Tree growth is regulated by a combination of exogenous and endogenous factors. Such factors also interact with each other, complicating the understanding of causal links. IN particular, resource ...allocation is sensitive to reproductive investment, especially in masting species, which in turn is regulated by climatic variables. Both resource allocation and seed production patterns are also sensitive to tree age. This study aims to (1) evaluate the effects of tree age and local and regional climate on tree ring width and seed production by Spanish black pine (
Pinus nigra
Arn. ssp.
salzmannii
) forest in Cuenca Mountains (Spain), and (2) assess the relationship between seed production and secondary growth of Spanish black pine. Seed fall was estimated using 60 rectangular seed traps (40 × 50 × 15 cm) from 2000 to 2014, randomly distributed across the study area. Standardized tree-ring chronologies were calculated using a random sample of 106 trees stratified into three age classes (> 80 years; 26–80 years, and ≤ 25 years). Local climate data was obtained from a meteorological station, and regional climate data from the CRU-TS 3.1 dataset. Average seed production ranged over time from 2 to 189 seeds m
−2
(coefficient of variation = 157%). We identified four masting years (2000, 2003, 2006, and 2014) using a classification based on percentile seed production. Seed production was regulated by climate of the previous 2–3 years, while tree growth responded to precipitation and temperature in the previous and current year. Independent of climate, high seed production had a negative effect on tree ring width and weakened climate growth relationships, indicating resource depletion. Tree age modulated climate sensitivity, increasing correlations between climate and tree-ring index in older trees.
P. nigra
has been showed to be a climate sensitive species with a bimodal masting behaviour, which should be taking into account for management purposes and silvicultural guidelines under climate change scenarios.
Beliefs, expectations and values are often assumed to drive decisions about climate change adaptation. We tested hypotheses based on this assumption using survey responses from 508 European forest ...professionals in ten countries. We used the survey results to identify communication needs and the decision strategies at play, and to develop guidelines on adequate communications about climate change adaptation. We observed polarization in the positive and negative values associated with climate change impacts accepted by survey respondents. We identified a mechanism creating the polarization that we call the 'blocked belief' effect. We found that polarized values did not correlate with decisions about climate change adaptation. Strong belief in the local impacts of climate change on the forest was, however, a prerequisite of decision-making favoring adaptation. Decision-making in favor of adaptation to climate change also correlated with net values of expected specific impacts on the forest and generally increased with the absolute value of these in the absence of 'tipping point' behavior. Tipping point behavior occurs when adaptation is not pursued in spite of the strongly negative or positive net value of expected climate change impacts. We observed negative and positive tipping point behavior, mainly in SW Europe and N-NE Europe, respectively. In addition we found that advice on effective adaptation may inhibit adaptation when the receiver is aware of effective adaptation measures unless it is balanced with information explaining how climate change leads to negative impacts. Forest professionals with weak expectations of impacts require communications on climate change and its impacts on forests before any advice on adaptation measures can be effective. We develop evidence-based guidelines on communications using a new methodology which includes Bayesian machine learning modeling of the equivalent of an expected utility function for the adaptation decision problem.
Background. Uncertainty about climate change impacts on forests can hinder mitigation and adaptation actions. Scientific enquiry typically involves assessments of uncertainties, yet different ...uncertainty components emerge in different studies. Consequently, inconsistent understanding of uncertainty among different climate impact studies (from the impact analysis to implementing solutions) can be an additional reason for delaying action. In this review we (a) expanded existing uncertainty assessment frameworks into one harmonised framework for characterizing uncertainty, (b) used this framework to identify and classify uncertainties in climate change impacts studies on forests, and (c) summarised the uncertainty assessment methods applied in those studies. Methods. We systematically reviewed climate change impact studies published between 1994 and 2016. We separated these studies into those generating information about climate change impacts on forests using models -'modelling studies', and those that used this information to design management actions-'decision-making studies'. We classified uncertainty across three dimensions: nature, level, and location, which can be further categorised into specific uncertainty types. Results. We found that different uncertainties prevail in modelling versus decision-making studies. Epistemic uncertainty is the most common nature of uncertainty covered by both types of studies, whereas ambiguity plays a pronounced role only in decision-making studies. Modelling studies equally investigate all levels of uncertainty, whereas decision-making studies mainly address scenario uncertainty and recognised ignorance. Finally, the main location of uncertainty for both modelling and decision-making studies is within the driving forces-representing, e.g. socioeconomic or policy changes. The most frequently used methods to assess uncertainty are expert elicitation, sensitivity and scenario analysis, but a full suite of methods exists that seems currently underutilized. Discussion & Synthesis. The misalignment of uncertainty types addressed by modelling and decision-making studies may complicate adaptation actions early in the implementation pathway. Furthermore, these differences can be a potential barrier for communicating research findings to decision-makers.
