Properties of dissolved organic matter in forest soils: Influence of different plant covering

The nature of different forest plant litters and the effect of their degradation processes on the properties of soil dissolved organic matter is a very important environmental issue in protected areas such as the “Natural Oriented Reserve Bosco delle Pianelle” in Southern Italy, Chemical and spectroscopic techniques were used to evaluate the influence of four different tree covers on the properties of dissolved organic matter (DOM) isolated from litter and surface soil layers. Fourier transform infrared spectroscopy analysis showed that all litter samples feature a prevalent aromatic character. Ligninolitic components of litters produced by Pinus halepensis L. and a mixture of Quercus trojana Webb. and Q. ilex L. were more degraded than those produced by either Q. ilex or a mixture of Carpinus betulus L. and C. orientalis Miller. The larger C/N ratios of the former litters might account for the greater degradation. Further, a lesser lignin decomposition was shown also for the latter samples, likely due to adverse topographical factors, such as less intense sunlight and greater moisture content. Spectroscopic analysis of litter DOM showed that easily degraded components, such as water-soluble compounds and carbohydrates, were preferentially degraded resulting in DOM that was enriched in lignin-derived compounds. Fluorescence analysis data of all litter DOM samples showed the occurrence of fluorescent units qualitatively similar regardless of plant covering, which suggests that in all cases simple structural components of low-molecular weight and small degree of aromatic polycondensation and content of conjugated chromophores are present. Soil DOM featured several numerous fluorescent units that differ as a function of the parent litter and/or its decomposition processes. Along the soil profiles water-soluble aliphatic compounds of low-molecular weight are found down to the deepest layer, whereas aromatic–ligninolitic compounds are decreasing with depth, probably because of their adsorption by mineral soil components. A greater amount of aromatic units, likely lignin-derived compounds, was found in the DOM from P. halepensis L., which suggested a more extended lignin decomposition. Further, with increasing soil depth, DOM was characterized by a decrease of low-molecular weight organic molecules and lower degree of humification.     

New type forest damage to mediterranean vegetation in Southern Sardinian forests (Italy)

This paper investigates some biological aspects of the decline of the Forest of Pikinamanna in Southern Sardinia: the evolution of forest deterioration, leaf diagnosis, analysis and observation with SEM. We present the hypothesis of a relationship between this decline and some adverse environmental factors, particularly atmospheric pollution and drought.     

Contribution to the knowledge of the folk plant medicine in Calabria region (Southern Italy)

A series of research on plants used in Calabria (Southern Italy) in the folk plant medicine was carried out in the last twenty years. The use of 104 taxa distributed into 42 families are described. Among the major findings: Ceterach officinarum as hypotensive; Heliotropium europaeum in the case of urinary inflammations; Silybum marianum for haemorrhoids; Arundo donax for pertussis and cystitis; Allium cepa for sties and flu; Laurus nobilis as galactagogue; Passiflora incarnata for burns, haemorrhoids and skin inflammations; Scrophularia canina for rhagas and wounds; Urtica membranacea for tussis and tonsillitis.     

Covariation between plant biodiversity and soil systems in a European beech forest and a black pine plantation: the case of Mount Faito,(Campania,Southern Italy)OA

Both climate and land-use changes, including the introduction and spread of allochthonous species, are forecast to affect forest ecosystems. Accordingly, forests will be affected in terms of species composition as well as their soil chemical and biological characteristics. The possible changes in both tree cover and soil system might impact the amount of carbon that is stored in living plants and dead biomass and within the soil itself. Additionally, such alterations can have a strong impact on ...     

不同采伐方式对阔叶林物种多样性的影响研究

对阔叶林皆伐人促更新和择伐人促更新对物种多样性影响的研究,结果表明不同采伐方式对群落物种丰富度、物种多样性指数和物种多样性均匀度指数均有一定的影响.皆伐人促更新林分物种比择伐人促更新少10种,乔木树种少了14种;不同采伐方式对群落的物种多样性指数和物种多样性均匀度指数影响不大,但对各层片有较大的影响,皆伐人促更新的乔木层物种多样性指数和物种多样性均匀度指数均比择伐人促更新林分低,但草本和藤本层物种多样性指数和物种多样性均匀度指数均比择伐人促更新林分高.     

