CREA Journals (Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria)
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Roe deer browsing effects on growth development of Turkey oak and chestnut coppices.
Get PDFOver the last three decades wild ungulates populations in Italy increased to values ranging from 300% to 600%. As a consequence, in Italy as well as in other European countries, situations with high ungulate density and, then, negative effects on the stability and dynamics of ecosystems, are increasing frequently. Starting from these evidences we investigated the effects of roe deer population on the vegetative regeneration of two different broadleaved tree species: Turkey oak (Quercus cerris L.) and chestnut (Castanea sativa Mill.) coppice stands. In Alpe di Catenaia (Apennines – Central Italy), after coppicing in 2002, we chose six experimental areas where fenced (P) and non-fenced (NP) plots were established. Measurements were performed at the beginning of the study period and in winter 2008 in both P and NP plots. Diameter and height of all sprouts were measured. Results showed a different impact of roe deer on the two species. After seven years chestnut did not show any significant browsing-related damage, while in Turkey oak heavy differences between protected and non-protected areas are present: in NP plots roe deer browsing has produced a significant reduction in basal area (58%) and volume (57%) compared to P plots. The results agree with previous studies and confirm: (a) a selective browsing pressure on Turkey oak; (b) the lasting effect of the early impact after clear cutting, visible even seven years after. Based on the findings, we discussed the need for an integrated management of forest vegetation and forest fauna which should define the density of ungulates not only according to the theoretical carrying capacity of ecosystems, but also considering (i) the preservation of the ecosystem overall functionality, (ii) the forest structure development and (iii) the forest management type
Enhancing chestnut coppices: silvicultural management and socio-economic context.
Get PDF Castanea sativa is one of the most important species for timber production in Italy but, both management system, ownership type and wood chain structure, aren’t able to enhance enough the market value of wood assortments. Although the high demand of quality timber, the internal production is heavily reduced, mainly as far as timber quality is concerned and because of the lack of suitable timber sizes. In this context, experimental trials have been approached to identify and verify which silvicultural methods are best suited to reach high yields depending to the investments needed and the local socio-economical condition. Two technical approaches were evaluated: stand silviculture and single-tree oriented silviculture. As for the socio-economical aspects, a few demographic indexes have been examined and the first-phase processing enterprises acting in the concerned area were analyzed. The goals of this paper are to evaluate the biological response to the applied silviculture, to analyze the problems arisen and to estimate the applicability of the proposed methods in relation to the different socio-economic contexts. The research has been carried out in Tuscany in two important forest areas - Monte Amiata and Colline Metallifere - in young chestnut coppices characterized by an homogeneous stand density and a good site index. The two examined districts showed some similarities but they have mainly highlighted important differences about the social structure and concerns and enterprises characteristics. The area of Monte Amiata is typified by a higher residents density then the Colline Metallifere but only 1/3 of the population is employed in the agro-forest sector. In addition, in the Monte Amiata district most concerns are sized less than 2 hectares and chestnut is the main forest species. On the contrary, in the Colline Metallifere the agro-forest sector (57% of workers) is one of the main sources of income for the local communities and medium-sized concerns are noteworthy present. Chestnut stands have here a marginal role, oaks are dominant and the prevailing assortment is firewood. From a silvicultural viewpoint, both the studied areas showed a quite good potentiality, suitabl
First surveys on genetic variability and structure of field maple (Acer campestre L.) in natural and managed populations in the landscape of central and southern Italy
