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Reconstructed forest age structure in Europe 1950-2010
Abstract
Forest age structure is an important factor for understanding the history of forests, their current functioning
and their future development. It is, for instance, crucial information to be able to assess sustainable
harvesting potentials. Furthermore, since the development of growing stock and increment, and thus the
patterns of net carbon exchange, are strongly affected by the age of the forest, information about the age
structure is needed to understand the temporal variability of the greenhouse gas budgets and potential
contributions of forest management (i.e. their additionality) to long-term removal of carbon from the
atmosphere. European forests have changed drastically in recent decades, but to date no European level
compilation of historical forest age structure data is available. In this study, country level historical ageclass
data was combined with a backcasting method to reconstruct the age-class structure for 25
European countries from 1950 to 2010 (total forest area in 2010: 118.3 million ha). Based on the results,
dynamic maps of forest age-class distributions on 0.25� � 0.25� grid were generated, and the change in
the forest age structure was analysed. Results show that the share of old forests (>100 years) has
decreased from 26% in 1950 to 17% in 2010, and the mean age over the studied area decreased from
67 to 60 years. However, when looking at the change of the mean age from 1950 to 2010 at country level,
there is a large variation between the countries. We discuss implications of the results and argue that the
development of forest age structure contributed less than previously thought to the carbon sink in
European forests from 1950 onwards.
Supplementary resource (1)
Data
November 2014
... With the current average age of 64 years (Figure 3 [33,50]. It is worth emphasising that in the period 1950-2010, the average age of stands in Poland's forests administered by SF increased by 18 years (Figure 3), whilst in Europe as a whole, it decreased by 7 years [108]. ...
... With the current average age of 64 years (Figure 3 [33,50]. It is worth emphasising that in the period 1950-2010, the average age of stands in Poland's forests administered by SF increased by 18 years (Figure 3), whilst in Europe as a whole, it decreased by 7 years [108]. Year Average stand age ...
This paper presents the results of an analysis of the effects of Poland’s forest management evolution over the last 75 years on forest biodiversity at the ecosystem level. Forest biodiversity changes in the two politically and economically different eras (socialism and democracy) are interpreted based on four indicators used in assessments of forest stands (naturalness; habitat diversity; forest management system; forest stand age structure). In the era of socialism (1945–1989), there were dynamic increases in the area of semi-natural forests as well as in the proportion of the most fertile habitats, whilst the proportion of the poorest habitats decreased quite dynamically. Then, the clearcutting management system was regularly implemented, with adverse impacts on forest spatial structure diversity. The proportion of old/mature tree stands and the stand average age increased at relatively slow rates. In the era of democracy (1990–2020), there were comparatively more dynamic increases observed in the area of forests undisturbed by man, as well as in the proportions of mixed broadleaved and wetland forest habitats. At the same time, the proportion of old/mature stands and stand average age kept increasing at relatively fast rates. The area of forests managed with the use of the shelterwood system increased and the area of forest plantations substantially decreased. On the other hand, irrespective of the era under study, there occurred a noticeable not-so-favourable decreasing trend in the proportion of the youngest forest stands. All in all, during the analysed period of more than seven decades, the evolution of forest management practice implemented in Poland’s forests by State Forests National Forest Holding led to the restoration of/an increase in biodiversity at the ecosystem level. Yet, there have remained unsolved issues, as regards the following aspects: organisational (the assurance of further reconstruction of forest stands, and the restoration of water profiles), political (a lack of up-to-date national forest policy), and financial (the costs of protecting/restoring biodiversity vs. State Forests’ self-financing), as well as conceptual (old-growth stands in managed forests, and controversy over clearcutting) and natural/anthropogenic (climate change, and the eutrophication of forest habitats) issues. The solutions may require measures outside the limits of Poland’s forestry, if not far beyond national borders.
... The age structure of European forests has significantly changed since 1950 (Vilén et al., 2012). The share of old stands (>100 years) in 25 European countries (excluding Russia) decreased from 26% in 1950 to 17% in 2010, and the mean age over the study area decreased from 67 to 60 years. ...
... One contributing factor for the decreasing average age was afforestation and natural forest expansion on abandoned agricultural lands, as this increased the share of young forests (Vilén and Lindner, 2014;Fuchs et al., 2015). The share of mature stands (> 80 years) increased in many countries after 1980, but the forest area of old forests was still lower in 2010 than in 1950 in absolute terms (Vilén et al., 2012). A more detailed analysis of national inventory data in Finland and the Czech Republic further showed that old forest stands had a significantly lower growing stock in the 1950s when compared to 2010 (Vilén et al., 2016). ...
Primary and old-growth forests in the EU are extremely rare and threatened, yet play an irreplaceable role in biodiversity conservation and the provision of other ecosystem services such as carbon storage. Recognising this, the EU Biodiversity Strategy for 2030 sets the target to strictly protect all remaining primary and old-growth forests. This target is part of a wider goal to protect 30% of EU land and to dedicate 10% of EU land for strict protection. Strict protection of the remaining EU primary and old-growth forests is a first and crucial step to ensure their long-term conservation. Despite the importance of this target, its implementation is currently prevented by several unanswered questions that require discussion among science and policy experts. This includes, for example, the question of how old-growth forest should be defined and where remaining primary and old-growth forests are located. In addition, there are ongoing discussions of how to best support strict protection of primary and old-growth forests and how to maintain and restore biodiversity, for example by preserving and allowing old-growth attributes to develop in forests that are managed for purposes other than conservation. This study specifically focuses on old-growth forests, given the increasing debate around this type of forest in Europe and their importance for forest biodiversity, but also includes information that is relevant for primary forests in a wider sense. The objective of this study is to inform discussions surrounding the implementation of the EU Biodiversity Strategy for 2030 target to strictly protect primary and old-growth forests. The methods of this study included a review of scientific literature on (i) Defining old-growth forests, (ii) Evidence of old and old-growth forests in Europe; (iii) Approaches to protect old-growth forests and to maintain and develop old-growth attributes, (iv) Associated benefits, consequences, and potential trade-offs of old-growth forest protection and management and development of old-growth forest attributes; and (v) Policy implications.
... and were aggregated to average annual country estimates (Supplementary Figure 2). Forest structural data were available from Seidl et al. 38 and Vilén et al. 40 and included national estimates of total growing stock and median age at 5-year intervals (1985-2015; Supplementary Figure 3). ...
... Mortality is considered stand-replacing if there are no live trees after the mortality event at the level of a 30 m pixel. Points indicate the median of the posterior probability distributions, and bars extent to the 95% credible interval demography of temperate forests in Europe39,40 and with empirical relationships between tree size and stem mortality47 . ...
Mortality is a key indicator of forest health, and increasing mortality can serve as bellwether for the impacts of global change on forest ecosystems. Here we analyze trends in forest canopy mortality between 1984 and 2016 over more than 30 Mill. ha of temperate forests in Europe, based on a unique dataset of 24,000 visually interpreted spectral trajectories from the Landsat archive. On average, 0.79% of the forest area was affected by natural or human-induced mortality annually. Canopy mortality increased by +2.40% year–1, doubling the forest area affected by mortality since 1984. Areas experiencing low-severity mortality increased more strongly than areas affected by stand-replacing mortality events. Changes in climate and land-use are likely causes of large-scale forest mortality increase. Our findings reveal profound changes in recent forest dynamics with important implications for carbon storage and biodiversity conservation, highlighting the importance of improved monitoring of forest mortality.
... and were aggregated to average annual country estimates (Supplementary Figure 2). Forest structural data were available from Seidl et al. 38 and Vilén et al. 40 and included national estimates of total growing stock and median age at 5-year intervals (1985-2015; Supplementary Figure 3). ...
... Mortality is considered stand-replacing if there are no live trees after the mortality event at the level of a 30 m pixel. Points indicate the median of the posterior probability distributions, and bars extent to the 95% credible interval demography of temperate forests in Europe39,40 and with empirical relationships between tree size and stem mortality47 . ...
Mortality is a key indicator of forest health, and increasing mortality can serve as bellwether for the impacts of global change on forest ecosystems. Here we analyze trends in forest canopy mortality between 1984 and 2016 over more than 30 Mill. ha of temperate forests in Europe, based on a unique dataset of 24,000 visually interpreted spectral trajectories from the Landsat archive. On average, 0.79% of the forest area was affected by natural or human-induced mortality annually. Canopy mortality increased by +2.40% year–1, doubling the forest area affected by mortality since 1984. Areas experiencing low-severity mortality increased more strongly than areas affected by stand-replacing mortality events. Changes in climate and land-use are likely causes of large-scale forest mortality increase. Our findings reveal profound changes in recent forest dynamics with important implications for carbon storage and biodiversity conservation, highlighting the importance of improved monitoring of forest mortality.
... While the expected future changes in C stocks are mostly an effect of the current age class structure of Europe's forests 4,69 , also C uptake is expected to change in the future, in response to a variety of global change factors. However, NPP changes are likely to be highly variable in space 71 . ...
... Supplementary Fig. 14). This variation represents, among other things, the considerable variation in stand ages and standing timber volumes in Europe at the continental scale 69 . Increasing the live C residence time also increased the simulated impact of alien pests on the C cycle. ...
Forests mitigate climate change by sequestering large amounts of carbon (C). However, forest C storage is not permanent, and large pulses of tree mortality can thwart climate mitigation efforts. Forest pests are increasingly redistributed around the globe. Yet, the potential future impact of invasive alien pests on the forest C cycle remains uncertain. Here we show that large parts of Europe could be invaded by five detrimental alien pests already under current climate. Climate change increases the potential range of alien pests particularly in Northern and Eastern Europe. We estimate the live C at risk from a potential future invasion as 1027 Tg C (10% of the European total), with a C recovery time of 34 years. We show that the impact of introduced pests could be as severe as the current natural disturbance regime in Europe, calling for increased efforts to halt the introduction and spread of invasive alien species.
... Current policies appear to be driving a shift from entirely mature forests to younger forest ecosystems both Türkiye and Europe. The study by Vilén et al. (2012) indicates that in Europe, the development of area-weighted forest mean age between 1950 and 2010 was only (negative) − 7 years. Looking at in detail it is seen such a great differences in some European countries. ...
... Forest ecosystems of European Russia arose in areas deforested after the last glaciation, relatively recent, 8-12 kyr ago, and were formed by a mixture of the Western and Eastern Palearctic species (Markova et al., 2008). Like most European forests, the forests of the East European Plain represent a huge successional system, in which most of the changes are initiated by various human activities (Smirnova et al., 2001;Vilén et al., 2012). Small mammals in the boreal forests of Tver Oblast represent the impoverished assemblage of the west and east boreal forest species (Emelyanova & Sidorova, 2014). ...
Due to their resilience, various biological systems under environmental changes typically exhibit nonlinear responses with sudden, abrupt shifts. Although such shifts are theoretically expected, few studies traced state-and-transition dynamics in nature (Liu et al., Science 317:1513–1516, 2007). We analysed 18 years’ data to trace biomass patterns, species assemblages and small mammals’ population trajectories in spontaneously growing forest on formerly ploughed field, hereafter, the postagrogenic forest, and in unmanaged former pasture, hereafter, the grassland. The clear response at individual, populational and ecosystem scales triggered by extraordinary 2010 drought was observed. In the postagrogenic forest, transitioning to the historical ecosystem state, we found a shift from the grassland type of the small mammals’ biomass pattern to the forest type with the abrupt reorganisation of the small mammals’ community. In the grassland, a relatively steady novel ecosystem, we revealed only a long-term diminishing of total small mammals’ biomass, i.e. a regime shift, while maintaining the same functional structure. The changes were based on population response. The bank vole did not show any population reaction, which testifies the ability of individuals to tolerate the drought. The common shrew experienced a population depression, which in postagrogenic forest resulted in the regimen shift after recovery, but in the grassland in only temporal decline with following return to the initial state. The root vole showed a delayed population response with the general decline of population in the grassland, and population collapse in the postagrogenic forest. Therefore, the same impact triggered various responses among different species and resulted in different effects in the successional and steady ecosystems.
... Current policies appear to be driving a shift from entirely mature forests to younger forest ecosystems both Türkiye and Europe. The study by Vilén et al. (2012) indicates that in Europe, the development of area-weighted forest mean age between 1950 and 2010 was only (negative) − 7 years. Looking at in detail it is seen such a great differences in some European countries. ...
This study investigates the evolving dynamics of forest management in Türkiye, focusing on the intersection of economic pressures, legal changes, and ecological consequences. In recent decades, Türkiye has experienced a paradigm shift toward multifunctional forest management, driven by global sustainability goals and the influence of international agreements. Despite these advancements and constitutional safeguards, rising wood production, driven by private sector demand, has led to concerns over the sustainability of forest ecosystems. Employing Cashore and Stone’s tripartite framework as a methodological outline under an institutional approach within a process tracing perspective, this research analyzes Türkiye’s regulatory evolution, economic dependencies, and the implications of sovereign authority on forest governance. Data sources include forest inventory reports, development plans, and economic and legal documents, analyzed to identify causal pathways and assess Türkiye’s alignment with international practices. The findings highlight inconsistencies between policy objectives and implementation, particularly regarding industrial plantations, which are critical for reducing pressure on forests. The study underscores the need for policies that balance economic exploitation and ecological protection. Strengthening industrial plantation efforts and aligning them with global best practices are recommended to ensure long-term sustainability. By integrating multifunctionality into policy frameworks and addressing emerging ecological risks, Türkiye can better manage its forests to support both economic development and biodiversity conservation.
