Bartolomeo Schirone

Structure, dynamics and dendroecology of an old-growth Fagus forest in the Apennines

Abstract Question: Which are the structural attributes and the history of old-growth Fagus forest in Mediterranean montane environments? What are the processes underlying their structural organization? Are these forests stable in time and how does spatial scale affect our assessment of stability? How do these forests compare to other temperate deciduous old-growth forests? Location: 1600–1850 m a.s.l., Fagus forest near the tree line, central Apennines, Italy. Methods: An old-growth Fagus forest was studied following historical, structural and dendroecological approaches. History of forest cover changes was analysed using aerial photographs taken in 1945, 1954, 1985 and 1994. The structural analysis was carried out in the primary old-growth portion of the forest using 18 circular and two rectangular plots. Dendroecological analyses were conducted on 32 dominant or co-dominant trees. Results: These primary old-growth Fagus remnants consist of four patches that escaped logging after World War II. Both living and dead tree components are within the range of structural attributes recognized for old-growth in temperate biomes. Dendroecological analyses revealed the roles of disturbance, competition and climate in structuring the forest. We also identified a persistent Fagus community in which gap-phase regeneration has led to a mono-specific multi-aged stand at spatial scales of a few hectares, characterized by a rotated-sigmoid diameter distribution. Conclusion: Even at the relatively small spatial scale of this study, high-elevation Apennine Fagus forests can maintain structural characteristics consistent with those of old-growth temperate forests. These results are important for managing old-growth forests in the Mediterranean montane biome. Nomenclature: Pignatti (1982). Abbreviations: BAI = Basal area increment; CCTRMD = Computer controlled tree ring measuring device; CV = Coefficient of variation; CWD = Coarse wood debris; DBH = Diameter at breast height; DIB = Diameter inside bark; IGM = Istituto Geografico Militare; OG = Old-growth; PGC = Percentage growth change; PNA = Abruzzo National Park; UTM = Universal transverse Mercator.

Prospects of barcoding the Italian wild dendroflora: oaks reveal severe limitations to tracking species identity.

DNA barcoding may be particularly important in influencing ecology, economic issues, and the fundamental crisis facing biodiversity as a standardized, species‐level identification tool for taxonomy assessment. Trees play important roles in the conservation of many land ecosystems, the wood trade, and the definition of biogeographical processes; nevertheless, peculiar biological, evolutionary and taxonomical features will probably constitute an intriguing challenge to barcoders. We examined whether four marker regions (trnh‐psba, rbcL, rpoc1, matK) proposed by the Consortium for the Barcode of Life (CBOL) matched species taxonomy in a preliminary tree biodiversity survey of Italian forested land. Our objective was to provide a test of future in situ applications of DNA barcodes by evaluating the efficacy of species discrimination under the criteria of uniformity of methods and natural co‐occurrence of the species in the main forest ecosystems. Fifty‐two species were included in a floristic study. We obtained 73% total discrimination success, with trnH‐psbA as the best performing marker and oaks as the least responsive plants to the markers used. A further taxon‐based study of Quercus (thirty specimens, 12 species) revealed that this genus is refractory to barcoding (0% discrimination success), a probable consequence of low variation rate at the plastid genome level, hybridization, and the incidence of biogeography. We conclude that some species‐rich tree genera in small geographical regions may prove exceptionally difficult to barcode. Until more efficient markers are developed, we recommend that improved and diversified sampling (multiple locations of sympatric and co‐occurring congenerics) be embraced as a timely and important goal for the precise assessment of haplotype specificity to facilitate the productive application of barcoding in practice.

A long-term tree ring beech chronology from a high-elevation old-growth forest of Central Italy

Summary This paper describes preliminary dendroecological analyses of tree ring collections from an old-growth beech forest in the Central Apennines (Cervara Valley, Abruzzi National Park). Tree ring series show that at high-elevation sites in Central Italy the potential longevity of beech trees is more than 500 years. A 425 year site chronology spanning the period 1577–2001 was built. Its comparison with other chronologies from the same and other species showed a good connection of tree-ring patterns especially for the contexts of high elevation chronologies. The climatic signals of beech trees were investigated by means of pointer intervals and bootstrapped response functions for the period 1832–2000. Mid summer precipitation (July–August) and May temperature were the prominent climatic signals.

Multiple genome relationships and a complex biogeographic history in the eastern range of Quercus suber L. (Fagaceae) implied by nuclear and chloroplast DNA variation.