Get PDFFour Tuscan populations (central Italy) and three Italian populations from southern Italy (Campania) were sampled to compare their genetic variability and genetic structure. In each geographical area one of the sampled populations is originated naturally in forest and used as a local reference. The remaining populations were originated artificially. Indeed, field maple was traditionally used in Italy to supply fresh fodder to animals in dry summer period as tree twigs or to train up grape trees in the fields edges. This tradition initiated at the time of Etruscans and continued throughout the Roman partitioning of agriculture landscape. Biochemical markers were used to explore variability in the examined populations (5 enzyme systems by 11 loci). Results showed that the main amount of variation is due to the individual component as for most of the scattered hardwoods in Europe and that differentiation among populations for these neutral traits is relatively low. On the other hand, the natural populations in both the geographical areas showed a very high level of panmittic equilibrium, whilst the artificial populations were really distant from this condition showing a high probability of “founder effect”. This could be determined by the former system of self-supplying reproductive material carried out by farmers, based on the wild offspring collection growing around few mother trees. Discussion is focused also on how handling the opportunity given by many hundreds kilometers of lines in the agriculture landscape as a way of managing diversity for this species
Juglans regia L., phenotypic selection and assessment of genetic variation within a simulated seed orchard
Get PDFNoble hardwoods are very important for the Italian furniture industry. Since 1985, approximately 170,000 ha have been planted in Italy with noble hardwoods. Among them, about 50% of species are represented by walnuts. Walnut (Juglans regia L.), not native in Italy, has been the focus of a substantial research effort for breeding and improvement programmes. The priority has been to preserve the in situ genetic resource still existing after intensive felling. Phenotypes suitable for timber production showing important traits such as straight stem, nice branch architecture, dominance and adaptation (phenology) have needed to be developed and selected. In order to reach this goals, selection of valuable progenies and the evaluation of the interaction genotype x environment, methods based essentially on a multi-trait Selection Index, were developed. Studies have been undertaken also to measure the variation of phenological traits, more correlated to traits valuable for architecture; in addition, neutral markers were used to assess genetic variation among different intensities of the adopted selections. The individual genetic component was found to be higher than at the inter-population level. Results showed that a hypothetical seed orchard made with progenies selected by morphology, phenology and genetic traits could provide material with a good performance and supply a variability similar to larger populations as the total plantation or the pseudo-natural system chosen for comparison
Tree canopy cover and natural regeneration into strictly-protected forest areas: the MaB reserve of Montedimezzo (Isernia,Italy).
Get PDFThe ecological analysis and the analysis of mechanisms underlying the natural regeneration process into strictly protected forest areas, is basic to the understanding of ecosystem functioning and to estimate the recovery ability as a function of time and environmental changes. Aim of the paper is to analyze the spatial-temporal dynamics of tree species regeneration into mixed Turkey oak-common beech stands growing undisturbed since more than one half- century. The ability of first establishment and following growth of natural regeneration related to the ecological parameters, the structural features of standing crop and its development stages, are analyzed in detail. The study was carried out into two permanent monitoring plots (A) and (B) where two different tree species play the main functional role. In (A) common beech is dominant (Fagus sylvatica L.-elevation 1040 m a.s.l.); in (B) Turkey oak is prevailing (Quercus cerris L.-elevation 940 m a.s.l.). In each plot, the analysis of vertical stand structure, of natural regeneration pattern and ecological surveys (LAI, trasmittance, soil moisture content, canopy interception of rainfall) were undertaken by monthly surveys from May to October into 57 sub-plots each 1m2 wide over the period 2005-2007. Results highlighted that (B), Turkey oak prevailing, shows a more complex structure, a higher tree canopy thickness and the lack of gaps. The area shows therefore a lower trasmittance and a higher LAI value; throughfall and soil moisture content are also reduced as compared to (A). As for the natural regeneration pattern, further to a first stage when seedlings mortality is high, their survival rate is being kept high and steady over time in (A). A further mortality peak has been detected vice versa over the following summer season in (B). The different main tree species composition and radiation regime seem to be the basic reasons of the dynamics observed as for mortality and survival rates. The way of seedlings establishment points out that optimal ecological conditions are present for the production and germination of seeds as well, but that the limiting factor is the reduced radiation amount that reaches the forest floor.
Analysis of self-thinning in Calabrian pine plantations (Pinus laricio Poiret) in Calabria (southern Italy).
