is, that photosynthesis is balanced by
respiration) was advanced in ref. 6 and was originally based on ten
years’ worth of data from a single site
. It is supported by the observed
decline of stand-level NPP with age in plantations
, but is not
apparent in some ecoregions
. Yet a decline in NPP is commonly
assumed in ecosystem models (Supplementary Information, section
1.4). Moreover, it has led to the view that old-growth forests are
redundant in the global carbon cycle.
If, however, the hypothesis of carbon neutrality
were correct, the
expected probabilities of observing a sink or source would be equal
and around one-half, the average sink strength for a random
ensemble of forests 200 years old and above would be zero and the
mean CO
release from heterotrophic respiration would equal the
mean CO
sequestration through NPP (thus, the ratio of hetero-
trophic respiration to NPP would be approximately one).
However, we observe this ratio to be well below one on average
(Fig. 1b) and not to increase with age. Hence, all three quantitative
tests fail to support the hypothesis of carbon neutrality. The currently
available data consistently indicate that carbon accumulation con-
tinues in forests that are centuries old.
In fact, young forests rather than old-growth forests are very often
conspicuous sources of CO
(Fig. 1a) because the creation of new
forests (whether naturally or by humans) frequently follows disturb-
ance to soil and the previous vegetation, resulting in a decomposition
rate of coarse woody debris, litter and soil organic matter (measured
as heterotrophic respiration) that exceeds the NPP of the
(Fig. 1b).
The scatter in the relationship between NPP and age is consid-
erable, but given the climatic, edaphic and biological diversity of the
observations in combination with differences in disturbance histor-
ies, this is to be expected. There is some degree of age-related decline
in NPP beyond 80 years of age (Fig. 1c), and temperate and boreal
forests both show a consistent pattern of declining NPP beyond an
early maximum (Supplementary Fig. 2a) when analysed separately.
The decline in NPP could be partly attributed to the presence or
absence of management (Supplementary Fig. 2b). However, we
expect that this decline is not strictly a management effect, but a
Department of Biology, Universi ty of Antwerp, 2610 Wilrijk, Belgium.
College of Forestry, Oregon State University, Corvallis, Oregon 97331-5752 , USA.
Max-Planck Institute for
Biogeochemistry, 07701 Jena, Germany.
ETH Zu¨rich, Institute of Plant Sciences, CH-8092 Zu¨rich, Switzerland.
Laboratoire des Sciences du Climat et de l’Environnement, IPSL-LSCE,
CEA-CNRS-UVSQ, 91191 Gif sur Yvette Cedex, France.
School of GeoSciences, The University of Edinburgh, Edinburgh EH9 3JN, UK.
Vol 455
11 September 2008
Macmillan Publishers Limited. All rights reserved
reflection of differences in disturbance history between managed and
unmanaged forests.
Consistent with earlier studies
, biomass continues to increase for
centuries irrespective of whether forests are boreal or temperate
(Supplementary Fig. 3). In the course of succession, plants compete
for resources and self-thinning
(or thinning by humans in the case
of managed forests) occurs (Fig. 2), so the older stands contain a
relatively small number of individuals, although of course these trees
tend to be large. Obviously biomass cannot accumulate forever. Our
data (Supplementary Fig. 3) suggest a possible upper limit some-
where between 500 and 700 tC ha
(equivalent to 1,400 to 1,800
cubic metres of wood per hectare); these high-biomass forests were
located in the Pacific Northwest USA
We speculate that when high above-ground biomass is reached,
individual trees are lost because of lightning, insects, fungal attacks of
the heartwood by wood-decomposers, or trees becoming unstable in
strong wind because the roots can no longer anchor them. If old-
growth forests reach high above-ground biomass and lose individuals
owing to competition or small-scale disturbances, there is generally
new recruitment or an abundant second canopy layer waiting in the
shade of the upper canopy to take over and maintain productivity.
Although tree mortality is a relatively rapid event (instantaneous
to several years long), decomposition of tree stems can take decades.
Therefore, the CO
release from the decomposition of dead wood
adds to the atmospheric carbon pool over decades, whereas natural
regeneration or in-growth occurs on a much shorter timescale. Thus,
old-growth forest stands with tree losses do not necessarily become
carbon sources, as has been observed in even-aged plantations (that
is, where trees are all of the same age). We recognize that self-thinning
theory was originally developed and validated for even-aged single-
species stands; however, it has been shown to hold for uneven-aged
multi-species plant communities (Supplementary Information, sec-
tion 1.3). In reasonable agreement with our observations (Fig. 1b),
self-thinning theory predicts that the ratio between heterotrophic
respiration and NPP is constant and around 0.65 6 0.02 (indicating
a carbon sink; Supplementary Fig. 4), as long as stand density is
driven by small-scale, rather than stand-replacing, disturbances.
Old stands, with sufficiently high densities (that is, through develop-
ment of a multilayer canopy structure) are thus expected to maintain
biomass accumulation for centuries. Hence, we postulate that bio-
mass accumulation and decline are largely driven by stand structure.
A stand must be spared for centuries from stand-replacing distur-
bances (such as fires, insect outbreaks, wind-throw and avalanches)
in order to accumulate sufficient aboveground biomass to become
old growth. Because the cumulative probability of disturbances is
higher in stands with high above-ground biomass, old stands are
rarer than young stands, even in unmanaged landscapes. At the land-
scape level, we expect a mosaic of forests characterized by different
times since the last stand-replacing disturbance
. Despite differences
in age and density, these forests are, however, expected to follow the
same relationship between biomass and density (Fig. 2).