... However, the majority of forests in Europe are semi-natural, with primary and old-growth forests covering only 0.7% of the forest area . The largest area is covered by managed tree stands aged 21-60 years, and the proportion of stands older than 140 years is the lowest (Barbati et al., 2014;Vil en et al., 2012). Even the oldest managed stands are relatively young, as forest rotations rarely exceed 200 years and most tree species reach harvest age at around 100-150 years (Pach et al., 2018;Schütz et al., 2016). ...
... Forest structure and species diversity are indicators of forest quality and key factors that affect carbon storage [23]. At the same time, the age-class structure provides information about the contribution of forest management to the long-term removal of carbon from the atmosphere [24]. Stable stands are necessary for the continual fulfillment of these requirements. ...
The high stability of stands with structures similar to natural ecosystems justifies adopting their composition as a management goal. Increasing the proportion of spruce in mixed forests and in deciduous forests in the Romanian Carpathian region, against the backdrop of climate change, may affect their stability. The natural distribution of tree species was investigated to establish natural forest types for defining future stand compositions. A forest in the Făgăraș Mountains of the Southeastern Carpathians was selected, and the mapping results were applied to a management unit of 4303.2 ha. Site conditions (e.g., altitude, exposure, etc.) are ecologically determined factors influencing the natural distribution of tree species and significantly influence species proportions. These factors, incorporated into models, estimate species proportions in future stand compositions with a root mean square error (RMSE) of 20%–24%. By adopting forest-type compositions as a management goal, the composition at the management unit level approaches that of natural ecosystems existing in 1950: Norway spruce (Picea abies (L.) Karst.) will decrease from 80.5% to 32.4%, while European beech (Fagus sylvatica L.) will increase from 12.5% to 41.7%, Silver fir (Abies alba Mill.) from 0.6% to 15.8%, and other species from 6.4% to 10.1%. Restoring ecosystems affected by their transformation into spruce monocultures leads to increased biodiversity and mitigates the effects of climate change, ensuring the long-term functionality of forest ecosystems, which are essential conditions for sustainable forest management.
... However, the foreseen rise in protected forest areas has triggered a debate about the influence of such action on forests as carbon pools [4][5][6]. Comprehensive knowledge of forest health across diverse ecosystems and maturity stages is essential for evaluating the long-term impact of various forest management decisions and protection scenarios on the long-term removal of carbon dioxide (CO2) from the atmosphere [7,8]. ...
Efforts to enhance carbon storage in forest ecosystems through policy and management decisions rely on accurate forest biomass assessments. However, most forest inventories consider tree mortality the only form of aboveground biomass loss, overlooking other important factors, such as wood decay in living trees. In this study, using linear mixed-effects models, we delve into the sustainability of mature and over-mature deciduous forests in Latvia by conducting a comprehensive analysis of stem rot severity, identifying species for which the impact of stem rot on their carbon stock reduction was most significant. The analysis focused on determining the proportion of discolored wood, decomposed wood, and hollow spaces within the stems of 190 living deciduous trees commonly found in hemiboreal forests. The study reveals a greater extent of stem rot and more extensive decay in Populus tremula trees than in Betula spp., Alnus glutinosa, and Alnus incana. It emphasizes the influence of tree species, age, and diameter at breast height on stem rot proportions. The stump rot area significantly predicts the amount of decomposed and discolored wood within the stem. The study provides valuable insights for sustainable forestry practices and highlights challenges in estimating stem rot severity, emphasizing the need for comprehensive diagnostic methods.
... The forest age structure is essential for understanding its current functioning and development and predicting the dynamics of future carbon sinks under changing climate conditions for the longterm removal of carbon dioxide (CO2) from the atmosphere [7,8]. Stem rot, a ubiquitous and natural phenomenon in forests, deteriorates tree vitality over time and mainly affects the lower parts of older trees [9][10][11]. ...
Efforts to enhance carbon storage in forest ecosystems through policy and management decisions
rely on accurate forest biomass assessments. However, most forest inventories consider tree mortality the only
form of aboveground biomass loss, overlooking other important factors, such as wood decay in living trees. In
this study, using linear mixed-effects models, we delve into the sustainability of mature and over-mature
deciduous forests in Latvia by conducting a comprehensive analysis of stem rot severity, identifying species
for which the impact of stem rot on their carbon stock reduction was most significant. The analysis focused on
determining the proportion of discolored wood, decomposed wood, and hollow spaces within the stems of 190
living deciduous trees commonly found in hemiboreal forests. The study reveals a greater extent of stem rot
and more extensive decay in Populus tremula trees than in Betula spp., Alnus glutinosa, and Alnus incana. It
emphasizes the influence of tree species, age, and diameter at breast height on stem rot proportions. The stump
rot area significantly predicts the amount of decomposed and discolored wood within the stem. The study
provides valuable insights for sustainable forestry practices and highlights challenges in estimating stem rot
severity, emphasizing the need for comprehensive diagnostic methods.
Keywords: internal decay; stem quality; discoloration; old forests; tree cavities; decay assessment;
resource management; political ecology
... Forest age structures are an important factor that determine the C sequestration potential of forests (Pan et al. 2011;Vilén et al. 2012;Besnard et al. 2018;Pugh et al. 2019;Repo et al. 2021). However, there are no country-specific panel data on European forest age structures for the period from 1992 to 2018. ...
We examine the evolution of European net sinks towards 2030 and the European Union's (EU) climate neutrality target by 2050. The EU's current land use policy for 2021-2030 is divided into two periods: 2021-2025 and 2026-2030. The national inventory data from several databases and statistical analyses are used to examine the trends and drivers and to forecast future forest sinks and the net sinks of the land use, land use change and forestry (LULUCF) sector. Our forecasts suggest that national forest sinks will be short of the agreed forest reference levels in most member states in 2021-2025, with a total of 128 MtCO 2 eq. For 2026-2030, the net sink for the whole EU LULUCF sector will be short of the EU target by 298 MtCO 2 eq. Thus, most member states must design more efficient LULUCF policies to fulfil their national targets. Furthermore, the decreasing trends in the LULUCF sinks also emphasize the need to reduce emissions and to increase the sinks in most member states so that the EU can achieve its climate neutrality goal by 2050.
... the approach used for estimation, with greater uncertainties associated with the allometric approach. Information of forest age is critical for a wide range of applications beyond forest inventory, including for carbon modeling and the development of greenhouse gas budgets, where knowledge of forest age allows for the understanding of future carbon cycling and variability (Pan et al., 2011a;Vilén et al., 2012). For carbon modeling, precision in age estimation may be most relevant for younger forests (<40 years; Zhou et al., 2015), which may be well captured within the Landsat record. ...
... As a result of past forest management practices, central European beech (Fagus sylvatica L.) forests are predominantly homogeneous . They are characterized by a single-layered, evenaged stand structure with little understory, an under-representation of old successional stages in many areas, and only small amounts of deadwood (Brunet et al., 2010;Hilmers et al., 2018;Vilén et al., 2012). However, deadwood is a key element of forest biodiversity (Stokland et al., 2012) and deadwood-dependent biodiversity is disproportionally threatened (Seibold et al., 2015). ...
Conservation tools to enrich habitat diversity in the widely distributed homogeneous production forests include stumps as logging residues but also the intentional creation of logs or snags, as well as varying canopy conditions. While an open canopy has been shown to foster forest biodiversity, the impact of different deadwood types at stand scale is less clear, which is crucial since this is the most relevant scale for silvicultural decisions. In this study, we experimentally manipulated canopy conditions (open vs. closed) and created deadwood (stumps, logs, snags) in different combinations in five mature European beech (Fagus sylvatica L.) forests to test the potential of active manipulations to increase the diversity of beetles, one of the most diverse insect orders in temperate forests. We estimated abundance, species number and species richness (controlled for abundance) of saproxylic (i.e., deadwood-dependent) and non-saproxylic beetles using flight-interception traps and analyzed species assemblages within the first 3 years of the experiment. Using generalized linear mixed effect models we found a 33.7 % and 43.4 % higher abundance as well as a 26.1 % and 23.5 % higher species number under open canopies for saproxylic and non-saproxylic beetles respectively, accompanied by a higher species richness of both groups. Stands with deadwood had a 38.6 % and 32.7 % higher species number followed by higher species richness of saproxylic and non-saproxylic beetles compared to stands without manipulation but manipulations did not affect beetle abundances. We identified sampling year, followed by canopy condition and deadwood type (in addition to an overall higher impact of spatial distance between stands and sites) by applying multiple regression analyses as most important to explain species assemblages of both beetle groups. Saproxylic abundance and species number in stump treatments were initially high but decreased over 3 years, while treatments containing snags and logs resulted in an increase in both abundance and species number over time. These temporal trends were mediated by canopy cover. Our findings provide three major insights for biodiversity-orientated management in mature beech forests: First, opening the canopy increases the stand-scale abundance, species number, and species richness of saproxylic and non-saproxylic beetles. Second, while stumps are attractive for saproxylics shortly after the logging operation, snags and logs provide longer-lasting deadwood resources, thus underlining longer sustainability of snag and log enrichment for forest biodiversity. Third, deadwood enrichment at the stand scale promotes not only deadwood-dependent but also other beetle species.
... However, stand structure and management can also contribute to changing mortality rates. In Europe, forest demography has changed notably since the 1950s, with average forest stand age becoming lower (Vilén et al 2012), as a consequence both of shorter rotation times, and regrowth of forests on land formerly used for agriculture or other purposes (Hunter and Schuck 2002). Younger stands typically exhibit higher growth rates and lower losses of biomass through mortality than older stands. ...
Increasing tree growth and mortality rates in Europe are still poorly understood and have been attributed to a variety of drivers. This study explored the role of climate drivers, management and age structure in driving changes in tree mortality rates in six Central European countries from 1985 to 2010, using the process-based vegetation model LPJ-GUESS. Simulations show a strong positive trend in canopy mortality rates in Central Europe, consistent with satellite observations. This trend was explained by an assumed increase in managed thinning in response to a modelled increase in forest productivity caused by climate change and rising atmospheric CO2 concentration. Simulated rates of canopy mortality were highly sensitive to the minimum tree size threshold applied for inclusion in the rate calculation, agreeing with satellite observations that are likely to only capture the loss of relatively large trees. The calculated trends in mortality rate also differed substantially depending on the metric used (i.e. carbon, stem or canopy mortality), highlighting the challenge of comparing tree mortality trends from different observation types. We conclude that changes in forest productivity and management in combination can profoundly affect regional-scale patterns of tree mortality. Our findings underscore the fact that increasing forest mortality can occur without reductions in forest growth when mediated by management responses to increasing productivity.
... During 1990-2020, the forest area and growing stock in Europe increased by 9% and 50%, respectively (Europe 2020), largely as a result of net planting and large areas of farmland being transformed into forest land (Fuchs 2013). In 2010, even-aged forests up to 40 years old covered ~36 M ha across Europe (Vilén et al. 2012), which will generate an increased need for thinning work. ...
Biomass derived from small-diameter, dense, thinning stands is largely underutilized within the European Union, mainly because of in-effective harvesting methods and cutting technology, leading to high supply costs. Therefore, the efficacy of boom-corridor thinning (BCT) and selective thinning (ST) on harvester felling and bunching productivity was compared for the first thinning of whole tree biomass in small-diameter, dense stands. BCT working method is when trees are cut with linear movements of the harvester’s boom reach, along narrow corridors, instead of cutting each tree selectively (ST). Trials were performed in six forest stands, one in Sweden, two in Finland, and three in Slovenia, using the same harvester and operator. A time-and-motion study was carried out in 64 pre-marked study units (32 replications per method), across a variety of stand conditions. The biomass removal for both treatments averaged 40.2 dry t ha -1 and BCT productivity averaged 5.4 dry t PMh -1. For BCT, harvester work time consumption (sec tree -1) and productivity (dry t PMh -1) were on average 27% lower and 16% higher, respectively, compared with ST. The effectiveness of the accumulating felling head technology used could potentially be increased by implementing a feed-roller system when handling excessive tree lengths. Developing dedicated harvesting technology for BCT could further boost productivity, facilitating cost-effective and sustainable utilization of low-value small-diameter tree biomass and replacing fossil resources.
... Examples of such species include bryophytes, lichens, fungi, and saproxylic beetles (Müller et al. 2007, Paillet et al. 2010, Brunet et al. 2010, Roth et al. 2019. Moreover, forest operations decreased the share of old European forests (Vilén et al. 2012, Sabatini et al. 2018 and modified their natural structure, composition, and dynamics for centuries, reducing their overall naturalness in several parts of Europe (Wallenius et al. 2010a, Brumelis et al. 2011. ...
In Europe, forest management has controlled forest dynamics to sustain commodity production over multiple centuries. Yet over‐regulation for growth and yield diminishes resilience to environmental stress as well as threatens biodiversity, leading to increasing forest susceptibility to an array of disturbances. These trends have stimulated interest in alternative management systems, including natural dynamics silviculture (NDS). NDS aims to emulate natural disturbance dynamics at stand and landscape scales through silvicultural manipulations of forest structure and landscape patterns. We adapted a “Comparability Index” (CI) to assess convergence/divergence between natural disturbances and forest management effects. We extended the original CI concept based on disturbance size and frequency by adding the residual structure of canopy trees after a disturbance as a third dimension. We populated the model by compiling data on natural disturbance dynamics and management from 13 countries in Europe, covering four major forest types (i.e., spruce, beech, oak, and pine‐dominated forests). We found that natural disturbances are highly variable in size, frequency, and residual structure, but European forest management fails to encompass this complexity. Silviculture in Europe is skewed toward even‐aged systems, used predominately (72.9% of management) across the countries assessed. The residual structure proved crucial in the comparison of natural disturbances and silvicultural systems. CI indicated the highest congruence between uneven‐aged silvicultural systems and key natural disturbance attributes. Even so, uneven‐aged practices emulated only a portion of the complexity associated with natural disturbance effects. The remaining silvicultural systems perform poorly in terms of retention compared to tree survivorship after natural disturbances. We suggest that NDS can enrich Europe's portfolio of management systems, for example where wood production is not the primary objective. NDS is especially relevant to forests managed for habitat quality, risk reduction, and a variety of ecosystem services. We suggest a holistic approach integrating NDS with more conventional practices.
