interventions is one of the most important measures for safeguarding biome-specific
biodiversity in managed forests and their reliable provisioning of ecosystem
services.
Natural forest development requires space and time. To preserve biodiversity and
sustain ecological continuity in managed forests therefore requires management
strategies that (1) avoid deforestation and land-use changes, (2) approach key
attributes of ‘natural forest communities’ (e.g. biome-specific tree species composition and diversity), (3) allow for senescence and natural disturbances (e.g. fires,
windstorms, insect outbreaks) as well as (4) prioritize the minimization of silvicultural interventions (Fähser 2012), and thus the optimization of forest ecosystem
functioning over the maximization of forestry use (e.g. maximum timber production
due to short-term rotation periods, intensive thinning or clearcutting). This
ecosystem-based management approach aims at sustaining ecological integrity (ecological processes and biodiversity) in managed forests by taking nature as role
model. Specifically, this includes promoting biome-specific tree species composition
and diversity, maintaining old and large-diameter trees, maintaining trees with
microhabitats and rare tree species, using single-tree or group selection harvesting,
avoiding deforestation and planting of non-native tree species, avoiding harvester
and tillage, avoiding application of fertilizer, pesticides and drainage. In this context
it should be noted that the reliable provisioning of wood supply may require
additional agroforestry to prioritize ecosystem functioning, biodiversity conservation and recreation over wood production in natural forests.
5.3 Forest Restoration
In the context of biodiversity conservation and climate change mitigation, regeneration of natural forests should be should be prioritized over afforestation measures,
such as establishing plantations that fail long-term ecological and social benefits
(Lewis et al. 2019). Similarly, biodiversity typical of cultural-based ecosystems
(e.g. grasslands or heathlands) should not be sacrificed for large-scale tree planting
programmes (Seddon et al. 2019; Temperton et al. 2019).
Recent meta-analyses have demonstrated that high levels of species diversity are
needed to support multiple ecosystem functions und the services provided by forest
ecosystems (Isbell et al. 2011). This also applies to the potential of forest ecosystems
to sequester carbon and thus to contribute to climate change mitigation. In a
large-scale subtropical forest experiment, for example, Huang et al. (2018) have
demonstrated that 16-species mixtures had accumulated over twice the amount of
aboveground carbon found in average monocultures after 8 years. Given that tree
species richness at the local neighbourhood scale enhances forest productivity
(Fichtner et al. 2018) and increases resistance of forests to drought (Fichtner et al.
2020), restoration and reforestation strategies should therefore prioritize planting
mixtures over monocultures by mixing tree species at the smallest spatial scale
(i.e. the local neighbourhood level) instead of mixing monospecific patches or forest
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A. Fichtner and W. Härdtle
biodiversity in managed forests and their reliable provisioning of ecosystem
services.
Natural forest development requires space and time. To preserve biodiversity and
sustain ecological continuity in managed forests therefore requires management
strategies that (1) avoid deforestation and land-use changes, (2) approach key
attributes of ‘natural forest communities’ (e.g. biome-specific tree species composition and diversity), (3) allow for senescence and natural disturbances (e.g. fires,
windstorms, insect outbreaks) as well as (4) prioritize the minimization of silvicultural interventions (Fähser 2012), and thus the optimization of forest ecosystem
functioning over the maximization of forestry use (e.g. maximum timber production
due to short-term rotation periods, intensive thinning or clearcutting). This
ecosystem-based management approach aims at sustaining ecological integrity (ecological processes and biodiversity) in managed forests by taking nature as role
model. Specifically, this includes promoting biome-specific tree species composition
and diversity, maintaining old and large-diameter trees, maintaining trees with
microhabitats and rare tree species, using single-tree or group selection harvesting,
avoiding deforestation and planting of non-native tree species, avoiding harvester
and tillage, avoiding application of fertilizer, pesticides and drainage. In this context
it should be noted that the reliable provisioning of wood supply may require
additional agroforestry to prioritize ecosystem functioning, biodiversity conservation and recreation over wood production in natural forests.
5.3 Forest Restoration
In the context of biodiversity conservation and climate change mitigation, regeneration of natural forests should be should be prioritized over afforestation measures,
such as establishing plantations that fail long-term ecological and social benefits
(Lewis et al. 2019). Similarly, biodiversity typical of cultural-based ecosystems
(e.g. grasslands or heathlands) should not be sacrificed for large-scale tree planting
programmes (Seddon et al. 2019; Temperton et al. 2019).
Recent meta-analyses have demonstrated that high levels of species diversity are
needed to support multiple ecosystem functions und the services provided by forest
ecosystems (Isbell et al. 2011). This also applies to the potential of forest ecosystems
to sequester carbon and thus to contribute to climate change mitigation. In a
large-scale subtropical forest experiment, for example, Huang et al. (2018) have
demonstrated that 16-species mixtures had accumulated over twice the amount of
aboveground carbon found in average monocultures after 8 years. Given that tree
species richness at the local neighbourhood scale enhances forest productivity
(Fichtner et al. 2018) and increases resistance of forests to drought (Fichtner et al.
2020), restoration and reforestation strategies should therefore prioritize planting
mixtures over monocultures by mixing tree species at the smallest spatial scale
(i.e. the local neighbourhood level) instead of mixing monospecific patches or forest
398
A. Fichtner and W. Härdtle