Phytosociology and phytogeography of fragmented Alnus glutinosa forests in a Tyrrhenian district (Central Italy)

Summary This study illustrates the results of a floristic and phytosociological study conducted in a small portion (375 ha) of the Merse valley. Following a brief description of the geomorphologic and climatic aspects, the bryological and vascular flora is presented, obtained through floristic field studies and bibliographic data. The bryological flora includes 25 moss species including Sphagnum subnitens and S. capillifolium, which are of interest from a conservationist viewpoint, and 5 liverworts; the vascular flora comprises 252 species (belonging to 68 families and 186 genera); there are only three endemic entities but many species considered as rare or of interest, including Anagallis minima, Blechnum spicant, Carex viridula, Dryopteris dilatata, Erythronium dens-canis, Juncus bulbosus, Osmunda regalis and Radiola linoides, thus highlighting the phytogeographical relevance of this biotope. Chorological analysis highlighted the dominance of eurosiberian and boreal elements. The principal vegetation types sampled can be ascribed to the following alliances: Cicendio filiformis-Solenopsion laurentiae (Isoetetalia, Isoeto-Nanojuncetea), Osmundo-Alnion and Alnion incanae (Populetalia albae, Querco-Fagetea), Erythronio dens-canis-Quercion petraeae and Teucrio siculi-Quercion cerridis (Quercetalia-pubescen- ti-petraeae, Querco-Fagetea), Sarothamnion scoparii (Cytisetalia scopario-striati, Cytisetea scopario-striati). There are three habitats of Community interest: alluvial forests with Alnus glutinosa (code 91EO), woods of Castanea sativa (code 9260) and rare short-lived small coenoses of Isoeto-Nanojuncetea (code 3130).

The paper presents changes in color and selected physico-chemical properties of alder (Alnus glutinosa) wood during the process of thermal treatment of the wood with a saturated steam-air mixture or saturated water steam in the temperature range t = 95–125 °C for τ = 3 to 12 h. During the process of thermal treatment of alder wood, the original light white-gray color changes depending on the temperature and time of modification to soft reddish-brown to dark brown color shades. Color changes of alder wood expressed in the form of the total color difference are in the range of values ∆E* = 2.7–31.7. Measurements of the density of thermally treated alder wood in the dry state indicate that due to the thermal treatment of alder wood, the density decreases by ρ ≤ 4.6% compared to the average density of native alder wood. Due to the hydrolysis of hemicelluloses, in the process of thermal treatment of wet alder wood, its acidity changes in the range of values: pH = 4.9 to 3.1. Analyzes of ATR-FTIR spectroscopy indicate changes in alder wood extractants and hemicellulose degradation. A decrease in unconjugated and an increase in conjugated carbonyls was observed at all temperatures of thermal modification of alder wood. Measurements indicate changes in the lignin of alder wood and the fact that as the temperature increases, the formation of new carbonyls increases, which is reflected in the change of the chromophoric system.

Riparian woods with Alnus glutinosa and Osmunda regalis in Tuscany (central Italy) were studied, whilst western European riparian alderwoods were analysed from a phytogeographical perspective, with particular reference to Osmundo–Alnion and its suballiances. Two associations were identified through the phytosociological analysis of the Tuscan coenoses: Carici pallescentis–Osmundetum regalis ass. nova for mainland Tuscany and Carici microcarpae–Alnetum glutinosae for the Tuscan islands. A phytogeographical analysis for western Europe (47 phytocoenoses, 567 relevés) was performed using floristic classification and chorology‐based discriminant analysis. These allowed us to identify phytocoenoses: (1) attributed to Alnion incanae, correlated with the Eurasian and Boreal chorotypes; and (2) attributed to Osmundo–Alnion, correlated with the west Mediterranean, wide‐distribution and Atlantic chorotypes. The floristic and ecological differences allowed us to divide Osmundo–Alnion into two suballiances: (1) phytocoenoses distributed on the Iberian peninsula, correlated with the Atlantic and endemic Iberian chorotypes, attributable to Osmundo–Alnenion; and (2) phytocoenoses distributed in Algeria, Corsica, Sardinia, Sicily and Tyrrhenian Italy, correlated with the Mediterranean, endemic Sardinian–Corsican and endemic Italian chorotypes, attributable to Hyperico hircini–Alnenion glutinosae.

