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Recognising the importance of unmanaged forests to mitigate climate change

December 2020
GCB Bioenergy 12(12)

DOI:10.1111/gcbb.12714

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CC BY

Authors:

Dominick A Dellasala

Geos Institute

H. Keith

Griffith University

Cyril Kormos

Wild Heritage

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The carbon stock in Europe's forests is decreasing and the importance of protecting ‘unmanaged’ forests must be recognised in reversing this process. In order to keep carbon out of the atmosphere and to meet the Paris Agreement goals, the remaining primary forests must be protected and secondary forests should be allowed to continue growing to preserve existing carbon stocks and accumulate additional stocks. Scientific evidence suggests that ‘unmanaged’ forests have higher total biomass carbon stock than secondary forests being actively managed for commodity production or recently abandoned. image

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GCB Bioenergy. 2020;12:1034–1035.

wileyonlinelibrary.com/journal/gcbb

Received: 12 May 2020

Accepted: 13 May 2020

DOI: 10.1111/gcbb.12714

LETTER TO THE EDITOR

Recognizing the importance of unmanaged forests to mitigate

climate change

The most effective means for keeping carbon out of the at-

mosphere to meet climate goals is to protect primary forests

(Mackey etal.,2020) and continue growing secondary forests

to accumulate additional carbon (proforestation; Moomaw,

Masino, & Faison,2019) while reducing emissions from all

sources including bioenergy. We find several assumptions

and conclusions in the Opinion piece by Schulze etal.(2020)

inaccurate or questionable.

The Opinion compares differences in carbon storage be-

tween ‘unmanaged’ and ‘managed’ European forests, and

states, ‘(f)or unmanaged forests, the contribution to climate

change mitigation through storage is very small or close to

nil’. However, no evidence is cited to support this conten-

tion, which is inconsistent with several published empirical

studies and theoretical analyses (Erb et al., 2017; Houghton

& Nassikas,2018; Lutz etal.,2018). In order to support ef-

fective climate policy, we are responding to identify some of

the errors of omission in the Opinion.

Based on UNFCCC accounting rules, climate mitigation

depends on the relative carbon stocks in the biosphere and

atmosphere, not on sequestration rates as annual flows. In

order to minimize the amount of carbon in the atmosphere,

the cumulative carbon in trees and soils must be maximized

(Mackey etal., 2020). The maximum carbon stored in for-

ests occurs when forests are allowed to continue growing,

a management practice called ‘proforestation’ (Moomaw

etal.,2019). As the harvest rotation period is shortened, less

carbon is stored in trees averaged over the harvest period in-

tervals, leaving more in the atmosphere (Sterman, Siegel, &

Rooney-Varga, 2018). Each harvest also releases additional

biogenic and fossil fuel carbon emissions from the harvest

process (Harris etal.,2016).

Schulze et al. cite two studies from outside Europe, which

found higher area-averaged stand volumes in unmanaged

compared to managed forests. However, they state that this

difference does not exist in the temperate zone of Central

Europe without offering any data to support the claim. A

number of studies confirm higher stand volumes in older

forests in Central Europe. The results from Jacob etal.(2012)

show a higher standing biomass carbon pool in old-growth

forest than younger developmental stages. Horváth et al.

(2012) also found that old-growth forests in reserves had the

highest proportion of large trees in diameter and height, and

the largest volume of dead wood, meaning that total biomass

carbon stock is higher compared with secondary forests that

were being actively managed or recently abandoned.

Schulze et al. do not acknowledge or investigate the ca-

pacity for unmanaged forest to store more carbon than

currently. The Opinion does not provide the age class dis-

tribution of the forests that were analysed, or reflect the fact

that even presently unmanaged forests in Europe have likely

been harvested at some time in the past. Forests in Europe do

not differ from North America or Australia in terms of their

ecological processes of carbon accumulation, but rather, have

not yet reached their ultimate cumulative carbon capacity.

Considering Fagus and Picea as the dominant tree spe-

cies in Central Europe is an over-simplification, as the

European Environment Agency maps five biogeographical

regions in this region: Continental, Pannonian, Alpine and to

a smaller extent Atlantic and Mediterranean. While Sabatini

etal.(2018) found an uneven distribution of primary forests

in Europe, with concentration often in mountainous areas

with Fagus and Picea, excluding the importance of oak forest

habitats and soft-wood riverine forests is a major oversight.

In their conclusions about mitigation benefits of forest

management, Schulze et al. use annual rates of carbon seques-

tration and emissions (flows) that are the incorrect metric to

assess forest carbon stocks or alternative forest management

on those stocks. It is also an inappropriate metric for meeting

the Paris Agreement goals. The authors also greatly underes-

timate the carbon stock in biomass, because only stemwood is

counted, and branches, bark, canopies and roots are excluded

along with soil carbon that is greatest in older forests.

The importance of primary (unlogged) forests lies in the

magnitude and longevity of their carbon stock. In order to re-

verse the decreasing forest carbon stocks in Europe (European

Environmental Agency, 2019), the largest forest carbon stores

must be protected and additional forests must be allowed to

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original

work is properly cited.

This is a letter regarding Schulze et al. 12, 186–197.

