Biomass estimation as a function of vertical forest structure and forest height. Potential and limiations for remote sensing (radar and LiDAR)

Forest biomass stock, spatial distribution and dynamics are unknown parameters for many regions of the world. Today’s information is largely based on ground measurements on a plot basis without coverage in many remote regions that are fundamental for the global carbon cycle. Thus, a method capable of quantifying biomass by means of Remote Sensing (RS) could help to reduce these uncertainties and contribute to a better understanding of it. In this study the capacity to improve the estimation of above-ground biomass (AGB) with a new approach based on forest vertical structure and its potential to improve RS estimations is analyzed. Height to biomass allometry allows biomass estimations from remote sensing systems capable to resolve forest height (LiDAR and polarimetric SAR interferometry (Pol-InSAR)). However, this approach meets its limitations for forest ecosystems under changing conditions in density and structure. To improve biomass estimation accuracy, additional parameters need to be measured. Pol-InSAR and LiDAR allow getting besides forest height vertical backscattering profiles which are connected to forest vertical structure. Thus, due to the relation between structural parameters and AGB expressed by the Structure to Biomass allometry, AGB can be potentially inverted from these systems. The best characterization of forest vertical structure is obtained using the Legendre polynomials. Biomass profiles can be then characterized by the decomposition into a set of Legendre-Fourier basis functions. This method is able to accurately reconstruct vertical biomass profiles with low frequency features. Vertical backscattering profiles are strongly dependent on the sensor used as the resulting profiles are very sensitive to the wavelength and system geometry. E.g. LiDAR profiles are more sensitive to leaves and crowns while Pol-InSAR tends to reconstruct more the woody compartments (stems and branches). In this study, vertical backscattering profiles from short footprint airborne LiDAR and Pol-InSAR data are evaluated for their potential to reconstruct vertical forest structure. With the Legendre decomposition it is possible to parameterize the vertical backscattering profiles and relate them to forest biomass; even though for each remote sensing system different calibration methodologies must be derived. A first step is achieved using the calibration of backscattering signal with known biomass levels showing optimum results. In order to reduce the need of known parameters a new calibration methodology that exploits height to biomass allometric relations has been derived. Inversions using this methodology are tested for LiDAR and SAR profiles showing good correlations for an optimum subset of samples. As each system (frequency) is sensitive to certain biomass components an underestimation is generally expected. Research in this area is ongoing and will be presented with special focus on each system capacity to reconstruct forest vertical biomass distribution for broader sets of samples

Sectoral policies cause incoherence in forest management and ecosystem service provisioning

Various national policies guide forest use, but often with competing policy objectives leading to divergent management paradigms. Incoherent policies may negatively impact the sustainable provision of forest ecosystem services (FES), and forest multifunctionality. There is uncertainty among policymakers about the impacts of policies on the real world. We translated the policy documents of Finland into scenarios including the quantitative demands for FES, representing: the national forest strategy (NFS), the biodiversity strategy (BDS), and the bioeconomy strategy (BES). We simulated a Finland-wide systematic sample of forest stands with alternative management regimes and climate change. Finally, we used multi-objective optimization to identify the combination of management regimes matching best with each policy scenario and analysed their long-term effects on FES.The NFS scenario proved to be the most multifunctional, targeting the highest number of FES, while the BES had the lowest FES targets. However, the NFS was strongly oriented towards the value chain of wood and bioenergy and had a dominating economic growth target, which caused strong within-policy conflicts and hindered reaching biodiversity targets. The BDS and BES scenarios were instead more consistent but showed either sustainability gaps in terms of providing timber resources (BDS) or no improvements in forest biodiversity (BES). All policy scenarios resulted in forest management programs dominated by continuous cover forestry, set-aside areas, and intensive management zones, with proportions depending on the policy focus. Our results highlight for the first time the conflicts among national sectoral policies in terms of management requirements and effects on forest multifunctionality. The outcomes provide leverage points for policymakers to increase coherence among future policies and improve implementation of multiple uses of forests

Sectoral policies as drivers of forest management and ecosystems services: A case study in Bavaria, Germany

European countries have national sectoral polices to regulate and promote the provision of a wide range of forest ecosystems services (FES). However, potential incoherencies among these policies can negatively affect the efficient provision of FES. In this work, we evaluated the coherence among three national policies from Germany and their ability to effectively provide FES in the future: the Forest Strategy 2020 (FS), the National Strategy on Biological Diversity (BDS), and the German National Policy Strategy on Bioeconomy (BES). Using forest inventory data from the Federal State of Bavaria, we simulated a range of forest management options under three climate trajectories for 100 years into the future (2012–2112). Then, with multi-objective optimization, we translated each policy into a specific scenario and identified the best combination of management regimes that maximizes the targets defined in each policy scenario. The three policies were vague in the definition of FES. The FS was the most comprehensive policy aiming for a higher degree of multifunctionality, whereas the BES and BDS focused on less FES. The FS and the BDS showed the highest coherence, while the BES showed a stronger focus on timber production. As a result, the optimal management programs of FS and BDS showed high integration, with a dominance of Continuous Cover Forestry (CCF), and certain shares of set asides. Climate change led to an increase of set aside areas due to increased productivity. In the BES, the share of land among management regimes was strongly segregated between CCF and rotation forestry. Our policy coherence analysis showed that achieving a multifunctional provision of FES requires policy coherence, fostering a diverse management of the landscape that mainly takes advantage of integrative management, like CCF, but also segregates important parts of the landscape for intensive use and set asides. Nevertheless, the current high standing volumes in Bavaria will pose an additional risk to implement such management.peerReviewe

