► Old-growth forests showed global commonalities when compared to mature stands. ► Old-growth showed higher amounts of large living trees, aboveground biomass and CWD. ► Stand age correlates to basal ...area, large living trees and aboveground biomass. ► Geographical, compositional and climatic influences most structural variables. ► There is a lack of studies on temperate forests in Russia, Western and Central Asia.
Temperate forests have been fundamentally altered by land use and other stressors globally; these have reduced the abundance of primary and old-growth forests in particular. Despite many regional studies, the literature lacks a global synthesis of temperate old-growth structural characteristics. In this study we compare literature derived data on mature and old-growth moist temperate forests with the aim of: (i) exploring global commonalities; (ii) investigating sources of variability among systems; and (iii) highlighting data gaps and research needs. We compiled a dataset of 147 records from 93 papers, and analyzed a set of structural indicators: basal area, stem density, large living trees, live aboveground biomass, quadratic mean diameter, and coarse woody debris volume. These indicators were contrasted between mature and old-growth age classes at a global level and across continents and broad forest types, testing for significance through Monte-Carlo permutation procedure. We also related structural indicators to age, climatic and geographical descriptors. Our results suggest that all structural indicators vary across systems in relation to geographical, compositional, and climatic influences. However old-growth forests showed global commonalities in structure when compared to mature forests: significantly higher densities of large living trees, higher quadratic mean diameter, and higher amounts of live aboveground biomass and coarse woody debris. Furthermore we found inconsistency in the structural variables reported by different papers; lack of studies on temperate forests in Russia, and Western and Central Asia. The findings improve our understanding of old-growth structure and function, and will help inform sustainable forest management and conservation approaches world-wide.
Beta‐diversity has been repeatedly shown to decline with increasing elevation, but the causes of this pattern remain unclear, partly because they are confounded by coincident variation in alpha‐ and ...gamma‐diversity. We used 8795 forest vegetation‐plot records from the Czech National Phytosociological Database to compare the observed patterns of beta diversity to null‐model expectations (beta‐deviation) controlling for the effects of alpha‐ and gamma‐diversity. We tested whether β‐diversity patterns along a 1200 m elevation gradient exclusively depend on the effect of varying species pool size, or also on the variation of the magnitude of community assembly mechanisms determining the distribution of species across communities (e.g. environmental filtering, dispersal limitation). The null model we used is a novel extension of an existing null‐model designed for presence/absence data and was specifically designed to disrupt the effect of community assembly mechanisms, while retaining some key features of observed communities such as average species richness and species abundance distribution. Analyses were replicated in ten subregions with comparable elevation ranges. Beta‐diversity declined along the elevation gradient due to a decrease in gamma‐diversity, which was steeper than the decrease in alpha‐diversity. This pattern persisted after controlling for alpha‐ and gamma‐diversity variation, and the results were robust when different resampling schemes and diversity metrics were used. We conclude that in temperate forests the pattern of decreasing beta‐diversity with elevation does not exclusively depend on variation in species pool size, as has been hypothesized, but also on variation in community assembly mechanisms. The results were consistent across resampling schemes and diversity measures, thus supporting the use of vegetation‐plot databases for understanding patterns of beta‐diversity at the regional scale.
The extension of forest area is a globally accepted tool to offset CO2 emissions from deforestation and the combustion of fossil fuels. The common assumption is that in addition to the perceived ...climate benefits increasing forest area will also support biodiversity, thus making afforestation a “win-win scenario”. Based on the existing scientific evidences, we show that joined climate and biodiversity benefits are strongly context-dependent and that the outcome of afforestation is often highly questionable. In Europe, grasslands managed at low intensity contribute substantially to biodiversity conservation and carbon storage. However, many of these grasslands have been lost due to abandonment and subsequent spontaneous succession towards woody vegetation, or due to land use intensification. Moreover, grasslands are the ecosystems most often deliberately afforested in the context of EU carbon-centered policies that may thus counteract biodiversity conservation programmes. By reviewing the main EU policies targeting forests and grasslands, we found a striking ambivalence between policies and funding schemes addressing grassland conservation on the one hand (e.g. Habitats Directive, green payments within the Common Agricultural Policy) and those supporting afforestation on the other (e.g. rural development funds). We suggest three measures towards a better harmonization of the European Union policies that target forest and grassland ecosystems: (1) promoting the alignment of the decisions taken across different policy sectors; (2) focusing on the whole range of ecosystem services and biodiversity issues rather than on carbon management only; (3) valuing systems managed at low-intensity for their multifunctionality.