1035

LETTER TO THE EDITOR

continue accumulating carbon (proforestation). Harvesting

for bioenergy increases atmospheric carbon, and slows the

accumulation of forest carbon (Sterman etal.,2018).

Based on the above, we disagree with the conclusions

by Schulze et al. The climate change mitigation potential of

unmanaged forests is significantly greater because of their

greater cumulative carbon storage than for forests managed

for lumber and bioenergy. Scientific findings are critically

important to decision makers addressing climate change.

We urge managers to disregard the erroneous carbon metrics

for forest carbon accounting in the Opinion and utilize more

valid sources.

ACKNOWLEDGEMENT

We thank Griffith University that financially supports the re-

search project on ‘Boreal and Temperate Primary Forests and

Climate Change’.

ZoltánKun1

DominickDellaSala2

HeatherKeith3

CyrilKormos4

BernardMercer5

William R.Moomaw6

MichalWiezik7

1Frankfurt Zoological Society, Frankfurt am Main,

Germany

2GEOS Institute, Ashland, KY, USA

3Griffith University, Brisbane, Qld, Australia

4Wild Heritage, Berkeley, CA, USA

5University of Cambridge, Cambridge, UK

6Tufts University, Medford, MA, USA

7Faculty of Ecology and Environmental Science, TU

in Zvolen, Slovakia/European Parliament, Brussels,

Belgium

Email: zoltankun71@yahoo.com

ORCID

Zoltán Kun https://orcid.org/0000-0002-4688-8936

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aaf354

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Concepts, objectives and values in German forest conservation - a comparative analysis, an assessment of practicability and future prospects - Dissertation for the award of the degree "Doctor rerum naturalium" (Dr. rer. nat.) of the Georg-August-Universität Göttingen