... Associations of GS attributes with the fraction of countries' forests under a production management plan also support this view (S4 Fig). The predominantly even-aged structure of European forests (70% of area) and its fair distribution across developmental stages (20% regeneration, 60% intermediate, 20% mature forests) lasts suggest a constant effort at renewing forests after final harvest [2,61]. ...
The current increase in European forest resources forms a singularity across the globe. Whether this trend will persist, and how biological and economic trends feature it form crucial issues to green economy challenges and C sequestration. The present screening of Forest Europe 2015 statistics explored the features, inertia and limits of this expansion, and its relationships with countries’ development, forest management and trade, intense in this area of the world. Persisting footprint of past demographic pressure on forests was identified, with opposed traces on their area and growing stock density. Steady growing stock (GS) increases, proportional to GS, not density-limited, and sustained by forest area increases, supported the view of an inflationary forest dynamic. Economic development and liberalism fostered both forest exploitation and production, yielding no significant impact on GS changes. Wood exports exerted a tension on forest exploitation and GS changes, thus lowering GS inflation but providing a resource security margin in the face of expected climate threats. Conflicting a common view, GS inflation and moderate felling-to-increment ratios make increased use of wood resources and C sequestration reconcilable, and GS expansion timely for ongoing EU forest policy processes. Anticipated adverse impacts of ongoing climate change were not clearly identified in these statistics.
... While tropical forests are disappearing rapidly, European forests have been expanding since the 1990s but are often intensively managed (Bryant et al. 1997;FAO 2010). This leads to a severe underrepresentation of old successional stages in many regions (Vilén et al. 2012) and a decline of species that depend on old-growth forest characteristics such as large amounts of dead wood and old trees (Brunet et al. 2010;Paillet et al. 2010;Eckelt et al. 2018). In temperate and boreal regions, 20-25% of forest species depend on the availability of dead wood (= saproxylic species; Stokland et al. 2012), which makes it a key element for biodiversity conservation in forests (MCPFE 2003;Stokland et al. 2012). ...
Context - Dead wood is a key habitat for saproxylic species, which are often used as indicators of habitat quality in forests. Understanding how the amount and spatial distribution of dead wood in the landscape affects saproxylic communities is therefore important for maintaining high forest biodiversity.
Objectives - We investigated effects of the amount and isolation of dead wood on the alpha and beta diversity of four saproxylic species groups, with a focus on how the spatial scale influences results.
Methods - We inventoried saproxylic beetles, wood-inhabiting fungi, and epixylic bryophytes and lichens on 62 plots in the Sihlwald forest reserve in Switzerland. We used GLMs to relate plot-level species richness to dead wood amount and isolation on spatial scales of 20-200 m radius. Further, we used GDMs to determine how dead wood amount and isolation affected beta diversity.
Results - A larger amount of dead wood increased beetle richness on all spatial scales, while isolation had no effect. For fungi, bryophytes and lichens this was only true on small spatial scales. On larger scales of our study, dead wood amount had no effect, while greater isolation decreased species richness. Further, we found no strong consistent patterns explaining beta diversity.
Conclusions - Our multi-taxon study shows that habitat amount and isolation can strongly differ in the spatial scale on which they influence local species richness. To generally support the species richness of different saproxylic groups, dead wood must primarily be available in large amounts but should also be evenly distributed because negative effects of isolation already showed at scales under 100 m.
... Post-deforestation recruitment is often prolific even in the absence of management (82). Globally, the recovery of harvested forests and abandoned agricultural land, along with establishment of new planta-tions, has resulted in younger forests (Fig. 1A), with associated reductions in tree size and biomass (83). Such post-deforestation recruitment may be limited by elevated VPD or drought, as is the case with recruitment after all-natural disturbances. ...
BACKGROUND: Forest dynamics arise from the interplay of chronic drivers and transient disturbances with the demographic processes of recruitment, growth, and mortality. The resulting trajectories of vegetation development drive the biomass and species composition of terrestrial ecosystems. Forest dynamics are changing because of anthropogenic-driven exacerbation of chronic drivers, such as rising temperature and CO 2 , and increasing transient disturbances, including wildfire, drought, windthrow, biotic attack, and land-use change. There are widespread observations of increasing tree mortality due to changing climate and land use, as well as observations of growth stimulation of younger forests due to CO 2 fertilization. These antagonistic processes are co-occurring globally, leaving the fate of future forests uncertain. We examine the implications of changing forest demography and its drivers for both future forest management and forecasting impacts of global climate forcing.
... Post-deforestation recruitment is often prolific even in the absence of management (82). Globally, the recovery of harvested forests and abandoned agricultural land, along with establishment of new planta-tions, has resulted in younger forests (Fig. 1A), with associated reductions in tree size and biomass (83). Such post-deforestation recruitment may be limited by elevated VPD or drought, as is the case with recruitment after all-natural disturbances. ...
Shifting forest dynamics
Forest dynamics are the processes of recruitment, growth, death, and turnover of the constituent tree species of the forest community. These processes are driven by disturbances both natural and anthropogenic. McDowell et al. review recent progress in understanding the drivers of forest dynamics and how these are interacting and changing in the context of global climate change. The authors show that shifts in forest dynamics are already occurring, and the emerging pattern is that global forests are tending toward younger stands with faster turnover as old-growth forest with stable dynamics are dwindling.
Science , this issue p. eaaz9463
... At the same time, while wood was the main fuel in France until the 1870s (Smil, 2017), providing energy for heating and cooking in French homes, the switch from wood to coal certainly relieved pressure on wood extraction and may have been the prime reason of the observed transition of forest biomass density ( Figure 4). Therefore, another relevant factor to explain the divergence between the CRAFT and bookkeeping models is the effect of forest age structure, controlled by the expansion of forest area and variation in harvest rates, which affects the growth rate of forest stand density (He, Chen, Pan, Birdsey, & Kattge, 2012;Noormets et al., 2015;Pan, Birdsey, Phillips, & Jackson, 2013;Pretzsch et al., 2014;Pugh et al., 2019;Vilén et al., 2012). This effect of age structure can be accounted by both the CRAFT and static CRAFT approaches thanks to the nonlinear relationship between NPP and standing biomass. ...
The development of appropriate tools to quantify long‐term carbon (C) budgets following forest transitions, i.e., shifts from deforestation to afforestation, and to identify their drivers are key issues for forging sustainable land‐based climate‐change mitigation strategies. Here, we develop a new modelling approach, CRAFT (CaRbon Accumulation in ForesTs) based on widely available input data to study the C dynamics in French forests at the regional scale from 1850 to 2015. The model is composed of two interconnected modules which integrate biomass stocks and flows (Module 1) with litter and soil organic C (Module 2) and build upon previously established coupled climate‐vegetation models. Our model allows to develop a comprehensive understanding of forest C dynamics by systematically depicting the integrated impact of environmental changes and land use. Model outputs were compared to empirical data of C stocks in forest biomass and soils, available for recent decades from inventories, and to a long‐term simulation using a bookkeeping model. The CRAFT model reliably simulates the C dynamics during France’s forest transition and reproduces C‐fluxes and stocks reported in the forest and soil inventories, in contrast to a widely used bookkeeping model which strictly only depicts C‐fluxes due to wood extraction. Model results show that like in several other industrialized countries, a sharp increase in forest biomass and SOC stocks resulted from forest area expansion and, especially after 1960, from tree growth resulting in vegetation thickening (on average 7.8 MtC yr‐1 over the whole period). The difference between the bookkeeping model, 0.3 MtC yr‐1 in 1850 and 21 MtC yr‐1 in 2015, can be attributed to environmental and land management changes. The CRAFT model opens new grounds for better quantifying long‐term forest C dynamics and investigating the relative effects of land use, land management, and environmental change.
... It is an Indicator not efficient in discriminating the management options from the point of view of C content in the soil; on the other hand, it contributes to the estimation of the Indicator Soil condition in terms of Criterion 2 "forest health and vitality". The 'Diameter distribution' gives only a qualitative information, although coherent to the dynamics of the stands (Vilen 2012 It is interesting to underline that in Natural Evolution, the best forest health conditions and the highest potential photosynthetic efficiency are concurrently registered for beech. This result is further strengthened by the low specific leaf area (SLA, projected leaf area per unit leaf dry mass), which is considered to be related to an enhanced photosynthetic capacity per unit leaf area (Evans and Poorter 2001), and by the high leaf thickness strongly related to the soil particle size with higher values usually associated to high presence of small particles and high organic matter contents. ...
2019. Report: Integrated scientific synthesis and evaluation of project results-LIFE FutureForCoppiceS-Shaping future forestry for sustainable coppices in Southern Europe: the legacy of past management trials (with Synthesis for resource managers and policy makers). Deliverable of LIFE FutureForCoppiceS project, Action B.9, 108 pp. In collaboration with the subcontractor TerraData srl environmetrics, Spin Off of the University of Siena. 3 Authors SUMMARY Extended abstract 6
... As a part of background information gathered for previous spatial modelling exercises in the study area, ages from forest inventory data have been used to estimate a one-time, pre-industrial (circa 1950-1970) landscape snapshot. This is done using the rollback technique, which a) back-casts the entire landscape to a point in time where fire control and harvesting impacts are minimal, and b) replaces all of the disturbance activity after that point in time with either the known, or the most likely, pre-disturbed age (Vilen et al. 2012). As previously discussed, forest inventory ages lack precision, but have minimal bias (Andison 1999a and1999b) and thus serve, at the very least, as reasonable plausibility tests. ...
... Forestry practices in many regions across Europe include the selection of relatively young trees (< 120 years), i.e., those that will not reach natural senescence for many years, and the removal of older as well as https://doi.org/10.1016/j.foreco.2019.117531 Received 28 April 2019; Received in revised form 1 August 2019; Accepted 5 August 2019 rotting trees (Vilén et al., 2012). In Central Europe, over 5000 years of forestry has changed the ecosystem (Grove, 2002). ...
Humans have widely extirpated large carnivores and simultaneously promoted overabundance of deer. The intense pressure imposed by these herbivores in forests has led to extremely low rates of natural forest regeneration. In natural old-growth forests, deadwood functions as a key driver of biodiversity and promotes ecosystem functioning, such as water retention and nutrient recycling. An as yet unappreciated function of deadwood is its ability to act as a physical barrier, excluding large herbivores from the obstructed patches and thereby reducing browsing pressure. However, this benefit may be minimized by an increase in rodent herbivory in the sheltered patches. In this study, a field experiment was conducted in a total of 384 plots in which tree crowns (0–4) from logging residuals were used as increasingly dense physical barriers to shelter five newly planted saplings of silver fir (Abies alba Mill.). Generalized linear mixed-effects models were applied to determine whether sapling browsing by roe deer and rodents was differentially affected by these barriers. The probability of roe deer browsing decreased from 26% (no crowns) to 2% (4 crowns) while that of rodent browsing increased from 1% to 17%, respectively, as the number of deadwood crowns used in barrier construction increased. In broadleaf stands, browsing by roe deer and rodents was generally higher than in coniferous stands. In forests with high numbers of visitors, browsing by roe deer was reduced, but browsing by rodents was not influenced. The retention of large amounts of deadwood or active deadwood increments may thus provide an effective barrier to roe deer browsing but promote the browsing activity of rodents. The landscape-level heterogeneity of browsing patterns associated with the presence of deadwood suggests that deadwood shelters in homogenized forests may encourage both natural forest regeneration and forest biodiversity, despite an overabundance of roe deer.
... It is an Indicator not efficient in discriminating the management options from the point of view of C content in the soil; on the other hand, it contributes to the estimation of the Indicator Soil condition in terms of Criterion 2 "forest health and vitality". The 'Diameter distribution' gives only a qualitative information, although coherent to the dynamics of the stands (Vilen 2012 It is interesting to underline that in Natural Evolution, the best forest health conditions and the highest potential photosynthetic efficiency are concurrently registered for beech. This result is further strengthened by the low specific leaf area (SLA, projected leaf area per unit leaf dry mass), which is considered to be related to an enhanced photosynthetic capacity per unit leaf area (Evans and Poorter 2001), and by the high leaf thickness strongly related to the soil particle size with higher values usually associated to high presence of small particles and high organic matter contents. ...
Deliverable of LIFE14 ENV/it/000514 FutureForCoppiceS project: Scientific synthesis and evaluation of project results (with Synthesis for resource managers and policy makers). https://www.futureforcoppices.eu/en/documents/summary-report.html
... Young and mid-age structurally simplified forest stands have become more frequent in modern forest landscapes of Northern Europe (UNECE & FAO 2011, Vilén et al. 2012. In particular, the availability of dead wood (e.g., standing and downed coarse and fine woody debris) is reduced by logging and it is considered that in European production forests the current volumes of dead wood are less than 10% of what is found in natural forests (Stokland et al. 2012). ...
