Ancient trees are a heritage of inestimable historical and cultural value and natural monuments. Their presence in woodlands is the evidence of a long and strong relationship between human activities and land uses. The big and tall trees have not only scenic and aesthetic values, but they are also important from ecological and historical point of views (Cannizzaro & Corinto, 2014). Ancient trees differ from others of their species for their old age and unusual size and shape. Several features, such as height, stem diameter, crown shape and involvement of them in historical events, make these trees of public interest and therefore protected by law (Artese, 2015). According to Castagneri et al. (2012), a relationship between longevity and growth rate has been demonstrate. Old-growth treeshave a lower growth rate than younger trees growing at the same site and low growth rate during early life stages is probably associated with longevity (Black et al., 2008; Matthes et al., 2008; Bigler & Velben, 2009; Johnson & Abrams, 2009). These trees contain several information about past dynamics and climate. They can represent unique habitats for many rare species (Rolstad et al., 2001; Nascimbene et al. 2009, Schweingruber & Wirth 2009; Castagneri et al., 2012). Ancient trees are important parts of ecosystems and they are usually included in ecological studies of forest management.

The importance of old-growth forests has been recognized worldwide. They are ecosystems that have achieved matureness without disturbance during their life and growing cycles. They are complex ecosystems, which also contain high tree diversity.

The proper management of old-growth forests represent one of the main objectives of forest conservation. Old-growth trees are key features of these forests and they constitute important elements for biodiversity. Therefore, major knowledge on their growth and mortality pattern is required and necessary (Blasi et al., 2010; Castagneri et al., 2012). A large variety of animal species can live there because there are different types of trees. The persistence of many specialized insects depends on the presence of ancient trees scattered in the woods (Scalercio et al., 2016), also in urban and peri-urban ecosystems or in open landscapes (Horák, 2017). In particular, old, dying and dead trees represent ideal lairs for animals and an important food source for them. Many animal species require intact old-growth forests to survive. In these ecosystems the regeneration of significant plant species is favored. The necromass and deadwood improve the forest soil and enrich the availability of nutrients for living trees and microfauna. The loss of oldgrowth forests negatively affects animal and plant species and biodiversity. In the past, necromass and deadwood were differently evaluated. In particular, the traditional forest management retains deadwood and necromass as a source of biotic and abiotic disturbances (Radu, 2006). Deadwood and necromass were wrongly considered by forest managers as indicators of bad-management and negligence of in the application of silvicultural practices (Pastorella et al., 2016). Over time, the development of biodiversity-oriented forest management has modified the perception of forest managers regarding deadwood and necromass in forests. Nowadays the goal of forest management is to increase the amount of deadwood and reduce the difference in necromass volume between managed and unmanaged forests (Swanson & Franklin, 1992). The presence of necromass preserves the functionality of the forest ecosystem (De Meo et al., 2018) by providing important habitats for arthropods, fungi and facilitating germination of conifers in mountain forests, playing an important ecological role for wildlife (Humphrey et al., 2004, Vallauri et al., 2003).

Necromass and deadwood are important carbon sinks due to their slow decomposition rate (Kalies et al., 2016). They represent a key factor in nutrient cycle of C, N and Mg (Holub et al., 2001; Krankina & Harmon, 1994), in natural regeneration (Vallauri et al., 2003) and in the geomorphological and soil hydrological processes (Bragg & Kershner, 1999).

The health and the mechanical stability of trees is highly related to tree density (Marchi et al., 2017). Height/Diameter at breast eight (Ht/DBH ratio) (Slenderness coefficient) has been demonstrated to be an easy and good indicator of mechanical stability of trees (Wang et al., 1998) unlike many other indicators developed to assess biodiversity in forest ecosystems (Becagli et al., 2013,Chiavetta et al., 2016, Latham et al., 1998, Neumann & Starlinger, 2001, Pretzsch et al., 2016). In particular, Ht/ DBH ratio (Slenderness coefficient) is widely used as the main indicator of single-tree mechanical stability in conifers stands (Marchi et al., 2018, Cantiani & Chiavetta, 2015). Recent studies showed that a high Ht/DBH can indicate that a tree has grown in a dense stand and can be more vulnerable to mechanical perturbations because their stems are not able cope with conditions of high mechanical perturbation, such as landslides and snow damage (Cremer et al., 1982).

