Michele De Sanctis

Developing conservation strategies for endemic tree species when faced with time and data constraints: Boswellia spp. on Socotra (Yemen)

Many endemic tree species have important scientific, ecological and economic value but the scarcity of information about their biological and ecological features makes it difficult to develop conservation strategies for them. A four-step approach is presented to address this problem, based on the analysis of data collected in a limited-duration field study: (1) Data collected are used to analyse the ecological niche, population structure and regeneration status of the species in question. (2) Several IUCN Red List (RL) parameters, useful for assessing the species’ risk of extinction, are measured, including population counts, number of locations, extent and area of occurrence. (3) The IUCN RL parameters are used together with the other information gathered to set preliminary conservation priorities. (4) The analysis of utilization pattern is used to develop conservation actions specific to the environmental and socio-economic context. To test the applicability of this approach Boswellia spp. of Socotra island were analysed. Ground-rooted species (B. ameero, B. elongata and B. socotrana) were the most abundant and widespread and, according to the spatial analysis, were characterised by a geo-altitudinal zonation. However, the Weibull functions fitted on their stem diameters, and the absence or presence of only a small number of saplings highlighted a poor regeneration status. In the absence of conservation actions, these species will probably be subject to a progressive decline because of uncontrolled grazing. Of the four cliff-rooted species, which grow in sites that are less accessible to livestock, two (B. popoviana and B. dioscorides) were of lower conservation priority and may become the most numerically abundant. Conversely, the other two (B. nana and B. bullata), which may be threatened by stochastic events because of their reduced populations and small number of locations, were considered of very high priority. Different conservation actions were then identified for each species. In particular, for Boswellia species producing gum, the conservation-through-use action was discussed as a potential option.

A multiple approach for the evaluation of the spatial distribution and dynamics of a forest habitat: the case of Apennine beech forests with Taxus baccata and Ilex aquifolium

An approach integrating phytosociological and stand structure surveys with the predictive modelling of species distribution was applied to analyse the spatial distribution and dynamics of the Apennine beech forests with Taxus and Ilex, a high conservation priority forest habitat in Europe. The homogeneity of the habitat was tested trough a Mann–Whitney test between beech woods with Taxus and those with Ilex with respect to climatic, topographic, structural and environmental parameters: the former have proven to be more microthermic, mesophilous and characterised by a closer canopy. Five statistical models were compared to analyse the relationship between bioclimatic parameters and Taxus and Ilex spatial distribution: Regression Tree Analysis, the most efficient model, has shown that the distribution of Taxus is influenced by precipitation variables, while Ilex is mainly influenced by temperature variables. This model highlighted that Ilex has a potential area that surrounds, at lower altitudes, that of Taxus. A stepwise multiple regression analysis has been applied to identify the factors influencing the regeneration of the two species: beside climatic parameters, Taxus regeneration is negatively influenced by soil nitrate concentration (an indicator of livestock disturbance) while Ilex is negatively influenced by beech forest cover. Traditional management practices seem to have an effect on the regeneration of the two species: frequent cuts favour the regeneration of Ilex, reducing the forest cover and allowing more light penetration, while Taxus, less resistant to grazing livestock, is confined to more inaccessible places. The multiple approach has proven to be useful for the elaboration of two differentiated conservation strategies for the two beech forest types.

Classifying and Mapping Potential Distribution of Forest Types Using a Finite Mixture Model

The present paper presents the application of a finite mixture model (FMM) to analyze spatially explicit data on forest composition and environmental variables to produce a high-resolution map of their current potential distribution. FMM provides a convenient yet formal setting for model-based clustering. Within this framework, forest data are assumed to come from an underlying FMM, where each mixture component corresponds to a cluster and each cluster is characterized by a different composition of tree species. An important extension of this model is based on including a set of covariates to predict class membership. These covariates can be climatic and topographical parameters as well as geographical coordinates and the class membership of neighbouring plots. FMM was applied to a national forest inventory of Italy consisting of 6,714 plots with a measure of abundance for 27 tree species. In this way, a map of potential forest types was produced. The limitations and usefulness of the proposed modelling approach were analyzed and discussed, comparing the results with an independently derived expert map.