Retention of live trees and dead wood structures in clear-cut sites is a common sylviculture measure for biodiversity purposes. We studied lichen assemblages on pine stumps and fine woody debris (FWD) in 16 post-cut (4–6 and 9–11 yr. old) dry boreal pine stands in Latvia to explore what type of substrata and stand-scale characters (e.g., retention level, time since harvest) are related to lichen species richness and differences in composition. We found 48 lichen species on stumps and 43 species on FWD. Majority of the species (except Cladonia parasitica) were common lichens of coniferous forests in hemiboreal regions. Time since harvest and retention level had positive impacts on richness on stumps, but not on FWD. Increase in total species richness on stumps in older post-harvest sites compared to the younger ones was strong and relatively rapid. Notwithstanding species richness, assemblages on FWD and on stumps were distinct between older and younger cut sites. The impact of time also emerged when assemblages on vertical and horizontal stump surfaces were separated. We conclude that pine stumps are important to lichen richness and post-harvest recovery of the epixylic lichen biota, especially in the face of alarming scarcity of snags and logs in cut-over sites in Latvia, where dead wood legacies (particularly snags) are not retained in sufficient amount.
... Most studies available for comparison (Figure 2) show the amount of C stored in forested areas as being similar to the amount stored in the LPW younger growth stands. European and U.S. forests had very low live C store per unit area around 1950 due to the large scale fellings that took place across western, central and eastern Europe during and after World War II ( Vilén et al. 2012) and to earlier periods of extensive forest harvest in the U.S. ( Turner et al. 1995). Although similar histories makes the increase in live C stores in the younger growth stands comparable to the rest of European forests, our study site has shown no increase in forest area, as has been suggested for European forests ( Kauppi et al. 2006). ...
Forest carbon stocks have increased in both Europe and North America in recent decades. National forest inventories are often used to indicate recent carbon dynamics, but the data from unmanaged forests are often incomplete. Here we calculate changing biomass carbon stocks for a mixed, unmanaged British woodland with two different management histories: (1) older growth stands untouched since 1902 and (2) younger growth stands clear felled in 1943 but have developed naturally since. Transects in the older growth have been monitored since 1945 and the younger growth since 1977. Separate estimates of tree carbon (C), soil C and dead wood C were obtained to verify how C is apportioned in these stands. Tree biomass C stocks had approximately doubled in the older growth stands since 1945 and 60% of C was stored in tree biomass, 38% was stored in soil and 2% stored in coarse woody debris. This study suggests that natural older growth stands are storing more C than typical managed forests, with tree biomass the most important compartment for C stores. If management is to be shifted from biomass production to increased C stores, due consideration should be given to the role of unmanaged, older growth forests.
... All the countries that have ratified the United Nations Framework Convention on Climate Change (UNFCCC 2006), the Kyoto Protocol (UNFCCC 1997) and the Paris Agreement (UNFCCC 2015) must report their greenhouse gas emissions, with particular attention on LULUCF, i.e. land use, land use change and the forestry sector (UNFCCC 2006). European forests are considered as carbon (C) sequestrating ecosystems (Pan et al. 2011) because of the increasing forest area and the relatively young age of the forests (Böttcher et al. 2008;Vilen et al. 2012). Estonian forests show similar tendencies, where the net balance of CO 2 emission has been positive since the 1990s (EEA 2017a; MoE 2018). ...
The crucial role of forests in terrestrial carbon (C) balance is well acknowledged, but nationwide C assessments still show some uncertainties. We estimated the effect of forest site type on various ecosystem C pools in premature- and mature-aged forests of hemiboreal Estonia. Furthermore, the effects of soil physico-chemical properties and the tree species on soil organic carbon (SOC) stocks were analysed. The weighted mean SOC stock of Estonian forests was 77 Mg C ha⁻¹ in humipedon layer and 118 Mg C ha⁻¹ in solum. The mean ecosystem C stock of Estonian forests was 174 (confidence range: 141 to 214) Mg C ha⁻¹, from which 111 Mg C ha⁻¹ was distributed in the solum layer, 61 Mg C ha⁻¹ in the overstorey tree layer, 0.5 Mg C ha⁻¹ in the understorey tree layer and 1.7 Mg C ha⁻¹ in the ground vegetation. Forest site type had a significant (p < 0.001) effect on all analysed C stocks. The variation of SOC stocks in the humipedon (R² = 0.71) and in the solum (R² = 0.79) was explained by the thickness of the layer, the total nitrogen stock, base saturation, hydrolytic acidity, soil trophic and moisture conditions. The higher quantity of deciduous tree species in a stand composition was in a positive correlation with the SOC stock in the humipedon of fertile site types. The accuracy of nationwide assessments of forest C reporting can be improved by using a site-specific approach, considering deeper soil layers and incorporating other structural forest layers.
... Stand age is a strong determinant of forest biomass C sequestration rates [19,[64][65][66][67][68], and thus also forest biomass C storage [14]. Information on the forest's stage of development should therefore be included in predictions of the future trajectories of forest biomass C storage. ...
Chinese forests, characterized by relatively young stand age, represent a significant biomass carbon (C) sink over the past several decades. Nevertheless, it is unclear how forest biomass C sequestration capacity in China will evolve as forest age, climate and atmospheric CO2 concentration change continuously. Here, we present a semi-empirical model that incorporates forest age and climatic factors for each forest type to estimate the effects of forest age and climate change on total forest biomass, under three different scenarios based on the fifth phase of the Coupled Model Intercomparison Project (CMIP5). We estimate that age-related forest biomass C sequestration to be 6.69 Pg C (∼0.17 Pg C a⁻¹) from the 2000s to the 2040s. Climate change induces a rather weak increase in total forest biomass C sequestration (0.52–0.60 Pg C by the 2040s). We show that rising CO2 concentrations could further increase the total forest biomass C sequestration by 1.68–3.12 Pg C in the 2040s across all three scenarios. Overall, the total forest biomass in China would increase by 8.89–10.37 Pg C by the end of 2040s. Our findings highlight the benefits of Chinese afforestation programs, continued climate change and increasing CO2 concentration in sustaining the forest biomass C sink in the near future, and could therefore be useful for designing more realistic climate change mitigation policies such as continuous forestation programs and careful choice of tree species.
... Research articles related to forest carbon sequestration have increased especially in last two decades. Silviculture and forest management practices have the ability to increase forest carbon sinks and reduce emissions from carbon sources [22][23][24][25][26][27][28]. Helms [29] defined silviculture as Bthe art and science of controlling the establishment, growth, composition, health, and quality of forests and woodlands to meet the diverse needs and values of landowners and society on a sustainable basis.^He ...
Purpose of Review
The primary focus of this paper is to review articles that incorporate forest carbon sequestration or bioenergy into an optimization framework for forest management at the stand and forest levels and to highlight the gaps in the literature. Forest management is seen as a cost-effective strategy to reduce carbon emission, and optimization techniques are a powerful tool to assist in developing an optimal strategy.
Recent Findings
Our review of literature shows a gap in research on the use of optimal management schemes to investigate the impact of silvicultural techniques such as site preparation, genetic improvement, and fertilization on carbon sequestration. For operational planning, spatial information is helpful in developing an optimal mitigation strategy. However, there is a gap in literature when it comes to the application of exact solution techniques to solve spatially constrained harvest scheduling problems that encourage carbon sequestration and timber production, while taking into account forest management prescriptions. The review further shows that assessing the impacts of using carbon sequestration and bioenergy strategies to mitigate the impact of greenhouse gas-induced climate change is complex due to the interaction between the forest sector, energy, and other industrial product sectors.
Summary
We suggest that more research should be directed towards using optimization techniques and an integrated system approach that tracks carbon flow in multiple sectors as a strategy to reduce carbon emissions. This strategy should encourage higher wood utilization and increase use of long-lived harvested wood products as well as bioenergy from waste wood.
... Furthermore, understanding the variation in biodiversity over the entire course of succession could also provide a more comprehensive perspective on the effects of different management strategies on biodiversity. In Europe, for instance, the majority of forests are currently of intermediate age, as a result of heavy exploitation during and after the first half of the 20th century (Vilén et al., 2012). Late stages of forest succession, such as the terminal and decay stages, are largely absent, as most forests are harvested before trees reach old age (Faustmann, 1995). ...
The successional dynamics of forests—from canopy openings to regeneration, maturation, and decay—influence the amount and heterogeneity of resources available for forest‐dwelling organisms. Conservation has largely focused only on selected stages of forest succession (e.g., late‐seral stages). However, to develop comprehensive conservation strategies and to understand the impact of forest management on biodiversity, a quantitative understanding of how different trophic groups vary over the course of succession is needed.
We classified mixed mountain forests in Central Europe into nine successional stages using airborne Li DAR . We analysed α‐ and β‐diversity of six trophic groups encompassing approximately 3,000 species from three kingdoms. We quantified the effect of successional stage on the number of species with and without controlling for species abundances and tested whether the data fit the more‐individuals hypothesis or the habitat heterogeneity hypothesis. Furthermore, we analysed the similarity of assemblages along successional development.
The abundance of producers, first‐order consumers, and saprotrophic species showed a U‐shaped response to forest succession. The number of species of producer and consumer groups generally followed this U‐shaped pattern. In contrast to our expectation, the number of saprotrophic species did not change along succession. When we controlled for the effect of abundance, the number of producer and saproxylic beetle species increased linearly with forest succession, whereas the U‐shaped response of the number of consumer species persisted. The analysis of assemblages indicated a large contribution of succession‐mediated β‐diversity to regional γ‐diversity.
Synthesis and applications . Depending on the species group, our data supported both the more‐individuals hypothesis and the habitat heterogeneity hypothesis. Our results highlight the strong influence of forest succession on biodiversity and underline the importance of controlling for successional dynamics when assessing biodiversity change in response to external drivers such as climate change. The successional stages with highest diversity (early and late successional stages) are currently strongly underrepresented in the forests of Central Europe. We thus recommend that conservation strategies aim at a more balanced representation of all successional stages.
... Forests are in a constant state of change, and tree demographics, particularly age, can be used to assess forest dynamics and to comprehend key forest processes and functions. For example, Vilén et al. (2012) stated that patterns of net carbon exchange are strongly affected by the age of a forest. Lucas-Borja et al. (2016) investigated the effects of stand age on microbiological soil properties and concluded that stand age influenced differences in soil attributes (e.g., pH, NH 4 + , etc.). ...
Quantifying the age characteristics of a forest can provide valuable information about the forest’s impact on the environment. For instance, the age of a forest can affect the ecosystem’s carbon exchange, soil enzyme activity, and biodiversity. In this paper, we investigate the use of different sampling methods to estimate the age characteristics of three simulated ponderosa pine (Pinus ponderosa Dougl. ex P. Lawson & C. Lawson) forests having different spatial and age patterns. This includes estimating the mean tree age and the age-class distribution of the trees in the forest. The trees in the sample are selected using k-tree sampling, fixed-radius plot sampling, or variable-radius plot sampling, and we compare the properties of the resulting estimators via design-based and model-based approaches. Analyses of the different sampling methods applied to the three forests suggest that the estimator associated with k-tree sampling, with the addition of a few extra trees per plot, is feasible for forests having a spatially mosaic or random spatial pattern. The estimator associated with fixed-radius plot sampling performed well for the forest having a clustered spatial pattern.
... Compared to naturally dynamic forest landscapes, this results in a truncated age-class distribution, with a reduced area of oldgrowth forest. In large parts of Finland and Sweden, for example, the mean forest age has decreased from the 1950s to the 2010s, with the share of young forests increasing and that of old forests decreasing (Vilén et al. 2012;Ecke et al. 2013). Due to a loss of old-growth forests, many boreal bird species associated with old-forest structures have declined (Helle & Järvinen 1986;Virkkala 1991;Väisänen et al. 1998;Imbeau et al. 2001;Laaksonen & Lehikoinen 2013). ...
Cambridge Core - Natural Resource Management, Agriculture, Horticulture and forestry - Ecology and Conservation of Forest Birds - edited by Grzegorz Mikusiński
... Compared to naturally dynamic forest landscapes, this results in a truncated age-class distribution, with a reduced area of oldgrowth forest. In large parts of Finland and Sweden, for example, the mean forest age has decreased from the 1950s to the 2010s, with the share of young forests increasing and that of old forests decreasing (Vilén et al. 2012;Ecke et al. 2013). Due to a loss of old-growth forests, many boreal bird species associated with old-forest structures have declined (Helle & Järvinen 1986;Virkkala 1991;Väisänen et al. 1998;Imbeau et al. 2001;Laaksonen & Lehikoinen 2013). ...