Alder wood (Alnus glutinosa L.) was steamed with a saturated steam-air mixture at a temperature of t = 95 °C, or saturated steam at t = 115 °C and t = 135 °C to obtain a pale brown colour, a light red-brown colour and a dark brown-grey colour. Subsequently, samples of unsteamed and steamed alder wood were irradiated with a UV lamp in a Xenotest Q-SUN Xe-3-HS after drying in order to test the colour stability of steamed alder wood. The colour change of the wood surface was evaluated by means of measured values on the coordinates of the colour space CIE L*a*b*. The results show that the surface of unsteamed alder wood as well as steamed alder wood with a steam-air mixture at t = 95 °C and saturated steam at t = 115 °C darkened and browned due to photochemical reactions caused by UV radiation. The opposite tendency was recorded at the surface of alder wood steamed with saturated steam with a temperature of t = 135 °C, where the deep dark-brown-grey colour lightened to a brown-reddish colour shade under the influence of UV radiation. The analysis of the changes in the coordinates of the colour space CIE L*a*b* shows that the greater the darkening and browning of the alder wood by steaming, the smaller the changes in the values of ΔL*, Δa*, Δb* of the steamed alder wood caused by UV radiation. The positive effect of steaming on UV resistance is evidenced by the decrease in the overall colour difference ΔE*. While the value of the total colour difference of unsteamed alder wood caused by UV radiation is ΔE* = 10.9, it decreased to ΔE* = 8.7 for alder wood steamed with steam-air mixture at t = 95 °C, which is a decrease of 20.2 %; for alder wood steamed at t = 115 °C it decreased to ΔE* = 6.5, which is a decrease of 40.3 %; and for alder wood steamed with saturated water steam with the temperature t = 135 °C it decreased to ΔE* = 5.7, which is a decrease of 47.7 %.

A comparative analysis of the riparian vegetation dominated by Alnus glutinosa in Italy and Tyrrhenian islands, based on literature data and unpublished relevés, is presented. A total of 456 phytosociological relevés were processed. For the definition of plant communities and alliances, hierarchical clustering was performed by using Bray-Curtis coefficient and Detrended Correspondence Analysis ordination methods. Identification of diagnostic species of the vegetation units was performed by means of the phi fidelity index. Quantum GIS software version 3.6 was used for the interpolation of the bioclimatic variables and A. glutinosa communities. Overall, a total of 18 A. glutinosa-riparian wood communities were distinguished for Italy and Tyrrhenian islands, of which two new associations and one new subassassociation are described. The classification of the relevés showed two main vegetation groups: the first one including the plant communities of the Osmundo-Alnion alliance, and the other including the vegetation of the Ligustro vulgaris-Alnion glutinosae alliance. This latest includes the riparian meso-thermophilous communities of central and northern Italy. Within the Osmundo-Alnion alliance, two subgroups can be recognized: the first one includes the thermophilous communities of the Hyperico hircini-Alnenion glutinosae sub-alliance, mainly spread in the Tyrrhenian islands, while the second group includes the mesophilous communities attributed to the new suballiance Struthioptero-Alnenion glutinosae, widespread in central Italy and the Corsican mountains. The present paper provides the first comprehensive and exhaustive scheme of the A. glutinosa riparian woodlands diversity in Italy and Corsica.

Spectral discrimination between riparian forests is a challenging issue due to the inherent complexity of species composition and the high spatial structural variability of these vegetation types. This study aimed to evaluate spectral separability among riparian forests, in small and medium-sized river catchment areas, in three bioclimatic zones of Portugal (temperate, transitional, and Mediterranean). We also assess the spectral differences using only the dominant riparian woody species in each riparian forest class, namely Alnus glutinosa, Salix salviifolia, and Nerium oleander. Pixel values were extracted from high-resolution airborne multispectral imagery (red, green, blue, and near-infrared, 50 cm pixels) of 26 riparian forests located in the three bioclimatic zones. Spectral separability was calculated using the transformed divergence (TD) distance. Discriminant analysis (DA) was used to select the bands that contribute most to the spectral separability and for the classification accuracy assessment of the riparian forests. Species composition and percentage of canopy closure were collected for all the riparian forests in a field campaign and subjected to hierarchical clustering in order to validate the spectral separability analyses. Optical traits derived from field data were used to interpret the spectral differences between riparian forest classes. The greatest spectral separability was observed between the temperate and the Mediterranean riparian forest classes. Global classification accuracy for the DA was 86.3% for riparian forest classes along medium-sized rivers and 70.1% in small-sized ones. The high floristic and spatial structure variability was responsible for the misclassification errors that occurred between the transitional and the other riparian forest classes. The spectral separability using only the dominant species was greater than that obtained using the overall species assemblages of the riparian forests. Alnus glutinosa had the highest level of classification accuracy, and this may be related to its peculiar yellowish-green tone. DA also revealed that all spectral bands were needed in order to distinguish the riparian forest classes. This study provided evidence that the spectral discrimination of riparian forests can be explained on the basis of differences in species composition and cover, and by a convergence of optical traits, at both leaf and canopy levels. Spectral signatures of these riparian forests and related spectral signatures of key species are useful tools for evaluating the floristic deviations of actual riparian forests from their near-natural benchmarks.

