STRUCTURAL PATTERNS, GROWTH PROCESSES, CARBON STOCKS IN AN ITALIAN NETWORK OF OLD-GROWTH BEECH FORESTS

In the framework of the Project of National Interest (PRIN) “Climate change and forests - Dendroecological and ecophysiological responses, productivity and carbon balance on the Italian network of old-growth beech forests”, 9 old beech (Fagus sylvatica L.) forests were sampled in the eastern Alps and in the central Apennines to assess: i) the degree of ‘old-growthness’ on a structural and dendroecological basis; ii) the carbon (C) stocks in the different ecosystem compartments; iii) some ecophysiological traits using stable isotopes. Live and dead tree structure, soil features and C stocks were examined in some among the oldest and less disturbed beech forests in Italy. Furthermore, leaves, litter and wood cores were sampled for concurrent dendroecological, nutrient and stable isotope analysis, to study age structure, disturbance history and medium- and long-term response to climate and ecophysiological traits. In all sampled stands, values of basal area, volume and large trees density reached or exceeded control values reported for European and North American old-growth forests, while total amount of deadwood was generally low, except in two sites. Diameter distribution showed a remarkable differentiation from bimodal to ‘rotated-sigmoid’ curve. In accordance with structural analyses, disturbance chronologies revealed the importance of frequent low-to-moderate events in generating a fine-scale structure, confirming previous results on beech forests. Different degrees of ‘old-growthness’ were identified for Alpine and Apennine beech stands through the ‘structural-based approach’, which proved to be a valid tool for old-growth forests detection. Preliminary results on carbon stocks on a subset of sites indicate that these old-growth forests are relevant carbon reservoirs, with 192-268 MgC ha-1 of total biomass (67-73% aboveground; 27-33% belowground, 4 stands) and 7-21 MgC ha-1 of deadwood. In these stands, also forest floor (excluding deadwood) and soils are stores of relevant amount of carbon (5-9 MgC ha-1 litter layer, 4 stands; 168-420 MgC ha-1 mineral soil, 3 stands). Finally, carbon isotope discrimination (Δ) analysis, a proxy of wateruse efficiency, was applied on tree-ring cores from a subset of sites. The perspectives of this technique for a retrospective ecophysiological interpretation of climate-change impact on old-growth forests were described. Preliminary results obtained within this PRIN project indicate that the reported ecological indicators can be used to produce a description of forest structures and processes driving stand dynamics (‘structural-based approach’). Furthermore, the use of multiple sampling and research techniques and the integration of research groups with complementary expertise can foster deeper understanding of the ecology and dynamics of old-growth forests.L'articolo è disponibile sul sito dell'editore http://www.aisf.it

The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data

The FLUXNET2015 dataset provides ecosystem-scale data on CO2, water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology studies, remote sensing studies, and development of ecosystem and Earth system models. FLUXNET2015 includes derived-data products, such as gap-filled time series, ecosystem respiration and photosynthetic uptake estimates, estimation of uncertainties, and metadata about the measurements, presented for the first time in this paper. In addition, 206 of these sites are for the first time distributed under a Creative Commons (CC-BY 4.0) license. This paper details this enhanced dataset and the processing methods, now made available as open-source codes, making the dataset more accessible, transparent, and reproducible.Peer reviewe

First record of Dinoderus (Dinoderastes) japonicus in Italy (Coleoptera: Bostrichidae)

Dinoderus (Dinoderastes) japonicus, a species native of the Eastern Palaearctic, is reported for the first time from Italy on the basis of a female specimen collected in a beech forest (Veneto Region, Treviso Province, Foresta del Cansiglio). The possible establishment of this alien species in Italy is briefly discussed

Biometric assessment of aboveground carbon pools and fluxes in three European forests by Randomized Branch Sampling

Accurate measurements of carbon pools and fluxes and of the related uncertainties are required to support the estimation of regional and continental carbon budgets. For this purpose a rigorous statistical method, known as Randomized Branching Sampling (RBS), has been applied for the direct assessment of carbon pools, fluxes (Net Primary Productivity) and plant surface areas in three forests. RBS is an unequal probability selection scheme that is design unbiased and efficient. Through its theory and design, RBS provides an unbiased estimate of uncertainties both at single tree and ecosystem scales. RBS designed samplings proved to be less time-consuming than traditional ones by lowering the number of sample branches needed to achieve the target precision levels and by getting rid of fresh weight measurements in the field. RBS estimates of C pools were compared and discussed to traditional estimates achieved by allometric functions fitted using the power equation Y ¼ b Xa revealing good agreement; differences between the RBS and allometric approaches were higher in older or more structured forests. Optimal scaling exponents for foliage, branch and stem components, for pool, flux and surface parameters in European beech, Scots pine and Norway spruce stands were estimated by analysis of the precision of target aggregate estimators. In all stands, the scaling exponent for the stand-scale estimates proved to be lower than the scaling exponent estimated from the allometric fitting and than analytically derived exponents. This discrepancy could lead, should the latter scaling exponents be used, to over-estimate C pools in forests.JRC.H.7-Climate Risk Managemen