Weed cover in hybrid poplar (Populus) plantations on Quebec forest soils under different lime treatments

Fast-growing trees such as hybrid poplars (Populus) have the potential to decrease rotation length (time to harvest) and thus produce wood products more quickly from smaller areas of land. Several forest companies in Quebec currently plant hybrid poplar on formerly logged forest sites, rather than on agricultural land as is more common elsewhere. The forest sites often have acidic soils, and lime addition has been proposed to improve hybrid poplar growth. In addition, forest sites present challenges with regard to control of competitive vegetation, particularly in jurisdictions such as Quebec where use of herbicides in forests is banned or restricted.     

辽河源自然保护区不同森林类型草本群落谱系结构及其环境影响

该研究以辽河源自然保护区草本植物为研究对象,分析不同森林类型中草本植物多样性和群落谱系结构的差异,并探讨影响其变化的环境因素.研究显示:次生蒙古栎林草本植物丰富度最高,人工落叶松林和油松林次之,人工混交林和次生山杨林最低;次生蒙古栎林草本群落谱系结构呈集聚状态,人工落叶松林草本群落谱系结构呈发散状态,人工混交林、次生山...     

Acidity in four coniferous forest soils after different harvesting regimes of logging slash

The soil acidity of four coniferous sites, two in S Sweden and two in N Sweden, were studied 7–9 years after clear‐felling. Each site had three different slash treatments; (a) all slash harvested, (b) only needles remaining, and (c) all slash remaining. Our results verify that harvesting of slash after clear‐cutting means an acidification of the organic horizon in acid forest soils. On plots subjected to full slash harvest the pH‐value of the forest floor was 0.2–0.4 units lower than that of slash‐covered ones, and at three of the four study sites the exchangeable acidity was significantly higher on the slash‐cleared plots. Plots with only needles remaining were generally intermediate in acidity. The change in exchangeable acidity corresponded to approximately 10% of the theoretically estimated proton load caused by slash harvesting. The rate of proton flux associated with whole‐tree harvesting varied between 7–65 meq m^‐3 yr^‐1, which roughly corresponds to the amounts deposited in precipitation. Harvesting of stems accounted for about one third and needles for one third of the proton load.     

Influence of plant species on physical,chemical and biological soil properties in a Mediterranean forest soil

In semiarid ecosystems plant cover plays an important role in the improvement of physical, chemical and biochemical soil properties. With the aim of studying the influence of different plant species on soil properties, and establishing the relationships between them, 160 soil samples from under four different plant species (Pinus halepensis, Quercus coccifera, Juniperus oxycedrus and Rosmarinus officinalis) were taken in a forest area of the province of Alicante (SE Spain). The following soil properties were analyzed in all soil samples: organic carbon content, microbial biomass, soluble organic carbon, aggregate stability, basal respiration, and some eco-physiological ratios. In addition, the near infrared spectra (NIR) of all soil samples were obtained to verify the similarities or differences between soil samples under the four species. Some differences in parameters such as organic carbon content or basal respiration were found mainly between the group of P. halepensis and Q. coccifera with respect to J. oxycedrus and R. officinalis. Despite this, the high organic carbon content found under the four plant species showed an influence on the rest of soil properties. Moreover, using a discriminant analysis with factorial scores from NIR absorbance data did not result in a good classification of samples in terms of the species, reflecting some similarities between them. Our results show that the high contents observed in some parameters under the four species, and the lack of significant differences in most of them, prove the important role of shrubland in semiarid conditions, it being capable of promoting good soil conditions.     