The Mediterranean forests have been altered by human activities for a very long time and practically no pristine forests appear to be present in the region (Bengtsson et al., 2000). The generally high human population densities have led to intensive cultivation practices like coppice with short rotations. Along with overgrazing and frequent f ires this resulted in severely degraded forests (Di Castri et al., 1981): this situation makes the remaining pristine or close to pristine forests even more valuable (Stanners & Bourdeau, 1995).

In Italy, an important old-growth forest reserve is located in the Sila National Park. This is the Fallistro Biogenetic Natural Reserve, a precious forest stand made up of ancient trees of Pinus nigra J.F.Arnold subsp. calabrica (Poir.) (Calabrian pine) so-called locally as “Giganti della Sila”, i.e. Giants pines. They were planted in the middle of 17th century in order to create a topsoil protection from cold winds as well as a shelter for shepherds and animals. This work represents the pursuance of a previous and already published study (Plutino et al., 2018). In the present paper, the result of 40 years of forest mensuration carried out by the Research Centre for Forest and Wood in the Fallistro Biogenetic Natural Reserve are reported. 58 ancient Giant pines were measured in 1976, 1986 and 2016. The purposes of the paper are: (1) to assess structural parameters of Giant pines; (2) to compare three inventories and relative parameters; (3) to assess mechanical stability of Giant pines; (4) to highlight some important reasons for preserving the Fallistro Biogenetic Nature Reserve, i.e. the role of the Reserve as a source of biodiversity and to maintain high levels of ecological stability characterizing this important Italian forest area.

We focus on overall structure and consequently provide a characterization of the structural attributes and history of this forest, as a representative case study of other old-growth realities in the Mediterranean environment.

Site description

The Biogenetic Natural Reserve of Fallistro has been studied since 1976. According to several authors (e.g.Bonavita et al., 2016, Avolio & Ciancio, 1985, Anzilotti 1950), it would be an artificial old-growth forest of Calabrian pine. The Authors report that the forest would be planted in the middle of 17th century by means of natural regeneration collected from surrounding forest areas in order to create topsoil protection from cold winds as well as a shelter for shepherds and animals. In 1987 the Reserve was established by law of the Italian Ministry of the Environment. It is located within the Neto River basin (Sila Grande), in Municipality of Spezzano della Sila (Province of Cosenza). It extends for about 5.4 hectares (Fig. 1). About 1500 uneven-aged trees are included, some of which are estimated to be over 390 years old (Avolio & Ciancio, 1985) (Fig. 2).

No current silvicultural activities in this area are carried out and the Fallistro Biogenetic Natural Reserve has been left to natural evolution for a long time (Bonavita et al., 2016). The census of all tree species has been carried out. These data and historical information allowed to identify the forest typologies in the reserve.

The Calabrian pine is a botanically interesting species because of its localized natural distribution within theMediterranean basin. Largest populations are in Calabria, especially in Sila Plateau, where major stands are within protected areas (Farjon, 2013). The area’s altitude is from 1,398 to 1,448 m a.s.l. and it is characterized by exposure from NW to SE. The bedrock is siliceous and the soil is poorly developed. The Climate is Humid temperate (Mediterranean) (Le Pera & Sorriso-Valvo, 2000). Precipitation is typically spread throughout the autumn–winter season. The mean annual temperature is 9.0 °C and mean annual rainfall is 1,639 mm (San Camigliatello Silano meteorological station, data provided by ARPACAL 2016) (Fig. S1 [suppl.]). According to the Pavari’s phytoclimatic classification (1916) the Fallistro site falls within the Fagetum, warm sub-zone.

Field measurements and data analysis

All trees and shrubs were counted. The species were identified for each individual. In order to describe the conditions of Giant pines of the Fallistro Reserve, the main dendrometric parameters were evaluated: diameter at breast height (DBH), totaltree height (Ht), early dry branches height, early alive branches height, stand density, cormometric volume.All data were published in Plutino et al. (2018) and archived in an open access dataset at https://zenodo.org/record/1100340 and metadata at https://zenodo.org/re-cord/1100340 (Pollastrini et al., 2017). Dataset is attached as supplementary (Table S1 [suppl.]).Cormometric volume has been calculated applying a form factor derived from measurements carried out on Giant pines fallen on the ground and already highlighted in Plutino et al. (2018).