NEP (tC ha
1 3 10 31 100 315 1,000
Age (years)
NPP (tC ha
Figure 1
Changes in carbon fluxes as a function of age. a, Observed NEP
versus age; positive values indicate carbon sinks and negative values indicate
carbon sources.
b, Observed ratio of heterotrophic respiration (Rh) to NPP
versus age; Rh:NPP , 1 indicates a carbon sink.
c, Observed NPP versus age.
It appears that temperate and boreal forests both show a pattern of declining
NPP. Most probably, the late-successional increase in NPP is caused by the
combination of data from different climate regions or the combination of
disturbance regimes (Supplementary Fig. 2a, b). In each panel, the green
dots show observations of temperate forests, the orange dots show
observations of boreal forests, the thick black line shows the weighted mean
within a moving window of 15 observations, the grey area around this line
shows the 95% confidence interval of the weighted mean and the thin black
lines delineate the 95% confidence interval (where visible) of the individual
flux observations.
100 315 1,000 3,150 10,000 31,500
Density (trees per hectare)
Biomass (tC ha
Figure 2
Biomass accumulation as a function of stand density. Each data
point represents a different forest, many of which have different growing
conditions and tree species. Not all growing conditions and species
compositions allow for the accumulation of the global maximum observed
biomass. Self-thinning, the process of density-dependent mortality, is shown
(solid line, of slope c) as the relationship between the logarithm of above-
ground biomass and the logarithm of stand density according to ref. 23
(c 520.51 6 0.08, r
5 0.25, P , 0.01). The green dots show observations of
temperate forests, the orange dots show observations of boreal forests and
the grey area (which is barely wider than the solid line) shows the 95%
confidence interval of the median.
Vol 455
11 September 2008
Macmillan Publishers Limited. All rights reserved
Under the Kyoto Protocol (
convkp/kpeng.pdf) only anthropogenic effects on ecosystems are con-
sidered (Article 2 of the Framework Convention on Climate Change
( onvkp/conveng.pdf); Supplementary
Fig. 5) and the accounting for changes in carbon stock by afforestation,
reforestation and deforestations is mandatory (Article 3.3), operating
from a base line of 1990. Leaving forests intact was not perceived as an
anthropogenic activity. In addition, the potential consequences of
excluding old-growth forests from national carbon budgets and from
the Kyoto Protocol were downplayed in the carbon-neutrality hypo-
. However, over 30% (1.3 3 10
ha) of the global forest area is
by the Food and Agriculture Organization of the United
Nations as primary forest, and this area contains the world’s remaining
old-growth forests. Half (0.6 3 10
ha) of the primary forests are located
in the boreal and temperate regions of the Northern Hemisphere. On the
basis of our analysis, we expect that these forests alone sequester at least
1.3 6 0.5 GtC yr
. Hence, 15% of the global forest surface, which is
currently not being considered for offsetting increasing atmospheric
concentrations, is responsible for at least 10% of the global NEP
Sporadic disturbances will interrupt carbon accumulation, implying
that net biome productivity
will be lower, but it will remain positive
as demonstrated by the accumulation of carbon in soils
debris and charcoal
The present paper shows that old-growth forests are usually carbon
sinks. Because old-growth forests steadily accumulate carbon for cen-
turies, they contain vast quantities of it. They will lose much of this
carbon to the atmosphere if they are disturbed, so carbon-accounting
rules for forests should give credit for leaving old-growth forest intact.
We conducted a literature and database search to determine the fate of the carbon
sequestered in forests. Observation-basedestimates were compiled for carbon-cycle
components, including biometry-based NPP, eddy-covariance or biometry-based
NEP and chamber-based heterotrophic respiration
. The data set was extended
with site information related to stand characteristics, standing biomass and stand
age. In general, uncertainties in flux estimates were not reported in the literature.
Therefore, weestimated the total uncertainty for every component flux containedin
the data set using a consistent framework based on expert judgment
(Supplementary Information, section 1.2). The uncertainty framework in our data-
base was designed to account for differences in data quality between sites due to
length of time series, methodology and conceptual difficulties (that is, gap filling
and dark respiration). Also, an uncertainty of 20% was assigned to the biomass, age
and density estimates. These uncertainties were propagated through the statistical
analyses by means of random realizations based on Monte Carlo principles. Within
each of the 1,000 random realizations, normally distributed random errors, based
on the uncertainty framework of our database, were added to the observed fluxes.
Therefore, all results that are based on flux data are reported as the weighted mean
and the 95% confidence interval of the probability distribution.
Despite the climatic, edaphic and biological diversity of our observations,
above-ground biomass was observed to be related to stand density in the way
described by self-thinning theory
. Although, this theory was initially developed
for even-aged single-species plant communities, we applied it to our data
(Supplementary Information, section 1.3) to determine the components of the
flux-computed NEP, specifically the above-ground biomass, woody debris and
soil sequestration. Furthermore, self-thinning theory was used to calculate the
theoretical ratio of heterotrophic respiration to NPP and compare it with the
observed ratio in support of the hypothesis that biomass accumulation and
decline are largely driven by stand structure.
Received 18 January; accepted 7 July 2008.
1. Carey, E. V., Sala, A., Keane, R. & Callaway, R. M. Are old forests underestimated
as global carbon sinks? Glob. Change Biol. 7, 339
344 (2001).
2. Pregitzer, K. S. & Euskirchen, E. S. Carbon cycling and storage in world forests:
biome patterns related to forest age. Glob. Change Biol. 10, 2052
2077 (2004).
3. Magnani, F. et al. The human footprint in the carbon cycle of temperate and boreal
forests. Nature 447, 848
850 (2007).
4. Zhou, G. Y. et al. Old-growth forests can accumulate carbon in soils. Science 314,
1417 (2006).
5. Kira, T. & Sihdei, T. Primary production and turnover of organic matter in different
forest ecosystems of the western pacific. Jpn. J. Ecol. 17, 70
87 (1967).