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•About 17% of EU grasslands have conservation value (sensu Habitats Directive)•An unfavourable conservation status is reported for about 80% of these grasslands•About 2000km2 of EU grasslands are lost annually, mostly those extensively managed•This loss is due to afforestation (30%) and to conversion to crops/urban sprawl (70%)•Afforestation cannot offset CO2 emissions and hampers biodiversity conservation
Policies to mitigate climate change and biodiversity loss often assume that protecting carbon‐rich forests provides co‐benefits in terms of biodiversity, due to the spatial congruence of carbon ...stocks and biodiversity at biogeographic scales. However, it remains unclear whether this holds at the scales relevant for management, and particularly large knowledge gaps exist for temperate forests and for taxa other than trees. We built a comprehensive dataset of Central European temperate forest structure and multi‐taxonomic diversity (beetles, birds, bryophytes, fungi, lichens, and plants) across 352 plots. We used Boosted Regression Trees (BRTs) to assess the relationship between above‐ground live carbon stocks and (a) taxon‐specific richness, (b) a unified multidiversity index. We used Threshold Indicator Taxa ANalysis to explore individual species’ responses to changing above‐ground carbon stocks and to detect change‐points in species composition along the carbon‐stock gradient. Our results reveal an overall weak and highly variable relationship between richness and carbon stock at the stand scale, both for individual taxonomic groups and for multidiversity. Similarly, the proportion of win‐win and trade‐off species (i.e., species favored or disadvantaged by increasing carbon stock, respectively) varied substantially across taxa. Win‐win species gradually replaced trade‐off species with increasing carbon, without clear thresholds along the above‐ground carbon gradient, suggesting that community‐level surrogates (e.g., richness) might fail to detect critical changes in biodiversity. Collectively, our analyses highlight that leveraging co‐benefits between carbon and biodiversity in temperate forest may require stand‐scale management that prioritizes either biodiversity or carbon in order to maximize co‐benefits at broader scales. Importantly, this contrasts with tropical forests, where climate and biodiversity objectives can be integrated at the stand scale, thus highlighting the need for context‐specificity when managing for multiple objectives. Accounting for critical change‐points of target taxa can help to deal with this specificity, by defining a safe operating space to manipulate carbon while avoiding biodiversity losses.
Can managing forests for storing carbon jointly achieve biodiversity conservation and climate change mitigation goals? Global and regional environmental policies often assume co‐benefits between carbon and biodiversity, but it is unclear whether this assumption holds at fine scales relevant for management. By modelling the carbon–biodiversity relationship for a broad range of taxa in temperate forests, we found that biodiversity and carbon stocks are not well‐aligned spatially at stand‐scale, and their relationship varied substantially across taxa. This suggests that forest management aimed at storing carbon may benefit some taxa but harm others, highlighting that broad‐scale co‐benefits may break down at fine scales.
Different assembly processes may simultaneously affect local-scale variation of species composition in temperate old-growth forests. Ground layer species diversity reflects chance colonization and ...persistence of low-dispersal species, as well as fine-scale environmental heterogeneity. The latter depends on both purely abiotic factors, such as soil properties and topography, and factors primarily determined by overstorey structure, such as light availability. Understanding the degree to which plant diversity in old-growth forests is associated with structural heterogeneity and/or to dispersal limitation will help assessing the effectiveness of silvicultural practices that recreate old-growth patterns and structures for the conservation or restoration of plant diversity. We used a nested sampling design to assess fine-scale species turnover, i.e. the proportion of species composition that changes among sampling units, across 11 beech-dominated old-growth forests in Southern Europe. For each stand, we also measured a wide range of environmental and structural variables that might explain ground layer species turnover. Our aim was to quantify the relative importance of dispersal limitation in comparison to that of stand structural heterogeneity while controlling for other sources of environmental heterogeneity. For this purpose, we used multiple regression on distance matrices at the within-stand extent, and mixed effect models at the extent of the whole dataset. Species turnover was best predicted by structural and environmental heterogeneity, especially by differences in light availability and in topsoil nutrient concentration and texture. Spatial distances were significant only in four out of eleven stands with a relatively low explanatory power. This suggests that structural heterogeneity is a more important driver of local-scale ground layer species turnover than dispersal limitation in southern European old-growth beech forests.