Thesis

Full-text available

Apr 2022

Laura Demant

The global biodiversity crisis is, along with climate change, the greatest challenge facing mankind. To ensure the long-term protection of biodiversity, conservation objectives must be agreed upon by all stakeholders, defined in concepts, and appropriate actions taken. This involves considering the often contrasting needs of nature and people and examining ethical-moral issues about the value of nature as well as different approaches to nature conservation. In this thesis, conservation objectives and values in German forest conservation concepts, considering ecological, political and social aspects are analysed in an interdisciplinary approach. The present state of forest conservation in Germany is discussed and current and future challenges are described. Based on this assessment of needs new methods for the classification of conservation objectives and for the assessment of forest conservation objects are presented and possible changes in conservation responsibility in view of climate change are proposed. Forests support a significant proportion of global biodiversity and provide essential ecosystem services, and their long-term conservation and sustainable use is becoming more important than ever in the face of climate change. Due to the diverse demands for conservation and use, a consensus on the objectives is necessary in forest conservation. Only a transparent system based on consistent objectives and measures is likely to be sufficiently accepted and implemented. Therefore, a hierarchical framework for the classification of nature conservation objectives was developed in Chapter 2 of this thesis. Within higher-level target areas, desired target properties were assigned to conservation objects, which are to be achieved through certain measures. Using this framework, the contents of biodiversity and forest conservation concepts were examined for commonalities and differences. A broad consensus on conservation objectives was found in the concepts across different stakeholder groups and spatial scales, with the conservation of species, ecosystems and structures in forests rated as particularly important. Deficits were identified with regard to genetic diversity, abiotic resources and social-cultural objectives, as well as a mismatch in the transfer of knowledge. The reasons for these inconsistencies in forest conservation include conflicting objectives, lack of coordination across scales and inadequate implementation of objectives. In private forests, which make up half of the German forest area, the implementation of nature conservation measures is a particular challenge. Private forest owners often have reservations about sovereign nature conservation regulations and are less willing to participate due to the financial expenses involved. In order to ensure higher acceptance, forest conservation measures should be financially compensated. However, the contractual agreement of nature conservation services and financial remuneration (= contract-based nature conservation) has so far found limited application in private forests. Since the successful implementation of contract-based forest conservation requires a system of reasonable measures, the conservation objects identified in Chapter 2 (forest habitat types, structures and processes in forests) were assigned a conservation value in Chapter 3 on the basis of the need for, and the worthiness of, protection. Oak and mixed oak forests, dry-warm beech forests, historical forms of forest use (coppice forests or wood pastures) and natural structures such as deadwood (deciduous tree species, standing and lying) or habitat trees have a high nature conservation value. Based on the initial value and the expected value development, it was assessed whether conservation or restoration measures within the framework of contract-based forest conservation with varying durations are suitable. Contract-based forest conservation is particularly suitable for conservation objects with a high initial value if a loss of value can be avoided and if a high increase in value can be expected. It is not suitable for low initial values and a low restoration potential. With this framework, private forest owners can easily assess which nature conservation measures are suitable in their forest, increasing the likelihood that they will apply contract-based forest conservation in the future. Climate change and its predicted effects in terms of intensity and frequency of disturbances require an adaptation of silvicultural management. In Germany, silvicultural planning tools such as forest development types are often only related to the economic productivity function, while nature conservation demands are given little consideration. Therefore, the framework developed in Chapter 3 for the conservation value assessment of forest habitat types was adapted in Chapter 4 to the economically relevant tree species (beech, oak, pine, spruce, fir, Douglas-fir and larch) and further developed for application in forest stands according to the potential natural vegetation of the location. With the new framework, the nature conservation impacts of silvicultural planning and future tree species composition in forest stands can be spatially-explicitly assessed. Certain silvicultural combinations of tree species can lead to a reduction in the initial nature conservation value, which is determined by the forest habitat type naturally occurring there. The highest nature conservation value can be achieved if the planned tree species are both autochthonous and a natural component of the respective forest habitat type. The framework was trialled to assess planned forest development types using a Germany-wide transect. In most cases, the forest development type combinations led to a reduction of the initial nature conservation value, as the restricted tree species selection of the forest development types did not correspond to the diverse species composition of the natural forest habitat types. With this evaluation framework, forest planning can also be assessed in terms of nature conservation and be adapted to a tree species composition that is as close to nature and site-specific as possible. The uncertainties of climate change and the associated changes in environmental conditions also pose new challenges for nature conservation and may require an adaptation of the conservation objectives and justifications. Chapter 5 therefore investigated whether the favourable conservation status of forest habitat types of the Habitats Directive remains a well-founded objective when confronted with climate change. In this context, both the question of the conservation justification and an assessment of the future development trend of the conservation status of forest habitat types of the Habitats Directive were addressed. It was shown that current niche and species distribution models of habitat types and tree species indicate that a climate change-induced increase in drought can lead to losses in area of forest habitat types such as the subalpine sycamore-beech forest and the montane-alpine soil-acid spruce forest. In the case of bog woodland and alluvial forests, successful restoration should be the first priority before future development can be assessed. Forest habitat types on secondary sites, such as mixed oak forests, will probably continue to require active management measures to restore and secure a favourable conservation status in the long term. The distribution models for beech forest habitat types showed increasing uncertainty regarding future distribution, and for the most part no significant negative change could be identified, even under climate change. Flexibilisation and adaptation of conservation objectives should therefore only take place on the basis of evidence and within the framework of adaptive management. Overall, no clear indications is found to abandon the favourable conservation status of forest habitat types under climate change as a well-founded objective of nature conservation. This thesis discusses the importance of forest conservation concepts in today’s world and the difficulties that can arise in the classification and implementation of forest conservation objectives. Furthermore, the challenges that may arise in the conservation value assessment of conservation objects and tree species as well as in future implementation of forest conservation measures are identified. It was found that the systematic analysis of conservation objectives has gained importance in conservation research and that there is a broad consensus on the objectives of forest conservation in Germany. Nevertheless, there is a considerable need for more specification, especially with regard to the implementation of contract-based nature conservation in private forests. The frameworks presented for the derivation of nature conservation values can be helpful in turning abstract properties such as nature conservation values into a simplified and comprehensible system. Forestry and nature conservation stakeholders can thus be sensitised to the conservation value of forest biodiversity. In order to reduce existing prejudices between stakeholders, it is also necessary to further revise the funding system in Germany with regard to its financial scope and the effectiveness of conservation measures, and to provide practical recommendations for action based on scientific findings. This thesis underlines that a constant adaptation of forest management strategies is necessary for forest conservation and silviculture to cope with the challenges of climate change. For forests to maintain their diverse functions and ecosystem services in the future, semi-natural, species-rich resilient mixed forests composed of predominantly native tree species should be favoured and the existing objectives in nature conservation should not be abandoned without reason. Only in this way can forest conservation in Germany and also worldwide be successful in the long term.

Strict forest protection: A meaningful contribution to Climate-Smart Forestry? An evaluation of temporal trends in the carbon balance of unmanaged forests in Germany

Article

Full-text available

Mar 2023

The role of unmanaged forests is discussed controversially in the context of climate change. One of the key questions is, whether they can contribute to the mitigation of climate change as a carbon sink and storage. However, carbon dynamics of forests after the cessation of management are not well understood. We analyzed a set of 64 forest sites, covering wide gradients of time since abandonment (0–68 years) and stand age (65–261 years) in even-aged, unmanaged beech forests. Five sites that were unmanaged for >100 years complemented the main dataset. We compiled site-specific carbon balances, distinguishing six carbon-compartments: Carbon in aboveground living and dead biomass, carbon in belowground living and dead biomass, and carbon in the organic layer and the mineral topsoil (0–30 cm). We found positive effects of increasing TSA on the carbon stock in living biomass and aboveground dead biomass for up to 50 years after management ceased. The average increase of the total carbon stock over 50 years of TSA was ≈ 80 Mg C ha –1 . The effect of stand age on aboveground living biomass showed a convex relation. Aboveground dead biomass increased logistically with TSA, while belowground dead biomass decreased. On average, the five sites unmanaged for >100 years held lower total carbon stocks compared to the observed biomass peak around 50 years of TSA. However, they contained considerably higher amounts of deadwood. Carbon in the mineral soil did neither change with TSA nor with stand age and was driven by pH. Carbon stocks in newly unmanaged forests increased almost linearly for approximately 50 years after cessation of management. Subsequently, a stabilization or medium-term decrease in carbon stock was observed, likely due to the initiating transition from even-aged to multi-aged structures. We conclude that, besides their value for biodiversity and ecosystem functions, the potential of naturally developing forests as a medium-term carbon sink and long-term stable carbon storage should be considered as a valuable contribution to Climate-Smart Forestry.