6. Odum, E. P. The strategy of ecosystem development. Science 164, 262
7. FAO. Global Forest Resources Assessment 2005. Progress towards sustainable forest
management. Forestry Paper 147 (Food and Agriculture Organization of the
United Nations, 2006).
8. Bolin, B. et al. in IPCC, Land Use, Land-Use Change, and Forestry. A Special Report of
the IPCC (eds Watson, R. T. et al. )23
51 (Cambridge Univ. Press, 2000).
9. Fontaine, S. et al. Stability of organic carbon in deep soil layers controlled by fresh
carbon supply. Nature 450, 277
280 (2007).
10. Acker, S. A., Halpern, C. B., Harmon, M. E. & Dyrness, C. T. Trends in bole biomass
accumulation, net primary production and tree mortality in Pseudotsuga menziesii
forests of contrasting age. Tree Physiol. 22, 213
217 (2002).
11. Knohl, A., Schulze, E. D., Kolle, O. & Buchmann, N. Large carbon uptake by an
unmanaged 250-year-old deciduous forest in Central Germany. Agric. For.
Meteorol. 118, 151
167 (2003).
12. Law, B. E. et al. Changes in carbon storage and fluxes in a chronosequence of
ponderosa pine. Glob. Change Biol. 9, 510
524 (2003).
13. Desai, A. R. et al. Comparing net ecosystem exchange of carbon dioxide between
an old-growth and mature forest in the upper Midwest, USA. Agric. For. Meteorol.
128, 33
55 (2005).
14. Gower, S. T., McMurtrie, R. E. & Murty, D. Aboveground net primary production
decline with stand age: Potential causes. Trends Ecol. Evol. 11, 378
382 (1996).
15. Binkley, D. et al. Age-related decline in forest ecosystem growth: an individual-
tree, stand-structure hypothesis. Ecosystems 5, 58
67 (2002).
16. Van Tuyl, S., Law, B. E., Turner, D. P. & Gitelman, A. I. Variability in net primary
production and carbon storage in biomass across Oregon forests—an
assessment integrating data from forest inventories, intensive sites, and remote
sensing. For. Ecol. Manage. 209, 273
291 (2005).
17. Harmon, M. E., Ferrell, W. K. & Franklin, J. F. Effects on carbon storage of
conversion of old-growth forests to young forests. Science 247, 699
702 (1990).
18. Janish, J. E. & Harmon, M. E. Successional changes in live and dead wood carbon
stores: implications for net ecosystem productivity. Tree Physiol. 22, 77
19. Wirth, C., Czimczik, C. I. & Schulze, E. D. Beyond annual budgets: carbon flux at
different temporal scales in fire-prone Siberian Scots pine forests. Tellus 54,
630 (2002).
20. Knohl, A. et al. Carbon dioxide exchange of a Russian boreal forest after
disturbance by wind throw. Glob. Change Biol. 8, 231
246 (2002).
21. Kowalski, A. S. et al. Paired comparisons of carbon exchange between undisturbed
and regenerating stands in four managed forests in Europe. Glob. Change Biol. 10,
1723 (2004).
22. Irvine, J., Law, B. E. & Hibbard, K. A. Postfire carbon pools and fluxes in semiarid
ponderosa pine in Central Oregon. Glob. Change Biol. 13, 1748
1760 (2007).
23. Yoda, K., Kira, T., Ogawa, H. & Hozumi, K. Self-thinning in overcrowded pure stands
under cultivated and natural conditions. J. Biol. Osaka City Univ. 14, 107
132 (1963).
24. Mladenoff, D. J., White, M. A., Pastor, J. & Crow, T. R. Comparing spatial pattern in
unaltered old-growth and disturbed forest landscapes. Ecol. Appl.3, 294
306 (1993).
25. Chapin, F. S. et al. Reconciling carbon-cycle concepts, terminology and
methodology. Ecosystems 9, 1041
1050 (2005).
26. Ciais, P. et al. in The Carbon Balance of Forest Biomes (eds Griffith, H. & Jarvis, P.)
150 (Taylor and Francis, 2005).
27. Jomura, M. et al. The carbon budget of coarse woody debris in a temperate broad-
leaved secondary forest in Japan. Tellus B 59, 211
222 (2007).
28. Preston, C. M. & Schmidt, M. W. I. Black (pyrogenic) carbon: a synthesis of
current knowledge and uncertainties with special consideration of boreal regions.
Biogeosciences 3, 397
420 (2006).
29. Luyssaert, S. et al. CO
-balance of boreal, temperate and tropical forest derived
from a global database. Glob. Change Biol. 13, 2509
2537 (2007).
Supplementary Information is linked to the online version of the paper at
Acknowledgements We thank all site investigators, their funding agencies and the
various regional flux networks (Afriflux, AmeriFlux, AsiaFlux, CarboAfrica,
CarboEuropeIP, ChinaFlux, Fluxnet-Canada, KoFlux, LBA, NECC, OzFlux,
TCOS-Siberia and USCCC), and the Fluxnet project, whose support was essential for
obtaining our measurements. S.L. was supported by CoE ECO UA-Methusalem and
the Research Foundation - Flanders (FWO-Vlaanderen) with a post-doctoral
fellowship and a research grant. A.K. was supported by the European Union with a
Marie Curie fellowship, and B.E.L. was supported by the regional North American
Carbon Program project ORCA (US Department of Energy, Terrestrial Carbon
Program, award number DE-FG02-04ER63917). E.-D.S. was supported by
DFG-Exploratories. Additional funding for this study was received from
CarboEuropeIP (project number GOCE-CT-2003-505572) and Ameriflux.