Abstract The complex evolutionary history of Quercus suber has been throughly investigated in many recent works, but the details of its differentiation processes are still largely unknown. In addition, the geographical and evolutionary roles of the eastern parts of the species range have gained much less attention compared to other southern European areas. In order to fill this gap, new insights to infer the species diversification and range establishment of the cork oak in the east-central Mediterranean are here provided by means of inter- and intra-specific plastid DNA and nuclear ribosomal ITS phylogeographic studies. We analyzed 95 natural cork oak populations; 6 closely related, sympatric oaks were included in the study and used for comparisons. Evidence for a clear phylogeographical structure was detected with PCR-RFLP at 5 chloroplast loci, while ITS sequence variation is apparently unrelated with the geographical distribution. Five chloroplast haplotypes and three ITS main lineages were identified. Three haplotypes and all ITS lineages occur in the Italian Peninsula, stressing the importance of these territories for the evolutionary history of the species. Two divergent “Italian” haplotypes are highly shared, and one ITS variant is basal to the ingroup, revealing sister relationships within Cerris taxonomic group. Hypotheses of hybridization, lineage sorting of ancient DNA polymorphisms and of reticulate evolution of the whole species group are presented and discussed.

Phylogeography and conservation perspectives of an endangered macaronesian endemic: Picconia azorica (Tutin) Knobl. (Oleaceae)

The Azores provide an excellent field test for research activities aimed at developing conservation strategies for endangered tree species. In this work, the urgency to promote Picconia azorica conservation programs addressed (a) insights into the biotaxonomy of the species (including an evaluation of its origin and relationships with the only congeneric species of P. azorica: P. excelsa from the Canary and Madeira islands) and (b) the evaluation of P. azorica genetic diversity. Plastid DNA sequence analysis and molecular markers (RFLP and SSR) were used for this purpose. Phylogenetic data suggest the monophyly of Picconia and support a late Miocene divergence of the two species. Three polymorphic cpSSR loci allowed the identification of five different haplotypes in P. azorica. Uniqueness and relictuality of lineages are presented and discussed. Picconia azorica intra-specific diversity patterns revealed low genetic diversity and a weak genetic structure, which could result from long-lasting ecological stability and efficient inter-island seed movement that have been severely affected in recent times. The species survival is at risk, and we suggest management practices focusing on ex situ and in situ conservation units based on eco-genetic data. Additional measures contributing to mild erosion of the genepool and to remove barriers to seed dispersal are indicated.

The longevity of broadleaf deciduous trees in Northern Hemisphere temperate forests: insights from tree-ring series

Understanding the factors controlling the expression of longevity in trees is still an outstanding challenge for tree biologists and forest ecologists. We gathered tree-ring data and literature for broadleaf deciduous (BD) temperate trees growing in closed-canopy old-growth forests in the Northern Hemisphere to explore the role of geographic patterns, climate variability, and growth rates on longevity. Our pan-continental analysis, covering 32 species from 12 genera, showed that 300-400 years can be considered a baseline threshold for maximum tree lifespan in many temperate deciduous forests. Maximum age varies greatly in relation to environmental features, even within the same species. Tree longevity is generally promoted by reduced growth rates across large genetic differences and environmental gradients. We argue that slower growth rates, and the associated smaller size, provide trees with an advantage against biotic and abiotic disturbance agents, supporting the idea that size, not age, is the main constraint to tree longevity. The oldest trees were living most of their life in subordinate canopy conditions and/or within primary forests in cool temperate environments and outside major storm tracks. Very old trees are thus characterized by slow growth and often live in forests with harsh site conditions and infrequent disturbance events that kill much of the trees. Temperature inversely controls the expression of longevity in mesophilous species (Fagus spp.), but its role in Quercus spp. is more complex and warrants further research in disturbance ecology. Biological, ecological and historical drivers must be considered to understand the constraints imposed to longevity within different forest landscapes.