The article presents preliminary results of the biological durability of oil heat treated (OHT) alder wood (Alnus glutinosa) against pure cultures of rot fungi (Postia placenta and Trametes versicolor) in lab condi- tions. The modifi cation was performed by heating of specimens immersed in soya oil. There were four heating regimes of different duration (6 and 10 hours) at fi nal temperature of 180 and 200 oC. The increase in mass (MI) caused by modifi cation and mass loss of wood caused by fungal decay (ML) were determined. In addition, the natural durability of alder wood was determined and compared to the natural durability of beech wood as the reference wood species. After modifi cation of alder wood at 200 °C, MI was lower than after treatment at 180 °C. MI was also lower after 10 hours of treatment than after 6 hours of treatment. The results showed signifi cantly increased biological dura- bility of modifi ed alder wood against both tested fungi. The effect of OHT on increasing the biological durability of alder wood was higher against the fungus P. placenta. It seems that the fungus T. versicolor favours the remained oil after modifi cation causing higher mass loss. The results showed that alder wood, thermally modifi ed in soya oil by testing regimens, is not suitable for applications in use classes 3-5.

Riparian forests are important ecosystems that support an enormous biodiversity in Brazil. Despite being protected under Brazilian legislation, these forests suffer great impact from the fragmentation of habitats. Orchid bees are a key group of pollinators in the Neotropical region, yet few data are available on the assamblage structure of these bees in riparian forests. We evaluated the role of fragments of riparian and terra-firme forest on the conservation and maintenance of orchid bees in an urban landscape in the southwestern Amazon basin. Specifically, we evaluated whether bee assemblages in riparian and terra-firme forests differed significantly in abundance, species richness and composition. We also evaluated whether species richness and abundance of bees vary with the size of the forest fragment. Male bees were attracted using odoriferous baits and collected with entomological nets in 10 forest fragments. There was no significant difference between riparian and terra-firme fragments in species abundance, richness and composition, but there was a positive correlation between fragment size and species richness and abundance. Our results suggest that, in an urban landscape, the remaining riparian and terra-firme forest fragments still could maintain 62.7% of the orchid bee species known to occur in the region, reinforcing the conservation value of these forest remnants. Our findings indicate that these fragments provide a potentially important habitat for the maintenance of local bee populations in the landscape.

Home range and habitat selection of southern flying squirrels in fragmented forests

Natural ecosystems are declining and fragmenting globally at unprecedented rates. Fragmentation of natural ecosystems leads to decline in functions and services with severe impact on people. In Ecuador, despite establishment of the nationwide ecosystem classification, this baseline information has not been fully exploited to generate a monitoring system for ecosystem changes. Forest ecosystems are altered daily in Ecuador by human impact, but the relationship between forest fragmentation and human land use has not been adequately explored. To provide an overview of how recent forest fragmentation at the national and ecosystem level was affected by practices in human land use, we quantified the degree of forest fragmentation using the forest fragmentation index (FFI). The relationship between the degree of forest ecosystem fragmentation and human land use of 64 natural forest ecosystems was analyzed during the time period 1990 to 2014. At the national level, the expansion of pasture and inhabited area significantly increased forest fragmentation. The regression models based on the FFI value indicated that the forest fragmentation was highly correlated to pastures in forest ecosystems with low, moderate, and high fragmentation in 2014 due to a progressive increase in pastures. This study showed the critical gaps between forest conservation strategies and actual practices in human land use.