Author Contributions S.L., B.E.L., A.K. and P.C. compiled the data set. S.L., A.B. and
D.H wrote code and analysed the data. S.L., E.-D.S., A.K., B.E.L., P.C. and J.G.
designed the analyses and wrote the manuscript.
Author Information Reprints and permissions information is available at Correspond ence and requests for materials should be
addressed to S.L. (
Vol 455
11 September 2008 LETTERS
Macmillan Publishers Limited. All rights reserved
... Numerous studies on the carbon storage ability of «natural forests», managed woodlands and plantations have highlighted the crucial role of management practices and tree diversity 8 . Faced with the enthusiasm for tree plantations, Luyssaert et al. (2008) 9 demonstrated on the contrary that «primary forests» (i.e. debated «natural forests», see section 2) «can continue to accumulate carbon, contrary to the long-standing view that they are carbon neutral». ...
... Numerous studies on the carbon storage ability of «natural forests», managed woodlands and plantations have highlighted the crucial role of management practices and tree diversity 8 . Faced with the enthusiasm for tree plantations, Luyssaert et al. (2008) 9 demonstrated on the contrary that «primary forests» (i.e. debated «natural forests», see section 2) «can continue to accumulate carbon, contrary to the long-standing view that they are carbon neutral». ...
... naturnahe Waldgesellschaften besitzen neben Selbstorganisationsfähigkeit und Stabilität vor allem eine hohe ökologische Qualität: Die Roten Listen zeigen, "dass vor allem solche Tier-, Pflanzen-und Pilzarten überproportional stark gefährdet sind, die auf typische Strukturen naturnaher Wälder spezialisiert sind" (BMU 2007). Zudem spielen naturnahe Waldgesellschaften eine herausragende Rolle als Kohlenstoffspeicher sowie als genetische "Reservebank" und besitzen zudem ein geringeres Produktionsrisiko als standortfremde Waldgesellschaften ( Köhle et al. 2017, Liang et al. 2016, Luyssaert et al. 2008, Stephenson et al. 2014). Durch den Verlust an Primärwäldern in Deutschland ist es von höchster Bedeutung zu wissen, wie es um die ökologische Qualität und die Selbstorganisationsfähigkeit der noch vorhandenen Waldflächen steht, und damit auch in Erfahrung zu bringen, inwieweit die aktuell praktizierte Bewirtschaftung dem nationalen und internationalen Ziel einer nachhaltigen Ressourcennutzung dient -einer Nutzung, die stabile Ökosysteme und die Vielfalt des Lebens auf unserem Planeten erhält, für die Gesundheit und zum Wohlergehen der Menschheit. ...
... von "Arten alter Wälder" ( Bollmann 2013, Winter et al. 2005, Müller et al. 2005). Internationale Studien haben zudem gezeigt, dass struktur-und artenreiche Altholzbestände nicht nur produktiver sind, sondern auch fortlaufend große Mengen an Kohlenstoff binden und langfristig speichern können, so dass diese Wälder als natürliche Kohlenstoffsenken fungieren und somit eine bedeutende Klimaschutzfunktion einnehmen ( Greenpeace 2018, Luyssaert et al. 2008, Stephenson et al. 2014, Liang J. et al. 2016, Musavi et al. 2017). ...
Full-text available
Überblick über den zustand der Naturnähe der in Deutschland vorkommenden Waldökosysteme
... However, there is evidence that ecological succession or ecosystem development does not stabilize biomass. Instead, it accumulates carbon, keeping the system's net production high (Schulze et al., 2000;Zhou et al., 2006;Luyssaert et al. 2008Luyssaert et al. , 2011Stephenson et al., 2014). ...
Coastal marine ecosystems have structural and functional features usually connected by the seasonal transfer of nutrients and organisms. These environments can utilize inter-ecosystem subsidies to increase resilience and maturity and support human activities like fishing. However, the importance of the connection and the role of the seasonal pulse of energy flows to enhance maturity are still poorly understood and reported. Our objective in this paper is to assess the effect of seasonal hydrological pulses on two tropical coastal interconnected ecosystems. Thus, we made four Ecopath models for estuarine and neritic environments considering the dry and rainy seasons, with a similar sampling design that allowed them to be compared. Our results provide evidence for the occurrence of the pulsed ecosystems since both environments seem driven by the river flow. Estuary presents more and more substantial differences (measured by ecosystem attributes) in both seasons because it is directly affected by river floods than the neritic environment. The neritic is affected indirectly by the movement of species from the estuary and by a weaker river flow. In the dry season, the differences between ecosystems are lower because the dry season trend to homogenize cycling, maturity, homeostasis, and resilience. We found that the seasonal river flow (pulse) forces the variability of biomass, flows, and ecosystem features, and this variance creates the required stability for both ecosystems. Still, these environments benefit through the exchange of components that relieve the pressures of predation on specific groups and maintain the energy flow necessary for the functioning of their trophic webs. The pulse by the rainfall favors connectivity and equalizes the two systems, increasing the connectivity between them and the exchange of subsidies that strengthens the trophic structures, contributing to the increase in maturity. In these ecosystems, seasonal changes become a key factor for exchanging flows that will promote sustainability, the accumulation of more biomass (growth), and the optimization of reserve energy (development) in both systems. This efficient joint strategy of perpetuation is what promotes resistance and resilience to these ecosystems, which together can reach different states of equilibrium, translated into maturity to withstand new environmental changes.