In 1986 a structural transect has been permanently traced in order to evaluate the stand vertical and ho-rizontal profile evolution. In 2016, the same transect (40m x 140m) was replaced and the horizontal profile was re-constructed. Trees’ coordinates (X, Y), diameter at breast height, tree total height, living branch height, crown length and crown projection area were measured again. Tree total height was measured using the ipsome-ter Vertex III. The measurement of the crown diameter was measured as vertical lineament of the crown projecion recorded in four directions and calculated as a mean of four measurement values.

Statistical analysis

For each variable the average values and standard error (SE) values were calculated to identify the level of varia-bility of data collection in 3 inventories (Table 1). A sum-mary of Ht/DBH statistical values of three inventories are shown in Table 2.A Fisher’s analysis of variance (ANOVA) was per-formed to test the effect of time and size on each of analyzed variables. The ANOVA allows to compare two or more groups of data by comparing the variability “wi-thin groups” with the variability “between groups”. To-tal height (Ht) was subjected to one-way ANOVA. The diameters, basal area (ba) and volume (v) were subjected to ANOVA of repeated measurements to define the degree of variability between and within the groups of 3 inventories considering DBH range of 40 cm A Tukey’s HSD test was done when these effects were identified as significant (Table 4).

Also Ht/DBH ratio (slenderness coefficient) was subjected to one-way ANOVA to define the degree ofvariability of trees’ stability between and within the groups of 3 inventories.

Necromass estimation

Necromass has been evaluate as following: (a) for standing necromass: number of dead stems standing, the percentage of dead trees standing on the total, the volume with Huber's formula; (b) for ground necromass: the volume of each linear segment and the total volume per hectare using the formulas by La Fauci et al., (2006).

Forest stand conditions are the result of several variables as age, site, area occupancy and intensity of competition, associated with number, dimensions, and distribution of trees in a given stand. The main results are shown below.

Forest typologies

Since1985 to last inventory, the age of trees was identified by counting tree rings in: a) several cross sections taken along the trunk from fallen trees (Fig. S2 [suppl.]) (Avolio & Ciancio, 1985); b) stumps and wood samples for several age classes. The count of the rings on the stumps and trunk of fallen trees over the years would seem to testify to a coetaneity of monitored population. Moreover, the hypothesis is based by old testimonies of the local population; the testimonies describe that small old smoothed surfaces are present in the forest and could serve as a shelter for animals. The old owners would be planted and used the pines to beautify and protect the soil (Allegri, 1954, Anzilotti, 1950). In 2012, core drilling and counting were repeated on medium diameter trees up to class 150-200 (Bonavita, 2012).

According to Avolio & Ciancio, (1985), the forest typologies of the area would be classified as follows: 390 years old pine high forest (11% on total surface); 150200 year pine high forest (33%); 80-120 year pine high forest (12%); 40-60 year pine forest (9%); 15-30 yearpine young growth forest (4%); beech (Fagus sylvatica L.) outgrown coppice (7%); 80-100 year poplar (Populus tremula L.) stand (5%). At the edge of the area ancient and large stumps of mountain maple (Acer pseudoplatanus L.) and chestnut (Castanea sativa Miller) are present. Renewal of alder (Alnus cordata Desf), beech and mountain maple has been affirmed at the edge of the pine and beech stands, hawhilst poplar and Calabrian pine renewal has been affirmed on forest clearings. In several forest typologies understory is poor. In growing coppices are exclusively present Asperula odorata L., Oxalis acetosella L., Anemone nemorosa L., Saxifraga rotundifolia L.. In other stands, understory is characterized by Pteridium aquilinum L., Crataegus oxyacantha L., Rosa canina L., Sambucus racemosa L., Sorbus aucuparia L., Malus silvestris Borkh., Prunus cocomilia Ten., Salix capraea L., Lithospermum calabrum Ten., Rubus fruticosus L.

