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Traditional thinning and stand silviculture had positive effects on tree stability, stand efficiency and tree growth if compared to the lack of management. Nevertheless, the tree oriented silviculture has proven to be a type of management best meets the multifunctionality pourpouses required by forests today. In Italy beech high forests are generally managed with traditional thinning from below ascribable to stand silviculture; in the last decades tree oriented silviculture, an innovative management system is spreading in Europe. The aim of the study is to compare two thinning types applied in two localities of central Italy, in beech stands deriving from shelterwood system, aged 45-50 years: stand silviculture (SS), treesilviculure (TS) and control (C). All trees were periodically measured in order to assess growth, mortality and production from 2008 onwards. Crop trees DBH, selected for each silvicultural approach, was annually measured while, an evaluation of the stem quality, crown development and stability were carried out between the 1st and last thinnings. Differences in vertical and horizontal diversity stand structures were assessed. Results pointed out similar growth rate at stand level; while a superior growth in diameter, in dimension of the crown and stability of the crop trees were observed in TS. The TS has proven to be the management option that best meets the multifunctionality required by forests today. [ABSTRACT FROM AUTHOR]

• Simple coppicing is the best suited coppice system for a light demanding species such as the chestnut tree. • The growing performance of chestnut coppices is a function of stool and standard densities. • Any standard release is detrimental for the growing performance of the chestnut shoots. • We recommend simple coppicing to produce high quality chestnut wood. In the last decades, releasing standards have become a very common and in some cases even mandatory management options in coppice systems in Europe. As for the chestnut tree, a light demanding and fast-growing species, however, there is a lively debate and a lack of scientific evidences about the pros and cons of releasing standards, especially in stands devoted to quality wood production. In this paper we used nine chestnut coppice stands growing on similar site conditions - but differing in stool density and number of standard trees released - to analyze the effects of the stand structure (i.e., stool and standard density) on the growing performance in terms of diameter increment of the dominant shoots and overall basal area production. Simple coppicing (i.e., no standards release) confirmed to be the most suitable system to enable an initial full growing performance of a light-demanding species such as the chestnut. We thus recommend avoiding the release of standards in quality-wood chestnut coppices in order to allow the new shoots generation to develop undisturbed until the stage of the first thinning. The release of standards in chestnut coppices may however be appropriate in particular cases, such as in stands whose main aim is to protect against shallow landslides along steep slopes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Tree planting on abandoned agricultural land could both restore the soil quality and increase the productivity of economically valuable woody species. Here, we assess the impact of mixed-species tree plantations on soil quality at a site in Central Italy where tree intercropping systems were established 20 years ago on a former agricultural land. These intercropping systems include two species of economic interest, Populus alba and Juglans regia, and one of three different nurse trees, i.e., Alnus cordata, Elaeagnus umbellata, both of which are N-fixing species, and Corylus avellana. We measured tree growth and compared how soil organic matter, soil extracellular enzymes, and nematodes of different feeding groups varied among the intercropping systems and relative to a conventional agricultural field. Our results indicate that tree plantation led to an increase in soil carbon and nitrogen, and enhanced enzyme activities, compared with the agricultural land. The proportion of nematode feeding groups was heterogeneous, but predators were absent from the agricultural soil. Multivariate analysis of soil properties, enzymatic activity, nematodes, and tree growth point to the importance of the presence N-fixing species, as the presence of A. cordata was linked to higher soil quality, and E. umbellata to growth of the associated valuable woody species. Our findings indicate that intercropping tree species provide a tool for both restoring fertility and improving soil quality. [ABSTRACT FROM AUTHOR]

• Three thinning treatments of different intensity were applied to Quercus robur mixed plantation. • Tree growth and WUEi were affected by crown asymmetry and competition. • High presence of alder influenced tree growth due to resources competitions. • The very high selective thinning resulted to be the most appropriate management practice. • Thinning increased productivity and limited water loss. Thinning intensity is an important factor affecting forest structure and density and influencing tree growth. The main objective of the study is to evaluate how the different intensity of thinning can influence, in the short and long term, the productivity and intrinsic water use efficiency (WUE i) of Quercus robur L., a widespread European species. Three thinning types of different intensity were applied in 14-year mixed plantation of Quercus robur L. growing with Alnus glutinosa (L) Gaertn., a N-fixing species, with an initial density of 625 trees/ha. A multidisciplinary approach was applied, coupling the tree-ring analyses with the measurements of stable isotopes of carbon and oxygen. Findings highlighted how the different conditions of light and competition, determined by the type and intensity of thinning, triggered different responses of Q. robur species in terms of growth and WUE i. Data suggested that the moderate selective thinning (31% reduction of total biomass) was not able to reduce the high competition for resources among individuals: this condition negatively influenced the trees growth. The presence of the N-fixing species, left after the thinning, was not able to counteract the negative effect of competition. A negative effect on productivity was recorded with the geometric thinning (62% reduction of total biomass). Indeed, this treatment resulted in an increase of asymmetry of the canopy (0.90 vs 0.83, respectively in pre- and post-thinning period), due to the partial crown competition from one side and with a consequent limitation of the photosynthetic activity of the trees. Finally, the very high selective thinning (75% reduction of total biomass) resulted to be the most appropriate management practice, as it guarantees positive effects both in terms of growth and intrinsic water use efficiency. The post thinning conditions determined high photosynthesis rates, an increase of productivity and a limited water loss. [ABSTRACT FROM AUTHOR]