... The effects of climate change on forest productivity and biodiversity may be predicted to be negative due to increased evapotranspiration and reduced rainfall in many forested areas; an increase in extreme events like droughts, wildfires, storms, and insect attacks; and local or regional extinctions of plant and animal species (Easterling et al., 2000;Seidl et al., 2011;Anderegg et al., 2013;Urban, 2015). On the other hand, productivity may increase due to the fertilising effect of increased nitrogen deposition and higher atmospheric CO 2 levels (Zaehle and Dalmonech, 2011;Luyssaert et al., 2008) and shifts in 6072 M. Lindeskog et al.: Forest management module in LPJ-GUESS v4.0, r9710 tree species composition and longer growing seasons at high latitudes caused by higher temperatures (Sitch et al., 2015;Morin et al., 2018). ...
Full-text available
Global forests are the main component of the land carbon sink, which acts as a partial buffer to CO2 emissions into the atmosphere. Dynamic vegetation models offer an approach to projecting the development of forest carbon sink capacity in a future climate. Forest management capabilities are important to include in dynamic vegetation models to account for the effects of age and species structure and wood harvest on carbon stocks and carbon storage potential. This article describes the implementation of a forest management module containing even-age and clear-cut and uneven-age and continuous-cover management alternatives in the dynamic vegetation model LPJ-GUESS. Different age and species structure initialisation strategies and harvest alternatives are introduced. The model is applied at stand and European scales. Different management alternatives are applied in simulations of European beech (Fagus sylvaticus) and Norway spruce (Picea abies) even-aged monoculture stands in central Europe and evaluated against above-ground standing stem volume and harvested volume data from long-term experimental plots. At the European scale, an automated thinning and clear-cut strategy is applied. Modelled carbon stocks and fluxes are evaluated against reported data at the continent and country levels. Including wood harvest in regrowth forests increases the simulated total European carbon sink by 32 % in 1991–2015 and improves the fit to the reported European carbon sink, growing stock, and net annual increment (NAI). Growing stock (156 m3 ha−1) and NAI (5.4 m3 ha1 yr1) densities in 2010 are close to reported values, while the carbon sink density in 2000–2007 (0.085 kg C m−2 yr1) equates to 63 % of reported values, most likely reflecting uncertainties in carbon fluxes from soil given the unaccounted for forest land-use history in the simulations. The fit of modelled and reported values for individual European countries varies, but NAI is generally closer to reported values when including wood harvest in simulations.
... Changing land cover (e.g., woody encroachment and boreal forest creep) however is not the only mechanism for a carbon sink (Stevens et al., 2017;Wang et al., 2020). Older aged forests also tend to have deepening roots and may act as the carbon sink (Luyssaert et al., 2008), although this is not the case in Konza. ...
Full-text available
Carbonate weathering is essential in regulating atmospheric CO2 and carbon cycle at the century timescale. Plant roots accelerate weathering by elevating soil CO2 via respiration. It however remains poorly understood how and how much rooting characteristics (e.g., depth and density distribution) modify flow paths and weathering. We address this knowledge gap using field data from and reactive transport numerical experiments at the Konza Prairie Biological Station (Konza), Kansas (USA), a site where woody encroachment into grasslands is surmised to deepen roots. Results indicate that deepening roots can enhance weathering in two ways. First, deepening roots can control thermodynamic limits of carbonate dissolution by regulating how much CO2 transports vertical downward to the deeper carbonate-rich zone. The base-case data and model from Konza reveal that concentrations of Ca and dissolved inorganic carbon (DIC) are regulated by soil pCO2 driven by the seasonal soil respiration. This relationship can be encapsulated in equations derived in this work describing the dependence of Ca and DIC on temperature and soil CO2. The relationship can explain spring water Ca and DIC concentrations from multiple carbonate-dominated catchments. Second, numerical experiments show that roots control weathering rates by regulating recharge (or vertical water fluxes) into the deeper carbonate zone and export reaction products at dissolution equilibrium. The numerical experiments explored the potential effects of partitioning 40 % of infiltrated water to depth in woodlands compared to 5 % in grasslands. Soil CO2 data suggest relatively similar soil CO2 distribution over depth, which in woodlands and grasslands leads only to 1 % to ∼ 12 % difference in weathering rates if flow partitioning was kept the same between the two land covers. In contrast, deepening roots can enhance weathering by ∼ 17 % to 200 % as infiltration rates increased from 3.7 × 10−2 to 3.7 m/a. Weathering rates in these cases however are more than an order of magnitude higher than a case without roots at all, underscoring the essential role of roots in general. Numerical experiments also indicate that weathering fronts in woodlands propagated > 2 times deeper compared to grasslands after 300 years at an infiltration rate of 0.37 m/a. These differences in weathering fronts are ultimately caused by the differences in the contact times of CO2-charged water with carbonate in the deep subsurface. Within the limitation of modeling exercises, these data and numerical experiments prompt the hypothesis that (1) deepening roots in woodlands can enhance carbonate weathering by promoting recharge and CO2–carbonate contact in the deep subsurface and (2) the hydrological impacts of rooting characteristics can be more influential than those of soil CO2 distribution in modulating weathering rates. We call for colocated characterizations of roots, subsurface structure, and soil CO2 levels, as well as their linkage to water and water chemistry. These measurements will be essential to illuminate feedback mechanisms of land cover changes, chemical weathering, global carbon cycle, and climate.
... In that study, the multivariate statistical model of NEP, using data from 126 forest eddy-covariance flux sites worldwide, postulated a nonlinear empirical relationship of NEP to age, adapted from Amiro et al. (2010), whereby NEP was negative (a net C source) for only a few years after forest establishment and then increased sharply above 0 (a net C sink), stabilized after around 30 years and remained at that level thereafter for mature forests (> 100 years). This model, therefore, did not assume any significant reduction in forest net productivity after maturity, up to 300 years, consistent with several synthesis studies that have reported significant NEP of centuriesold forest stands (Buchmann and Schulze, 1999;Kolari et al., 2004;Luyssaert et al., 2008). ...