Comparison of inventories

The data reported in Table S1 [suppl.] (Plutino et al. 2018) compare: average diameter, basal area, total height and cormometric volume of the individual alive plants measured in 1976, 1986 and 2016. Table 1 shows all means values. The one-way ANOVA of Ht doesn’t show significant differences among three inventories (F=0,456; p=0,634435). DBH, ba and v showed significant differences within DBH size (Table 3). The survival was 86.2% over 1976-1986, 90.0% over 1986-2016, 77.6% over 1976-2016. The alive trees’ average DBH has increased from 124.0 to 128.7 cm. The dead trees’ average DBH in 1986 and 2016 is 132.2 and 136.3 cm. Total basal area values have decreased from 73.2 to 60.4 m2. From 1986 to 2016, dead trees’ total basal area has decreased from 11.0 to 7.3 m2. The decrease is probably due to mortality. Total height values of alive pines vary between 35.0 (1976) and 36.0 m (2016). Total height values of dead pines in the years 1986 and 2016 measure 34.2 and 36.0 m.

The alive trees total volume in 1976, 1986 and 2016 are respectively 1,394.4, 1,285.0 and 1,203.5 m3. For dead trees, total volume values are 197.2 and 139.1 m3 in 1986 and 2016. Average volume measures 24.6 and 27.8 m3 respectively. Diameter distribution for all inventories are reported in Fig. 3.

Necromass

Data collected in the field were elaborated to assess necromass volume.

Necromass is a fundamental substrate for numerous species and a key factor in carbon and nutrient cycles. In 2016 the Calabrian pine forest was characterized by a high quantity of necromass (51.7 m3 ha−1) in which 69% was lying necromass, 31% standing dead trees, showing an increase if compared to the values recorded in 1986 (30.3 m3 ha-1) where the necromass was com-posed by 65% of lying necromass and 35% of standing dead trees.

Mechanical Stability of Forest System differences in Ht/DBH

The principal statistical parameters of Ht/DBH ratio are reported in Table 2 The 1-way ANOVA don’t show statistically differences among three inventories (F=0.045 p=0.956383). The Ht/DBH ratio slightly decreased from 1976 to 2016. The decrease of the Ht/DBH ratio correspond to increase of mechanical stability of trees.

Other characteristics of stem and foliage

Some trees were subjected to slotting, a procedure for harvesting the pine’s resin. Local shepherds and lumberjacks used this practice in order to obtain splinters to be used as torches or for lighting fires. In 2016, 10 slotted trees were present. The most slotted plant is the n. 40, showing a cavity of m 3.77x1.52x1.33 m. Twenty-tree pines (23) present columnar stems, without dried branches and stumps until the insertion of the f irst alive branches. This is the consequence of self-pruning started many years ago and which continues progressively upwards. Along the stem of other 22 trees, instead, remains of stumps or dry branches of various sizes are present.

The average height of insertion of the first alive branch is at 13.8 m with the minimum at 3.2 m (tree 53) and the maximum at 30.8 m (tree 19). The average crown amplitude is 21.8 m varying from m 3.0 (tree 19) to m 34.0 (tree 21) (Data just illustrated are attached as supplementary (Table S2 [suppl.]). In Fig. 4 is represented the two transects profile and cover projections obtained following mensuration in 1986 and 2016.

Fallistro Reserve is the last remnant of ancient forest in Sila preserved until the beginning of the 17th century.

It has remained undisturbed until the Unity of Italy (1861), when started an intensive exploitation of forest resources (Anzilotti, 1950). Since 2016, the Reserve is managed by the Fondo Ambiente Italiano (FAI). 40 years after first measurements on the Giant pines, the most emblematic and ancient trees of the population confirmed the peculiar ecological characteristics of Calabrian pines: their posture, rapidity of growth, productivity and longevity. The pine forest would be 390 years old and it is represented by 45 green monuments in good vegetative and health status. Certainty does not exist on the origin of pine forest, but the studies conducted since 1950 would lead to the hypothesis that it is coetaneous and artificial (Allegri, 1954, Anzilotti, 1950). The affirmation is based on considerations that mainly derive from testimonies of the local population collected by authors: the old owners would be used the pines to beautify and protect the soil (Avolio & Ciancio, 1985, Anzilotti, 1950).

Total survival is 77.6%; 86.2% after the first 10 years and 90.0% at the end of the study. The greatest trees are characterized by maximum size in diameter (189 cm) and height (44 m), by high structural heterogeneity and by stratification of the tree cover. The pine forest maintains the prerogative of acting as a true center of propagation of the species. Nowadays there are no evidences of the decline of the species, although undoubtedly stands have been logged and replaced by other land use or woodland types in the past and threatened by environmental disturbances, especially fires.