What drives forest multifunctionality in central and northern Europe? Exploring the interplay of management, climate, and policies

Forests provide a range of vital services to society and are critical habitats for biodiversity, holding inherent multifunctionality. While traditionally viewed as a byproduct of production-focused forestry, today's forest ecosystem services and biodiversity (FESB) play an essential role in several sectoral policies’ needs. Achieving policy objectives requires careful management considering the interplay of services, influenced by regional aspects and climate. Here, we examined the multifunctionality gap caused by these factors through simulation of forest management and multi-objective optimization methods across different regions - Finland, Norway, Sweden and Germany (Bavaria). To accomplish this, we tested diverse management regimes (productivity-oriented silviculture, several continuous cover forestry regimes and set asides), two climate scenarios (current and RCP 4.5) and three policy strategies (National Forest, Biodiversity and Bioeconomy Strategies). For each combination we calculated a multifunctionality metric at the landscape scale based on 5 FESB classes (biodiversity conservation, bioenergy, climate regulation, wood, water and recreation). In Germany and Norway, maximum multifunctionality was achieved by increasing the proportion of set-asides and proportionally decreasing the rest of management regimes. In Finland, maximum MF would instead require that policies address greater diversity in management, while in Sweden, the pattern was slightly different but similar to Finland. Regarding the climate scenarios, we observed that only for Sweden the difference in the provision of FESB was significant. Finally, the highest overall potential multifunctionality was observed for Sweden (National Forest scenario, with a value of 0.94 for the normalized multifunctionality metric), followed by Germany (National Forest scenario, 0.83), Finland (Bioeconomy scenario, 0.81) and Norway (National Forest scenario, 0.71). The results highlight the challenges of maximizing multifunctionality and underscore the significant influence of country-specific policies and climate change on forest management. To achieve the highest multifunctionality, strategies must be tailored to specific national landscapes, acknowledging both synergistic and conflicting FESB

Forestry projections for species diversity-oriented management: an example from Central Europe

Abstract Introduction Changes in socio-economy and climate are affecting the demand of wood products globally. At the same time, society requires that forest supporting structures like biodiversity are maintained and preserved while the demand for wood products is also covered. Management support systems, like forest simulation models, that are able to analyze connections as well as quantify trade-offs between forest structure management and biodiversity indicators are highly sought. However, such models are generally developed for the local plot or stand scale only and ecosystem-scale analyses are missing. In this study, we analyzed ways to interpret results from the single-tree forest simulator SILVA from the local to the ecosystem scale. We also analyzed the impacts of forest management on biodiversity using two species diversity indicators, the species profile index and the species intermingling, for scenarios adapted from the GLOBIOM model in the case study “Augsburg Western Forests”, a high productive region in South-Germany. In order to evaluate diversity tendencies across the ecosystem, we applied a moving window methodology. Results The relevance of scale for the interpretation of management effects on species diversity was shown and clear differences between scenarios revealed. The differences between scenarios were particularly visible when comparing the two diversity indicators, especially because the species profile index focuses on vertical and horizontal information and the species intermingling focuses mainly on horizontal structures. Under a multifunctional scenario, biodiversity values could be preserved at all scales in the vertical dimension. However, under a bio-energy-oriented scenario diversity at the local scale was reduced, although at the ecosystem level, and only in the horizontal dimension, diversity remained at relatively high values. Conclusions With this work, we can conclude that integrative modeling, with multiple scenarios, is highly needed to support forestry decision making and towards the evolution of forest management to consider the ecosystem scale, especially when the optimization of diversity is a management priority

Stand Structural Characteristics Derived from Combined TLS and Landsat Data Support Predictions of Mushroom Yields in Mediterranean Forest

Forest fungi provide recreational and economic services, as well as ecosystem biodiversity. Wild mushroom yields are difficult to estimate; climatic conditions are known to trigger temporally localised yields, and forest structure also affects productivity. In this work, we analyse the capacity of remotely sensed variables to estimate wild mushroom biomass production in Mediterranean Pinus pinaster forests in Soria (Spain) using generalised additive mixed models (GAMMs). In addition to climate variables, multitemporal NDVI derived from Landsat data, as well as structural variables measured with mobile Terrestrial Laser Scanner (TLS), are considered. Models are built for all mushroom species as a single pool and for Lactarius deliciosus individually. Our results show that, in addition to autumn precipitation, the interaction of multitemporal NDVI and vegetation biomass are most explanatory of mushroom productivity in the models. When analysing the productivity models of Lactarius deliciosus, in addition to the interaction between canopy cover and autumn minimum temperature, basal area (BA) becomes relevant, indicating an optimal BA range for the development of this species. These findings contribute to the improvement of knowledge about wild mushroom productivity, helping to meet Goal 15 of the 2030 UN Agenda