Ecology and Conservation of Forest Birds - edited by Grzegorz Mikusiński March 2018
Globally, the increasing fire events in addition to climate change due to the emission of carbon dioxide (CO 2 ) as well as other greenhouse gases exerts huge pressure on natural resources and their management. This phenomenon is more severe in the tropical region due to increasing population, urbanization, industrialization, existing pressures, and limiting conditions. In the present study, carbon (C) stock, carbon sequestration (C seq ), CO 2 mitigation potential, C budget, and C flux of the seasonally dry forest ecosystem of Chhattisgarh under the influence of wildfire in the protected area and its proximity were evaluated. Four sites namely, high fire zone (HFZ), medium fire zone (MFZ), low fire zone (LFZ), and non‐fire zone (NFZ) were selected and marked based on fire return intervals (frequency) and extent of damage. The present work is a novel approach that assesses the impact of different fire frequencies on C dynamics of fire‐affected zones. The stratified sampling technique was used within a permanent plot of 1 hectare. Forest stands on each site were analyzed using 10 randomly placed quadrats (each 10 × 10 m in size) and data were collected from each site. Across the sites higher tree density was observed at NFZ and the lowest at HFZ.Total tree biomass ranged between 116.0 and 358.4 t ha ⁻¹ across the fire regimes. Total vegetation C stock ranged between 59.1 and 169.5 t ha ⁻¹ in different sites. The C mitigation and C seq potential ranged between 186.2 and 575.3 t ha ⁻¹ , and 7.1 and 15.9 t ha ⁻¹ , respectively being highest in NFZ and lowest in HFZ. The species such as Anogeissus latifolia, Buchanania lanzan, Shorea robusta, Lannea coromandelica, Lagerstroemia parviflora, Ougeinia oojeinensis, Terminalia chebula, Terminalia tomentosa are the major contributor in biomass, C stock, C mitigation, and C seq potential in different fire regimes. Thus, our findings would be highly useful in the restoration process of fire‐affected zones through the plantation of selective plant species. Therefore, the aforementioned species could be effectively utilized while going for an afforestation/reforestation program, and will be helpful in climate change adaptation and mitigation strategies under different fire zones.
Young forest age mapping at a fine spatial resolution is important for increasing the accuracy of estimating land–atmosphere carbon fluxes and guiding forest management practices. In recent decades, China has actively conducted afforestation and forest protection projects, thereby laying the foundation for the realization of carbon neutrality. However, very few studies have been conducted which map the ages of young forests for the whole of China at a fine spatial resolution. In this research, a continuous change detection and classification (CCDC)-based method suitable for large-scale forest age mapping is proposed and used to estimate young forest ages across China in 2020 at a spatial resolution of 30 m. First, a 10 m spatial-resolution land cover dataset (WorldCover2020) from the European Space Agency (ESA) was used to determine the forest cover areas in 2020. Then, the CCDC algorithm was used to identify stand-replacing disturbances to determine the stand age based on 436 967 Landsat tiles across China from 1990 to 2020. A validation sample set composed of multiple land use and land cover (LULC) products was used to calculate the overall accuracy (OA) of the 2020 young forest age (1–31-year) map of China, and the OA was 90.28 %. The reliability and applicability of the proposed CCDC-based forest age mapping method were validated by comparing the forest age map with Hansen's forest change dataset, Max Planck Institute for Biogeochemistry (MPI-BGC) 1 km global forest age datasets, and field measurements. The CCDC-based method has strong application potential in real-time mapping of the age of young forests at the global scale. The produced forest age map provides a basic dataset for research on the forest carbon cycle and forest ecosystem services as well as important guidance for government departments, such as the National Forestry and Grassland Administration and the National Development and Reform Commission in China. Data presented in this study is available at 10.6084/m9.figshare.21627023.v7 (Xiao, 2022).
The gray wolf (Canis lupus) expanded its distribution in Europe over the last few decades. To better understand the extent to which wolves could re-occupy their historical range, it is important to test if anthropization can affect their fitness-related traits. After having accounted for ecologically relevant confounders, we assessed how anthropization influenced i) the growth of wolves during their first year of age (n = 53), ii) sexual dimorphism between male and female adult wolves (n = 121), in a sample of individuals that had been found dead in Italy between 1999 and 2021. Wolves in anthropized areas have a smaller overall variation in their body mass, during their first year of age. Because they already have slightly higher body weight at 3–5 months, possibly due to the availability of human-derived food sources. The difference in the body weight of adult females and males slightly increases with anthropization. However, this happens because of an increase in the body mass of males only, possibly due to sex-specific differences in dispersal and/or to “dispersal phenotypes”. Anthropization in Italy does not seem to have any clear, nor large, effect on the body mass of wolves. As body mass is in turn linked to important processes, like survival and reproduction, our findings indicates that wolves could potentially re-occupy most of their historical range in Europe, as anthropized landscapes do not seem to constrain such of an important life-history trait. Wolf management could therefore be needed across vast spatial scales and in anthropized areas prone to social conflicts.
In Central Europe, the focus of forest restoration is less on increasing the forest area than on increasing or improving the multifunctionality and ecosystem services of existing forests, particularly through an appropriate and sustainable silvicultural management. Forest history, forest ecology and vegetation as well as the ecosystem services of Central European forests are outlined. Specific strategies and measures of forest restoration are addressed. A focus is put on the conversion of anthropogenic coniferous forests into near-natural mixed broad-leaved forests. As a case study, the successful forest restoration in the north-western German lignite mining area after approximately 80 years is documented.
Over the last decades, the natural disturbance is increasingly putting pressure on European forests. Shifts in disturbance regimes may compromise forest functioning and the continuous provisioning of ecosystem services to society, including their climate change mitigation potential. Although forests are central to many European policies, we lack the long-term empirical data needed for thoroughly understanding disturbance dynamics, modeling them, and developing adaptive management strategies. Here, we present a unique database of >170,000 records of ground-based natural disturbance observations in European forests from 1950 to 2019. Reported data confirm a significant increase in forest disturbance in 34 European countries, causing on an average of 43.8 million m3 of disturbed timber volume per year over the 70-year study period. This value is likely a conservative estimate due to under-reporting, especially of small-scale disturbances. We used machine learning techniques for assessing the magnitude of unreported disturbances, which are estimated to be between 8.6 and 18.3 million m3 /year. In the last 20 years, disturbances on average accounted for 16% of the mean annual harvest in Europe. Wind was the most important disturbance agent over the study period (46% of total damage), followed by fire (24%) and bark beetles (17%). Bark beetle disturbance doubled its share of the total damage in the last 20 years. Forest disturbances can profoundly impact ecosystem services (e.g., climate change mitigation), affect regional forest resource provisioning and consequently disrupt long-term management planning objectives and timber markets. We conclude that adaptation to changing disturbance regimes must be placed at the core of the European forest management and policy debate. Furthermore, a coherent and homogeneous monitoring system of natural disturbances is urgently needed in Europe, to better observe and respond to the ongoing changes in forest disturbance regimes.
Landslide mobility likely changes in response to the effects of standing trees on the landslide runout. However, the properties of standing trees that influence landslide runout are not well understood. In this study, the relationships between the properties of landslides and the heights of standing trees and the runout distances of rainfall‐induced landslides (primarily 101–103 m3 in volume) in the Hiroshima Prefecture, Japan, were examined to investigate whether the heights of the trees around the runout area change the landslide mobility. The results indicate that the landslide runout was constrained not only by the landslide area and volume but also by the tree height around the runout area. Tall but sparse standing trees did not prevent landslide runout, whereas dense standing trees resulted in relatively low landslide mobility, irrespective of whether the trees were broadleaf or coniferous. A comparison between our landslide inventory and previously reported landslides showed that the landslide mobility was lower in areas with standing trees than in areas without standing trees, such as under experimental conditions and for landslides in Martian and submarine environments. Therefore, differences in the heights of the trees around the runout area can result in variations in the extent of landslide‐related hazards and disturbances.
Today, European forests face many challenges but also offer opportunities, such as climate change mitigation, provision of renewable resources, energy and other ecosystem services. Large-scale analyses to assess these opportunities are hindered by the lack of a consistent, spatial and accessible forest structure data. This study presents a freely available pan-European forest structure data set. Building on our previous work, we used data from six additional countries and consider now ten key forest stand variables. Harmonized inventory data from 16 European countries were used in combination with remote sensing data and a gap-filling algorithm to produce this consistent and comparable forest structure data set across European forests. We showed how land cover data can be used to scale inventory data to a higher resolution which in turn ensures a consistent data structure across sub-regional, country and European forest assessments. Cross validation and comparison with published country statistics of the Food and Agriculture Organization (FAO) indicate that the chosen methodology is able to produce robust and accurate forest structure data across Europe, even for areas where no inventory data were available.
Forest ecosystems contain many tree-related microhabitats (TreMs), which are used by various groups of organisms. Birds use TreMs for shelter, foraging and breeding. The abundance and variability of TreMs is related to tree stand composition and age. Over the last few centuries there has been a drastic decline in the structural and biological diversity of temperate forests over large areas of the Northern Hemisphere. These changes have reduced the diversity and quantity of TreMs. In this study we showed the relationships between stand composition, the abundance of TreMs, and the species richness of birds in a managed forest. We focused on TreMs that are important to birds: woodpecker breeding cavities, rot holes, dead branches, broken treetops, and perennial polypores. Our study was performed in a managed lowland temperate forest. In 94 plots (10 ha each) we made bird surveys and inventoried the stand composition and TreMs. Our results show that the tree stand composition of a managed forest affects the abundance of TreMs. The share of deciduous trees in the stand favors the occurrence of such TreMs as dead branches, rot holes and perennial polypores. The overall richness of bird species and the species richness of primary cavity nesters depended on the total basal area of oak, hornbeam and birch, whereas the species richness of secondary cavity nesters increased with the total basal area of birch and oak.
Increasing tree mortality can have pervasive impacts on forest dynamics. Yet, large-scale trends in tree mortality and their effects on forest demography remain poorly quantified despite the important role of forest demography for forest carbon pools and biodiversity. Analyzing satellite data at 19,896 plots, we here show that canopy mortality in 35 European countries increased from 1985 to 2018 (+1.5% ± 0.28% yr⁻¹). Using simulations, we demonstrate that recent levels of canopy mortality will halt the aging trend of Europe's forests and that a further increase in canopy mortality has the potential to strongly alter Europe's forest demography toward younger forests. These demographic changes will have cascading negative effects on forest biodiversity and carbon storage. Developing strategies to address the increasing canopy mortality should thus be a key priority of forest policy and management in Europe.
The high diversity of insects has limited the volume of long‐term community data with a high taxonomic resolution and considerable geographic replications, especially in forests. Therefore, trends and causes of changes are poorly understood. Here we analyse trends in species richness, abundance and biomass of nocturnal macro moths in three quantitative data sets collected over four decades in forests in southern Germany. Two local data sets, one from coppiced oak forests and one from high oak forests included 125K and 48K specimens from 559 and 532 species, respectively. A third regional data set, representing all forest types in the temperate zone of central Europe comprised 735K specimens from 848 species. Generalized additive mixed models revealed temporal declines in species richness (−38%), abundance (−53%) and biomass (−57%) at the regional scale. These were more pronounced in plant host specialists and in dark coloured species. In contrast, the local coppiced oak forests showed an increase, in species richness (+62%), while the high oak forests showed no clear trends. Left and right censoring as well as cross validation confirmed the robustness of the analyses, which led to four conclusions. First, the decline in insects appears in hyper diverse insect groups in forests and affects species richness, abundance and biomass. Second, the pronounced decline in host specialists suggests habitat loss as an important driver of the observed decline. Third, the more severe decline in dark species might be an indication of global warming as a potential driver. Fourth, the trends in coppiced oak forests indicate that maintaining complex and diverse forest ecosystems through active management may be a promising conservation strategy in order to counteract negative trends in biodiversity, alongside rewilding approaches.
Pulses of tree mortality have been reported for many ecosystems across the globe. Yet, large-scale trends in tree mortality remain poorly quantified. Manually analyzing more than 680,000 satellite image chips at 19,896 plot locations, we here show that forest canopy mortality in Europe has continuously increased since 1985 (+1.5 ± 0.28 % yr-1), with the highest canopy mortality rate of the past 34 years observed in 2018 (1.14 ± 0.16 %). Using simulation modeling we further demonstrate that a continued increase in canopy mortality will largely alter forest demography, with the median forest age falling below 30 years in nearly half of Europe's countries by 2050. These demographic changes will have substantial cascading effects on the regeneration, biodiversity, and carbon storage. The current trend of increasing canopy mortality reported herein thus challenges the future of Europe's forests, and should be a key priority of forest policy and management.
Die mittleren Breiten zwischen etwa 35 und 60° Nord bzw. Süd liegen im Einflussbereich der außertropischen Westwindzonen und werden von kühl-gemäßigten (nemoralen) Klimaten geprägt. Diese Regionen fasst man auch zur temperaten Zone zusammen. Thermische Kennzeichen sind der ausgeprägte Jahreszeitenwechsel mit einer mehr oder weniger ausgeprägten Winterruhe der Vegetation, eine Vegetationsperiodenlänge von 5 bis 7 Monaten (wenn monatliche Mitteltemperaturen >10 °C als Kriterium verwendet werden), Maximaltemperaturen, die nur selten 30 °C übersteigen, und mäßige bis starke Fröste in bis zu 6 Monaten. In wintermilden ozeanischen Gebieten der temperaten Zone können immergrüne Laub- und Nadelwälder sogar mehr als 250 Tage im Jahr für den Stoffgewinn nutzen. Die temperate Zone genießt einen jährlichen Strahlungsinput von 2500 bis 6000 MJ m⁻².
Traditionally the purpose of National Forest Inventories (NFIs) has been to provide continuously updated information regarding the state of a given nation's forest resources, including their timber volumes, species composition and sustainable development. But with increased international reporting requirements - to the FAO, the ITTO, the UN's Framework Convention on Climate Change, the Ministerial Conference Protecting Forest in Europe and other international bodies - the potential role of how NFIs can accurately respond to these requirements has received some considerable attention. Addressing the issue of how well countries are able to respond to current international reporting requirements, this book discusses the importance of comparable reporting, and the possible approaches for achieving comparability across Europe and globally. It includes country status reports from 37 countries, worldwide, and it discusses methodologies and techniques for a common reporting system. With its collection of inventories and detailed discussions on the current status and future needs of NFIs, this book provides an invaluable resource for anyone involved in developing, managing, monitoring or contributing to forest inventories, as well as to those who are researching or practising forest resource management.
