Climate change impacts on tree ranges: model intercomparison facilitates understanding and quantification of uncertainty

Model-based projections of shifts in tree species range due to climate change are becoming an important decision support tool for forest management. However, poorly evaluated sources of uncertainty require more scrutiny before relying heavily on models for decision-making. We evaluated uncertainty arising from differences in model formulations of tree response to climate change based on a rigorous intercomparison of projections of tree distributions in France. We compared eight models ranging from niche-based to process-based models. On average, models project large range contractions of temperate tree species in lowlands due to climate change. There was substantial disagreement between models for temperate broadleaf deciduous tree species, but differences in the capacity of models to account for rising CO(2) impacts explained much of the disagreement. There was good quantitative agreement among models concerning the range contractions for Scots pine. For the dominant Mediterranean tree species, Holm oak, all models foresee substantial range expansion.     

Changes in ATP sulfurylase and adenosine 5'-phosphosulfate sulfotransferase activity during autumnal senescence of beech leaves

The decrease in extractable activity of ribuloscbisphosphate carboxylase (EC 4.1.1.39), ATP sulfurylase (EC 2.7.7.4) and adenosine 5'-phosphosulfate sulfotransferase and the content in chlorophyll and protein was compared in leaves of cloned beech trees ( Fagus sylvatica L.) during autumnal senescence. Leaves excised at the same time but containing different amounts of chlorophyll gave extracts with correspondingly varying amounts of ribulosebisphosphate carboxylase activity. Leaves which had almost completely lost this enzyme activity contained still appreciable ATP sulfurylase and adenosine 5'-phosphosulfate sulfotransferase activity and soluble protein. For all components determined, there was a period lasting until mid or end of October during which there was no or only a small decrease. They were then all lost rapidly from the leaves. The specific activity of ribulosebisphosphate carboxylase decreased during this phase of rapid loss, whereas it remained essentially constant for ATP sulfurylase and adenosine 5'-phosphosulfate sulfotransferase. During this period, the mean half life of ribulosebisphosphate carboxylase was shorter than the one of ATP sulfurylase and of adenosine 5'-phosphosulfate sulfotransferase. These experiments clearly show that ribulosebisphosphate carboxylase was preferentially lost from beech leaves during autumnal senescence as compared to ATP sulfurylase and adenosine 5'-phosphosulfate sulfotransferase.     

Variazioni stagionali di nutrienti minerali ed elementi in traccia nelle foglie di Fagus sylvatica L. a Vallombrosa (FI)

Abstract

Seasonal variations of mineral nutrients and trace elements in Fagus sylvatica L. leaves at Vallombrosa (FI). - During the vegetative periodo 1987 monthly samples of beech leaves were collected in Vallombrosa forest area to determine the nutritive situation of beech trees by leaves analysis. Among nutrients, potassium appears the worst supplied one. Even copper is present in very low values, under the critical level. Heavy metals as manganese, aluminium, lead, cadmium and also iron show a clear increase during the vegetative season.     

欧洲水青冈(Fagus sylvatical L.)构筑型与形态多样性研究

通过对植物构件和构筑型的分析,可以了解植物的整体结构与系统演化关系。高等植物构筑型的研究以树木最为深入,植物学家对全球的树木进行了构筑模式的分类,并确定了２３个基本的构筑类型。植物的构筑型和其形态的多样性是密不可分的。构筑奕型确定了植物所属的整体形态类型,而对每种植物具体的形态多样性分析可以深入了解每种构筑型的数量特征及其形成过程。在概述了树木树筑型研究的基础上,系统说明了欧洲水青冈构筑才形态多样性分析的步骤和步骤和分析的意义。水青冈属（Fagus)为Ｔroll型构筑模式,处于不同生态条件下的同一种的不同种群之间,在形态、解剖、生理和遗传多样性方面都存在着差异。树木的形态多样性虽然主要受遗传因素的控制,但生态条件对其形态和遗传多样性也有非常显著的影响。在对树木进行构筑型分析时,道德要根据构筑要素（主要是形态与生长特性）确定它所属的构筑类型,其次是分析它的形态特征与环境条件的关系,进行进一步分析其遗传多样性。     

Effet de l'acide gibberellique (GA3) sur la croissance d'Asparagopsis armata (Rhodophycées,Bonnemaisoniales) en culture

Abstract

Effect of gibberellic acid (GA₃) on the growth of Asparagopsis armata in culture.—The gibberellic acid (GA₃) stimulates the growth of the Asparagopsis armata in culture. This effect was observed by adding doses of 6,5X10^?5M or 6,5X10^?7M of this acid in Von Stosch medium.     

Water relations and gas exchange in Fagus sylvatica L. and Quercus petraea (Mattuschka) Liebl. in a mixed stand at their southern limit of distribution in Europe

Water status and gas exchange of beech (Fagus sylvatica L.) and sessile oak [Quercus petraea (Mattuschka) Liebl.] were studied in a mixed stand in the Montejo de la Sierra forest (central Iberian Peninsula), one of the southernmost locations of both species in Europe. Gas exchange and water potential were measured in leaves at different canopy levels over several days in two growing seasons. The daily variation pattern was established with the measurements of three selected dates per year, representative of the soil moisture content situations in early, mid- and late summer. A similar daily time course of leaf water potential was found for the two species. Nevertheless, beech showed a most noticeable decrease of water potential at midmorning and maintained lower leaf water potential than oak in the early afternoon. In 1994 the sessile oak saplings showed higher values of predawn water potential (Ψ_pd) than beech at the end of summer, when soil moisture content was lowest (20 cm depth). Beech showed a significantly lower net assimilation rate (A) than sessile oak for leaves under the same PPFD. Maximum net photosynthesis values (A _max) for beech and sessile oak on sunny leaves were 10.1±0.4 μmol m^–2 s^–1 and 17.8±1.7 μmol m^–2 s^–1 respectively, and those for water vapour stomatal conductance (g _wv) were 265±31 mmol m^–2 s^–1 and 438±74 mmol m^–2 s^–1. Differences in A and g _wv between the two species were maintained throughout the day on all measurement dates. No clear relationship was found between water status of saplings and stomata performance; there was only a negative correlation between Ψ_pd and g _wvmid in beech. Nevertheless, a significant response to the air vapour pressure gradient between leaf and air was translated into stomata closure on an hourly basis, more intensively in beech. Received: 4 March 1999 / Accepted: 21 December 1999     