Pheromone detection of the introduced forest pest Megaplatypus mutatus (=Platypus mutatus) (Chapuis) (Platypodinae, Curculionidae) in Italy

Megaplatypus mutatus (Chapuis) (=Platypus mutatus), an ambrosia beetle native to South America, attacks standing live trees of a wide range of forest and fruit tree species, and it is particularly damaging to commercial poplar plantations. In 2000, M. mutatus was observed for the first time in Italy, in the province of Caserta, near Naples. The development of a pheromone-based monitoring system, for detecting the spread and for managing M. mutatus infestations, is an important goal for both European and South American control and surveillance programs. Using a three component pheromone blend developed in Argentina into commercial funnel traps we were able to asses the level of dispersion of this pest in the Italian Campania region. Insects were captured in all the plantations suspected of being infested based on the presence of active parental and larval galleries. We also provide the first report of the attack followed by completion of the life cycle of M. mutatus in European hazelnut, Corylus avellana L. (Betulaceae), an important nut species native to Europe and Western Asia.     

Mineralization processes in some samples from the fossil forest of Dunarobba (Umbria, Central Italy)

 Two isolated twigs (samples A and B) from the site of the fossil forest of Dunarobba (Central Italy) were examined to assess both the degree of degradation of the organic fraction and the composition of the inorganic component. Sample A, although showing the presence of minute crystals, is mineralised only to little larger extent with respect to the trunks of the fossil forest and exhibits a wood composition almost comparable to that of the fossil forest. Main minerals are silica, calcite, chloroapatite, chloromagnesite, and clays. Residual terpenes perfectly match, as either components or proportions, those found in the fossil forest trunks. Sample B is much more mineralised and physical parts are hard (sample BII, 84% mineralisation) along with others that are quite loose (sample BI, 62% mineralisation). Goethite constitutes the major mineral in both parts. Calcite, on the contrary, is higher in BII than in BI. In agreement with the literature, goethite is present in the interstitial spaces of the cell walls whereas calcite is found in the cell lumina. The wood components are limited to lignin and terpenes; being absent cellulose or other polysaccharides. BI contains the same types of terpenes present in the fossil trunks, whereas only diterpenes have been found in BII. The samples B contain, with respect to either sample A or fossil trunks, a lower content of fully or partly aromatic sesquiterpenes and diterpenes. This fact is probably due to the oxidative environment of iron deposition. The difference in the mineralogical structures exhibited by the two samples must be searched in the different environmental conditions under which the samples were maintained. In particular, an essential role must have been played by water sources much richer in soluble salts and more differentiated than the current spring waters of the region. Received 6 March 1999     

Monitoring managed forest structure at the compartment-level under different silvicultural heritages: An exploratory data analysis in Italy

ABSTRACT

The more and more diffused multifunctional role addressed nowadays to public forests, calls for targeted analysis aimed at highlighting the overall outcome of different practices implemented on the same forest compartment, according to the locally prevailing function. This study was carried out in four Italian beech forests across a latitudinal gradient representative of multiple management history, stand structure, and dominant stand age. We analyze forest structure at the compartment scale before and after silvicultural practices. We aim to explore relationships and similarities between 10 stand attributes (mensurational and structural variables) to identify relevant indicators for the monitoring and management of forest ecosystems. Results indicate changing patterns of correlation and similarity among mensurational variables following practice implementation. A sensitivity gradient to silvicultural practice was finally identified within the four sites investigated as a result of the diverging stand structure. Our approach suggests a way and provides an insight for the design of adaptive forestry management practices required to meet environmental targets, in addition to the already acknowledged supply of primary goods and services.     