Sustaining Carbon Storage: Lessons from Hemiboreal Old-Growth Coniferous and Deciduous Forest Stands

Article

Dec 2022
FOREST SCI

For the last three decades, the area of old-growth forest stands in Europe has continued to increase as has their importance in achieving forest-related policy goals. This has triggered an increase in research interest in old-growth forests, both from climate change mitigation and biodiversity protection perspectives. However, carbon stock in old-growth stands in European hemiboreal forests had not been systematically studied. Therefore, in this article, we characterize differences in carbon stock between mature and old-growth stands on fertile mineral soils in hemiboreal Latvia to contribute to the understanding of carbon storage changes under different management strategies for forest lands. Carbon stock varied significantly both between old-growth stands of different dominant tree species and between mature (1.9–2.3 times younger) and old-growth stages of the same dominant species in forest stands. The carbon stock of tree biomass and deadwood was larger in old-growth stands, but their mean annual carbon stock change was significantly lower than in mature stands (27% to 47% depending on dominant tree species). Old-growth stands can serve as carbon reservoirs in areas with limited natural disturbances; however, for maintenance of climate neutrality, it is essential to expand the area of managed stands with larger annual carbon stock increase. Study Implications: Forest ecosystems play a major role in regulation of global climate: They can store high quantities of carbon and also can gain or lose it rather quickly. For the last three decades, the area of old-growth forest stands in Europe has continued to increase as has their importance in achieving forest-related policy goals. Old-growth forests can represent the baseline carbon-carrying capacity in particular conditions. Therefore, we characterized differences in carbon stock between mature and old-growth stands on fertile mineral soils in hemiboreal Latvia to contribute to the understanding of carbon storage and for planning forest management activities.

Barking up the wrong tree? Can forest expansion help meet climate goals?

Article

Full-text available

Oct 2022
ENVIRON SCI POLICY

Forest expansion can make an important contribution to the 2015 Paris Agreement, through offsetting Greenhouse gas (GHG) emissions. EU, UK and Scottish forest policy encourages substantial forest expansion. Unfortunately, policy is still inadequately informed by high resolution data, and often assumes a fairly homogenous landscape, uniformly suitable soil types and idealised ‘average’ tree timber yields, while carbon emissions caused by soil disturbance during planting, and changes in climate are rarely adequately considered. Also, the proportional contribution of afforestation targets to national mitigation needs is often overlooked which could lead to over-reliance on tree planting. We address these shortcomings through an integrated modelling approach which estimates net carbon gain for eleven tree species accounting for the interactions between climate, soil and planting practices. We present detailed spatial results for a case study area (Scotland), showing where forest expansion would be likely to result in overall carbon gains, accounting for the differentiated spatial variability of timber yield classes for each one of the species considered including present and future climate. The results showed that upland ecosystems, whose soils are rich in carbon, were vulnerable to net carbon loss, particularly with intensive ground preparation and planting practices. While the prevalence of mineral soils in the lowlands makes them a safer option for planting in theory, these are also areas which might conflict with agricultural activities. Our findings strongly support the notion that both “the right tree in the right place” and “no trees in the wrong place” are important messages for practitioners. In terms of the total UK and Scottish carbon footprints, the magnitude of the offset obtained in 30 years if afforestation goals were fully reached would likely be around 1% of the UK total business as usual GHG footprint and around 10% of the Scottish footprint. Our results can help to improve the targeting of incentives and investments in forest and woodland expansion, but also reinforce the need to pursue emissions reductions in a variety of ways throughout all sectors.

Primeval, natural and commercial forests in the context of biodiversity and climate protection. Part 2: The narrative of the climate neutrality of wood as a resource

Article

Full-text available

Jan 2022

In the debate on climate protection and the promotion of renewable energies, the increased material and thermal use of wood as a supposedly climate-neutral building material and energy source is often promoted as necessary and sensible. The adoption of this narrative is increasingly leading to more intensive use of forests, to a further increase in the global supply of raw wood with a concomitant reduction in wood reserves, and is also contributing to the disappearance of the last primeval forests in Europe. This second part of a literature-based review on primeval forests, natural forests and managed forests in the context of biodiversity and climate protection analyses the development of wood reserves and wood use in Germany and discusses the CO2 sink performance of wood in the prevailing usage pathways. This issue has important implications for biodiversity conservation. The climate relevance of wood as a substitute for other resources and the supposed CO2 neutrality of wood as an energy source are critically examined. The climate policy goals of the EU and Germany and their instrumental implementation overestimate the performance of forests as CO2 sinks and their potential supply of wood. This is especially true in light of the consequences of climate change. The demand this paper makes of policy-makers is to prohibit logging in primeval and natural forests and to introduce corresponding normative requirements and criteria to restrict the use of timber for energy purposes. This applies in particular to imports of pellets and wood chips for electricity generation in large power plants. Thermal use of wood and short-life wood products usually leads to little or no reduction in greenhouse gas emissions compared to the fossil fuel benchmark. Wood that cannot be further utilised for materials, along with residual or sawmill by-products, may be utilised thermally, but then as locally as possible and only in efficient facilities. Wood that remains in the forest in the form of living trees or deadwood can make at least as great and often even greater a contribution to climate protection than when it is used for energy and inefficient materials. The primary goal of forestry must not be maximum yield but forest preservation with stands that are as robust and resilient as possible and use of long-life wood products.