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Questions: To what extent have semi-natural grassland plant species composition and functional traits changed during the past five decades? Which are the main directions of change? Which ...environmental, management and landscape factors have determined these changes? Location: Central and southern Apennines of Italy. Methods: In 2013-2014, we used a stratified random sampling design to revisit 132 semi-natural grasslands originally sampled between 1966 and 1992. The exact locations of the historical plots were not available but they were associated with detailed vegetation maps. Plots were divided in 17 groups based on study area and original community type. To assess changes in species composition we ran PERMANOVA and RDA. The extent of change was estimated by comparing each new plot with the quantitative species pool of the corresponding historical group; species composition changes were calculated using Bray-Curtis coefficient, and shifts in functional traits were quantified as differences in community-weighted means. These measures of change were used as response variables in mixed effects models including climate, topography, management and landscape metrics as explanatory variables. Results: The largest changes were related to successional dynamics, which occurred mainly in grasslands developing at low altitude and in the flattest sites where the soil organic horizon was relatively thick. Colonization by shrubs and trees was facilitated by high soil pH and amount of adjacent forests. Also, management factors affected the patterns of shifts in species composition and functional traits: grazing intensity was negatively related to the degree of compositional change as well as to the abundance of woody species, whereas the increase of species associated with frequent grazing disturbance was found at sites with higher values of soil salinity. Conclusions: Apennine semi-natural grasslands have undergone substantial changes in species composition and functional traits during recent decades. Compositional changes mainly indicated successional dynamics, likely following a decrease in grazing intensity, whereas some more accessible grasslands experienced an increase in disturbance-tolerant species. The combination of the re-visitation approach with functional traits allowed us to clarify different directions of changes in species composition, adding information on the ecological processes related to these changes.
Natura 2000 is a European network of protected sites that should enable natural habitats to be maintained or restored at a favorable conservation status. Progress toward this objective must be ...periodically reported by states members of the European Union. We investigated how forest management plans might provide data to support the reporting. The study was done in the forests of the Dolomites and Venetian Prealps, Italy. Here, about 200 forest management plans, divided into several forest compartments, have been drawn up and revised every 10–15 years. Stand structure variables were retrieved from past (OR, 1970–1980) and more recent revisions (NR, 2000–2010) of 331 forest compartments ranging between 0.35 and 53.1 ha. In the beech and spruce forest habitat types (coded 9130 and 9410 in Annex I of the Directive 92/43/EEC, respectively), we found an increase from OR to NR in the density of large trees (from 32 to 46/ha and from 31 to 50/ha, respectively for the two habitats), basal area (from 27.3 to 31.5 m
2
/ha and from 31 to 34.5 m
2
/ha), mean diameter (from 34.1 to 36.2 cm and from 33.9 to 36 cm) and Gini index (from 0.35 to 0.37 and from 0.33 to 0.36). Pursuant to the Directive 92/43/EEC, the conservation status of these two habitat types should be taken as “favorable” with regards to the criterion related to the habitats’ specific structure and functions that are necessary for its long-term maintenance. We conclude that forest management plans provide a great portion of the information needed for assessing and monitoring the conservation status of forest habitat types in the Natura 2000 framework.
Simulations of the land surface carbon cycle typically compress functional diversity into a small set of plant functional types (PFT), with parameters defined by the average value of measurements of ...functional traits. In most earth system models, all wild plant life is represented by between five and 14 PFTs and a typical grid cell (≈100 × 100 km) may contain a single PFT. Model logic applied to this coarse representation of ecological functional diversity provides a reasonable proxy for the carbon cycle, but does not capture the non‐linear influence of functional traits on productivity. Here we show through simulations using the Energy Exascale Land Surface Model in 15 diverse terrestrial landscapes, that better accounting for functional diversity markedly alters predicted total carbon uptake. The shift in carbon uptake is as great as 30% and 10% in boreal and tropical regions, respectively, when compared to a single PFT parameterized with the trait means. The traits that best predict gross primary production vary based on vegetation phenology, which broadly determines where traits fall within the global distribution. Carbon uptake is more closely associated with specific leaf area for evergreen PFTs and the leaf carbon to nitrogen ratio in deciduous PFTs.