Local differentiation of Albanian provenances and chorology of beech species in balcan area

Abstract

Some quantitative characters of different Albanian beech provenances are analysed in order to study their local differentiation. The results obtained by discriminant analysis showed the formation of two principal groups. Biza provenance was discriminated from both groups. Principal components and cluster analysis give a good evidence on the similarities among Albanian and Bulgarian beech populations. The results suggest that all area of Balcan is the contact zone of Fagus sylvatica L. and Fagus orientalis Lypski.     

Beech forest communities in the Nordic countries – a multivariate analysis

In this study we present the first comprehensive multivariate analysis of beech (Fagus sylvatica) forest communities in the Nordic countries. The history of beech and beech forests in Scandinavia are described. In the north, the species is climatically restrained and, at present, restricted to Denmark and the southern parts of Sweden and Norway.More than 2000 sample plots were compiled, partly from literature, partly from new and unpublished data. The material included more than 20 studies of beech forests, often recorded by different non-standardised sampling designs. Therefore, prior to data analysis, a large number of plots had to be excluded to reduce the heterogeneity of the data. Only such sample plots were considered that showed a predominance of Fagus sylvatica in the canopy, that had a size within the interval of 16–100 m2, and that could be located by geographical coordinates. All species abundance values were transformed into simple species presences, and data from different vegetation layers were merged into one.A TWINSPAN cluster analysis resulted in 15 types. Three main communities with several sub-communities and varieties can be distinguished: (1) the Fagus sylvatica-Fraxinus excelsior-Stachys sylvatica community on the most basic and fertile soils, (2) the Fagus sylvatica-Corylus avellana-Galium odoratum community on moderately fertile and acid soils, and (3) the Fagus sylvatica-Sorbus aucuparia-Deschampsia flexuosa community on very acid and oligotrophic soils. Synonyms in the recent literature on Nordic beech forests to these communities are given. An ordination with the program DECORANA confirmed the primary significance of soil acidity and nutrient status for community differentiation.p>     

Do community‐level models describe community variation effectively?

Aim The aim of community‐level modelling is to improve the performance of species distributional models by taking patterns of co‐occurrence among species into account. Here, we test this expectation by examining how well three community‐level modelling strategies (‘assemble first, predict later’, ‘predict first, assemble later’, and ‘assemble and predict together’) spatially project the observed composition of species assemblages. Location Europe. Methods Variation in the composition of European tree assemblages and its spatial and environmental correlates were examined with cluster analysis and constrained analysis of principal coordinates. Results were used to benchmark spatial projections from three community‐based strategies: (1) assemble first, predict later (cluster analysis first, then generalized linear models, GLMs); (2) predict first, assemble later (GLMs first, then cluster analysis); and (3) assemble and predict together (constrained quadratic ordination). Results None of the community‐level modelling strategies was able to accurately model the observed distribution of tree assemblages in Europe. Uncertainty was particularly high in southern Europe, where modelled assemblages were markedly different from observed ones. Assembling first and predicting later led to distribution models with the simultaneous occurrence of several types of assemblages in southern Europe that do not co‐occur, and the remaining strategies yielded models with the presence of non‐analogue assemblages that presently do not exist and that are much more strongly correlated with environmental gradients than with the real assemblages. Main conclusions Community‐level models were unable to characterize the distribution of European tree assemblages effectively. Models accounting for co‐occurrence patterns along environmental gradients did not outperform methods that assume individual responses of species to climate. Unrealistic assemblages were generated because of the models’ inability to capture fundamental processes causing patterns of covariation among species. The usefulness of these forms of community‐based models thus remains uncertain and further research is required to demonstrate their utility.     

21st century climate change threatens mountain flora unequally across Europe

Continental‐scale assessments of 21st century global impacts of climate change on biodiversity have forecasted range contractions for many species. These coarse resolution studies are, however, of limited relevance for projecting risks to biodiversity in mountain systems, where pronounced microclimatic variation could allow species to persist locally, and are ill‐suited for assessment of species‐specific threat in particular regions. Here, we assess the impacts of climate change on 2632 plant species across all major European mountain ranges, using high‐resolution (ca. 100 m) species samples and data expressing four future climate scenarios. Projected habitat loss is greater for species distributed at higher elevations; depending on the climate scenario, we find 36–55% of alpine species, 31–51% of subalpine species and 19–46% of montane species lose more than 80% of their suitable habitat by 2070–2100. While our high‐resolution analyses consistently indicate marked levels of threat to cold‐adapted mountain florae across Europe, they also reveal unequal distribution of this threat across the various mountain ranges. Impacts on florae from regions projected to undergo increased warming accompanied by decreased precipitation, such as the Pyrenees and the Eastern Austrian Alps, will likely be greater than on florae in regions where the increase in temperature is less pronounced and rainfall increases concomitantly, such as in the Norwegian Scandes and the Scottish Highlands. This suggests that change in precipitation, not only warming, plays an important role in determining the potential impacts of climate change on vegetation.