Effects of mixture and thinning in a tree farming valuable broadleaves plantation more than 20 years after the establishment.

The results of peduncolate Oak plantation trials where the Oak is mixed to wild Cherry and narrow-leaf Ash per line and per close mixture with different proportions (25% and 50%) of N-fixing species (Black Locust and Italian Alder) are described in the paper. The plantation, carried out in winter 1988-89, was framed into a reafforestation plan for spoil banks restoration. On a share of the plantation area, free thinnings foreseeing the release of about 70 target trees per hectare, were undertaken in 2001 and 2003; 21% and 27% of basal area were removed, respectively. In the latter trial, the crowns of target trees were completely isolated by felling all the surrounding trees. The performances of valuable timber broadleaves, the effects of intercropping and thinning on the growth of Oak target trees were analysed. Three inventories (2001, 2004 and 2008) and the annual monitoring of target trees growth were performed at the purpose. The two peduncolate Oak and narrow-leaf Ash trees showed the best performances among the set of valuable broadleaves, whilst wild cherry resulted not suited to local site conditions. A higher tree mortality occurred in the mixture with Black Locust. The mixture with both Nfixing species provided a stimulus to the Oak growth both in terms of dbh and tree height. Italian Alder resulted anyway less competitive and easy to manage, considering its progressive self-thinning, while Black Locust was aggressive enough to necessitate the control of its development by pollarding 7 years after the plantation. In the thinned plots, target trees showed significant diameter increments in comparison with control plots; maintaining year by year constant dbh increments of about 1 cm and crown’s diameter increment of about 50 cm. Intercropping with Italian Alder showed to be more effective than thinning on growth of the target trees

Volume function for the tree farming English oak plantations of the Valdarno (Tuscany, Italy)

In the past centuries a notable reduction of lowland forests in Italy was detected as a result of the spreading of intensive agriculture and deforestation activities. According to the national forest inventory (INFC 2005) the English oak (Quercus robur L.) is mainly a scattered species and is distributed across 146,000 hectares of mixed forests. However this species has often been used in many national programs to recreate new woodlands in the lowlands as well as tree farming plantations. In the '80s, during the restoration program of the Santa Barbara mining area in the Municipality of Cavriglia (Valdarno, Tuscany), about 172 hectares of tree farming plantations were created with English oak. Due to the lack of a specific volume equation for Italian plantations a sampling campaign was carried out. The volume of 299 sample trees was measured using the Heyer formula and a volume equation was studied as a polynomial function of DBH and total height of trees. The final equation demonstrated to be quite robust with a RMSE of 0.0176 m3 corresponding to a relative RMSE of 10%

Prove di diradamento in acero-frassineti di neoformazione nella Comunità Montana Agno-Chiampo (VI). Risultati dopo il secondo intervento

Thinning trials in secondary growth ash-maple stands carried out in the Agno-Chiampo district (VI): results after second thinning. The second thinning results undertaken in four ash-maple stands of different age are described. In three stands a target tree management system (free thinning around few target trees) was applied. In the oldest stand one mixed thinning has been implemented. In the youngest stand 400 target trees have been preselected and numerically half reduced after a second free thinning (aged 18 yr). The basal area of this stand decreased globally with 34%. In the middle aged stand (aged 28 and 31 yr), all the target trees, previously selected, were favoured. Among them, only those seriously damaged (by logging and frost) were cut down. The overall uptake in this stand has been the 30% of basal area. In the oldest stand the second traditional thinning (aged 37 yr) was more intensive, than the previous: the 34% of basal area has been felled. The analysis of target trees diameter growth has revealed that free thinning has been efficient for the youngest stand (a constant diameter increment of 8,6 mm yr-1). Conversely, a progressive reduction of diameter increment (5,5 mm yr-1) has been found in the control plot. The reaction to thinning in the middle aged stand was inferior in terms of homogeneity and diameter increment through years (6 mm yr-1 average), this underline a less reaction of crowns. In the oldest stand, late thinnings had little incremental effect, however the general stability and specific diversity improved . The experimental results confirm the necessity to carry out the first thinning in young stands (aged 15-20 yr) with a frequency of 4-6 yr in a restricted number of target trees (100-200 per hectare). In the oldest stands the chance to improve the production of good quality timber is reduced, but timber with fairly good technological characteristics can be however obtained

Confronto tra metodi di diradamento in un impianto puro d farnia (Quercus robur L.)

Comparison between different thinning systems in a pure common oak plantation.- First results of thinning trials, in a 19 years old pure common oak plantation, carried out during winter 2001/2 are reported. A previous thinning had been applied in 1993. Two different thinning methods were tested: systematic-selective method (50% tree felling) and selective thinning method (felling around 80 target tree per hectare). In spite of different thinning intensity (43% and 28% of basal area) in order to keep constant the diameter increments of target trees, the effects of both methods were similar. During the first five years after thinning, the target trees in both thinned plots showed constant diameter increments around 1,1 cm , while in the control plot the diameter increment decreased progressively to 0,7 cm. After thinning and pruning, epicormic branches developed on target trees. In the specific, about 68% of target trees in the thinned plots are characterized by epicormic branches, although only the 17% are vigorous. In the control plot, 62% of target trees developed epicormic branches, none of them vigorous

One and two-entry tree volume tables for the new-established ash-sycamore forest types at a pre-alpine territory.