Full-text available
The effects of atmospheric nitrogen deposition (Ndep) on carbon (C) sequestration in forests have often been assessed by relating differences in productivity to spatial variations of Ndep across a large geographic domain. These correlations generally suffer from covariation of other confounding variables related to climate and other growth-limiting factors, as well as large uncertainties in total (dry + wet) reactive nitrogen (Nr) deposition. We propose a methodology for untangling the effects of Ndep from those of meteorological variables, soil water retention capacity and stand age, using a mechanistic forest growth model in combination with eddy covariance CO2 exchange fluxes from a Europe-wide network of 22 forest flux towers. Total Nr deposition rates were estimated from local measurements as far as possible. The forest data were compared with data from natural or semi-natural, non-woody vegetation sites. The response of forest net ecosystem productivity to nitrogen deposition (dNEP ∕ dNdep) was estimated after accounting for the effects on gross primary productivity (GPP) of the co-correlates by means of a meta-modelling standardization procedure, which resulted in a reduction by a factor of about 2 of the uncorrected, apparent dGPP ∕ dNdep value. This model-enhanced analysis of the C and Ndep flux observations at the scale of the European network suggests a mean overall dNEP ∕ dNdep response of forest lifetime C sequestration to Ndep of the order of 40–50 g C per g N, which is slightly larger but not significantly different from the range of estimates published in the most recent reviews. Importantly, patterns of gross primary and net ecosystem productivity versus Ndep were non-linear, with no further growth responses at high Ndep levels (Ndep > 2.5–3 g N m−2 yr−1) but accompanied by increasingly large ecosystem N losses by leaching and gaseous emissions. The reduced increase in productivity per unit N deposited at high Ndep levels implies that the forecast increased Nr emissions and increased Ndep levels in large areas of Asia may not positively impact the continent's forest CO2 sink. The large level of unexplained variability in observed carbon sequestration efficiency (CSE) across sites further adds to the uncertainty in the dC∕dN response.
... (Rockström et al. 2009). Dem Schutz und -wo immer möglich -der Wiederherstellung intakter Wälder kommt eine zentrale Rolle zu, wenn es darum geht, den Verlust an biologischer Vielfalt zu stoppen, den Klimawandel zu verlangsamen und die globalen Nachhaltigkeitsziele zu erreichen (Luyssaert et al. 2008;Paillet et al. 2010;Watson et al. 2018). Entsprechende Schutzanstrengungen können von Entwicklungsund Schwellenländern nur dann glaubhaft eingefordert werden, wenn es auch in Deutschland -als einem der reichsten Industrieländer -gelingt, die biologische Vielfalt wirkungsvoll zu schützen und den eigenen Wohlstand sicherzustellen, ohne dabei die Natur auszubeuten und negative externe Effekte in Drittländer zu verlagern. ...
Die Bundesregierung hat 2007 im Rahmen der Nationalen Strategie zur biologischen Vielfalt (NBS) u.a. das Ziel formuliert, 5% der deutschen Waldfläche einer natürlichen Entwicklung zu überlassen. Die andauernde Kritik von forst- und holzwirtschaftlichen Lobbyverbänden nimmt der vorliegende Artikel zum Anlass aufzuzeigen, dass der Beitrag, den ungenutzte Wälder zur Erhaltung der Biodiversität leisten können, nicht durch forstlich bewirtschaftete Wälder erbracht werden kann und dass durch die Umsetzung des 5%-Ziels weder eine Verknappung des Rohstoffs Holz noch eine Gefährdung der Versorgung des deutschen Clusters Forst und Holz, noch signifikant zunehmende Importströme von Holz und Holzprodukten zu befürchten sind. Durch die Fokussierung auf die vermeintlich negativen ökonomischen Effekte von Waldnaturschutzmaßnahmen droht vielmehr die Diskussion um die eigentlichen Probleme - um die mangelnde Kontrolle der hohen Holzeinfuhren nach Deutschland, um die Mitverantwortung des Wirtschaftsbereichs Forst und Holz sowie um den zu hohen Ressourcenverbrauch unseres Gesellschafts- und Wirtschaftssystems - aus dem Blick zu geraten.
Full-text available
Climate change will have a significant impact on forests as most of the factors determining their condition are modified by the effects of the climate change process. Some of these effects are a change in the distribution and amount of precipitation, an increase in the frequency of extreme meteorological phenomena, including hurricane winds, temperature distribution, or a change in the length of the growing season. In order to maintain the productivity of Polish forests and the range of ecosystem services they provide, the forestry sector will have to adapt to these changes. However, forestry will also have to take a part in holding back climate change. Achieving climate neutrality by mid-21st century and ensuring a 55% reduction in greenhouse gas emissions by 2030 will not be possible without using the ability of forests to absorb and permanently store carbon.
Conference Paper
Full-text available
Стр. 17-21 Малонарушеные лесные территории (МЛТ) – последние сохранившиеся крупные лесные массивы, не преобразованные деятельностью человека. В 2014 г. проанализировано сокращение МЛТ за 2000-2013 годы. Около 20% всех лесов мира являются малонарушенными. Площадь МЛТ в мире сократилась на 7,2%. Основной причиной деградации МЛТ является фрагментация лесных массивов, и лишь в 14% случаев - непосредственное сокращение лесного покрова.