Human activities have the potential to enhance carbon sequestration by the world’s forests and contribute to climate change mitigation. Voluntary carbon trading is currently the only option to pursue ...and reward carbon sequestration by forestry activities. Carbon credits for enhanced sequestration can be sold to partners wishing to offset their own emissions. Here we illustrate the steps taken to design guidelines for the generation of voluntary carbon credits by improved forest management in Piemonte, Italy. The guidelines have been developed in a joint effort by academia, regional administrations, forest owners and professional consultants. In particular, we show how to compute the baseline and the additionality of credit-generating forest management activities, and how to reconcile the generation of forest carbon credits with law requirements, technical limitations, and the provision of other ecosystem services. To illustrate the profitability of carbon credit generation, we simulated the application of carbon credit guidelines to two forest-rich mountain watersheds in the southern part of the Piemonte region. The two dominating tree species are beech (Fagus sylvatica L.) and chestnut (Castanea sativa Mill.). We computed current forest carbon stock and carbon credits generated in 20 years under business as usual and an alternative biomass retention scenario. The IFM resulted in an avoided harvest of 39.362 m3 for a net total of 64.014 MgCO2e after subtracting harvest emissions, or 38 Mg ha-1 throughout the permanence period of 20 years. These steps can be replicated in other mountain regions where there is interest in promoting this ecosystem service as an alternative or an addition to production-oriented forest management.
Mast seeding is one of the most intriguing reproductive traits in nature. Despite its potential drawbacks in terms of fitness, the widespread existence of this phenomenon suggests that it should have ...evolutionary advantages under certain circumstances. Using a global dataset of seed production time series for 219 plant species from all of the continents, we tested whether masting behaviour appears predominantly in species with low foliar nitrogen and phosphorus concentrations when controlling for local climate and productivity. Here, we show that masting intensity is higher in species with low foliar N and P concentrations, and especially in those with imbalanced N/P ratios, and that the evolutionary history of masting behaviour has been linked to that of nutrient economy. Our results support the hypothesis that masting is stronger in species growing under limiting conditions and suggest that this reproductive behaviour might have evolved as an adaptation to nutrient limitations and imbalances.
KEY MESSAGE : In the inner-Alpine Aosta Valley, severe growth reductions occurred in Scots pine stands during 1987–1993 and 2003–2005. Trees more sensitive to May precipitation exhibited stronger ...growth decline during these periods. Over the last decades, Scots pine (Pinus sylvestris L.) decline has involved large areas in the European Alps. Although the species is supposed to be drought resistant, increased temperatures and droughts are often indicated as predisposing causes of the decline. Nevertheless, the exact climate conditions that initiate the decline, and the reasons why they differentially affect individual trees, are largely unknown. Our aims were to identify climate constraints on Scots pine growth, and elucidate the effect of individual characteristics, such as tree age, size, crown condition, mistletoe occurrence, competition, and sensitivity to climate, on tree growth decline and recovery after repeated climatic stress. We analysed 232 trees in four second-growth stands located at 985–1350 m a.s.l. in the inner-Alpine Aosta Valley, NW Italy. Multi-year growth declines, occurred in 1987–1993 and 2003–2005, were related to repeated May precipitation shortage, while temperatures and summer precipitations played a minor role. Growth decline was stronger in the stand at lower elevation and with higher competition intensity. At the individual scale, trees more sensitive to May precipitation exhibited lower growth rates during both dry periods, but not a faster recovery. In the lower elevation stand, tree growth decline was significantly related to both crown transparency and mistletoe abundance, which was almost absent in the other stands. We conclude that future variations in the spring precipitation regime could threaten Scots pine more than warming per se, in inner-Alpine valleys around 1000–1400 m a.s.l. Still, different individual sensitivity to precipitation will likely result in patchy patterns of healthy and declining trees within the same stand.