The low anthropogenic disturbance experienced in this area for longtime has determined particular features of longevity, and uniqueness of pine posture in this centuries-old pine forest. These conditions have determined a progressive natural aging and the affirmation of a precious woodlot representing the natural populations of the past of Calabrian pine to be preserved for future generations. Calabrian pine stand is far from having started degenerative processes which inexorably and slowly accompanies forest stands close to their biological decline due to age limits, hence depauperating also the high natural, scenic, ecological and genetic value of the giant pines’ nucleus. It is a forest stand that fully responds to the definition proposed by FAO of old-growth forest in 2001 Montreal conference: “Old growth forest stands are stands in primary or secondary forests that have developed the structures and species normally associated with old primary forest of that type have sufficiently accumulated to act as a forest ecosystem distinct from any younger age class” (UNEP/CBD/SBSTTA, 2001). The pine stand is a centuries-old pine forest characterized by a natural dynamic that had determined for decades the presence of all the regenerations phases of the Calabrian pine including the senescent one.

Fallistro forest is constituted by “green patriarchs” and presents large quantities of necromass. The natural aging of the pine forest proceeds slowly if compared to other old forests. Why this phenomenon occur is still little known, but probably it is correlate with the good management practice of the pine stand and with the institution of the Biogenetic Natural Reserve “Sila’s Giants” (D.M. n. 426 of 1987 July 21, Ministry of Environment) that reduced the negative effects connected to the anthropic disturbance.

Other crucial events for conservation and valorization of this area were: Calabria National Park’s institution in 1968; Sila National Park’s institution and collocation of Biogenetic Natural Reserve as integral reserve and integral protection; a free-loan agreement between the Calabria Region to the Sila National Park Authority for 29 years, and successively entrusted to FAI (Fondo Ambiente Italiano) on a loan-for-used basis by the Sila National Park. The main objective of the management of the great patriarchs must be the conservation of senescent ecosystem for the collection of Calabrian pine seeds and for production of direct descents, on which to start genetic studies. In conclusion, Giants pines of Fallistro have particular meaning and suggestiveness not so much for size and age reached by the trees, but for representing the last tangible testimony of the ancient “Silva brutia” (Avolio & Ciancio, 1985).

