Dynamic coupling of allometric ratios to a process-based forest growth model for estimating the impacts of stand density changes

2020 ◽  
Vol 93 (5) ◽  
pp. 601-615
Author(s):  
Rüdiger Grote ◽  
David Kraus ◽  
Wendelin Weis ◽  
Rasmus Ettl ◽  
Axel Göttlein
Keyword(s):  
Climate Change ◽  
Early Development ◽  
Stand Density ◽  
Climate Change Impacts ◽  
Forest Growth ◽  
Canopy Layer ◽  
Mature Trees ◽  
Development Stages ◽  
Allometric Relations ◽  
Forest Growth Model

Abstract Process-based models are increasingly applied for simulating long-term forest developments in order to capture climate change impacts and to investigate suitable management responses. Regarding dimensional development, however, allometric relations such as the height/diameter ratio, branch and coarse root fractions or the dependency of crown dimension on stem diameter often do not account for environmental influences. While this may be appropriate for even-aged, monospecific forests, serious biases can be expected if stand density or forest structure changes rapidly. Such events occur in particular when forests experience disturbances such as intensive thinning or during early development stages of planted or naturally regenerated trees. We therefore suggest a calculation of allometric relationships that depends primarily on neighbourhood competition. Respective equations have been implemented into a physiology-based ecosystem model that considers asymmetric competition by explicit simulation of resource acquisition and depletion per canopy layer. The new implementation has been tested at two sites in Germany where beech (Fagus sylvatica) saplings have either been planted below a shelterwood of old spruces (Picea abies) or grown under clear-cut conditions. We show that the modified model is able to realistically describe tree development in response to stand density changes and is able to represent regeneration growth beneath a gradually decreasing overstorey of mature trees. In particular, the model could represent the faster crown size development in saplings until full ground coverage is established and a faster height growth afterwards. The effect enhances leaf area and thus assimilation per tree and increases carbon availability for stem growth at early development stages. Finally, the necessity to consider dynamic allometric relations with respect to climate change impacts is discussed, and further improvements are suggested.

scholarly journals Hurricane effects on climate-adaptive silviculture treatments to longleaf pine woodland in southwestern Georgia, USA

2020 ◽  
Author(s):  
Seth W Bigelow ◽  
Christopher E Looney ◽  
Jeffery B Cannon
Keyword(s):  
Climate Change ◽  
Functional Groups ◽  
Longleaf Pine ◽  
Stand Density ◽  
Climate Change Impacts ◽  
Species Selection ◽  
Destructive Effect ◽  
Individual Tree ◽  
Density Reduction ◽  
Resistant Species

Abstract The Adaptive Silviculture for Climate Change (ASCC) network tests silvicultural treatments to promote ‘resistance’ or ‘resilience’ to climate change or speed ‘transition’ to new forest types. Based on projected increases in air temperatures and within-season dry periods in southeastern USA, we installed resistance, resilience and transition treatments involving species selection and varied intensities of density reduction, plus an untreated control, in mixed longleaf pine-hardwood woodland in southwest Georgia USA. Within a year of treatment a tropical cyclone, Hurricane Michael, exposed the site to the unforeseen climatic stress of >44-m s−1 winds. We measured inventory plots post-cyclone and compared the data to pre-storm and pre-treatment values. We analysed stand density index (metric SDI, species maximum value = 1000), stand complexity index (SCI), composition and individual tree characteristics. The ASCC treatments decreased both SDI (from 220 to 124 in the transition treatment) and SCI. The cyclone did not greatly decrease SDI (mean decrease 4.5 per cent) and decreased SCI only in the Controls. Xeric hardwoods were more prone to damage than other functional groups, and ordination showed that the cyclone shifted species composition to greater longleaf pine dominance. Taller trees were more likely to be damaged, except in the resilience treatment, which had a relatively large representation of shorter, more easily damaged xeric hardwoods. The open canopy of the longleaf-hardwood woodland, only 22 per cent of maximum SDI before treatment, evidently fostered wind-firmness, thereby limiting the destructive effect of the cyclone. The sensitivity of xeric hardwoods to hurricane damage suggests that there may be a trade-off between wind tolerance and drought tolerance among functional groups. Maintaining a mixture of drought and wind-resistant species, as in the resilience treatments, may provide broader insurance against multiple climate change impacts in longleaf pine and other forested systems dominated by a single foundation species.

scholarly journals Identifying decision-relevant uncertainties for dynamic adaptive forest management under climate change

2020 ◽  
Vol 163 (2) ◽  
pp. 891-911
Author(s):  
Naomi Radke ◽  
Klaus Keller ◽  
Rasoul Yousefpour ◽  
Marc Hanewinkel
Keyword(s):  
Climate Change ◽  
Forest Management ◽  
Volume Growth ◽  
European Beech ◽  
Forest Growth ◽  
West Germany ◽  
Forest Growth Model ◽  
Study Results ◽  
Planning Cycle