Most forests of the world are recovering from a past disturbance. It is well known that forest disturbances profoundly affect carbon stocks and fluxes in forest ecosystems , yet it has been a great challenge to assess disturbance impacts in estimates of forest carbon budgets. Net sequestra-tion or loss of CO 2 by forests after disturbance follows a predictable pattern with forest recovery. Forest age, which is related to time since disturbance, is a useful surrogate variable for analyses of the impact of disturbance on forest carbon. In this study, we compiled the first continental forest age map of North America by combining forest inventory data, historical fire data, optical satellite data and the dataset from NASA's Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS) project. A companion map of the standard deviations for age estimates was developed for quantifying uncertainty. We discuss the significance of the disturbance legacy from the past, as represented by current forest age structure in different regions of the US and Canada, by analyzing the causes of disturbances from land management and nature over centuries and at various scales. We also show how such information can be used with inventory data for analyzing carbon management opportunities. By combining geographic information about forest age with estimated C dynamics by forest type, it is possible to conduct a simple but powerful analysis of the net CO 2 uptake by forests, and the potential for increasing (or decreasing) this rate as a result of direct human intervention in the disturbance/age status. Finally, we describe how the forest age data can be used in large-scale carbon modeling, both for land-based biogeo-chemistry models and atmosphere-based inversion models, in order to improve the spatial accuracy of carbon cycle simulations .
We present a new dynamical global vegetation model principally designed to be included in atmospheric general circulation models (AGCMs) or regional climate models. The model consists of a surface-vegetation-atmosphere transfer scheme coupled to a dynamical global vegetation model. It therefore simulates the principal processes of the continental biosphere influencing the global carbon cycle (photosynthesis, autotrophic and heterotrophic respiration of plants and in soils, fire, \ldots) as well as latent, sensible and kinetic energy exchanges at the surface of soils and plants. As a dynamical vegetation model, it explicitly represents competitional processes such as light competition, gaps, establishment, etc. It can thus be used in transient simulations of climate change, but it can also be used with a prescribed vegetation distribution. The whole seasonal phenological cycle is calculated prognostically without any prescribed dates or use of satellite data. The model is designed for an easy use as biosphere module in an AGCM, and first simulations with this model coupled to the LMDz atmospheric general circulation model are under way. This coupled hydrological-vegetation model is validated in stand-alone experiments against local observations of, for example, vegetation types, carbon stocks and fluxes. Simulated vegetation distribution and leaf area index in a global simulation is evaluated against observations.
Early-successional forest ecosystems that develop after stand-replacing or partial disturbances are diverse in species, processes, and structure. Post-disturbance ecosystems are also often rich in biological legacies, including surviving organisms and organically derived structures, such as woody debris. These legacies and postdisturbance plant communities provide resources that attract and sustain high species diversity, including numerous early-successional obligates, such as certain woodpeckers and arthropods. Early succession is the only period when tree canopies do not dominate the forest site, and so this stage can be characterized by high productivity of plant species (including herbs and shrubs), complex food webs, large nutrient fluxes, and high structural and spatial complexity. Different disturbances contrast markedly in terms of biological legacies, and this will influence the resultant physical and biological conditions, thus affecting successional pathways. Management activities, such as post-disturbance logging and dense tree planting, can reduce the richness within and the duration of early-successional ecosystems. Where maintenance of biodiversity is an objective, the importance and value of these natural early-successional ecosystems are underappreciated.
Natural disturbances play a key role in ecosystem dynamics and are important factors for sustainable forest ecosystem management. Quantitative models are frequently employed to tackle the complexities associated with disturbance processes. Here we review the wide variety of approaches to modelling natural disturbances in forest ecosystems, addressing the full spectrum of disturbance modelling from single events to integrated disturbance regimes. We applied a general, process-based framework founded in disturbance ecology to analyze modelling approaches for drought, wind, forest fires, insect pests and ungulate browsing. Modelling approaches were reviewed by disturbance agent and mechanism, and a set of general disturbance modelling concepts was deduced. We found that although the number of disturbance modelling approaches emerging over the last 15 years has increased strongly, statistical concepts for descriptive modelling are still largely prevalent over mechanistic concepts for explanatory and predictive applications. Yet, considering the increasing importance of disturbances for forest dynamics and ecosystem stewardship under anthropogenic climate change, the latter concepts are crucial tool for understanding and coping with change in forest ecosystems. Current challenges for disturbance modelling in forest ecosystems are thus (i) to overcome remaining limits in process understanding, (ii) to further a mechanistic foundation in disturbance modelling, (iii) to integrate multiple disturbance processes in dynamic ecosystem models for decision support in forest management, and (iv) to bring together scaling capabilities across several levels of organization with a representation of system complexity that captures the emergent behaviour of disturbance regimes.
A conceptual model is presented as a guide to the maintenance and restoration of ecologically sustainable boreal forest. The model is based on the hypothesis that self‐sustained forest ecosystems can be (re‐)created, and their biodiversity developed, if forest management can simulate the composition and structure of boreal forest landscapes by introducing and maintaining disturbances leading to naturally dynamic spatial and temporal patterns of forest regeneration.
The major explanatory variable in the model is the effect of wildfire on sites with different fuel characteristics and climates found in the European boreal forest. Four levels of fire intensity are distinguished, based on mean fire frequencies. These range from extremely low in some wet tall‐herb sites or sites at high altitudes or latitudes with a humid climate, where fire is absent or rare, to dry lichen‐rich sites where fire occurs often. The model is called ASIO, after the words Absent, Seldom, Infrequent and Often, indicating the four levels.
Three main disturbance regimes are distinguished in the European boreal forest, based on the complex interactions between probabilistic (e.g. mean fire intervals at different site types) and random events (e.g. where and when a fire occurs): (1) gap‐phase Picea abies dynamics; (2) succession from young to old‐growth mixed deciduous/coniferous forest; and (3) multi‐cohort Pinus sylvestris dynamics. The model stems mainly from studies in Fennoscandia, but some studies from outside this region are reviewed to provide support for a more general application of the model.
The model has been implemented in planning systems on the landscape level of several large Swedish forest enterprises, and is also used as an educational tool to help private land owners with the location and realization of forest management regimes. Finally, the model can be used to develop an administrative system for the monitoring of biodiversity in boreal forest.
Risks can generally be described as the combination of hazard, exposure and vulnerability. Using this framework, we evaluated
the historical and future development of risk of fire and wind damage in European forestry at the national level. Fire risk
is expected to increase, mainly as a consequence of an increase in fire hazard, defined as the Fire Weather Index in summer.
Exposure, defined as forest area, is expected to increase slightly as a consequence of active afforestation and abandonment
of marginal agricultural areas. Adaptation options to fire risk should therefore aim to decrease the vulnerability, where
a change in tree species from conifers to broadleaves had most effect. Risk for wind damage in forests is expected to increase
mainly as a consequence of increase in exposure (total growing stock) and vulnerability (defined by age class and tree species
distribution). Projections of future wind climate indicate an increase in hazard (storminess) mainly over Western Europe.
Adaptation options should aim to limit the increase in exposure and vulnerability. Only an increase in harvest level can stop
the current build-up of growing stock, while at the same time it will lower vulnerability through the reduction of the share
of old and vulnerable stands. Changing species from conifers to broadleaves helps to reduce vulnerability as well. Lowering
vulnerability by decreasing the rotation length is only effective in combination with a high demand for wood. Due to data
limitations, no forecast of future fire area or damaged timber amount by storms was possible.
KeywordsAdaptation-Climate change-Forest fire-Forestry-Natural disturbance-Windstorm-EFISCEN
This work presents a new dynamic global vegetation model designed as an extension of an existing surface-vegetation-atmosphere transfer scheme which is included in a coupled ocean-atmosphere general circulation model. The new dynamic global vegetation model simulates the principal processes of the continental biosphere influencing the global carbon cycle (photosynthesis, autotrophic and heterotrophic respiration of plants and in soils, fire, etc.) as well as latent, sensible, and kinetic energy exchanges at the surface of soils and plants. As a dynamic vegetation model, it explicitly represents competitive processes such as light competition, sapling establishment, etc. It can thus be used in simulations for the study of feedbacks between transient climate and vegetation cover changes, but it can also be used with a prescribed vegetation distribution. The whole seasonal phenological cycle is prognostically calculated without any prescribed dates or use of satellite data. The model is coupled to the IPSL-CM4 coupled atmosphere-ocean-vegetation model. Carbon and surface energy fluxes from the coupled hydrology-vegetation model compare well with observations at FluxNet sites. Simulated vegetation distribution and leaf density in a global simulation are evaluated against observations, and carbon stocks and fluxes are compared to available estimates, with satisfying results.
This paper describes a simple and adaptive methodology for large area forest/non-forest mapping using Landsat ETM+ imagery and CORINE Land Cover 2000. The methodology is based on scene-by-scene analysis and supervised classification. The fully automated processing chain consists of several phases, including image segmentation, clustering, adaptive spectral representativity analysis, training data extraction and nearest-neighbour classification. This method was used to produce a European forest/non-forest map through the processing of 415 Landsat ETM+ scenes. The resulting forest/non-forest map was validated with three independent data sets. The results show that the map’s overall point-level agreement with our validation data generally exceeds 80%, and approaches 90% in central European conditions. Comparison with country-level forest area statistics shows that in most cases the difference between the forest proportion of the derived map and that computed from the published forest area statistics is below 5%.
Most forests of the world are recovering from a past disturbance. It is well known that forest disturbances profoundly affect carbon stocks and fluxes in forest ecosystems, yet it has been a great challenge to assess disturbance impacts in estimates of forest carbon budgets. Net sequestration or loss of CO2 by forests after disturbance follows a predictable pattern with forest recovery. Forest age, which is related to time since disturbance, is a useful surrogate variable for analyses of the impact of disturbance on forest carbon. In this study, we compiled the first continental forest age map of North America by combining forest inventory data, historical fire data, optical satellite data and the dataset from NASA's Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS) project. A companion map of the standard deviations for age estimates was developed for quantifying uncertainty. We discuss the significance of the disturbance legacy from the past, as represented by current forest age structure in different regions of the US and Canada, by analyzing the causes of disturbances from land management and nature over centuries and at various scales. We also show how such information can be used with inventory data for analyzing carbon management opportunities. By combining geographic information about forest age with estimated C dynamics by forest type, it is possible to conduct a simple but powerful analysis of the net CO2 uptake by forests, and the potential for increasing (or decreasing) this rate as a result of direct human intervention in the disturbance/age status. Finally, we describe how the forest age data can be used in large-scale carbon modeling, both for land-based biogeochemistry models and atmosphere-based inversion models, in order to improve the spatial accuracy of carbon cycle simulations.
EFISCEN is a forest resource projection model, used to gain insight into the future development of European forests. It has been used widely to study issues such as sustainable management regimes, wood production possibilities, nature oriented management, climate change impacts, natural disturbances and carbon balance issues. This report describes the history of EFISCEN and the current state of the model, version 3.1.3. It contains a user guide as well as a description of past validations and an uncertainty analysis
European forests are intensively exploited for wood products, yet they also form a sink for carbon. European forest inventories, available for the past 50 years, can be combined with timber harvest statistics to assess changes in this carbon sink. Analysis of these data sets between 1950 and 2000 from the EU-15 countries excluding Luxembourg, plus Norway and Switzerland, reveals that there is a tight relationship between increases in forest biomass and forest ecosystem productivity but timber harvests grew more slowly. Encouragingly, the environmental conditions in combination with the type of silviculture that has been developed over the past 50 years can efficiently sequester carbon on timescales of decades, while maintaining forests that meet the demand for wood. However, a return to using wood as biofuel and hence shorter rotations in forestry could cancel out the benefits of carbon storage over the past five decades
Understanding the relationship between the age of a forest stand and its biomass is essential for managing the forest component of the global carbon cycle. Since biomass increases with stand age, postponing harvesting to the age of biological maturity may result in the formation of a large carbon sink. This article quantifies the carbon sequestration capacity of forests by suggesting a default rule to link carbon stock and stand age.
The age dependence of forest biomass is shown to be a power-law monomial where the power of age is theoretically estimated to be 4/5. This theoretical estimate is close to the known empirical estimate; therefore, it provides a scientific basis for a quick and transparent assessment of the benefits of postponing the harvest, suggesting that the annual magnitude of the sink induced by delayed harvest lies in the range of 1-2% of the baseline carbon stock.
The results of this study imply that forest age could be used as an easily understood and scientifically sound measure of the progress in complying with national targets on the protection and enhancement of forest carbon sinks.
A general formalism of the time evolution of an ensemble of forests within an ecological province is developed using the formalism of the Leslie matrix. It could be shown that the present distribution of forest age classes for the United States, Canada, Europe, or the Former Soviet Union does not correspond to a quasi-stationary state. The present CO2 sink function will not persist in the next century, if harvesting rates increase with 0.5% annually or even less. The future state will also be influenced by the effect of the greenhouse climate, the impact of which is calculated by the Frankfurt biosphere model. -from Authors
Estimates of the role of the European terrestrial biosphere in the global carbon cycle still vary by a factor 10. This is due to differences in methods and assumptions employed, but also due to difference in reference periods of the studies. The magnitude of the sink varies between years because of inter‐annual variation of short‐term climate, but also due to long‐term trends in development of the vegetation and its management. For this purpose, we present the results of an application of a carbon bookkeeping model to the forest sector of the European forests from 1950 to 1999. The analysis includes the compartments trees, soils, and wood products. The model uses statistics on European (30 countries excl. CIS) stemwood volume increment, forest area change, fellings, wood products and their international trade, and natural disturbances, supplemented with conversion coefficients, soil parameters and information on management.