Allegri E, 1954. Pino nero, Pino laricio. Monti e Boschi 11-12: 525-530.Artese C, 2015. Monumental trees of Abruzzo: from knowledge to the protection. Ita J For Mount Env 70 (6): 453-462.https://doi.org/10.4129/ifm.2015.6.05Anzilotti F, 1950. Il pino laricio silano. Monti e Boschi 3: 107-116.Arpacal, 2016.http://cfd.calabria.itAvolio S, Ciancio O, 1985. The Sila giants. Ann Ist Sperim Selvic 16: 373-421.Becagli C, Puletti N, Chiavetta U, Cantiani P, Salvati L, Fabbio G, 2013. Early impact of alternative thinning approaches on structure diversity and complexity at stand level in two beech forests in Italy. Ann Silvic Res 37(1): 55-63.Bengtsson J, Nilsson SG, Franc A, Menozzi P, 2000. Biodiversity, disturbances, ecosystem function and management of European forests. For Ecol Manag 132: 39-50.https://doi.org/10.1016/S0378-1127(00)00378-9Bigler C, Veblen TT, 2009. Increased early growth rates decrease longevities of conifers in subalpine forests. Oikos 118: 1130-1138.https://doi.org/10.1111/j.1600-0706.2009.17592.xBlack BA, Colbert JJ, Pederson N, 2008. Relationship between radial growth rates and lifespan within North American species. Ecoscience 15: 349-357.https://doi.org/10.2980/15-3-3149Blasi C, Burrascano S, Maturani A, Sabatini FM, 2010. Old-growth Forests in Italy. A thematic contribution to the National Biodiversity Strategy. Ministero per la Protezione dell'Ambiente, del Territorio e del Mare. ISBN 978-88-6060-270-1Bonavita S 2012. Genetic diversity assessment in pinus laricio poiret populations using microsatellites analysis and inferences on population history. PhD thesis, University of Calabria.Bonavita S, Vendramin GG, Bernardini V, Avolio S, Regina TMR, 2016. The first SSR-based assessment of genetic variation and structure among Pinus laricio Poiret populations within their native area. Plant Biosyst 150 (6): 1271-1281.https://doi.org/10.1080/11263504.2015.1027316Bragg DC, Kershner JL, 1999. Coarse woody debris in Riparian Zones. J For 4: 30-35.Cannizzaro S, Corinto GL, 2014. The role of monumental trees in defining local identity and in tourism. a case study in the Marches region. Geo J 1 (1): 29-48.Cantiani P, Chiavetta U, 2015. Estimating the mechanical stability of Pinus nigra Arn. using an alternative approach across several plantations in central Italy. iForest 8: 846-852.https://doi.org/10.3832/ifor1300-007Castagneri D, Storaunet KO, Rolstad J, 2012. Longevity and growth patterns of ancient Norway spruce trees in Trillemarka forest, Norway. In: Age and growth-patterns of old Norway spruce trees in Trillemarka forest, Norway, Scandinavian J Forest Res.https://doi.org/10.1080/02827581.2012.724082Chiavetta U, Skudnik M, Becagli C, Bertini G, Ferretti F, Cantiani P, Di Salvatore U, Fabbio G, 2016. Diversity of structure through silviculture Diversity of structure through silviculture. Ital J Agron 11(April): 18-22.Cremer KW, Borough CJ, McKinnell FH, Carter PR, 1982. Effects of stocking and thinning on wind damage in plantations. N Z J For Sci 12: 244-268.De Meo I, Agnelli AE, Graziani A, Kitikidou K, Lagomarsino A, Milios E, Radoglou K, Paletto A, 2018. Deadwood volume assessment in Calabrian pine (Pinus brutia Ten.) peri-urban forests: Comparison between two sampling methods. J Sust For 36 (7): 666-686.https://doi.org/10.1080/10549811.2017.1345685Di Castri F, Godall DW, Specht RL, 1981. Mediterranean type shrublands. Elsevier, Amsterdam.Farjon A, 2013. Pinus nigra ssp. laricio. The IUCN Red List of Threatened Species 2013: eT20453493A20453502. http://www.iucnredlist.org/details/20453493/0Holub SM, Spears JDH, Lajtha K, 2001. A reanalysis of nutrient dynamics in coniferous coarse woody debris. Can J For Res 31: 1894-1902.https://doi.org/10.1139/x01-125Horák J, 2017. Insect ecology and veteran trees. J Ins Cons 21:1-5.https://doi.org/10.1007/s10841-017-9953-7Humphrey JW, Sippola AL, Lempérière G, Dodelin B, Alexander KNA, Butler JE, 2004. Necromass as an indicator of biodiversity in European forests: From theory to operational guidance. In M. Marchetti (eds.), Monitoring and indicators of forest biodiversity in Europe - from ideas to operationality. Joensuu, Finland: EFI Proceedings 51, pp. 193-206.Johnson SE, Abrams MC, 2009. Age class, longevity and growth rate relationships: protracted growth increases in old trees in the eastern United States. Tree Physiology 29: 1317-1328.https://doi.org/10.1093/treephys/tpp068Kalies EL, Haubensak KA, Finkral AJ, 2016. A meta-analysis of management effects on forest carbon storage. J Sust For 35 (5): 311-323.https://doi.org/10.1080/10549811.2016.1154471Krankina