AbstractThe decision on how to manage a forest under climate change is subject to deep and dynamic uncertainties. The classic approach to analyze this decision adopts a predefined strategy, tests its robustness to uncertainties, but neglects their dynamic nature (i.e., that decision-makers can learn and adjust the strategy). Accounting for learning through dynamic adaptive strategies (DAS) can drastically improve expected performance and robustness to deep uncertainties. The benefits of considering DAS hinge on identifying critical uncertainties and translating them to detectable signposts to signal when to change course. This study advances the DAS approach to forest management as a novel application domain by showcasing methods to identify potential signposts for adaptation on a case study of a classic European beech management strategy in South-West Germany. We analyze the strategy’s robustness to uncertainties about model forcings and parameters. We then identify uncertainties that critically impact its economic and ecological performance by confronting a forest growth model with a large sample of time-varying scenarios. The case study results illustrate the potential of designing DAS for forest management and provide insights on key uncertainties and potential signposts. Specifically, economic uncertainties are the main driver of the strategy’s robustness and impact the strategy’s performance more critically than climate uncertainty. Besides economic metrics, the forest stand’s past volume growth is a promising signpost metric. It mirrors the effect of both climatic and model parameter uncertainty. The regular forest inventory and planning cycle provides an ideal basis for adapting a strategy in response to these signposts.

scholarly journals Using 3PG to assess climate change impacts on management plan optimization of Eucalyptus plantations. A case study in Southern Brazil

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
João HN Palma ◽  
Rodrigo Hakamada ◽  
Gabriela Gonçalves Moreira ◽  
Silvana Nobre ◽  
Luiz Carlos Estraviz Rodriguez
Keyword(s):  
Climate Change ◽  
Climate Change Impacts ◽  
Management Plan ◽  
Empirical Models ◽  
Forest Growth ◽  
Future Climate ◽  
Empirical Equations ◽  
Complete Replacement ◽  
Physiological Models ◽  
The Impact

AbstractEucalyptus plantations around the world have been largely used by the paper industry. Optimizing the management of resources is a common practice in this highly competitive industry and new forest growth models may help to understand the impact of climate change on the decisions of the optimization processes. Current optimized management plans use empirical equations to predict future forest stands growth, and it is currently impractical to replace these empirical equations with physiological models due to data input requirements. In this paper, we present a different approach, by first carrying out a preliminary assessment with the process-based physiological model 3PG to evaluate the growth of Eucalyptus stands under climate change predictions. The information supplied by 3PG was then injected as a modifier in the projected yield that feeds the management plan optimizer allowing the interpretation of climate change impacts on the management plan. Modelling results show that although a general increase of rain with climate change is predicted, the distribution throughout the year will not favor the tree growth. On the contrary, rain will increase when it is less needed (summer) and decrease when it is most needed (winter), decreasing forest stand productivity between 3 and 5%, depending on the region and soil. Evaluation of the current optimized plan that kept constant the relation between wood price/cellulose ton shows a variation in different strategic management options and an overall increase of costs in owned areas between 2 and 4%, and a decrease of cumulated net present value, initially at 15% with later stabilization at 6–8%. This is a basic comparison to observe climate change effects; nevertheless, it provides insights into how the entire decision-making process may change due to a reduction in biomass production under future climate scenarios. This work demonstrates the use of physiological models to extract information that could be merged with existing and already implemented empirical models. The methodology may also be considered a preliminary alternative to the complete replacement of empirical models by physiological models. Our approach allows some insight into forest responses to different future climate conditions, something which empirical models are not designed for.

scholarly journals Sampling bias overestimates climate change impacts on forest growth in the southwestern United States

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Stefan Klesse ◽  
R. Justin DeRose ◽  
Christopher H. Guiterman ◽  
Ann M. Lynch ◽  
Christopher D. O’Connor ◽  
...  
Keyword(s):  
Climate Change ◽  
United States ◽  
Climate Change Impacts ◽  
Sampling Bias ◽  
Forest Growth ◽  
Southwestern United States

scholarly journals Large-Scale Forest Modeling: Deducing Stand Density from Inventory Data

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Oskar Franklin ◽  
Elena Moltchanova ◽  
Florian Kraxner ◽  
Rupert Seidl ◽  
Hannes Böttcher ◽  
...  
Keyword(s):  
Large Scale ◽  
Model Performance ◽  
Stand Density ◽  
Forest Growth ◽  
Data Availability ◽  
Inventory Data ◽  
Combined Model ◽  
Age Cohorts ◽  
Forest Growth Model ◽  
Forest Modeling

While effects of thinning and natural disturbances on stand density play a central role for forest growth, their representation in large-scale studies is restricted by both model and data availability. Here a forest growth model was combined with a newly developed generic thinning model to estimate stand density and site productivity based on widely available inventory data (tree species, age class, volume, and increment). The combined model successfully coupled biomass, increment, and stand closure (=stand density/self-thinning limited stand density), as indicated by cross-validation against European-wide inventory data. The improvement in model performance attained by including variable stand closure among age cohorts compared to a fixed closure suggests that stand closure is an important parameter for accurate forest growth modeling also at large scales.