The effect of thinning on bat activity in Italian high forests: the LIFE+ " ManFor C.BD." experience

Bats represent a major component of forest biodiversity. In forest, bats find many roosting and foraging opportunities. When foraging in forest, different bat species exploit a range of microhabitats according to their echolocation and flight style. When roosting, bats require sufficient numbers of suitable tree cavities. Overall, forest structure may influence both foraging and roosting behaviour, and in turn the number of bat species present and their population size. The exploitation of forests for commercial purposes may be a threat to biodiversity when logging leads to habitat loss, alteration or fragmentation. While some bat species may benefit from an increase in the amount of edge habitat determined by logging, others, more specialized to exploit forest interiors, may be potentially harmed. In this study we set out to assess the effect on foraging bats of different management approaches, comparing locally applied traditional approaches with innovative multifunctional management options and delayed logging. Within the framework of the LIFE+ ManFor C.BD. Project we surveyed the effects of thinning at four Italian forest sites, each representing a separate case study. We found that in logged plots bat activity either showed no difference from unlogged plots or resulted in an increase in foraging activity, suggesting that thinning, at least in the forest types we dealt with, has no adverse consequences on bat foraging. However, in our case the effects varied greatly across sites and were detected mostly when all bat species were pooled together for analysis. We conclude that forest exploitation may be sustainable and even favour foraging bats, but since our work neither covered direct mortality linked with forestry operations nor roost loss, further studies are needed to analyze these important aspects. We also highlight that total bat activity revealed by acoustic surveys carried out with automatic recorders may be used as an appropriate indicator of forestry effects on bats

Generalisation within specialization: inter-individual diet variation in the only specialized salamander in the world

Specialization is typically inferred at population and species level but in the last decade many authors highlighted this trait at the individual level, finding that generalist populations can be composed by both generalist and specialist individual. Despite hundreds of reported cases of individual specialization there is a complete lack of information on inter-individual diet variation in specialist species. We studied the diet of the Italian endemic Spectacled Salamander (Salamandrina perspicillata), in a temperate forest ecosystem, to disclose the realised trophic niche, prey selection strategy in function of phenotypic variation and inter-individual diet variation. Our results showed that Salamandrina is highly specialized on Collembola and the more specialized individuals are the better performing ones. Analyses of inter-individual diet variation showed that a subset of animals exhibited a broader trophic niche, adopting different foraging strategies. Our findings reflects the optimal foraging theory both at population and individual level, since animals in better physiological conditions are able to exploit the most profitable prey, suggesting that the two coexisting strategies are not equivalent. At last this species, feeding on decomposers of litter detritus, could play a key role determining litter retention rate, nutrient cycle and carbon sequestration

Patchiness of forest landscape can predict species distribution better than abundance: the case of a forest-dwelling passerine, the short-toed treecreeper, in central Italy

Environmental heterogeneity affects not only the distribution of a species but also its local abundance. High heterogeneity due to habitat alteration and fragmentation can influence the realized niche of a species, lowering habitat suitability as well as reducing local abundance. We investigate whether a relationship exists between habitat suitability and abundance and whether both are affected by fragmentation. Our aim was to assess the predictive power of such a relationship to derive advice for environmental management. As a model species we used a forest specialist, the short-toed treecreeper (Family: Certhiidae; Certhia brachydactyla Brehm, 1820), and sampled it in central Italy. Species distribution was modelled as a function of forest structure, productivity and fragmentation, while abundance was directly estimated in two central Italian forest stands. Different algorithms were implemented to model species distribution, employing 170 occurrence points provided mostly by the MITO2000 database: an artificial neural network, classification tree analysis, flexible discriminant analysis, generalized boosting models, generalized linear models, multivariate additive regression splines, maximum entropy and random forests. Abundance was estimated also considering detectability, through N-mixture models. Differences between forest stands in both abundance and habitat suitability were assessed as well as the existence of a relationship. Simpler algorithms resulted in higher goodness of fit than complex ones. Fragmentation was highly influential in determining potential distribution. Local abundance and habitat suitability differed significantly between the two forest stands, which were also significantly different in the degree of fragmentation. Regression showed that suitability has a weak significant effect in explaining increasing value of abundance. In particular, local abundances varied both at low and high suitability values. The study lends support to the concept that the degree of fragmentation can contribute to alter not only the suitability of an area for a species, but also its abundance. Even if the relationship between suitability and abundance can be used as an early warning of habitat deterioration, its weak predictive power needs further research. However, we define relationships between a species and some landscape features (i.e., fragmentation, extensive rejuvenation of forests and tree plantations) which could be easily controlled by appropriate forest management planning to enhance environmental suitability, at least in an area possessing high conservation and biodiversity values