Ash-sycamore stands have been assuming a considerable territorial importance in Northern Italy over the last decades. According to the National Forest and Carbon Sinks Inventory (INFC), these stands form the type of “sycamore-lime mountain & ash forests” and “Apennine maple forests”. These forests amount to 153904 hectares (88% in the Northern regions) and 23600 hectares, respectively. In the Veneto Region, ash-sycamore are mainly secondary forests and occupy 9258 hectares. These stands spread easily throughout the agriculture set-aside lands thanks to their colonizing ability and to the favourable soil conditions in the pre-alpine region. Experimental thinnings framed into a wider project aimed at producing management guidelines according to a single-tree oriented approach, provided a sample of 385 trees. On the basis of this dataset, the first tree volume tables for these ash-sycamore stands have been elaborated. Data collection and data processing are being described in the paper. A two-entry tree volume table was set up by the stepwise analysis procedure and a one tree volume table was derived from the two-entry tree volume table

Comparing growth rate in a mixed plantation (walnut, poplar and nurse trees) with different planting designs: results from an experimental plantation in northern Italy

Results of a mixed plantation with poplar, walnut and nurse trees established in winter 2003 in Northern Italy, are reported. Main tree species (poplar and walnut) were planted according to a rectangular design (10 x 11m), with different spacings and alternate lines. The experimental trial was carried out to verify the following working hypotheses: (i) possibility to combine main trees with different growth levels (common walnut, hybrid walnut, and different poplar clones) and test two different poplar and walnut spacings (5.0 and 7.4 m) in the same plantation; (ii) opportunity to reduce cultivation’s workload, in comparison with poplar monoculture, using mixtures with different poplar clones and N-fixing nurse trees; (iii) verifying the growth pattern of two new poplar clones in comparison with the traditional clones cultivated for different purposes in Italy.The use of different valuable crop trees’ mixtures intercropped with nurse trees and shrubs (including N-fixing trees) allows to decrease the cultivation’s workload. In fact, a heavy reduction of cultural practices - fertilizers, weed control, irrigation and pesticides applications (-61%) are the main concurrent, supplementary benefits. The best growth performances (DBH and tree height), associated with the higher competition towards walnuts, were recorded with the new clones Lena and Neva in comparison with the I214 and Villafranca. The closer spacing (5 m between poplar and walnut trees) was found to be unsuited to get merchantable poplars sized 30 cm without developing a heavy competition towards walnut trees. The wider spacing (7.4 m) resulted vice versa suitable to get poplar trees sized as requested by veneer factories and to maintain an acceptable competitive level with walnut. Within this plantation design, a shorter rotation (8 yrs) is needed for Lena and Neva clones in comparison with I214 and Villafranca (10 yrs). Walnut intercropped with poplar showed cone-shaped crowns, light branching and a good stem quality in comparison with walnut grown in pure plantations. This model of mixed plantation can become an interesting optional choice to walnut's and poplar's monoculture with notable advantages both for farm economics, landscape quality and environment preservation

Tree Species Composition in Mixed Plantations Influences Plant Growth, Intrinsic Water Use Efficiency and Soil Carbon Stock

Species interactions in mixed plantations can influence tree growth, resources capture and soil fertility of the stands. A combined approach of tree-ring analyses and carbon stable isotope was used to check tree growth and water use efficiency of two species, Populus alba L. and Juglans regia L., intercropped with each other and with N-fixing or competitive production species. Furthermore, soil analyses were performed to understand how the different intercropping systems can influence soil characteristics, in particular soil carbon stock. Dendrochronological data showed that during the first years, the growth of principal species was favored by intercropping. This positive effect decreased in the following years in most of intercropped stands, due to light competition with the crown of companion species. Carbon isotope data showed that P. alba and J. regia had the highest intrinsic water use efficiency when growing with Elaeagnus umbellata Thunb, a shrubby species with a shallow root system that favors a non-competitive exploitation of soil water resources. Finally, the intercropping of the principal species with Corylus avellana L. promoted the highest soil C stock. Our findings confirmed the importance to consider the plantation dynamics and wood formation in the long-run and to apply appropriate thinning and pruning interventions to counteract interspecific competition

Tree-oriented silviculture for growing valuable broadleaved tree species in Turkey oak coppices

Valuable broadleaved tree species can play an important role in mixed-forest management; in these forests, silviculture may play an important role in getting high value timber. This paper illustrates a tree-oriented silviculture approach with an application in a Turkey oak coppice stand in Central Italy. This silvicultural approach has been developed in the last decades in France, Germany, Switzerland. The rationale behind the tree-oriented approach is to select a number of target sporadic tree species with valuable timber and to support their growth through repeated thinning from above. We tested the effectiveness of this silviculture approach as an alternative to customary coppice management in Italy, which is traditionally focused on the dominant tree species and does not consider valuable broadleaved tree species. The two silviculture approaches (tree-oriented and customary coppicing) were compared through a financial evaluation of the economic convenience of the two alternatives in a Turkey oak coppice stand in Central Ital

Comparison between crown thinning and girdling to enhance sporadic tree species in a coppice stand in Central Italy

Sporadic valuable tree species and especially Sorbus species have gained importance in forest management as they increase tree biodiversity, ensure a higher resilience of the stand to climate change, and enhance valuable timber production. This paper reports the first results of a trial carried out in Central Italy in a Turkey oak coppice stand (aged 17 years) where three different silvicultural treatments (crown thinning, girdling and unthinned control) were applied to favour sporadic tree species. The monitoring was carried out for 5 years and showed the limits of girdling application as Mediterranean species like Turkey oak form easily scar cords and epicormic sprouting. Furthermore, the progressive reduction of canopy cover of the competitors resulted from girdling and the effect of the thinning and girdling on the growth of selected service trees (Sorbus domestica L.) were evaluated. The first results of this research have pointed out some difficulties in the girdling application and a higher effect of crown thinning in stimulating the growth of selected service trees