Urwälder, Natur- und Wirtschaftswälder im Kontext von Biodiversitäts- und Klimaschutz. Teil 2: Das Narrativ von der Klimaneutralität der Ressource Holz

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Jan 2022

In der Debatte um Klimaschutz und Förderung erneuerbarer Energien wird eine verstärkte Verwendung von Holz als vermeintlich klimaneutraler Baustoff und Energieträger häufig pauschal als sinnvoll propagiert. Die Umsetzung dieses Narrativs führt zu intensiverer Nutzung der Wälder sowie zum weiteren Anstieg des globalen Rohholzaufkommens bei gleichzeitiger Verminderung der Holzvorräte und trägt auch zum Schwund der letzten europäischen Urwälder bei. Der vorliegende zweite Teil eines literaturbasierten Diskussionsbeitrags zu Urwäldern, Naturwäldern und Wirtschaftswäldern im Kontext des Biodiversitäts- und des Klimaschutzes analysiert die Entwicklung der Holzvorräte und Holzverwendung in Deutschland und beleuchtet die CO2-Senkenleistung von Holz für die vorherrschenden Nutzungspfade. Dieser Komplex hat wichtige Rückkopplungen zu Anliegen des Biodiversitätsschutzes. Kritisch betrachtet werden die Klimarelevanz von Holz als Substitut für andere Ressourcen und die vermeintliche CO2-Neutralität von Holz als Energiequelle. Die klimapolitischen Ziele der EU und Deutschlands und deren instrumentelle Umsetzung Überschätzen die Leistungsfähigkeit von Wäldern als CO2-Senke und die Lieferfähigkeit für die Ressource Holz. Dies gilt besonders in Anbetracht der Folgen des Klimawandels. Die Forderung an die Politik ist der Verzicht auf Holzeinschlag in Ur- und Naturwäldern und die Einführung entsprechender normativer Vorgaben sowie Kriterien, um die Stammholznutzung für energetische Zwecke einzuschränken. Dies gilt speziell für Importe von Pellets und Hackschnitzeln zur Verstromung in Großkraftwerken. Eine thermische Nutzung von Holz und kurzlebigen Holzprodukten führt gegenüber der fossilen Referenz meist nur zu geringen bis keinen Reduktionen der Treibhausgasemissionen. Stofflich nicht weiter verwertbares Holz, Restholz oder Sägenebenprodukte sollten thermisch und dann möglichst ortsnah in effizienten Anlagen eingesetzt werden. Holz, das in Form von lebenden Bäumen oder Totholz im Wald verbleibt, kann im Vergleich zur energetischen und ineffizienten stofflichen Verwertung einen mindestens ebenso hohen, oft sogar größeren Beitrag zum Klimaschutz leisten. Nicht maximaler Ertrag, sondern Walderhalt mit möglichst resistenten und resilienten Beständen muss das vorrangige Ziel der Forst- und Holzwirtschaft sein.

Limited sink but large storage: biomass dynamics in naturally developing beech (Fagus sylvatica) and oak (Quercus robur, Quercus petraea) forests of northwestern Germany

Article

Full-text available

Jul 2021

1. Currently, the dynamics underlying the storage and acquisition of biomass, and thus carbon, in naturally developing forests are under debate. A better understanding of the biomass dynamics of forests is needed to clarify the role played by naturally developing forests in the mitigation of climate change. 2. Long‐term monitoring data from unmanaged strict forest reserves (SFRs) in northwestern Germany were used to analyze the biomass dynamics of pure beech, mixed beech, and mixed oak forests. A complete balance of aboveground woody biomass (biomass) and growth, density‐dependent and ‐independent mortality, as well as deadwood decay was derived. Density‐independent mortality served as a proxy for disturbance severity. 3. After a time of abandonment (TSA) of 50 years, the average biomass ranged between 334 t ha‐1 in mixed oak and 478 t ha‐1 in pure beech stands. The net change in biomass was positive in all forest types. Density‐independent mortality and decay rates were much lower than the growth rates. Pure beech forests reached higher levels of biomass, a higher net change in biomass, and more growth than either of the mixed forest types. Biomass increased linearly with TSA in pure beech stands but followed an asymptotic course in the mixed forests. In the latter, the net change in biomass and growth were consistent with a unimodal development pattern. The development of biomass could not be explained by the aging of the tree communities. 4. Synthesis: We hypothesized that the observed biomass dynamics are a result of the interaction between resource supply within a limited growing space and the resource‐use efficiency of the tree stand in conjunction with disturbances. The still‐linear increase in the biomass of pure beech forests was assumed to reflect the high resource‐use efficiency of beech, especially its use of light. The aboveground capacity of naturally developing broadleaved forests to store and acquire carbon, is substantial. Accordingly, allowing broadleaved forests to develop naturally can contribute substantially to carbon storage and sequestration. However, our study also suggests that the aboveground carbon sink decreases after several decades.