Plain Language Summary
Plants play a critical role in the global carbon cycle, and diversity has been shown to influence vegetation productivity. However, when the land surface is simulated in a global model all wild plant life is reduced to a small number of plant functional types. Here we estimate how incorporating diversity influences ecosystem carbon uptake in 15 globe spanning landscapes. We find that diversity has a strong influence on modeled productivity, particularly in the arctic and tropics. Further, we find that whether plants shed their leaves annually has a strong influence on where traits fall within the global distribution and thus how traits and productivity interact.
Key Points
We implemented distributions of leaf economic spectrum traits in a land surface model in 15 diverse landscapes
Trait variation has a substantial influence on gross primary production (GPP)
Phenology plays a key role in guiding where traits fall within the global trait distribution and hence trait‐GPP relationships
Questions
Semi‐natural habitats are threatened by shifts in management with worrying effects on multiple facets of biodiversity. We revisited sites once representing a reference for a calcareous ...semi‐natural grassland habitat aiming to: (a) identify the drivers of taxonomic, functional and phylogenetic diversity, and habitat conservation state; (b) assess the role of characteristic and derived diversity in determining these patterns; and (c) discuss the possibility of reconciling the goals of habitat conservation and enhancement of different facets of plant diversity.
Location
Seven sites along the Apennines (Italy), from Mt. Catria (43.46206° N, 12.70397° E) to Mt. Alpi (40.11768° N, 15.98341° E).
Methods
For 132 revisited plots, we calculated vascular plant taxonomic, functional and phylogenetic diversity using Hill numbers, and used boosted regression trees to investigate their response to the compositional dissimilarity from historical plots, to grazing intensity and to environmental variables. We identified characteristic and derived diversity and summarized them in an index of habitat conservation state whose drivers were investigated using the same approach.
Results
Plant diversity was influenced by the site, whereas the habitat conservation state responded more markedly to vegetation type. Grazing intensity, slope and soil variables drove taxonomic and functional diversity, and the habitat conservation state, with some differences in their relative importance. Phylogenetic diversity responded only partly to grazing intensity, while it showed a major response to increasing temperatures.
Conclusions
Patterns and drivers of different facets of plant diversity partially differ from those of the habitat conservation state, suggesting that the management of semi‐natural habitats should be carefully tailored on specific conservation objectives. Generalized actions on grazing regimes and litter removal can promote habitat conservation, whereas the outcomes of these actions for plant diversity may differ across sites. Identifying areas particularly subjected to land‐use changes and/or climate warming may drive conservation actions.
By revisiting reference sites of calcareous semi‐natural grasslands, we found different patterns and drivers of plant diversity and habitat conservation state. Vegetation deviation from the habitat reference state, taxonomic and functional diversity mainly respond to grazing regimes, while phylogenetic diversity does to climate warming.
Tree invasions in Italian forests Campagnaro, Thomas; Brundu, Giuseppe; Burrascano, Sabina ...
Forest ecology and management,
10/2022, Letnik:
521
Journal Article
Recenzirano
Odprti dostop
•Riparian forests are particularly vulnerable to non-native tree invasion.•Robinia pseudoacacia and Ailanthus altissima are by far the most frequent invaders.•Eucalyptus camaldulensis, ...Populus × canadensis and Ulmus pumila have spread recently.•Potentially invasible forests can provide information on the future threat posed by non-native trees.•Tailored strategies are needed for the management of non-native tree species.
Many forest tree species have been moved outside their native range to provide goods and services elsewhere, but some of them have become invasive, causing negative impacts on biodiversity and human activities. The assessment and knowledge on the degree and scale to which forest ecosystems are invaded by non-native trees is of paramount importance for tailored policies and strategies aiming at forest conservation. By analyzing main databases and literature and applying a four-level scale of invasion (not currently invaded and with low invasibility; potentially invasible; moderately invaded; massively invaded), we assessed the current and potential occurrence of twenty-five invasive non-native trees across forest ecosystems in Italy. Vulnerability to invasion substantially differed across forest categories, with riparian forests being particularly vulnerable to invasion. Acacia dealbata, Juglans nigra, Populus × canadensis and Prunus laurocerasus invaded a relatively small number of forest categories but showed their potential to widen their impact on others. Furthermore, some non-native species showed a recent increase of their invasive status in Italy. This study identified the Italian forest categories and non-native tree species that deserve primary attention, and can support proper management and allocation of funding to protect forests from the spread of invasive tree species.
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