Get PDFSelf-thinning is the natural process whereby numbers of trees per unit area decrease as average tree size increases over time. It is a process intrinsic to all forest and plant communities whose composition and structure are influenced by competition for growing space. Stands follow a relatively predictable course of density-dependent tree mortality as numbers of trees per unit area decrease with increasing average tree size. It is generally assumed that the combined effects of crown expansion and tree mortality are compensatory so that canopy closure is always maintained. In forest management, knowledge of self-thinning point and information about tree density showing a sharp increase of natural mortality is useful to determine the optimal thinning regimes at stand level. Yoda’s self-thinning line and Reineke’s stand density index are useful and widely used in plantation growth models to predict natural mortality and in process-based models; calibrating these relationships is anyway difficult. Self-thinning and size-density relationships in unthinned even-aged Calabrian pine stands in Calabria (Southern Italy) were studied. Four different diameter-density equations were fitted and compared: the Reineke's model (1933), the modification of this model proposed by Zeide (1995), the self-thinning model developed by Tang et al. (1994), the self-thinning frontier adjusted by Vanclay & Sands (2009). Data from ninety untreated or control permanent plots in experimental areas located in artificial stands were used. Reineke's equation for fully stocked stands relates the number of trees of a stand with their square mean diameter. Zeide proposed a modication to Reineke's equation considering that the slope would not be constant, but changing with age. The selfthinning model developed by Tang et al. relates the number of trees with the square mean diameter, and assumes that in a unthinned stand, which has not reached the maximum density, the self-thinning rate increases with stand density index. The model proposed by Vanclay & Sands can be solved analytically and yields equations for the stocking and the stand basal area as an explicit function of stem diameter. It predicts that self-thinning may be regulated by the maximum basal area. Linear regressions were fitted using the REG procedure of SAS for Reineke's and Zeide’s models. For the non-linear regression the Gauss-Newton algorithm from NLIN procedure was performed. Akaike's information criterion, as a measure of the goodness of fit of the four estimated statistical models, was applied. The slope obtained by Reineke’s model (1.580) not is significantly different from the costant value of -1.605 at the 95% confidence level. When height was included in the relationships between number of trees and diameter (modification proposed by Zeide) the adjusted correlation coefficient increased and the squared mean error decreased. The stand density index calculated from Reineke's straight line previously fitted (1283 trees∙ha-1) is lower than the value obtained from the Tang’s model (1919 trees∙ha-1) but these values are not statistically different. The stand self-thinning model proposed by Tang et al., although showing an objective uncertainty due to a relatively wide confidence interval, describes better than other models the relationships between stand density and average diameter in unthinned even-aged Calabrian pine stands in Calabria (Southern Italy)
Stand dynamics of a beech coppice beyond the rotation age and under conversion into high forest.
Get PDF One of major issues dealing with forest management in Italy is the lack or the suspension of silvicultural practices over an increased share of the forest area, in progress since a few decades ago. The abandonment of rural areas, the emerging environmental functions being nowadays addressed to natural resources, include also many forests and management systems formerly devoted mainly to wood production. This occurrence has its major evidence on coppice forests, i.e. about a half of the country forest area and the forest type historically submitted to the more intensive management practices. The results of an experimental trial started in 1972 in a beech coppice aged 27, i.e. a few years after the age of traditional rotation, comparing the natural evolutive pattern as well as the silvicultural practices aimed at its conversion into high forest, are here reported. The trial included the control thesis and three different thinning intensities. Each thesis was arranged within the same thinning type, taking into account the volume of former standing crop in each plot. The analysis includes the growth pattern and the dynamics of stand structure in the populations under natural evolution and under conversion into high forest. Four inventories were carried out since 1972 at each decade up to 2002. Three thinnings were undertaken within the same time. Results show that both the tested management options, alternative and/or complementary to the traditional coppice system, are based on reliable biological assumptions. The natural evolutive pattern highlights the growth trend at ages older than those monitored under the coppice system. Beech shows a peculiar behaviour in the range observed due to its specific shade-tolerance. The shoot population reveals a sustained growth between the ages of 30 to 40; then, the occurrence of a heavy, regular mortality up to 50; finally, the recovery of a high growth rate up to the age of 60 (ending of the monitored period at now). Such growth pattern moves up the current volume increment, delays its intersection to mean increment and postpones substantially the age of growth rates