Full-text available
Tropical forest degradation from logging, fire, and fragmentation not only alters carbon stocks and carbon fluxes, but also impacts physical land surface properties such as albedo and roughness length. Such impacts are poorly quantified to date due to difficulties in accessing and maintaining observational infrastructures, as well as the lack of proper modeling tools for capturing the interactions among biophysical properties, ecosystem demography, canopy structure, and biogeochemical cycling in tropical forests. As a first step to address these limitations, we implemented a selective logging module into the Functionally Assembled Terrestrial Ecosystem Simulator (FATES) by mimicking the ecological, biophysical, and biogeochemical processes following a logging event. The model can specify the timing and aerial extent of logging events, splitting the logged forest patch into disturbed and intact patches; determine the survivorship of cohorts in the disturbed patch; and modifying the biomass and necromass (total mass of coarse woody debris and litter) pools following logging. We parameterized the logging module to reproduce a selective logging experiment at the Tapajós National Forest in Brazil and benchmarked model outputs against available field measurements. Our results suggest that the model permits the coexistence of early and late successional functional types and realistically characterizes the seasonality of water and carbon fluxes and stocks, the forest structure and composition, and the ecosystem succession following disturbance. However, the current version of FATES overestimates water stress in the dry season and therefore fails to capture seasonal variation in latent and sensible heat fluxes. Moreover, we observed a bias towards low stem density and leaf area when compared to observations, suggesting that improvements are needed in both carbon allocation and establishment of trees. The effects of logging were assessed by different logging scenarios to represent reduced impact and conventional logging practices, both with high and low logging intensities. The model simulations suggest that in comparison to old-growth forests the logged forests rapidly recover water and energy fluxes in 1 to 3 years. In contrast, the recovery times for carbon stocks, forest structure, and composition are more than 30 years depending on logging practices and intensity. This study lays the foundation to simulate land use change and forest degradation in FATES, which will be an effective tool to directly represent forest management practices and regeneration in the context of Earth system models.
Full-text available
Used geographic information systems to analyze the structure of a second-growth forest landscape (9600 ha) in Michigan and Wisconsin, that contains scattered old-growth patches, and compared this landscape to a nearby, unaltered old-growth landscape on comparable landforms and soils to assess the effects of human activity on forest spatial pattern. The natural old-growth landscape is dominated by the original forest cover of eastern hemlock Tsuga canadensis, sugar maple Acer saccharum and yellow birch Betula alleghaniensis. The disturbed landscape has only scattered, remnant patches of old-growth ecosystems among a greater number of early successional hardwood and conifer forest types. The disturbed landscape has significantly more small forest patches and fewer large, matrix patches than the intact landscape. Forest patches in the fragmented landscape are significantly simpler in shape (lower fractal dimension, D) than in the intact old-growth landscape. Change in fractal dimension with patch size, a relationship that may be characteristics of differing processes of patch formation at different scales, is present within the intact landscape but has been obscured by human activity in the disturbed landscape. Important ecosystem juxtapositions of the old-growth landscape, such as hemlock with lowland conifers, have been lost in the disturbed landscape. Significant landscape heterogeneity in this glaciated region is produced by landforms alone, without natural or human disturbances. -from Authors
Full-text available
Temperate and boreal forests in the Northern Hemisphere cover an area of about 2 × 107 square kilometres and act as a substantial carbon sink (0.6-0.7 petagrams of carbon per year). Although forest expansion following agricultural abandonment is certainly responsible for an important fraction of this carbon sink activity, the additional effects on the carbon balance of established forests of increased atmospheric carbon dioxide, increasing temperatures, changes in management practices and nitrogen deposition are difficult to disentangle, despite an extensive network of measurement stations. The relevance of this measurement effort has also been questioned, because spot measurements fail to take into account the role of disturbances, either natural (fire, pests, windstorms) or anthropogenic (forest harvesting). Here we show that the temporal dynamics following stand-replacing disturbances do indeed account for a very large fraction of the overall variability in forest carbon sequestration. After the confounding effects of disturbance have been factored out, however, forest net carbon sequestration is found to be overwhelmingly driven by nitrogen deposition, largely the result of anthropogenic activities. The effect is always positive over the range of nitrogen deposition covered by currently available data sets, casting doubts on the risk of widespread ecosystem nitrogen saturation under natural conditions. The results demonstrate that mankind is ultimately controlling the carbon balance of temperate and boreal forests, either directly (through forest management) or indirectly (through nitrogen deposition).
This review is intended to introduce an outline of the results of community metabolism studies on various forest ecosystems of the Western Pacific area made by Japanese investigators in these past ten years. In 1955,SATOO opened this line of research by publishing his first report(65)on the productivity of artificial plantations in this country. A few years later, in 1957 and 1958,four groups of ecologists and forest scientists including ourselves began almost simultaneously to follow him, and the fields of study were expanded to include various types of natural and artificial vegetation ranging from subarctic conifer forests of Hokkaido to the tropical jungle of Southeast Asia. Since that time, more than one hundred stands belonging to some forty different forest types have been investigated, of course mostly within Japan Proper, but also in the Ryukyus(40), Thailand(21,22,24,42,44-47,93,100)and Cambodia(23). Steady progress has been made in the methodology for analysing the metabolism of forest community. These studies were, therefore, not always based on one and the same method, making it difficult to compare the results obtained by different authors. Thus the contents of this review are more or less tentative ; yet we hope, this may well be a useful starting point for more advanced studies to be made under the framework of the International Biological Programme.