Adaptation of phoD-harboring bacteria to broader environmental gradients at high elevations than at low elevations in the Shennongjia primeval forest

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Nov 2021
GEODERMA

Disentangling responses of phoD-harboring bacteria to environmental factors in different habitats, crucial for understanding the ecosystem’s potential for organic phosphorus mineralization and plant productivity, is an important but poorly investigated subject. Using MiSeq sequencing and multiple statistical analyses, we investigated activity, abundance, taxonomic and phylogenetic diversity of phoD-harboring bacteria at low (<1500 m) and high (>1500 m) elevations in the Shennongjia primeval forest. We found significant difference in phoD gene abundance and no significant divergence in alkaline phosphomonoesterase activity between low elevations and high elevations. Soil phoD-harboring bacteria showed stronger phylogenetic signals and broader environmental thresholds at high elevations than at low elevations based on threshold indicator taxa analysis, Blomberg’s K statistic, and Fritz-Purvis D-test. In addition, phoD-harboring bacteria showed closer phylogenetic clustering at high elevations than at low elevations. Null model reflected that community assembly at low elevations was determined by both deterministic and stochastic processes, and community assembly at high elevations was mainly determined by stochastic processes. To our knowledge, this study first reports that phoD-harboring bacteria are less environmentally constrained and have stronger environmental adaptation at high elevations than at low elevations. Our findings expand knowledge of the diversity maintenance of phoD-harboring bacteria at low and high elevations, and might offer the prediction of potential changes in organic phosphorus mineralization in the Shennongjia primeval forest.

Schriftliche Stellungnahme zu Beschlussantrag "Die wertvollen ökologischen Leistungen unserer Wälder anerkennen und ein entsprechendes Vergütungssystem für Waldbewirtschaftung schaffen" vom 5.7.2022, Drucksache 20/2554, Deutscher Bundestag (Ausschussdrucksache 20(10)42-D)

Technical Report

Full-text available

Nov 2022

Pierre L Ibisch

Foreword: uncensored science is crucial for global conservation

Chapter

Jan 2021

James E. Hansen

Understanding the importance of primary tropical forest protection as a mitigation strategy

Article

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May 2020

Given the short time-frame to limit global warming, and the current emissions gap, it is critical to prioritise mitigation actions. To date, scant attention has been paid to the mitigation benefits of primary forest protection. We estimated tropical forest ecosystem carbon stocks and flows. The ecosystem carbon stock of primary tropical forests is estimated at 141–159 Pg C (billion tonnes of carbon) which is some 49–53% of all tropical forest carbon, the living biomass component of which alone is 91–103% of the remaining carbon budget to limit global warming to below 1.5 degrees above pre-industrial levels. Furthermore, tropical forests have ongoing sequestration rates 0.47–1.3 Pg C yr−1, equivalent to 8–13% of annual global anthropogenic CO2 (carbon dioxide) emissions. We examined three main forest-based strategies used in the land sector—halting deforestation, increasing forest restoration and improving the sustainable management of production forests. The mitigation benefits of primary forest protection are contingent upon how degradation is defined and accounted for, while those from restoration also depend on how restoration is understood and applied. Through proforestation, reduced carbon stocks in secondary forests can regrow to their natural carbon carrying capacity or primary forest state. We evaluated published data from studies comparing logged and unlogged forests. On average, primary forests store around 35% more carbon. While comparisons are confounded by a range of factors, reported biomass carbon recovery rates were from 40 to 100+ years. There is a substantive portfolio of forest-based mitigation actions and interventions available to policy and decision-makers, depending on national circumstances, in addition to SFM and plantation focused approaches, that can be grouped into four main strategies: protection; proforestation, reforestation and restoration; reform of guidelines, accounting rules and default values; landscape conservation planning. Given the emissions gap, mitigation strategies that merely reduce the rate of emissions against historic or projected reference levels are insufficient. Mitigation strategies are needed that explicitly avoid emissions where possible as well as enabling ongoing sequestration.

The climate change mitigation effect of bioenergy from sustainably managed forests in Central Europe

Article

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Mar 2020

We compare sustainably managed with unmanaged forests in terms of their contribution to climate change mitigation based on published data. For sustainably managed forests, accounting of carbon (C) storage based on ecosystem biomass and products as required by UNFCCC is not sufficient to quantify their contribution to climate change mitigation. The ultimate value of biomass is its use for biomaterials and bioenergy. Taking Germany as example, we show that the average removals of wood from managed forests are higher than stated by official reports, ranging between 56 and 86 Mill. m3 ha‐1 y‐1 due to the unrecorded harvest of firewood. We find that total removals can substitute of 0.87 m3 ha‐1 y‐1 of diesel, or 7.4 MWh/ha y‐1, taking into account the unrecorded firewood, the use of fuel for harvesting and processing, and the efficiency of energy conversion. Resultantly, energy substitution ranges between 1.9 and 2.2 t CO2equiv. ha‐1 y‐1 depending on the type of fossil fuel production. Including bioenergy and carbon storage, the total mitigation effect of managed forest ranges between 3.2 and 3.5 tCO2 equiv. ha‐1 y‐1. This is more than previously reported because of the full accounting of bioenergy. Unmanaged nature conservation forests contribute via C storage only about 0.37 t CO2 equiv. ha‐1 y‐1 to climate change mitigation. There is no fossil fuel substitution. Therefore, taking forests out of management reduces the climate mitigation benefits substantially. There should be a mitigation‐cost for taking forest out of management in Central Europe. Since the energy sector is rewarded for the climate benefits of bioenergy, and not the forest sector, we propose that a CO2 tax is used to award the contribution of forest management to fossil fuel substitution and climate change mitigation. This would stimulate the production of wood for products and energy substitution.