Bird traits and their responses to forest structure in Central European forests

Forest structure, as resulting from management practices, have an effect on habitat quality and thus the occurrence of birds using and depending on these landscapes. We hypothesized that the species responses to forest structure is influenced by their ecological traits. The aim of our study is thus to examine the relationship between bird traits and their responses to forest structure in Central European forests. For this purpose, we used occurrence data from breeding bird censuses in the Canton of Zürich (Switzerland) and in Bavaria (Germany), forest inventory and climate data for the same regions, as well as a trait database for the studies species. We used single species distribution models, and multispecies predictive trait models to identify critical response traits and to quantify their relationships to species’ responses to forest structure, landscape configuration and climate. Finally, and based on our results, we conclude by giving general forest management recommendations for the promotion of forest bird diversity. This work is part of the BiodivERsA project GreenFutureForest.peerReviewe

Sectoral policies cause incoherence in forest management and ecosystem service provisioning

Various national policies guide forest use, but often with competing policy objectives leading to divergent management paradigms. Incoherent policies may negatively impact the sustainable provision of forest ecosystem services (FES), and forest multifunctionality. There is uncertainty among policymakers about the impacts of policies on the real world. We translated the policy documents of Finland into scenarios including the quantitative demands for FES, representing: the national forest strategy (NFS), the biodiversity strategy (BDS), and the bioeconomy strategy (BES). We simulated a Finland-wide systematic sample of forest stands with alternative management regimes and climate change. Finally, we used multi-objective optimization to identify the combination of management regimes matching best with each policy scenario and analysed their long-term effects on FES. The NFS scenario proved to be the most multifunctional, targeting the highest number of FES, while the BES had the lowest FES targets. However, the NFS was strongly oriented towards the value chain of wood and bioenergy and had a dominating economic growth target, which caused strong within-policy conflicts and hindered reaching biodiversity targets. The BDS and BES scenarios were instead more consistent but showed either sustainability gaps in terms of providing timber resources (BDS) or no improvements in forest biodiversity (BES). All policy scenarios resulted in forest management programs dominated by continuous cover forestry, set-aside areas, and intensive management zones, with proportions depending on the policy focus. Our results highlight for the first time the conflicts among national sectoral policies in terms of management requirements and effects on forest multifunctionality. The outcomes provide leverage points for policymakers to increase coherence among future policies and improve implementation of multiple uses of forests

Impacts of Forest Management on Forest Bird Occurrence Patterns—A Case Study in Central Europe

The global increase in demand for wood products, calls for a more sustainable management of forests to optimize both the production of wood and the conservation of forest biodiversity. In this paper, we evaluate the status and future trends of forest birds in Central European forests, assuming different forest management scenarios that to a varying degree respond to the demand for wood production. To this end, we use niche models (Boosted Regression Trees and Generalized Linear Models) to model the responses of 15 forest bird species to predictors related to forest stand (e.g., stand volume of specific tree species) and landscape structure (e.g., percentage cover), and to climate (bioclimatic variables). We then define five distinct forest management scenarios, ranging from set-aside to productivity-driven scenarios, project them 100 years into the future, and apply our niche models into these scenarios to assess the birds’ responses to different forest management alternatives. Our models show that the species’ responses to management vary reflecting differences in their ecological niches, and consequently, no single management practice can benefit all species if applied across the whole landscape. Thus, we conclude that in order to promote the overall forest bird species richness in the study region, it is necessary to manage the forests in a multi-functional way, e.g., by spatially optimizing the management practices in the landscape. forestry, sustainable management, forest birds, niche modeling, scenario projectionspublishedVersio

Impacts of Forest Management on Forest Bird Occurrence Patterns—A Case Study in Central Europe

The global increase in demand for wood products, calls for a more sustainable management of forests to optimize both the production of wood and the conservation of forest biodiversity. In this paper, we evaluate the status and future trends of forest birds in Central European forests, assuming different forest management scenarios that to a varying degree respond to the demand for wood production. To this end, we use niche models (Boosted Regression Trees and Generalized Linear Models) to model the responses of 15 forest bird species to predictors related to forest stand (e.g., stand volume of specific tree species) and landscape structure (e.g., percentage cover), and to climate (bioclimatic variables). We then define five distinct forest management scenarios, ranging from set-aside to productivity-driven scenarios, project them 100 years into the future, and apply our niche models into these scenarios to assess the birds’ responses to different forest management alternatives. Our models show that the species’ responses to management vary reflecting differences in their ecological niches, and consequently, no single management practice can benefit all species if applied across the whole landscape. Thus, we conclude that in order to promote the overall forest bird species richness in the study region, it is necessary to manage the forests in a multi-functional way, e.g., by spatially optimizing the management practices in the landscape. forestry, sustainable management, forest birds, niche modeling, scenario projection