Forest development following stand-replacing disturbance influences a variety of ecosystem processes including carbon exchange with the atmosphere. On a series of ponderosa pine (Pinius ponderosa var. Laws.) stands ranging from 9 to> 300 years in central Oregon, USA, we used biological measurements to estimate carbon storage in vegetation and soil pools, net primary productivity (NPP) and net ecosystem productivity (NEP) to examine variation with stand age. Measurements were made on plots representing four age classes with three replications: initiation (I, 9–23 years), young (Y, 56–89 years), mature (M, 95–106 years), and old (O, 190–316 years) stands typical of the forest type in the region. Net ecosystem productivity was lowest in the I stands (−124 g C m−2 yr−1), moderate in Y stands (118 g C m−2 yr−1), highest in M stands (170 g C m−2 yr−1), and low in the O stands (35 g C m−2 yr−1). Net primary productivity followed similar trends, but did not decline as much in the O stands. The ratio of fine root to foliage carbon was highest in the I stands, which is likely necessary for establishment in the semiarid environment, where forests are subject to drought during the growing season (300–800 mm precipitation per year). Carbon storage in live mass was the highest in the O stands (mean 17.6 kg C m−2). Total ecosystem carbon storage and the fraction of ecosystem carbon in aboveground wood mass increased rapidly until 150–200 years, and did not decline in older stands. Forest inventory data on 950 ponderosa pine plots in Oregon show that the greatest proportion of plots exist in stands ∼ 100 years old, indicating that a majority of stands are approaching maximum carbon storage and net carbon uptake. Our data suggests that NEP averages ∼ 70 g C m−2 year−1 for ponderosa pine forests in Oregon. About 85% of the total carbon storage in biomass on the survey plots exists in stands greater than 100 years, which has implications for managing forests for carbon sequestration. To investigate variation in carbon storage and fluxes with disturbance, simulation with process models requires a dynamic parameterization for biomass allocation that depends on stand age, and should include a representation of competition between multiple plant functional types for space, water, and nutrients.
We evaluated the carbon budget of coarse woody debris (CWD) in a temperate broad-leaved secondary forest. On the basis of a field survey conducted in 2003, the mass of CWD was estimated at 9.30 tC ha−1, with snags amounting to 60% of the total mass. Mean annual CWD input mass was estimated to be 0.61 tC ha−1 yr−1 by monitoring tree mortality in the forest from 1999 to 2004. We evaluated the CWD decomposition rate as the CO2 evolution rate from CWD by measuring CO2 emissions from 91 CWD samples (RCWD) with a closed dynamic chamber and infrared gas analysis system. The relationships between RCWD and temperature in the chamber, water content of the CWD, and other CWD characteristics were determined. By scaling the measured RCWD to the ecosystem, we estimated that the annual RCWD in the forest in 2003 was 0.50 tC ha−1 yr−1 or 10%–16% of the total heterotrophic respiration. Therefore, 0.11 tC ha−1 yr−1 or 7% of the forest net ecosystem production was sequestered by CWD. In a young forest, in which CWD input and decomposition are not balanced, the CWD carbon budget needs to be quantified for accurate evaluation of the forest carbon cycle and NEP.
Forest fire dramatically affects the carbon storage and underlying mechanisms that control the carbon balance of recovering ecosystems. In western North America where fire extent has increased in recent years, we measured carbon pools and fluxes in moderately and severely burned forest stands 2 years after a fire to determine the controls on net ecosystem productivity (NEP) and make comparisons with unburned stands in the same region. Total ecosystem carbon in soil and live and dead pools in the burned stands was on average 66% that of unburned stands (11.0 and 16.5 kg C m−2, respectively, P<0.01). Soil carbon accounted for 56% and 43% of the carbon pools in burned and unburned stands. NEP was significantly lower in severely burned compared with unburned stands (P<0.01) with an increasing trend from −125±44 g C m−2 yr−1 (±1 SD) in severely burned stands (stand replacing fire), to −38±96 and +50±47 g C m−2 yr−1 in moderately burned and unburned stands, respectively. Fire of moderate severity killed 82% of trees <20 cm in diameter (diameter at 1.3 m height, DBH); however, this size class only contributed 22% of prefire estimates of bole wood production. Larger trees (> 20 cm DBH) suffered only 34% mortality under moderate severity fire and contributed to 91% of postfire bole wood production. Growth rates of trees that survived the fire were comparable with their prefire rates. Net primary production NPP (g C m−2 yr−1, ±1 SD) of severely burned stands was 47% of unburned stands (167±76, 346±148, respectively, P<0.05), with forb and grass aboveground NPP accounting for 74% and 4% of total aboveground NPP, respectively. Based on continuous seasonal measurements of soil respiration in a severely burned stand, in areas kept free of ground vegetation, soil heterotrophic respiration accounted for 56% of total soil CO2 efflux, comparable with the values of 54% and 49% previously reported for two of the unburned forest stands. Estimates of total ecosystem heterotrophic respiration (Rh) were not significantly different between stand types 2 years after fire. The ratio NPP/Rh averaged 0.55, 0.85 and 1.21 in the severely burned, moderately burned and unburned stands, respectively. Annual soil CO2 efflux was linearly related to aboveground net primary productivity (ANPP) with an increase in soil CO2 efflux of 1.48 g C yr−1 for every 1 g increase in ANPP (P<0.01, r2= 0.76). There was no significant difference in this relationship between the recently burned and unburned stands. Contrary to expectations that the magnitude of NEP 2 years postfire would be principally driven by the sudden increase in detrital pools and increased rates of Rh, the data suggest NPP was more important in determining postfire NEP.
Old forests are important carbon pools, but are thought to be insignificant as current atmospheric carbon sinks. This perception is based on the assumption that changes in productivity with age in complex, multiaged, multispecies natural forests can be modelled simply as scaled-up versions of individual trees or even-aged stands. This assumption was tested by measuring the net primary productivity (NPP) of natural subalpine forests in the Northern Rocky Mountains, where NPP is from 50% to 100% higher than predicted by a model of an even-age forest composed of a single species. If process-based terrestrial carbon models underestimate NPP by 50% in just one quarter of the temperate coniferous forests throughout the world, then global NPP is being underestimated by 145 Tg of carbon annually. This is equivalent to 4.3–7.6% of the missing atmospheric carbon sink. These results emphasize the need to account for multiple-aged, species-diverse, mature forests in models of terrestrial carbon dynamics to approximate the global carbon budget.