A review of the roles of forest canopy gaps

Treefall gap, canopy opening caused by the death of one or more trees, is the dominant form of disturbance in many forest systems worldwide. Gaps play an important role in forest ecology helping to pre- serve bio- and pedo-diversity, influencing nutrient cycles, and maintain- ing the complex structure of the late-successional forests. Over the last 30 years, numerous reviews have been written describing gap dynamics. Here we synthesize current understanding on gap dynamics relating to tree regeneration with particular emphasis on gap characteristics consid- ered critical to develop ecologically sustainable forest management sys- tems and to conserve native biodiversity. Specifically, we addressed the question： how do gaps influence forest structure？ From the literature re- viewed, the size of gaps induces important changes in factors such as light intensity, soil humidity and soil biological properties that influence tree species regeneration and differ in gaps of different sizes. Shade- tolerant species can colonize small gaps; shade-intolerant species need large gaps for successful regeneration. Additionally, gap dynamics differ between temperate, boreal, and tropical forests, showing the importance of climate differences in driving forest regeneration. This review summa- rizes information of use to forest managers who design cutting regimes that mimic natural disturbances and who must consider forest structure, forest climate, and the role of natural disturbance in their designs.

Short-term effects of different fire severities on soil properties and Pinus halepensis regeneration

Considering that diverse fire severities can affect soil properties differently,the aim of this study was to examine to what extent changes in soil properties caused by fire could condition seedling establishment.This new approach is for identifying a new fire cause-effect chain to qualify the impacts of fire on soils with the purpose of using fire as a tool in forest management to favour Pinus halepensis Mill.regeneration.The study area was a reforested P.halepensis area which had been crossed by fire for78.8 ha,causing various degrees of damage.The forest was subdivided into three large areas according to the gravity of crown scorch,[low(LS),medium(MS)and high(HS)severity],on the basis of needle yellowing which usually occurs after exposure to direct flames.Results showed significant differences in soil properties with respect to fire severity.In the HS area,total nitrogen and carbon were considerably reduced while ash and phosphorus contents significantly increased.The changes in soil properties,in particular to nutrient levels,affected P.halepensis regeneration,mainly the first year after the fire.Greater regeneration occurred in areas affected by moderate fire severity in which the temperatures reached increased the mineralization of soil organic matter with the consequent release of nutrients available for seedling growth.Additionally,moderate fire severity suppressed the regeneration of grasses,reducing the interspecific competition.Heights of seedlings were inversely proportional to the density of grasses.Where the number was abundant(LS),the height was modest;conversely,where the number was low(HS),the greater hypsometric differentiation of pine seedlings was observed.These results suggest that moderate fire severity represents an environmental stress(hormesis)altering microscale conditions to increase pine germination and establishment.The exposure of P.halpensis to a moderate environmental factor that is damaging at higher intensities,induces an adaptive beneficial effect on seedling regeneration.This data can re-evaluate the assertion that coniferous burned areas,if left unmanaged,would remain unproductive for an indefinite period.

Forest structure of a maple old-growth stand: a case study on the Apennines mountains(Southern Italy)

In Europe, very small forest areas can be considered to be old-growth, and they are mainly located in Eastern Europe. The typical structures of old growth forests infrequently occur in Mediterranean mountainous environments, since they have been affected by human activities for centuries. This study focused on a remote and almost pure Italian maple stand located in southern Italy, which has not been managed for long time due to its inaccessibility. The effects of natural evolution on the forest stand were evaluated through the analysis of the spatial and chronological structure and the regeneration patterns, then estimating the amounts and quality of deadwood occurrence. Across the whole stand, all the trees with DBH （diameter at breast height） larger than 50 cm （LLT, large living trees） were measured （DBH and height） and age was also determined through a dendrochronological approach. The diameters observed ranged between 50 and 145 cm with ages of 12o to ~5o years. The Latham index calculated for trees within the sample plot highlighted a multilayered canopy with a dominant layer of largeliving trees （age 〉 120 years）. The size-class distribution of stems had a reverse-J shape, and basal area was 52 m2 ha-1. Deadwood was exclusively constituted by standing dead trees and CWD and its volume was on average 31 m3 ha-1. Pure Italian maple forests are generally rare in Europe, and it was unexpected to find a forest stand characterized by a so complex structure with old growth attributes. The study of complex forest stand, even if small, could give precious information on the forest evolution, clarifying also diverse auto-ecological traits of tree species that usually are not common in our forests.

Genetic diversity in old populations of sessile oak from Calabria assessed by nuclear and chloroplast SSR

In the framework of forest resources conservation, this study aims to understand the dynamic and the genetic structure of sessile oak forests in Calabria, Italy. Two old populations of sessile oak(Quercus petraea(Mattuschka) Liebl.) from two areas of Sila and Aspromonte massifs in Calabria were analyzed for genetic diversity and population structure based on 6 nuclear simple sequence repeat(nSSR) and 4 chloroplastic SSR(cpSSR) loci. The populations displayed high amount of genetic diversity, which was toughly structured according to their geographical origins. Number of alleles at SSR loci ranged from 11 to 20 with an average of 13.5 per locus. Gene diversity(expected heterozygosity, He) estimates ranged from 0.575 to 0.834 with a mean of 0.749. The observed heterozygosity(Ho) was on average 0.458 ranging from 0.150 to 0.682. Polymorphism information content(PIC) values ranged from 0.625 to 0.865 with an average of 0.787. The analysis of molecular variance(AMOVA) highlighted a significant higher estimated variance within populations compared to among populations. Finally, the analysis of haplotypes by using cpSSR suggested a higher diversification in the population from Sila. Hierarchical clustering analysis grouped the genotypes into two major clusters, which agreed with the geographic origin of populations, and was confirmed by the Discriminant Analysis of Principal Components(DAPC). The first cluster included plants/population from Sila massif, while the second encompassed mostly plants/population sampled in Aspromonte massif. Finally, model-based clustering by STRUCTURE analysis also supported the presence of clear genetic structuring in the collection with two major populations(K=2) supported to PCoA analysis as well. Finally, our data indicated the Aspromonte population as a marginal forest with fragmented distribution suggesting different strategies of preservation than in Sila massif.