Modeling the age of tropical moist forest fragments in heavily-cleared lowland landscapes of Colombia

Production of hypogeous fungi (truffles) in high-elevation, 180-year-old mature forest fragments of Pseudotsugamenziesii (Mirb.) Franco was compared with surrounding regenerated clearcuts ranging from 4 to 27 years since harvest at two study areas. Thirty pairs of plots, one of each pair in soil, the other in brown-cubical-rotted coarse woody debris (CWD), were searched for truffles in each stand during four periods; August and November 1990, and February and May 1991. Overall analysis of presence/absence of truffles using log-linear models revealed that CWD and mature forest status of stands each significantly influence truffle occurrence. Mature forest fragments had greater percent frequency of occurrence and truffle number and dry weight than did plantations. Truffle numbers and dry weight were 30 and 20 times greater, respectively, in mature forests than in plantations. The plantations did not differ significantly among each other for any parameter. CWD yielded higher numbers and biomass of truffles than soil in the mature forest, but production in plantations did not differ between substrates. The total dry weight of truffles in CWD exceeded that in soil by more than 10 times in mature forests. Of 21 truffle species found, 13 were only in the mature forest and 8 only under coarse woody debris. Forest practices that emphasize the retention of mature trees and coarse woody debris promote the abundance and diversity of truffles, which are integral and functionally important members of forest ecosystems.

Calorimetric properties of water and triacylglycerols in fern spores relating to storage at cryogenic temperatures

QuestionsWhat are the species and functional trait composition of riparian forests in near‐natural Southwest European rivers? Are functional trait and species assemblages constrained by environment?LocationNear‐natural riparian habitats throughout mainland Portugal, Southwest Europe.MethodsWe collected data on riparian woody abundances and environmental variables from 175 river locations. Twenty‐eight key functional traits were assigned to the surveyed species. Hierarchical clustering and indicator species analysis were used to derive compositional and functional groups of sites. We used Mantel tests to relate species and trait abundances and environmental gradients, and identified sets of relevant variables at diverse spatial scales. Then, four Dispersion indicators were developed to assess the extent to which the groups are constrained by the environment. These measures were tested for significance using iteration procedures.ResultsClustering revealed four compositional groups of sites: Alder woods, Ash woods, Tree–heath shrublands and Semi‐arid shrublands; and three functional groups: Mixed riparian forests, Shrublands with fleshy fruits and Stress‐tolerant shrublands. These groups were primarily defined by broad‐scale gradients of climate, elevation and river hierarchy. The most dispersed groups had broad trait composition (e.g. Mixed riparian forests) and were floristically diverse (Alder woods). In general, the compositional groups were more closely related to environmental gradients than the functional groups.ConclusionsAssemblages with very specific functional traits or with homogeneous species composition were largely constrained to the most extreme environmental conditions in the study area. Future research to assist environmental management should be directed to the role of fine‐scale environmental determinants of riparian assemblages, especially those related to flow variability and water stress.

In forest–grassland mosaics, patches can result from two processes: forest expansion over grassy ecosystems and forest fragmentation. We tested the hypothesis that patches produced by these processes differed in structure and spatial context in a forest–grassland mosaic in the southern Brazilian highlands. We compared a present‐day land cover map with a past vegetation map to identify natural forest patches and forest fragments. Patches were described according to structure (size, core area and shape metrics) and spatial context (distance from roads and urban areas, edge contrast). Principal component analyses were used to examine gradients of patch types, and differences were tested by analysis of variance with randomization test. We found 878 natural patches and 214 fragments. Natural forest patches, riparian forest patches and forest fragments differed in structure and spatial context. In comparison to natural forest patches, fragments tend to be larger, with larger core areas, and more irregular and complex in shape. Fragments are situated in a different spatial context, tending to be closer to roads and urban areas and to present higher edge contrast. Riparian natural forest patches are similar to natural forest patches, except for shape. The smaller area and regular shape of natural patches probably result from the mechanisms involved in nucleus formation in the grassland matrix and from current grassland management. Natural patches are less exposed to some anthropogenic stresses, since most of them remain in a native grassland matrix context. Our results show that inferring process from pattern is not trivial, because different processes – forest expansion and forest fragmentation – may lead to either distinct or similar patterns of patch shape and spatial context. Studying patch structure and spatial context may then provide further insight into understanding changes in vegetation pattern at landscape scale, and in disentangling the effects of concurrent processes.