Occurrence of Phytophthora cinnamomi in cork oak forests in Italy

An increasing decline and mortality of cork oak trees have been recently observed in central Italy and Sardinia Island. Following surveys conducted in three declining cork oak forests, a Phytophthora species was consistently isolated from soil samples collected from trees displaying different level of decline. Based on morphological features, growth rates at different temperatures and analysis of DNA sequences of the ITS region, all isolates were identified as Phytophthora cinnamomi Rands. This pathogen caused large brownish lesions on inoculated freshly cut branches of cork oak. It was re‐isolated from all infected tissues. These findings represent the first report of P. cinnamomi on cork oak trees in Italy.     

Diversity of woody plant seedling banks under closed canopy in fragmented coppice forests

? Seedling banks of woody species established under closed canopy have received little consideration in coppice forests despite their potential importance for natural regeneration.

? This study aimed to evaluate the influences of canopy composition and of distance from the nearest forest edge on the abundance and species richness of the seedling bank, for different ecological groups of seedlings (age, successional status and dispersal vector) in 68 fragmented coppice stands.

? Seedlings were found in 67 stands, with 19 species identified. Eight species present as older seedlings were lacking as first-year old seedlings, suggesting temporal variability of species recruitment. Seedling abundances of species with low-dispersal ability were positively correlated with the abundances of their conspecific adults. Seedling abundance of mid-successional species was negatively correlated with the distance from the nearest forest edge, while mid-to-late successional species seedling abundance presented the opposite pattern.

? Our results showed that woody species were able to establish frequently under closed canopy in these fragmented coppices and form a seedling bank which may be used for natural regeneration.

     

Degradability of soils under oak and pine in Central Spain

The purpose of this research was to study the influence of the vegetation on the soil C pool of forests of pines (Pinus sylvestris) and oaks (Quercus pyrenaica), located in Central-Western Spain. Horizons from selected soils located in these forests were sampled, and the soil organic C (SOC) was determined. In addition, in vitro incubation experiments were carried out, under controlled conditions, to monitor the stability of SOC against the microbial activity. Soil humus fractions were isolated following a classical procedure of chemical fractionation using alkaline solutions, before and after the incubation experiment. A deeper O horizon was found under the pine forest than under oak one; however, higher SOC content was found in the oak site than that under pine one. During the in vitro mineralization process, a lower CO₂ production by the soil sample from pine forest was observed, in relation to that emitted by the oak soil. In addition, a lower humification degree was estimated for the soil humus under pines than for that under oaks. In conclusion, replacement of oaks by pines produced a decrease in SOC accumulation and a lower quality of humus in the forest soils.     

不同立地条件下休宁倭竹生长差异分析

在安徽省绩溪县和休宁县按照随机抽样的方法,设置了15个样方调查休宁倭竹的竹高、地径、叶片长度、叶片宽度和鞭径等生长指标,以及日照和湿度等立地因子。分析这些生长指标和立地条件的关系,结果表明：日照和湿度是影响休宁倭竹生长的关键立地因子,日照对休宁倭竹竹高和叶片生长的影响较大,湿度对休宁倭竹根系生长的影响较大,多重比较结果差异显著,同时日照条件对休宁倭竹叶片的变异性影响较大。因此,休宁倭竹应在光照条件好、土壤湿润的立地条件下栽植。     

Development of oak and beech seedlings planted under varying shelterwood densities and with different site preparation methods in southern Sweden

Effects of site preparation, shelterwood density and planting depth on the survival and growth of planted beech and oak seedlings were studied. Experiments were performed in one oak and one beech stand in southern Sweden. Two areas with different densities of shelterwood and one clearcut were established in each stand. Growth, damage and survival of the planted seedlings were observed for three years. Soil water potential was recorded weekly and radiation and soil temperatures were recorded continuously during the growing seasons.Neither site preparation methods nor planting depth affected oak seedling growth, when planting was carried out on fresh clearcuts or in shelterwoods, while growth of beech seedlings was positively affected by mounding. Growth of oak seedlings was inhibited by the shelterwood treatments. In beech seedlings, growth was lowest in dense shelterwood, while there was no difference in growth between seedlings on the clearcut area and in the shelterwood of low density. Differences in growth may be explained by differences in radiation and soil water potential.When planting was carried out on a one-year-old clearcut, site preparation improved the subsequent growth of oak and beech seedlings.     