ON, Harmon ME, 1994. The impact of intensive forest management on carbon stores in forest ecosystems. W J Res Rev 6: 161-177.La Fauci A, Bagnato S, Gugliotta OI, Mercurio R, 2006. First observations on dead wood in Calabrian pine (Pinus laricio Poiret) stands in the Aspromonte National Park (Italy). Forest@ 3: 54-62.https://doi.org/10.3832/efor0344-0030054Latham P, Zuuring H, Coble D, 1998. A Method For Quantifying Vertical Forest Structure. For Ecol Manag 104 (1-3): 157-70.https://doi.org/10.1016/S0378-1127(97)00254-5Le Pera E, Sorriso-Valvo M, 2000. Weathering and morphogenesis in a mediterranean climate, Calabria, Italy. Geomorphology 34: 251-270.https://doi.org/10.1016/S0169-555X(00)00012-XMarchi M, Chiavetta U, Cantiani P, 2017. Assessing the mechanical stability of trees in artificial plantations of Pinus nigra J. F. Arnold using the LWN tool under different site indexes. Ann Silvic Res 41: 48-53.Marchi M, Paletto A, Cantiani P, Bianchetto E, De Meo I, 2018. Comparing Thinning System Effects on Ecosystem Services Provision in Artificial Black Pine (Pinus nigra J. F. Arnold) Forests. Forests 9: 188-204.https://doi.org/10.3390/f9040188Matthes U, Kelly PK, Douglas WL, 2008. Predicting the age of ancient Thuja occidentalis on cliffs. Can J For Res 38: 2923-2931.https://doi.org/10.1139/X08-131Nascimbene J, Marini L, Motta R, Nimis PL, 2009. Influence of tree age, tree size and crown structure on lichen communities in mature Alpine spruce forests. Biol Conserv 18: 1509- 1522.https://doi.org/10.1007/s10531-008-9537-7Neumann M, Starlinger F, 2001. The significance of different indices for stand structure and diversity in forests. For Ecol Manag 145(1-2): 91-106.https://doi.org/10.1016/S0378-1127(00)00577-6Pastorella F, Avdagić A, Čabaravdić A, Mraković A, Osmanović M, Paletto A, 2016. Tourists' perception of necromass in mountain forests. Ann For Res 59: 311-326.https://doi.org/10.15287/afr.2016.482Pavari A, 1916. Studio preliminare sulla coltura di specie forestali esotiche in Italia. Ann R. Ist Sup For Naz 1 (1914-1915): 160-379.Plutino M, Pollastrini M, Avolio S, Bernardini V, 2018. Tree inventory data of Pinus nigra J.F.Arnold subsp. calabrica (Poir.) Maire in southern Italy. Ann Silvic Res 42 (1): 43-45.Pollastrini M, Plutino M, Avolio S, Bernardini V, 2017. Forest mensuration data of Pinus nigra J.F.Arnold subsp. calabrica (Poir.) Maire from southern Italy.Pretzsch H, del Río M, Schütze G, Ammer C, Annighöfer P, Avdagic A, Barbeito I, Bielak K, Brazaitis G, Coll L, Drössler L, Fabrika M, Forrester DI, Kurylyak V, Löf M, Lombardi F, Matović B, Mohren F, Motta R, 2016. Mixing of Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) enhances structural heterogeneity, and the effect increases with water availability. For Ecol Manag 373: 149-66.https://doi.org/10.1016/j.foreco.2016.04.043Radu S, 2006. The ecological role of deadwood in natural forests. Env Eng Sci 3: 137-141.https://doi.org/10.1007/978-3-540-47229-2_16Rolstad J, Gjerde I, Storaunet KO, Rolstad E, 2001. Epiphytic lichens in Norwegian coastal spruce forest: historic logging and present forest structure. Ecol Applications 11: 421-436.https://doi.org/10.1890/1051-0761(2001)011[0421:ELINCS]2.0.CO;2Scalercio S, Bonacci T, Turcio R, Bernardini V, 2016. Relationships between Psychidae communities (Lepidoptera: Tineoidea) and the ecological characteristics of old-growth forests in a beech dominated landscape. E J Entom 113: 113-121.https://doi.org/10.14411/eje.2016.014Schweingruber FH, Wirth C, 2009. Old trees and the meaning of 'old'. In: Wirth, C., Gleixner, G. & Heimann, M. (eds.). Old-growth 127 forests: function, fate and value. Ecol Studies, Springer, New York, Berlin, Heidelberg.https://doi.org/10.1007/978-3-540-92706-8_3Stanners D, Bourdeau P, (Eds.) 1995. Europe's Environments. European Environment Agency, Copenhagen. Denmark.Swanson FJ, Franklin JF, 1992. New forestry principles from ecosystem analysis of Pacific Northwest forests. Ecol Appl 2: 262-274.https://doi.org/10.2307/1941860UNEP/CBD/SBSTTA 2001. Invasive Aliens Species. Progress report on matters identified in decision V/5, paragraphs 5, 11 and 14 and an analysis of national reports. Convention on Biological Diversity.Vallauri D, André J, Blondel J, 2003. Le bois mort, une lacune des forêt gérérs. Rev For Franç 2: 99-112.https://doi.org/10.4267/2042/5172Wang Y, Titus SJ, LeMay VM, 1998. Relationships between tree slenderness coefficients and tree or stand characteristics for major species in boreal mixedwood forests. Can J of For Res 28(1995): 1171-83.https://doi.org/10.1139/x98-092