Vegetation mapping from high-resolution satellite images in the heterogeneous arid environments of Socotra Island (Yemen)

Abstract Socotra Island (Yemen), a global biodiversity hotspot, is characterized by high geomorphological and biological diversity. In this study, we present a high-resolution vegetation map of the island based on combining vegetation analysis and classification with remote sensing. Two different image classification approaches were tested to assess the most accurate one in mapping the vegetation mosaic of Socotra. Spectral signatures of the vegetation classes were obtained through a Gaussian mixture distribution model, and a sequential maximum a posteriori (SMAP) classification was applied to account for the heterogeneity and the complex spatial pattern of the arid vegetation. This approach was compared to the traditional maximum likelihood (ML) classification. Satellite data were represented by a RapidEye image with 5 m pixel resolution and five spectral bands. Classified vegetation relevés were used to obtain the training and evaluation sets for the main plant communities. Postclassification sorting was performed to adjust the classification through various rule-based operations. Twenty-eight classes were mapped, and SMAP, with an accuracy of 87%, proved to be more effective than ML (accuracy: 66%). The resulting map will represent an important instrument for the elaboration of conservation strategies and the sustainable use of natural resources in the island.

The Vegetation of the Buna River Protected Landscape (Albania)

Abstract The vegetation of Buna River Protected Landscape is described. The area comprises both the alluvial plain of the lower course of the Buna river that marks the boundary between Montenegro and Albania, and a carbonatic range. The vegetation is characterized by a high β-diversity (27 alliances and 46 associations), especially in wetlands and dry grasslands. In the area it is possible to distinguish 1 dunal and 4 hygro-sequences in the alluvial plain and 3 xeroseries in the carbonatic range. Associations Clematido viticellae-Punicetum granati and Periploco graecae-Alnetum glutinosae are described as new. Izvleček V članku je opisana vegetacija v zavarovanega območja ob reki Buna. Območje obsega aluvialno ravnino ob spodnjem teku reke Buna, ki predstavlja mejo med Črno goro in Albanijo in karbonatnim hribovjem. Za vegetacijo je značilna visoka β diverziteta (27 zvez in 46 asociacij), še posebej pa mokrišča in suha travišča. V območju smo izločili 1 sekvenco na sipinah, 4 higro sekvence na aluvialni ravnici in 3 ksero serije na karbonatnem masivu. Asociaciji Clematido viticellae-Punicetum granati in Periploco graecae-Alnetum glutinosae sta novo opisani.

The ophiolitic communities of Shebenik-Jablanice National Park (Albania)

The Shebenik-Jablanice National Park is located in east central Albania which is characterized by one of the most important outcrops of the Mirdita ophiolitic formation. Ophiolites are often serpentinized and rich in metals, and present therefore a specialized flora and vegetation, which has attracted much research, but which is still incompletely known. In this paper we present the main communities of this vegetation, which encompasses subalpine grasslands, scrub and dry grasslands. Six associations are presented as new (Stachyo scardicae-Buxertum sempervirentis, Daphno oleoidi-Ericetum herbaceae, Carici sempervirentis-Seslerietum coerulantis, Carici macrolepidis-Genistetum hassertianae, Alysso bertolonii subsp. scutarinum-Euphorbietum glabriflorae, Sedo serpentini-Festucopsietum serpentini) and a few others are presented without a formal description (Bornmuellera baldaccii community, Astragalus angustifolius community, Viola magellensis scree vegetation). Serpentinicolous dry grassland vegetation of the Shebenik mountains is compared to other communities of serpentines in Italy, Balkans and Greece and a new alliance is described for this community, Festucopsion serpentini (Halacsyetalia sendtneri) vicariant of the Centaureo-Bromion fibrosi which occurs in northern Albania and Kosovo. The alliance is characterized by a set of species which do not occur or are rare further north and by a relatively dry climate with Mediterranean affinity. We also present a thorny cushion vegetation with Astragalus angustifolius, which grows on limestone but is vicariant to the analogous community with Genista hassertiana. Finally, considering the rarity of these communities at continental scale, and their richness of endemic and rare species, we present the description of a new habitat for future inclusion in the Annex I of the Habitat Directive.

Socotra Vegetation Database

The Socotra Vegetation Database (GIVD ID AS-YE-001) contains 396 releves (including 500 species). Ten percent of the releves come from the scientific literature; the remaining 90% have been collected by the authors during several field campaigns carried out between 2007 and 2009. Phytosociological investigation was performed according to the methods described by Westhoff & van der Maarel and Braun-Blanquet. The location of the releve was selected in relation to the homogeneity of physical features, vegetation structure and species dominance. According to these criteria forest, woodland, shrubland, grassland and halophytic communities were sampled. Plot sizes ranged from 200 m2 to 4 m2 depending on the plant community. Cover/abundance data for all vascular plants were recorded in the field using the Braun-Blanquet scale. The database was created in TURBOVEG. A classification analysis was performed to identify the main vegetation communities of the islands and the results are included in the database.