Intact Forests in the United States: Proforestation Mitigates Climate Change and Serves the Greatest Good

Article

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Jun 2019

Climate change and loss of biodiversity are widely recognized as the foremost environmental challenges of our time. Forests annually sequester large quantities of atmospheric carbon dioxide (CO 2), and store carbon above and below ground for long periods of time. Intact forests-largely free from human intervention except primarily for trails and hazard removals-are the most carbon-dense and biodiverse terrestrial ecosystems, with additional benefits to society and the economy. Internationally, focus has been on preventing loss of tropical forests, yet U.S. temperate and boreal forests remove sufficient atmospheric CO 2 to reduce national annual net emissions by 11%. U.S. forests have the potential for much more rapid atmospheric CO 2 removal rates and biological carbon sequestration by intact and/or older forests. The recent 1.5 Degree Warming Report by the Intergovernmental Panel on Climate Change identifies reforestation and afforestation as important strategies to increase negative emissions, but they face significant challenges: afforestation requires an enormous amount of additional land, and neither strategy can remove sufficient carbon by growing young trees during the critical next decade(s). In contrast, growing existing forests intact to their ecological potential-termed proforestation-is a more effective, immediate, and low-cost approach that could be mobilized across suitable forests of all types. Proforestation serves the greatest public good by maximizing co-benefits such as nature-based biological carbon sequestration and unparalleled ecosystem services such as biodiversity enhancement, water and air quality, flood and erosion control, public health benefits, low impact recreation, and scenic beauty.

Reply to comment on ‘Does replacing coal with wood lower CO 2 emissions? Dynamic lifecycle analysis of wood bioenergy’

Article

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Dec 2018
ENVIRON RES LETT

We respond to Prisley et al's (2018 Environ. Res. Lett. 13 128002) critique of Sterman et al (2018 Environ. Res. Lett. 13 015007), which found that using wood to produce electricity can worsen climate change at least through 2100, even if wood displaces coal. The result arises because (1) wood generates more CO2/kWh than coal, creating an initial carbon debt; (2) regrowth of harvested land can remove CO2 from the atmosphere, but takes time and is not certain; and (3) until the carbon debt is repaid, atmospheric CO2 is higher, increasing radiative forcing and worsening climate change long after the initial carbon debt is repaid by new growth. We correct several errors in Prisley et al's critique, and show that our results are robust to the harvest and land management practices they prefer.

Where are Europe’s last primary forests?

Article

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May 2018

Aim Primary forests have high conservation value but are rare in Europe due to historic land use. Yet many primary forest patches remain unmapped, and it is unclear to what extent they are effectively protected. Our aim was to (1) compile the most comprehensive European‐scale map of currently known primary forests, (2) analyse the spatial determinants characterizing their location and (3) locate areas where so far unmapped primary forests likely occur. Location Europe. Methods We aggregated data from a literature review, online questionnaires and 32 datasets of primary forests. We used boosted regression trees to explore which biophysical, socio‐economic and forest‐related variables explain the current distribution of primary forests. Finally, we predicted and mapped the relative likelihood of primary forest occurrence at a 1‐km resolution across Europe. Results Data on primary forests were frequently incomplete or inconsistent among countries. Known primary forests covered 1.4 Mha in 32 countries (0.7% of Europe’s forest area). Most of these forests were protected (89%), but only 46% of them strictly. Primary forests mostly occurred in mountain and boreal areas and were unevenly distributed across countries, biogeographical regions and forest types. Unmapped primary forests likely occur in the least accessible and populated areas, where forests cover a greater share of land, but wood demand historically has been low. Main conclusions Despite their outstanding conservation value, primary forests are rare and their current distribution is the result of centuries of land use and forest management. The conservation outlook for primary forests is uncertain as many are not strictly protected and most are small and fragmented, making them prone to extinction debt and human disturbance. Predicting where unmapped primary forests likely occur could guide conservation efforts, especially in Eastern Europe where large areas of primary forest still exist but are being lost at an alarming pace.