•3-PGmix model was applied to European F. sylvatica and P. sylvestris stands.•3-PGmix predicted mixing effects that corresponded well with observed mixing effects.•Mixing responses varied with ...climate, soil water, age, thinning and soil fertility.
The productivity and functioning of mixed-species forests often differs from that of monocultures. However, the magnitude and direction of these differences are difficult to predict because species interactions can be modified by many potentially interacting climatic and edaphic conditions, stand structure and previous management. Process-based forest growth models could potentially be used to disentangle the effects of these factors and thereby improve our understanding of mixed forest functioning while facilitating their design and silvicultural management. However, to date, the predicted mixing effects of forest growth models have not been compared with measured mixing effects. In this study, 26 sites across Europe, each containing a mixture and monocultures of Fagus sylvatica and Pinus sylvestris, were used to calculate mixing effects on growth and yield and compare them with the mixing effects predicted by the forest growth model 3-PGmix. The climate and edaphic conditions, stand structures and ages varied greatly between sites. The model performed well when predicting the stem mass and total mass (and mixing effects on these components), with model efficiency that was usually >0.7. The model efficiency was lower for growth or smaller components such as foliage mass and root mass. The model was also used to predict how mixing effects would change along gradients in precipitation, temperature, potential available soil water, age, thinning intensity and soil fertility. The predicted patterns were consistent with measurements of mixing effects from published studies. The 3-PG model is a widely used management tool for monospecific stands and this study shows that 3-PGmix can be used to examine the dynamics of mixed-species stands and determine how they may need to be managed.
Surface biomass characterization plays a key role in wildfire management. It allows classifying vegetation fuels flammability for fire risk analysis, to define silvicultural prescriptions for fire ...hazard reduction, to plan prescribed burning, or to model fire behavior and its effects, such as greenhouse gas and pollutant emissions. To facilitate fuel classification and analysis of potential fire behavior and effects in Italy, we harmonized 634 measurements of surface wildland fuels from Alpine, temperate and Mediterranean environments. The dataset provides quantitative data for duff, fine dead fuels and downed woody material, live grasses and shrubs fuel components. Surface fuel data were harmonized by subdividing loads (Mg ha-1) to standard size classes for dead (0-6, 6-25 and 25-75 mm) and live (0-6, 6-25 mm) fuels, collecting percent cover and depth/height (cm) of the various fuel components, and classifying observations into 19 fuelbed categories. To ensure comparability with existing vegetation classification systems, we classified each observation according to the European Fuel Map, the Corine Land Cover classes (level IV), the European Forest Types, and the forest categories of the Italian National Forest Inventory. The dataset and a photo description of each fuelbed category are available as Supplementary material. This dataset is the first step to develop several products at the national scale such as: (i) fuel type classification and mapping; (ii) carbon stock and wildfire emission estimates; (iii) calibration of fuel models for the simulation of fire behavior and effects.
A petition entitled “Italian forests: an invaluable environmental heritage under attack” was recently published on the web. The petition is a perfect example of how environmental communication and ...public awareness can be manipulated. And, even more seriously, how people claiming to be environmental experts, use the “environment” label to spread their messages and slogans without accurately checking their sources. It is nevertheless of high importance that people are able to express their opinion and ideas freely and this communication between politics, communities and the academic world contribute to our growth as a society. However, any discussions must be underpinned with accurate and precise information. Furthermore, it is the scientific community’s duty to check sources of information and contribute to the spread of accurate environmental communication.
Is forest harvesting increasing in Europe? There is scientific debate about methodological approach and data regarding clearcut increment in Europe but, besides the discussion, there is a general ...agreement about the need to collect reliable scientifically robust remote sensing data for sound forest policy-making.
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