An (almost uninterrupted) increasing sink (Net Biome Production) in the European forest sector was found, increasing from 0.03 Pg C year −1 in the 1950s to 0.14 Pg C year −1 in the 1990s (for resp. 132 million hectares and 140 million hectares of forest). The sink in the tree and the soil compartment were approximately of the same size until 1970. After the 1970s the size of the sink in the tree biomass increases quickly, causing the tree biomass to account for some two thirds of the total sink in the 1990s. The results as presented here have to be regarded with caution especially with regard to the early decades of the analysis and with regard to the soil compartment.
Our analysis of the carbon budget of Canada's forests (1920-1989)
indicates that these forest ecosystems have been a C sink of
approximately 0.2 Gt C yr 1.
This result challenges the previously-held assumption that forests not
directly affected by land use make zero net C contribution to the
atmosphere. We attribute our observed C sink to a shift in the forest
age-class structure towards a greater average forest age. Forest
disturbances, which largely determine Canadian forest dynamics on a time
scale of decades, appear to have been less frequent in the period
1920-1970 than in previous decades. They have, however, increased
greatly in recent years (1970-1989) and have contributed to a decrease
in the C sink. Forests that are subject to large-scale fluctuations in
natural disturbance regimes on a time-scale comparable to tree lifetimes
do not appear to reach an equilibrium C-exchange with the atmosphere on
these time-scales. Assessing C budgets of such forest ecosystems
requires an accounting of C dynamics for the entire forest area, not
merely for that portion which has recently been affected by
anthropogenic disturbances.
Natural disturbances like wildfire, windthrow and insect outbreaks are critical drivers of composition, structure and functioning of forest ecosystems. They are strongly climate-sensitive, and are thus likely to be distinctly affected by climatic changes. Observations across Europe show that in recent decades, forest disturbance regimes have intensified markedly, resulting in a strong increase in damage from wind, bark beetles and wildfires. Climate change is frequently hypothesized as the main driving force behind this intensification, but changes in forest structure and composition associated with management activities such as promoting conifers and increasing standing timber volume (i.e. ‘forest change’) also strongly influence susceptibility to disturbances. Here, we show that from 1958 to 2001, forest change contributed in the same order of magnitude as climate change to the increase in disturbance damage in Europe's forests. Climate change was the main driver of the increase in area burnt, while changes in forest extent, structure and composition particularly affected the variation in wind and bark beetle damage. For all three disturbance agents, damage was most severe when conducive weather conditions and increased forest susceptibility coincided. We conclude that a continuing trend towards more disturbance-prone conditions is likely for large parts of Europe's forests, and can have strong detrimental effects on forest carbon storage and other ecosystem services. Understanding the interacting drivers of natural disturbance regimes is thus a prerequisite for climate change mitigation and adaptation in forest ecosystem management.
In this study, we present estimated ranges in carbon (C) sequestration per kg nitrogen (N) addition in above-ground biomass and in soil organic matter for forests and heathlands, based on: (i) empirical relations between spatial patterns of carbon uptake and influencing environmental factors including nitrogen deposition (forests only), (ii) 15N field experiments, (iii) long-term low-dose N fertilizer experiments and (iv) results from ecosystem models. The results of the various studies are in close agreement and show that above-ground accumulation of carbon in forests is generally within the range 15–40 kg C/kg N. For heathlands, a range of 5–15 kg C/kg N has been observed based on low-dose N fertilizer experiments. The uncertainty in C sequestration per kg N addition in soils is larger than for above-ground biomass and varies on average between 5 and 35 kg C/kg N for both forests and heathlands. All together these data indicate a total carbon sequestration range of 5–75 kg C/kg N deposition for forest and heathlands, with a most common range of 20–40 kg C/kg N. Results cannot be extrapolated to systems with very high N inputs, nor to other ecosystems, such as peatlands, where the impact of N is much more variable, and may range from C sequestration to C losses.
Deadwood is a key indicator for assessing policy and management impacts on forest biodiversity. We developed an approach to include deadwood in the large-scale European Forest Information Scenario (EFISCEN) model and analysed impacts of intensifying forest biomass removal on the amount and type of deadwood in forests of 24 European Union member states. In EFISCEN, deadwood consists of standing and downed deadwood, resulting from mortality, and stem residues from felling activities. To include deadwood in EFISCEN we developed mortality functions and re-estimated the model's increment functions. Further, we modelled the development of standing deadwood. Decomposition of downed deadwood and stem residues was modelled through the soil model YASSO. We used the extended model to analyse the impacts of a baseline scenario (no policy changes, a moderate increase in wood removals and no extraction of residues) and a bio-energy scenario (an increase of wood and residue removals to the maximum potential) on deadwood in 2030. In our baseline scenario the average amount of deadwood was 12.3tonha−1 in 2005 and increased by 6.4% in 2030. Intensified biomass removal could fully counteract this development and lead to a reduction of 5.5% in 2030 below the levels in 2005. The type of deadwood changed as well; residue removal led to a general decrease in the amount of smaller deadwood fractions (i.e. stem residues). Further, if felling levels are increased as in our bio-energy scenario, a decrease can be expected in the amount of standing deadwood and of large-diameter deadwood. We conclude that without additional management measures to protect deadwood, intensification of biomass removal could negatively affect deadwood-dependent species, which constitute an important part of biodiversity in European forests.
We used the European Forest Information Scenario Model (EFISCEN) to project the development of forest resources for 15 European countries from 2000 to 2100 under a broad range of climate scenarios, which were based on the a1fi, a2, b1 and b2 storylines of the Special Report on Emissions Scenarios of the Intergovernmental Panel on Climate Change. Each climate scenario was associated with consistent land-use change and wood demand assumptions. Climate change-induced growth changes were incorporated into the calculations by scaling inventory-based stem growth in EFISCEN by net primary productivity estimated from the Lund–Potsdam–Jena dynamic global vegetation model. The impact of changes in wood demand, climate and forest area were studied separately, and in combination, in order to assess their respective effects. For all climate scenarios under consideration, climate change resulted in increased forest growth, especially in Northern Europe. In Southern Europe, higher precipitation in spring and the projected increased water-use efficiency in response to rising atmospheric CO 2 concentrations mitigated the effects of increasing summer drought. Climate change enhanced carbon sequestration in tree biomass. The climate change-induced increase in tree growth led to a faster increase in growing stocks compared with the simulation using current climate. As productivity decreased in higher stocked forests, the positive impact of climate change began to level off during the second half of the 21st century in the scenarios where wood demand was low. Afforestation measures had the potential to increase growing stock and annual increment; however, large areas were needed to obtain notable effects. Despite noticeable differences in the growth response between the climate scenarios, changes in wood demand proved to be the crucial driving force in forest resource development. Tree carbon stocks increased by 33–114% between 2000 and 2100 when only changes in wood demand were regarded. Climate change added another 23–31% increase, while changes in forest area accounted for an additional increase of 2– 40%. Our results highlight potential future pathways of forest resource development resulting from different scenarios of wood demand, land use and climate changes, and stress the importance of resource utilization in the European forest carbon balance.
Forests are important for providing wood for products and energy and the demand for wood is expected to increase. Our aim was to estimate the potential supply of woody biomass for all uses from the forests in the European Union (EU), while considering multiple environmental, technical and social constraints. The potential woody biomass supply was estimated for the period 2010–2030 for stemwood, residues (branches and harvest losses), stumps and other biomass (woody biomass from early thinnings in young forests). We estimated the theoretical biomass potential from recent, detailed forest inventory data using the EFISCEN model. Constraints reducing the availability of woody biomass were defined and quantified for three mobilisation scenarios (high, medium, low). Finally, the theoretical potentials from EFISCEN were combined with the constraints to assess the realisable potential from EU forests. The realisable potential from stemwood, residues, stumps and other biomass was estimated at 744 million m 3 yr −1 overbark in 2010 and could range from 623 to 895 million m 3 yr −1 overbark in 2030, depending on the mobilisation scenario. These potentials represented 50–71% of the theoretical potential. Constraints thus significantly reduced the biomass potentials that could be mobilised. Soil productivity appeared to be an important environmental factor when considering the increased use of biomass from forests. Also the attitude of private forest owners towards increased use of forest biomass can have an important effect, although quantifying this is still rather difficult. The analysis showed that it is possible to increase the availability of forest biomass significantly beyond the current level of resource utilisation. Implementing these ambitious scenarios would imply quite drastic changes in forest resource management across Europe.
Deadwood is a key indicator for assessing policy and management impacts on forest biodiversity. We
developed an approach to include deadwood in the large-scale European Forest Information Scenario
(EFISCEN) model and analysed impacts of intensifying forest biomass removal on the amount and type of
deadwood in forests of 24 European Union member states. In EFISCEN, deadwood consists of standing
and downed deadwood, resulting from mortality, and stem residues from felling activities. To include
deadwood in EFISCEN we developed mortality functions and re-estimated the model’s increment
functions. Further, we modelled the development of standing deadwood. Decomposition of downed
deadwood and stemresidues wasmodelled through the soil model YASSO.We used the extended model
to analyse the impacts of a baseline scenario (no policy changes, a moderate increase in wood removals
and no extraction of residues) and a bio-energy scenario (an increase of wood and residue removals to
the maximum potential) on deadwood in 2030. In our baseline scenario the average amount of
deadwood was 12.3 ton ha�1 in 2005 and increased by 6.4% in 2030. Intensified biomass removal could
fully counteract this development and lead to a reduction of 5.5% in 2030 below the levels in 2005. The
type of deadwood changed as well; residue removal led to a general decrease in the amount of smaller
deadwood fractions (i.e. stem residues). Further, if felling levels are increased as in our bio-energy
scenario, a decrease can be expected in the amount of standing deadwood and of large-diameter
deadwood. We conclude that without additional management measures to protect deadwood,
intensification of biomass removal could negatively affect deadwood-dependent species, which
constitute an important part of biodiversity in European forests.
This paper, based on a literature review, presents a quantitative overview of the role of natural disturbances in European forests from 1850 to 2000. Such an overview provides a basis for modelling the possible impacts of climate change and enables one to assess trends in disturbance regimes in different countries and/or periods. Over the period 1950–2000, an annual average of 35 million m3 wood was damaged by disturbances; there was much variation between years. Storms were responsible for 53% of the total damage, fire for 16%, snow for 3% and other abiotic causes for 5%. Biotic factors caused 16% of the damage, and half of this was caused by bark beetles. For 7% of the damage, no cause was given or there was a combination of causes. The 35 million m3 of damage is about 8.1% of the total fellings in Europe and about 0.15% of the total volume of growing stock. Over the period 1961–2000, the average annual area of forest fires was 213 000 ha, which is 0.15% of the total forest area in Europe. Most types of damage seem to be increasing. This is partly an artefact of the improved availability of information. The most likely explanations for an increase in damage from disturbances are changes in forest management and resulting changes in the condition of the forest. Forest area, average volume of growing stock and average stand age have increased considerably, making the forest more vulnerable and increasing the resources that can be damaged. Since forest resources are expected to continue to increase, it is likely that damage from disturbances will also increase in future.
The rôle of the temperate and boreal forests as a global CO2 source or sink is examined, both for the present time and for the next hundred years. The results of the Forest Resource Assessment for 1990 of the Economic Comission for Europe and the Food and Agricultural Organisation of the United Nations (1992) serve as the main database in this study. Out of the estimated total area of approximately 20?106 km2 of forests and wooded lands in the temperate and boreal zone only approximately fifty percent is documented within the category of exploitable forests, which are examined in detail here. In this study, a general formalism of the time evolution of an ensemble of forests within an ecological province is developed using the formalism of the Leslie matrix. This matrix can be formulated if the age class dependent mortalities which arise from the disturbances are known. A distinction is made between the natural disturbances by fire, wind throw and insect infestations and disturbances introduced through harvesting of timber. Through the use of Richards growth function each age class of a given biome is related to the corresponding biomass and annual increment. The data reported on the mean net annual increment and on the mean biomass serve to calibrate the model. The difference of the reported net annual increment and annual fellings of approximately 550 ? 106 m3 roundwood correspond to a sink of 210-330 Mt of carbon per year excluding any changes in the soil balance. It could be shown that the present distribution of forest age classes for the United States, Canada, Europe, or the former Soviet Union does not correspond to a quasi-stationary state, in which biomass is accumulated only due to a stimulated growth under enhanced atmospheric CO2 levels. The present CO2 sink function will not persist in the next century, if harvesting rates increase with 0.5% annually or even less. The future state will also be influenced by the effect of the greenhouse climate, the impact of which may range from a stimulating effect on growth, which is calculated by the Frankfurt biosphere model, up to a transitional negative effect through a shift in vegetation zones.