Acquired Pigmentation of Porcine Lymph Nodes: Dietary Polyphenolic Compounds as Biological Markers?

The investigation aimed at exploring whether 1) high contents of natural polyphenols from the diet can induce pigment accumulation in lymph nodes (LNs);2) if so, whether polyphenolic compounds and derivates can be used as biological markers;3) and whether a lymph node from a specific anatomical region can be univocally identified, so as to be con sidered as a sentinel for the identification of the dietary origin of pigments. A paired match approach was used to switch 20 pigs (range of initial body weight, BW: 113 - 121 kg) to two experimental diets, for four weeks: ten pigs (pair housed) were fed with an experimental acorn based diet (acorns: 50% in the diet, as fed;total polyphenols, 78.1 g TP/Kg DM in the diet;tannic acid equivalent, 25.8 g TAE/kg DM);the remainder ten, received a pelleted complete diet for finishers (0% acorns in the diet). Daily feed intake in the last two weeks of the experimental feeding was recorded per pair of pigs in both groups of animals, showing an average intake of 610 mg TAE/kg BW/d. At an average final BW of between 127 to 137 kg, all pigs were slaughtered and LNs from different anatomical regions of the carcass were removed and analysed. At gross inspection, LNs from both groups displayed different grades of intensity and diffusion of pigmentation: a partial and incidental pigmentation was randomly detected in renal or sub-iliac LNs in the control group;a constant and uniform pigmentation of LNs was observed in acorns fed pigs: a dark brown staining diffused to the whole LN associated with a brownish colour of the muscles was found systematically. At light microscope intracytoplasmic granules were found in macrophages and dendritic cells from both groups, but, at confocal laser analysis, an intense auto-fluorescence was observed in medial-iliac LNs from the carcasses of acorn-fed pigs (green emission). However, intracellular sources of blue and green fluorescence at different wavelengths, likely due to tryptophan, indoleamine and derivates were also found in medial-iliac and inguinal LNs from the control group. A dietary origin was attributed to the different discoloration of LNs between the carcasses of the two groups: such acquired pigmentation is relevant in the left sub-iliac LN, but the confocal laser microscopic test to elicit auto-fluorescence of polyphenolic compounds (biological markers) displayed a 76.9% specificity, despite a 100% of sensitivity for the univocal identification of the carcass from acorn-fed pigs. Cranial sternal LNs resulted to suit the sentinel role in the distinction of carcass from acorns fed pigs at confocal laser microscopic analysis.

Economic and environmental sustainability assessment of wine grape production scenarios in Southern Italy

The low resilience of ecosystems imposes a sustainable management of natural resources through more rational uses, land protection, energy saving and low carbon production technologies. Agriculture has a great responsibility in managing these resources that are the principal inputs of its processes. Production systems must pay attention, at the same time, to economic viability and environmental protection. Since decades, the international scientific community is facing the great challenge of assessing the sustainability of agricultural engineering techniques, in order to help both private and public decision making, but also to meet consumer’s requirements for high quality and low impact products. To achieve that, widely accepted assessment instruments, whose results have to be clear and understandable to a broad public, and that are necessary. In this direction, Life Cycle Thinking (LCT) is gaining consensus as conceptual model, considering goods and services production and consumption all along the whole life cycle, from planning to disposal. Its methodological frame- work, the Life Cycle Management (LCM), offers many standardised tools to assess impacts of products and processes: Life Cycle Assessment (LCA), to evaluate environmental impacts and Life Cycle Costing (LCC) for economic ones. Among many impacts categories LCA also allows to identify the carbon footprint, that can be quantified in terms of Global Warming Potential (GWP). This research has analyzed and compared different scenarios of wine grapes production in Cirò, an important viticultural area located in Calabria region (Southern Italy). LCA and LCC methodologies have been useful to assess them from an environmental and economic standpoint. Results have allowed the authors to rank training and farming systems performances.

An automated medium scale prototype for anaerobic co-digestion of olive mill wastewater

Olive oil production constitutes one of the most important agro-industrial business for Mediterranean countries,where 97% of the international production is focused.Such an activity,mainly carried out through three phase olive oil mill plants,generates huge amounts of solid and liquid by-products further than olive oil.Physico-chemical features of these by-products depend on various factors such as soil and climatic conditions,agricultural practices and processing.As currently carried out,the disposal of these byproducts may lead to numerous problems taking into account management,economic and particularly environmental aspects.Indeed,olive mill wastewater is not easily biodegradable due to its high chemical and biochemical oxygen demand,its high content in phenolic compounds,high ratio C/N and low pH,leading consequently to soil and water source pollution.Considering,the above-mentioned statements,olive mill waste disposal constitutes nowadays a challenge for oil industry stakeholders.It becomes necessary to look for alternative solutions in order to overcome environmental problems and ensure the sustainability of oil industry.Anaerobic co-digestion of olive mill wastewater with other agro-industrial matrices could be one of these solutions;since it offers the possibility to produce green energy and break down toxicological compounds contained in these wastewater for a better disposal of the digested matrices as soil conditioner.In this contest,this note reports the functioning principle of an automated medium scale plant for anaerobic co-digestion of olive mill wastewater.