Unexpectedly large impact of forest management and grazing on global vegetation biomass

Article

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Jan 2018
NATURE

Carbon stocks in vegetation have a key role in the climate system. However, the magnitude, patterns and uncertainties of carbon stocks and the effect of land use on the stocks remain poorly quantified. Here we show, using state-of-the-art datasets, that vegetation currently stores around 450 petagrams of carbon. In the hypothetical absence of land use, potential vegetation would store around 916 petagrams of carbon, under current climate conditions. This difference highlights the massive effect of land use on biomass stocks. Deforestation and other land-cover changes are responsible for 53-58% of the difference between current and potential biomass stocks. Land management effects (the biomass stock changes induced by land use within the same land cover) contribute 42-47%, but have been underestimated in the literature. Therefore, avoiding deforestation is necessary but not sufficient for mitigation of climate change. Our results imply that trade-offs exist between conserving carbon stocks on managed land and raising the contribution of biomass to raw material and energy supply for the mitigation of climate change. Efforts to raise biomass stocks are currently verifiable only in temperate forests, where their potential is limited. By contrast, large uncertainties hinder verification in the tropical forest, where the largest potential is located, pointing to challenges for the upcoming stocktaking exercises under the Paris agreement.

Attribution of net carbon change by disturbance type across forest lands of the conterminous United States

Article

Full-text available

Nov 2016
Carbon Bal Manag

Background Locating terrestrial sources and sinks of carbon (C) will be critical to developing strategies that contribute to the climate change mitigation goals of the Paris Agreement. Here we present spatially resolved estimates of net C change across United States (US) forest lands between 2006 and 2010 and attribute them to natural and anthropogenic processes. ResultsForests in the conterminous US sequestered −460 ± 48 Tg C year−1, while C losses from disturbance averaged 191 ± 10 Tg C year−1. Combining estimates of net C losses and gains results in net carbon change of −269 ± 49 Tg C year−1. New forests gained −8 ± 1 Tg C year−1, while deforestation resulted in losses of 6 ± 1 Tg C year−1. Forest land remaining forest land lost 185 ± 10 Tg C year−1 to various disturbances; these losses were compensated by net carbon gains of −452 ± 48 Tg C year−1. C loss in the southern US was highest (105 ± 6 Tg C year−1) with the highest fractional contributions from harvest (92%) and wind (5%). C loss in the western US (44 ± 3 Tg C year−1) was due predominantly to harvest (66%), fire (15%), and insect damage (13%). The northern US had the lowest C loss (41 ± 2 Tg C year−1) with the most significant proportional contributions from harvest (86%), insect damage (9%), and conversion (3%). Taken together, these disturbances reduced the estimated potential C sink of US forests by 42%. Conclusion The framework presented here allows for the integration of ground and space observations to more fully inform US forest C policy and monitoring efforts.

Peripheral nervous system involvement in lymphomas

Article

Dec 2018

The peripheral nervous system may be involved at any stage in the course of lymphoproliferative diseases. The different underlying mechanisms include neurotoxicity secondary to chemotherapy, direct nerve infiltration (neurolymphomatosis), infections, immune‐mediated, paraneoplastic or metabolic processes and nutritional deficiencies. Accordingly, the clinical features are heterogeneous and depend on the localization of the damage (ganglia, roots, plexi, peripheral nerves) and on the involved structures (myelin, axon, cell body). Some clinical findings, such a focal or diffuse involvement, symmetric or asymmetric pattern, presence of pain may point to the correct diagnosis. Besides a thorough medical history and neurological examination, neurophysiological studies, cerebrospinal fluid (CSF) analysis, nerve biopsy (in selected patients with suspected lymphomatous infiltration) and neuroimaging techniques (Magnetic resonance neurography and nerve ultrasound) may be crucial for a proper diagnostic work‐up.

Global importance of large-diameter trees

Article

May 2018
GLOBAL ECOL BIOGEOGR

Aim To examine the contribution of large‐diameter trees to biomass, stand structure, and species richness across forest biomes. Location Global. Time period Early 21st century. Major taxa studied Woody plants. Methods We examined the contribution of large trees to forest density, richness and biomass using a global network of 48 large (from 2 to 60 ha) forest plots representing 5,601,473 stems across 9,298 species and 210 plant families. This contribution was assessed using three metrics: the largest 1% of trees ≥ 1 cm diameter at breast height (DBH), all trees ≥ 60 cm DBH, and those rank‐ordered largest trees that cumulatively comprise 50% of forest biomass. Results Averaged across these 48 forest plots, the largest 1% of trees ≥ 1 cm DBH comprised 50% of aboveground live biomass, with hectare‐scale standard deviation of 26%. Trees ≥ 60 cm DBH comprised 41% of aboveground live tree biomass. The size of the largest trees correlated with total forest biomass (r2 = .62, p < .001). Large‐diameter trees in high biomass forests represented far fewer species relative to overall forest richness (r2 = .45, p < .001). Forests with more diverse large‐diameter tree communities were comprised of smaller trees (r2 = .33, p < .001). Lower large‐diameter richness was associated with large‐diameter trees being individuals of more common species (r2 = .17, p = .002). The concentration of biomass in the largest 1% of trees declined with increasing absolute latitude (r2 = .46, p < .001), as did forest density (r2 = .31, p < .001). Forest structural complexity increased with increasing absolute latitude (r2 = .26, p < .001). Main conclusions Because large‐diameter trees constitute roughly half of the mature forest biomass worldwide, their dynamics and sensitivities to environmental change represent potentially large controls on global forest carbon cycling. We recommend managing forests for conservation of existing large‐diameter trees or those that can soon reach large diameters as a simple way to conserve and potentially enhance ecosystem services.

Negative Emissions from Stopping Deforestation and Forest Degradation, Globally

Article