Forest age, which is affected by stand-replacing ecosystem disturbances (such as forest fires, harvesting, or insects), plays a distinguishing role in determining the distribution of carbon (C) pools and fluxes in different forested ecosystems. In this synthesis, net primary productivity (NPP), net ecosystem productivity (NEP), and five pools of C (living biomass, coarse woody debris, organic soil horizons, soil, and total ecosystem) are summarized by age class for tropical, temperate, and boreal forest biomes. Estimates of variability in NPP, NEP, and C pools are provided for each biome-age class combination and the sources of variability are discussed. Aggregated biome-level estimates of NPP and NEP were higher in intermediate-aged forests (e.g., 30–120 years), while older forests (e.g., >120 years) were generally less productive. The mean NEP in the youngest forests (0–10 years) was negative (source to the atmosphere) in both boreal and temperate biomes (−0.1 and –1.9 Mg C ha−1 yr−1, respectively). Forest age is a highly significant source of variability in NEP at the biome scale; for example, mean temperate forest NEP was −1.9, 4.5, 2.4, 1.9 and 1.7 Mg C ha−1 yr−1 across five age classes (0–10, 11–30, 31–70, 71–120, 121–200 years, respectively). In general, median NPP and NEP are strongly correlated (R2=0.83) across all biomes and age classes, with the exception of the youngest temperate forests. Using the information gained from calculating the summary statistics for NPP and NEP, we calculated heterotrophic soil respiration (Rh) for each age class in each biome. The mean Rh was high in the youngest temperate age class (9.7 Mg C ha−1 yr−1) and declined with age, implying that forest ecosystem respiration peaks when forests are young, not old. With notable exceptions, carbon pool sizes increased with age in all biomes, including soil C. Age trends in C cycling and storage are very apparent in all three biomes and it is clear that a better understanding of how forest age and disturbance history interact will greatly improve our fundamental knowledge of the terrestrial C cycle.
Natural environmental changes and human activities have altered forest growth for centuries. Recent long-term growth investigations indicate an increasing growth trend in European forests. The investigations are based on forest inventory, permanent plot and tree analysis data. The observed trends are species specific, locally varying and modified by remarkably large periodic growth variations. On a European scale, species and site specific quantitative information about the extent and spatial as well as temporal variation in growth acceleration is lacking. Future growth development may differ from past observations. A better understanding of changes in site conditions, their causes and consequences is needed to guide sustainable management of European forests.
Multi-national statistics are frequently based on data, whichoriginate from national surveys. The systems of nomenclatureapplied for key attributes often show national differences.Different error sources which are incorporated in multi-nationalstatistics are discussed. The paper presents approaches forharmonisation and standardisation of multi-nationalenvironmental statistics and gives examples from the forestrysector. The effect of differences of national forest areaestimates on multi-national figures is quantified. An examplefrom forest health surveys is presented that shows the impact ofdifferent interpretation and application of the attribute crown transparency that is already harmonised on theEuropean level.
Abstract We present a new synthesis, based on a suite of complementary approaches, of the primary production and carbon sink in forests of the 25 member states of the European Union (EU-25) during 1990–2005. Upscaled terrestrial observations and model-based approaches agree within 25% on the mean net primary production (NPP) of forests, i.e. 520±75 g C m−2 yr−1 over a forest area of 1.32 × 106 km2 to 1.55 × 106 km2 (EU-25). New estimates of the mean long-term carbon forest sink (net biome production, NBP) of EU-25 forests amounts 75±20 g C m−2 yr−1. The ratio of NBP to NPP is 0.15±0.05. Estimates of the fate of the carbon inputs via NPP in wood harvests, forest fires, losses to lakes and rivers and heterotrophic respiration remain uncertain, which explains the considerable uncertainty of NBP. Inventory-based assessments and assumptions suggest that 29±15% of the NBP (i.e., 22 g C m−2 yr−1) is sequestered in the forest soil, but large uncertainty remains concerning the drivers and future of the soil organic carbon. The remaining 71±15% of the NBP (i.e., 53 g C m−2 yr−1) is realized as woody biomass increments. In the EU-25, the relatively large forest NBP is thought to be the result of a sustained difference between NPP, which increased during the past decades, and carbon losses primarily by harvest and heterotrophic respiration, which increased less over the same period.
European forests are an important carbon sink; however, the relative contributions to this sink of climate, atmospheric CO2 concentration ([CO2]), nitrogen deposition and forest management are under debate. We attributed the European carbon sink in forests using ORCHIDEE-FM, a process-based vegetation model that differs from earlier versions of ORCHIDEE by its explicit representation of stand growth and idealized forest management. The model was applied on a grid across Europe to simulate changes in the net ecosystem productivity (NEP) of forests with and without changes in climate, [CO2] and age structure, the three drivers represented in ORCHIDEE-FM. The model simulates carbon stocks and volume increment that are comparable – root mean square error of 2 m3 ha-1 yr-1 and 1.7 kg C m-2 respectively – with inventory-derived estimates at country level for 20 European countries. Our simulations estimate a mean European forest NEP of 175 ± 52 g C m-2 yr-1 in the 1990s. The model simulation that is most consistent with inventory records provides an upwards trend of forest NEP of 1 ± 0.5 g C m-2 yr-2 between 1950 and 2000 across the EU 25. Furthermore, the method used for reconstructing past age structure was found to dominate its contribution to temporal trends in NEP. The potentially large fertilizing effect of nitrogen deposition cannot
be told apart, as the model does not explicitly simulate the nitrogen cycle. Among the three drivers that were considered in this study, the fertilizing effect of increasing [CO2] explains about 61% of the simulated trend, against 26% to changes in climate and 13% only to changes in forest age structure. The major role of [CO2] at the continental scale is due to its homogeneous impact on net primary productivity (NPP). At the local scale, however, changes in climate and forest age structure often dominate trends in NEP by affecting NPP and heterotrophic respiration.
Today, forests in the northern hemisphere are a sink for carbon dioxide (CO2) from the atmosphere, partly due to changes in forest management practice and intensity. Parties of the Kyoto Protocol had the option to elect to account for direct human-induced carbon (C) sources and sinks from land management activities since 1990. The effect of age–class structure of a forest landscape resulting from past practices and disturbances before the reference year 1990 should be excluded, but methods for “factoring out” the effects of this age–class legacy on carbon emissions and removals are lacking. The legacy effect can be strong and can even overwhelm effects of post-1990 management. It therefore needs to be “factored out”, i.e., removed from the direct human-induced post-1990 effects. In this study we examine how the contributions to forest biomass carbon stock changes of (1) past (pre-1990) disturbances and harvest and (2) recent (post-1990) changes in forest management can be differentiated in present and future observable carbon dynamics in managed forest ecosystems. We also calculate the consequences of different accounting rules for the magnitude and direction of accountable C stock changes in European countries in the period 2013–2017.
Forest structure and diversity have generally been well studied, but the effects of anthropogenic disturbance on structural differences of hemi-boreal old-growth and managed mature stands have not been quantified along a wide range of the productivity gradient. This study compared 39 quantitative or qualitative characteristics and various widely accepted biodiversity indicators of a stand, its understorey and the forest floor in old-growth and conventionally managed mature stands of dry alvar and fresh boreo-nemoral forests. This study has to produce a statistically supported set of indicators for evaluating of forest “naturalness”. We examined 154 stands over a wide biogeographical range in Estonia.
Strategies for preserving biodiversity in boreal forests should include the maintenance of coarse woody debris (CWD) because this substrate is a key feature for the preservation of many threatened species. Computer simulation programs are useful tools for predicting the amount of CWD that will arise if certain management practices are applied in the long term. We have constructed and used a simulation program based on stochastic equations, which aims at predicting the amount of CWD in homogenous stands of Norway spruce in central Scandinavia. Because the rate of tree mortality is a critical factor in such simulations, we present such data derived from spruce-dominated forests surveyed in the Swedish National Forest Inventory.A comparison between simulation outcomes and field data shows that the average quantity of CWD in today’s managed forest is possible to predict using the simulation model. If the forest is managed according to the Forest Certification Standard, the amount of CWD (diameter larger than 10 cm) will be almost three times higher as the amount in today’s managed forests. The amount of CWD was found to be highest in old stands and immediately after cutting. In stands of an intermediate age the amount of CWD was low, especially CWD in early decay stages and of larger sizes. High productivity and long rotation time tended, on average, to increase the amount of CWD in stands. Among the management practices recommended in the new biodiversity-oriented forestry, retention of small areas with living trees is the most efficient way to increase the average amount and continuous occurrence of CWD within a stand, at least if the retained areas are as productive as the main part of the stands.
The European forest carbon balance studied by various methods shows different results. We compared the regional and national net primary production (NPP) estimated by the forest inventory-based model EFISCEN and the climate-based terrestrial ecosystem models (TEMs: BIOME-BGC, ORCHIDEE, and JULES), and single forests NPP derived from the international network of eddy-covariance towers (FLUXNET). In addition, the paper presents the net ecosystem production (NEP) and the net biome production (NBP) calculated with EFISCEN and discusses the influence of forest management onto carbon fluxes. We aimed to better understand the variance between EFISCEN and TEMs NPP estimates, and to improve the assessment of European forest mitigation potential for the year 2005.
The study deals with the challenge of adjusting inconsistencies in the historical data series over time for the main forest resources parameters (forest area, growing stock and increment) based on the UNECE/FAO Forest Resources Assessments (FRA) source data. It describes the methods used to improve the quality of long-term series based on national inventory data and assesses trends for a number of European countries. It attempts to identify driving forces behind major long-term changes in key forest resources parameters.
The net gain of carbon in European Union (EU) forest vegetation during 1990–2005 was estimated at 360–400 Tg CO2 year−1 by analysing international data. This amount is at low end of the range of recent corresponding estimates, but greater than earlier estimates published for the period 1971–1990. The sequestration took place almost exclusively in areas which were already forested in 1990. In 2005, new plantations, established after 1990, contributed only about 8% to the estimated net gain. The sequestration was estimated to be the greatest in Germany, France, Italy, Finland and Poland regardless of data source and method of estimation. On a per capita basis, the sequestration was estimated to be the greatest in Finland and Latvia. Carbon sequestration in forests is an important component of the long-term carbon balance of the EU. Carbon sequestration in forests is partly driven by a recovery of the ecosystems from human-induced degradation in the 19th century and the first half of the 20th century. Forest management has affected carbon sequestration and merits attention in climate policy presuming that new policies and measures are reconciled with those already in place for the promotion of the diverse goals of land management in Europe.
Natural disturbances play a key role in ecosystem dynamics and are important factors for sustainable forest ecosystem management. Quantitative models are frequently employed to tackle the complexities associated with disturbance processes. Here we review the wide variety of approaches to modelling natural disturbances in forest ecosystems, addressing the full spectrum of disturbance modelling from single events to integrated disturbance regimes. We applied a general, process-based framework founded in disturbance ecology to analyze modelling approaches for drought, wind, forest fires, insect pests and ungulate browsing. Modelling approaches were reviewed by disturbance agent and mechanism, and a set of general disturbance modelling concepts was deduced. We found that although the number of disturbance modelling approaches emerging over the last 15 years has increased strongly, statistical concepts for descriptive modelling are still largely prevalent over mechanistic concepts for explanatory and predictive applications. Yet, considering the increasing importance of disturbances for forest dynamics and ecosystem stewardship under anthropogenic climate change, the latter concepts are crucial tool for understanding and coping with change in forest ecosystems. Current challenges for disturbance modelling in forest ecosystems are thus (i) to overcome remaining limits in process understanding, (ii) to further a mechanistic foundation in disturbance modelling, (iii) to integrate multiple disturbance processes in dynamic ecosystem models for decision support in forest management, and (iv) to bring together scaling capabilities across several levels of organization with a representation of system complexity that captures the emergent behaviour of disturbance regimes.
Current approaches to modelling the recreational value of forests are described, based upon regression models which relate forest inventory data to public preferences for different forest stands. An alternative method is proposed, which is less resource intensive and with potential to be applied across large spatial scales, based upon a typology of forest management alternatives with common silvicultural characteristics across Europe. Recreational scores are derived for each of 20 forest stand types in a given European region through the use of Delphi surveys supported by a literature review of European forest preference research. Forest growth simulators are then used to forecast changes in the area of each forest stand type under a given scenario, and hence to the total recreational value of the forests in the region. A stepwise description of the approach is provided, and its application is illustrated using indicative recreational scores to assess the impacts of two contrasting levels of implementation of the Natura 2000 policy on the recreational value of conifer forests in the United Kingdom. The discussion considers the opportunities and risks associated with use of the approach in a European-wide context to guide policy decisions and planning
We show the implications of the commonly observed age-related decline in aboveground productivity of forests, and hence forest age structure, on the carbon dynamics of European forests in response to historical changes in environmental conditions. Size-dependent carbon allocation in trees to counteract increasing hydraulic resistance with tree height has been hypothesized to be responsible for this decline. Incorporated into a global terrestrial biosphere model (the Lund-Potsdam-Jena model, LPJ), this hypothesis improves the simulated increase in biomass with stand age. Application of the advanced model, including a generic representation of forest management in even-aged stands, for 77 European provinces shows that model-based estimates of biomass development with age compare favorably with inventory-based estimates for different tree species. Model estimates of biomass densities on province and country levels, and trends in growth increment along an annual mean temperature gradient are in broad agreement with inventory data. However, the level of agreement between modeled and inventory-based estimates varies markedly between countries and provinces. The model is able to reproduce the present-day age structure of forests and the ratio of biomass removals to increment on a European scale based on observed changes in climate, atmospheric CO2 concentration, forest area, and wood demand between 1948 and 2000. Vegetation in European forests is modeled to sequester carbon at a rate of 100 Tg C/yr, which corresponds well to forest inventory-based estimates.