culmination. The observed trend deviates from the canonical stand growth pattern and seems to be grounded on beech auto-ecology. This extends the time of reaction between the opposite feedbacks of mortality and growth and allows monitoring a likely different behaviour ruling ageing coppice growth. The same occurrence had not been highlighted before studying light-demanding species (deciduous oaks in the case) under the same stand types, these species being able to settle much more rapidly the cycle mortality-growth recovery-incremental culmination. The thesis of conversion into high forest provides the technical cultivation rules (type, intensity and interval of thinning repetition) and suggests it as enforceable also in the private domain due to the shortly-repeated harvestings and intermediate volumes that make each intervention profitable. The basic outcomes of the applied silvicultural practices are (i) the early crown shaping of shoot dendrotypes; (ii) the modeling of clustered stand structure; (iii) the individual development of well-balanced trees, more suited to tackle the grown-up and mature stages till the time of regeneration from seed, ending of the transitory cycle
Modifiche compositive e strutturali in soprassuoli in evoluzione naturale della riserva M.a.B. di Montedimezzo (Isernia)
Get PDFTree species composition and structural dynamics in forest stands under natural evolution in the Montedimezzo M.a.B. reserve. This study is included in an experimental protocol established in 1954 aimed at examining the natural dynamics in mixed broadleaves high forests dominated by Turkey oak (Quercus cerris L.) and beech (Fagus sylvatica L.). Stand development patterns in the last fifteen years are reported. Repeated quantitative and qualitative inventories were carried out in two permanent plots (3 ha each) and in two structural transects (0.2 ha each) located in Collemeluccio-Montedimezzo M.a.B. reserve (Is). The study highlighted, as already observed in 1954, the differences between the two multilayered stands. In the higher elevation beech is the predominant species recording 53% of importance value index (I), followed by Turkey oak (I=25%). In the lower elevation the dominant species is Turkey oak (I=46%), followed by hornbeam (Carpinus betulus L.) (I=28%) and beech (I=12%). The decreased presence of Turkey oak and the increase of beech density are confirmed in each plot over the last fifteen years. Among the other tree species, importance values rise only for silver fir (Abies alba Mill.) (introduced) and holly tree (Ilex aquifolium L.), while hornbeam and hedge maple have been reducing their own presence
Prove di avviamento ad altofusto in un ceduo di cerro (Quercus cerris L.) del Gargano: primi risultati
Get PDFConversion trials in turkey oak (Quercus cerris L.) coppices of Gargano (Puglia, Italy): first results. Six plots have been drawn in an aged turkish oak coppice stand, 35 years after last clearcut. Compared treatments are: natural evolution of the coppice without thinning versus two thinning regimes with different intensity, both aimed to convert the stands into high forests. From 600 to 800 stems per hectare were released in the conversion plots. Plots, drawn and treated in 1996, have been measured before and immediately after thinning and remeasured five and ten years later. Conversion is successfully proceeding, the stands are assuming a high forest structure with a markedly dominated understory layer. In control plots many stems died while in the thinned stands no damage or significant natural selection occurred
Indici strutturali e di competizione per la caratterizzazione di popolamenti cedui di castagno
Get PDFStructural and competition indexes to characterise chestnut coppice stands. Structure, tree density and variation of tree specific composition are parameters useful to describe both natural dynamics and competition processes. In the field forestry, synthetic indices descriptive of both specific - structural diversity and competition are used, especially for high forests. In the present paper, the relations between silvicultural treatment and some synthetic indices descriptive of thinned chestnuts coppice stands differently aged are analysed. The main goals of the paper are: i) to verify the application of some in coppice stands, to evaluate their adaptation to differentiate and quantify the structural complexity, stand dynamics and competition processes as a function of past silvicultural history; ii) to ascertain the utility of the indices for the planning of future thinnings. The study was carried out in three experimental plots of the “Altopiano delle Pizzorne, (Lu)”. The stands analysed are differently aged (43 and 64 years) and as for silvicultural background which affected both the present structure and the ongoing competitive process. The detailed of stands structure analysis was carried out within experimental areas (1200m2), besides manserational parameters, data necessary to determine the competition indices were acquired. Data analysis led to determine synthetic indices of distributive, structural and specific diversity. The analysed stands show a one-storied, monospecifici structure with a tree distribution from regular to random and reduced level of individual competition. The chosen indices describe the effect of the applied treatment and show that the analysed stands are not characterized by the clustered distribution typical of coppices. The active silvicultural treatment determines the simplification of the stand structure. Furthermore, the selected indices, synthetic and easy to calculate, represent a useful operational instrument in silvicultural planning