INFOCARB: A regional scale forest carbon inventory (Provincia Autonoma di Trento,Southern Italian Alps)

The aim of this inventory (acronym: INFOCARB) was to measure the organic carbon stored in the forest ecosystems of the Trento region (Provincia Autonoma di Trento, Northern Italy) in both above- and belowground pools, according to the Kyoto protocol and IPCC requirements. A total of 150 forest sampling points were selected on the entire regional area (6206 km²) with a statistical sampling approach, based on the timber volume as a proxy variable for a stratified sampling. Each sampling point was located with a GPS receiver and a 600 m² circular plot was delimited around each point. Inside the plots, the biomass of trees, shrubs and herbaceous vegetation was measured, while litter was collected in systematically placed subplots. Topsoil (down to 30 cm depth) was sampled with the excavation method on three systematically located pits, to determine the organic carbon content, the bulk density and the volume occupied by stones and roots.     

Effects of environmental factors on plant functional traits across different plant life forms in a temperate forest ecosystem

New Forests - Plant functional traits have been shown to vary with environmental conditions. However, we lack empirical data on how plant functional traits of different plant life forms respond to...     

The influence of canopy patch mosaics on understory plant community composition in boreal mixedwood forest

We assessed the composition of understory vascular plant communities in relation to the mosaic of canopy patch types, and their associated structure and environment, within unmanaged, mature boreal mixedwood forests in western Canada. Within a 30 km² area, we sampled patches of four different canopy types: conifer-dominated, broadleaf-dominated, mixed conifer-broadleaf, and canopy gaps (total n = 98). There were significant differences in understory composition among the four patch types (based on multi-response permutation procedure (MRPP)) and these were mainly due to differences in relative abundances of understory species. The understory communities of conifer patches were characterized by low abundances of shade intolerant species while shade-tolerant and evergreen species were indicators (based on an indicator species analysis (ISA)). Understory communities under gap and broadleaf patches were characterized by higher abundances of grasses and shade intolerant species. Gap, broadleaf, and mixed patches had higher abundances of certain shrub species than did conifer patches. The patch types also differed in terms of their environmental conditions. Conifer patches had drier, cooler soils and the lowest understory light. Broadleaf patches had the warmest soils while understory light during the leaf-off period was similar to that of canopy gaps. Gap patches had the lowest litter cover and PO₄⁻ availability and the highest light. Seven environmental variables (soil moisture, soil temperature, total light during the leaf-off period, cover of coarse and fine downed woody material, and availability of NH₄⁺ and Ca²⁺) were significantly related to understory species composition (in a constrained ordination by means of a distance-based redundancy analysis (db-RDA); 16.5% of variation in understory community data explained). Even within a single patch type, there was substantial environmental variation that was related to understory species composition. Our study suggests that the mosaic of canopy patches within mixedwood forests supports coexistence of both early and late successional understory plant species in mixedwood stands. Maintaining the mixture of canopy patch types within mixedwood stands will be important for conserving the natural patterns of understory plant composition in boreal mixedwood forests.     

Nitrification and denitrification as sources of gaseous nitrogen emission from different forest soils in Changbai Mountain

The contributions of nitrification and denitrification to N₂O and N₂ emissions from four forest soils on northern slop of Changbai Mountain were measured with acetylene inhibition methods. In incubation experiments, 0.06% and 3% C₂H₂ were used to inhibit nitrification and denitrification in these soils, respectively. Both nitrification and denitification existed in these soils except tundra soil, where only denitrification was found. The annually averaged rates of nitrification and denitrification in mountain dark brown forest soil were much higher than that in other three soils. In mountain brown coniferous soil, contributions of different processes to gaseous nitrogen emissions were Denitrification N₂O>nitrification N₂O>Denitrification N₂. The same sequence exists in mountain soddy soil as that in the mountain brown coniferous soil. The sequence in mountain tundra soil was Denitrification N₂O>Denitrification N₂. Foundation item: This paper was supported by the National Natural Science Foundation of China (No.49701016) and the “Hundred Scientists” Project of Chinese Academy of Sciences. Biography: XU Hui (1967-), male, Ph. Doctor, associate research fellow in Laboratory of Ecological Process of Trace Substance in Terrestrial Ecosystem, Institute of Applied Ecology, Chinese Academy of sciences, Shenyang 110015, P. R. China. Responsible editor: Song Funan