scholarly journals Gains or Losses in Forest Productivity under Climate Change? The Uncertainty of CO2 Fertilization and Climate Effects

Climate ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 141
Author(s):  
Dominik Sperlich ◽  
Daniel Nadal-Sala ◽  
Carlos Gracia ◽  
Jürgen Kreuzwieser ◽  
Marc Hanewinkel ◽  
...  
Keyword(s):  
Climate Change ◽  
Tree Mortality ◽  
Abies Alba ◽  
Forest Productivity ◽  
Forest Growth ◽  
Climate Change Scenarios ◽  
Co2 Fertilization ◽  
Study Region ◽  
Productivity Losses ◽  
Forest Growth Model

Global warming poses great challenges for forest managers regarding adaptation strategies and species choices. More frequent drought events and heat spells are expected to reduce growth and increase mortality. Extended growing seasons, warming and elevated CO2 (eCO2) can also positively affect forest productivity. We studied the growth, productivity and mortality of beech (Fagus sylvatica L.) and fir (Abies alba Mill.) in the Black Forest (Germany) under three climate change scenarios (representative concentration pathways (RCP): RCP2.6, RCP4.5, RCP8.5) using the detailed biogeochemical forest growth model GOTILWA+. Averaged over the entire simulation period, both species showed productivity losses in RCP2.6 (16–20%) and in RCP4.5 (6%), but productivity gains in RCP8.5 (11–17%). However, all three scenarios had a tipping point (between 2035–2060) when initial gains in net primary productivity (NPP) (6–29%) eventually turned into losses (1–26%). With eCO2 switched off, the losses in NPP were 26–51% in RCP2.6, 36–45% in RCP4.5 and 33–71% in RCP8.5. Improved water-use efficiency dampened drought effects on NPP between 4 and 5%. Tree mortality increased, but without notably affecting forest productivity. Concluding, cultivation of beech and fir may still be possible in the study region, although severe productivity losses can be expected in the coming decades, which will strongly depend on the dampening CO2 fertilization effect.

scholarly journals High temperatures drive offspring mortality in a cooperatively breeding bird

2020 ◽  
Vol 287 (1931) ◽  
pp. 20201140
Author(s):  
Amanda R. Bourne ◽  
Susan J. Cunningham ◽  
Claire N. Spottiswoode ◽  
Amanda R. Ridley
Keyword(s):  
Climate Change ◽  
Group Size ◽  
High Temperatures ◽  
Environmental Conditions ◽  
Environmental Variability ◽  
Arid Zone ◽  
Climate Change Impacts ◽  
Daily Maximum ◽  
Development Stages ◽  
Maximum Temperatures

An improved understanding of life-history responses to current environmental variability is required to predict species-specific responses to anthopogenic climate change. Previous research has suggested that cooperation in social groups may buffer individuals against some of the negative effects of unpredictable climates. We use a 15-year dataset on a cooperative breeding arid zone bird, the southern pied babbler Turdoides bicolor , to test (i) whether environmental conditions and group size correlate with survival of young during three development stages (egg, nestling, fledgling) and (ii) whether group size mitigates the impacts of adverse environmental conditions on survival of young. Exposure to high mean daily maximum temperatures (mean T max ) during early development was associated with reduced survival probabilities of young in all three development stages. No young survived when mean T max > 38°C, across all group sizes. Low survival of young at high temperatures has broad implications for recruitment and population persistence in avian communities given the rapid pace of advancing climate change. Impacts of high temperatures on survival of young were not moderated by group size, suggesting that the availability of more helpers in a group is unlikely to buffer against compromised offspring survival as average and maximum temperatures increase with rapid anthropogenic climate change.

Organising the unthinkable in times of crises: Will climate engineering become the weapon of last resort in the Anthropocene?

Organization ◽  
2018 ◽  
Vol 25 (4) ◽  
pp. 472-490 ◽  
Author(s):  
Markus Lederer ◽  
Judith Kreuter
Keyword(s):  
Climate Change ◽  
Early Development ◽  
Global Climate Change ◽  
Nuclear Weapons ◽  
Global Climate ◽  
The Other ◽  
Climate Engineering ◽  
Technical Feasibility ◽  
Development Stages

In this article, we ask how the approaches of climate engineering – mostly highly technological approaches to address the challenge of global climate change – might be organised in the age of the Anthropocene. We understand the term ‘Anthropocene’ to be characterised by crisis, on one hand, and by promise, on the other. In particular, we aim to raise doubts on the dominant perspective on the organisation of climate engineering, which assumes these approaches to be regulated through legalistic means. Drawing an analogy to the early development stages of nuclear weapons, we point out that, instead of following a legalistic rationale, climate engineering organisation might pursue a logic of technical feasibility, political acceptance and bureaucratic momentum.

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