Ecological behavior of Quercus suber and Quercus ilex inferred by topographic wetness index (TWI)

The ecological behaviors of a network of pure evergreen oak stands (Quercus suber L. and Quercus ilex L.) in the Central-Western Mediterranean Basin were investigated toward climatic and edaphic factors implemented with the application of topographic wetness index (TWI). A Categorical Principal Component Analysis (Catpca) using climatic and soil physico-chemical parameters was performed on 23 cork oak and holm oak pure stands with the aim to understand better the effectiveness of TWI for characterizing soil ecology of the two species. Catpca pointed out that, although cork oak and holm oak are able to growth in similar Mediterranean conditions, they show different behaviors in terms of needs and tolerance to soil water content. TWI confirmed such results at local scale, allowing highlighting some interesting features of the species differential ecology. Although both species confirmed to be drought-tolerant, the heliophilous cork oak revealed to dominate the landscape on wettest soils with high TWI values—indicating the capacity to tolerate stresses due to periods of waterlogging—, while the shade-tolerant holm oak prevails for low-medium TWI values—drier and mesophilous sites. Despite the application of TWI to vegetation science and ecology is relatively recent, results are encouraging and suggest considering this user-friendly and synthetic index in ecological investigations and modeling.

Quercus macranthera Fisch. & Mey. ex Hohen. and Quercus iberica M. Bieb.: Taxonomic definition and systematic relationships with European oaks inferred from nuclear internal transcribed spacer (ITS) data

Abstract Systematic relationships of the two most widespread oaks in Armenia, Quercus iberica M. Bieb. and Quercus macranthera ssp. macranthera Fisch. & Mey. ex Hohen. (Fagaceae), were examined by means of internal transcribed spacer (ITS) sequence variation. The analysis included recently published and several newly derived ITS fragments of most common Eurasian Quercus spp. Orthology of sequences was supported by inspection of ITS secondary structure features. Analyses were implemented with parsimony and maximum likelihood criteria to check the position of all taxa. The robustness of the phylogenetic hypothesis was tested with bootstrap, decay, and Bayesian analysis. Three main clades emerged from the root, corresponding to subg. Quercus, Cerris, and Sclerophyllodrys. Q. iberica and Q. macranthera were included in the subg. Quercus clade and related to Quercus petraea and Q. frainetto-Q. pyrenaica, respectively. The taxonomical status of Q. iberica (Q. petraea ssp. iberica according to some authors) was analysed with respect to Q. petraea. Despite the strict phylogenetic relationship among these two species, the genetic distance (Kimura) was compatible with the hypothesis of maintaining the two taxa separated. A hypothesis on the differentiation of Q. iberica and Q. macranthera before the last glaciation, and their subsequent re-expansion from glacial refugia located in the southern shores of the Black Sea, is proposed. Q. petraea ssp. huguetiana (sequenced for the first time in this study) turned out to be an outgroup with respect to the clade formed by the other accessions of Q. petraea (including Q. iberica). On this basis, this taxon could also assume specific status. The phylogenetic position of Q. pyrenaica is discussed for the first time.

Wood anatomy and technological properties of an endangered species: Picconia Azorica (Oleaceae)

Picconia azorica (Tutin) Knobl. is an Azorean endemic species of the Oleaceae, exploited over centuries and recently classified as endangered. It suffers from reduction and fragmentation of its habitat, and from competition with exotic species. Wood anatomy was examined and compared with Picconia excelsa, enhancing our knowledge about the genus Picconia which contains only these two species. Macroscopic and technological characterizations by colour, pH, wood density, compression and bending strengths, shrinkages, static quality factor, ash content and Higher Heating Value were investigated and compared with other Oleaceae and other hardwoods. At the anatomical level, P. azorica does not differ from P. excelsa, except for the number of vessels and rays per mm2 and the ray type. The technological features support the profitable use of P. azorica for the furniture industry instead of biomass production. Because of its valuable wood, P. azorica might be reconsidered and its properties emphasized to combat the species’ decline and to encourage the restoration of its habitat.

Degradation, rehabilitation and sustainable management of a dunal ecosystem in central Italy

The history of the Feniglia Dune is an example of human-induced degradation and rehabilitation of a Mediterranean ecosystem. Between 1700 and 1900 the forest almost completely disappeared owing to intensive exploitation. The rehabilitation of Feniglia started at the beginning of 1900 with dune consolidation and the sowing of Mediterranean pines. Reforestation was long and complex, and was finished in the 1950s. The evolution of the vegetation can be studied from an aerophotogrammetric series (1955, 1968, 1985 and 1989). GIS was used to analyse the cartographic images. The vegetation dynamics was positive, showing increased plant cover at least until 1985. The 1989 map showed the beginning of cover recession, probably as the result of a number of concurrent disturbing factors: the evolution of the coastline, and an increase in grazing and tourism. Since the Feniglia Dune vegetation is not a resilient natural coenosis, it still needs the support of human interventions to safeguard its natural dynamism.