Effects of site conditions and methods of cultivation on growth of sawtooth oak plantations

The effects of site conditions and cultivation on the growth of sawtooth oak (Quercus acutissima Carr.) plantations were evaluated at the Hongyashan forest farm, in Chuzhou City, Anhui Province, China. The results indicate that the position on the slope, the amount of gravel and the thickness of the soil were important factors in the growth of the sawtooth oak. Lower slope positions with small amounts of gravel and a thick soil were better for the growth of this species than middle slope positions with more gravel and a thin soil. Given the site conditions of the hilly and mountainous areas in Chuzhou City, the mixed Chinese fir (Cunninghamia lanceolata Hook.) and sawtooth oak forests did not improve forest productivity compared with pure sawtooth oak forests. Both urea and compound fertilizers promoted the growth of sawtooth oak, as did site preparation and intercropping. Two years after planting, the height growth of ordinary seedlings with a starting height of 0.6 m was higher than that of supper seedlings with a starting height of 1.0 m. Compared with planting, the early growth of the coppices was faster, but the later growth of the coppices was slower. __________ Translated from Journal of Fujian College of Forestry, 2008, 28(2): 130–135 [译自: 福建林学院学报]     

Effect of moisture on physical parameters of timber from Turkey oak (<Emphasis Type="Italic">Quercus cerris</Emphasis> L.) coppice in Central Italy

This study aims to investigate wood density at different levels of moisture, basic density and shrinkage of timber from Turkey oak (Quercus cerris L.) coppice forests growing in Central Italy. We also studied the variability in density in the trees within and among sites. Density shows no significant statistical differences in the tested population. A higher variability in the shrinkage than in the density was found. Wood moisture is referred to as dry mass and fresh mass, which is related to many performance characteristics of wood, i.e., energy production. Trends in moisture and water content were studied because these physical parameters play an important role in the specific area of firewood which requires an accurate estimation of mass, volume and energy content. This work is a contribution to improve xylo-energy estimates of small and medium forestry issues.     

Incidence of Phytophthora species in oak forests in Austria and their possible involvement in oak decline

A survey on the occurrence of Phytophthora species in oak ecosystems in Austria was conducted from April to May 1999 and in June 2000. The investigations were carried out at 35 study sites distributed throughout the zone of oak forests in eastern Austria. Four oak species, including Quercus robur, Q. petraea, Q. cerris and Q. pubescens were considered in the survey. Rhizosphere soil samples were taken from sample trees, which consisted of healthy and declining trees as indicated by their crown transparency. Young oak leaflets were used as baits to recover Phytophthora species. The assemblage of Phytophthora spp. detected in Austrian oak forests consisted of five species, including Phytophthora quercina, P. citricola, P. gonapodyides, P. europaea and P. syringae. P. quercina and P. citricola were isolated from 11 and seven sites, respectively, and were thus the most common and most widely distributed species. The three other species were recovered only sporadically. P. citricola could be separated into two morphologically and genetically well‐characterized types (A and B). Phytophthora species, in particular the common P. quercina and P. citricola occurred on sites showing a wide variety of soil types, soil textures and moisture classes. There was mild evidence for connection between deteriorating crown status and the presence of Phytophthora spp. Furthermore, significant differences in contents of magnesium, as well as calcium, aluminium, nitrogen and carbon at different soil depths (0–10, 10–20 and 20–40 cm) were detected between Phytophthora‐infested and Phytophthora‐free sites. The results of the present study provide circumstantial evidence that Phytophthora species are involved in oak decline at certain sites in Austria.     

Occurrence of Phytophthora species in oak stands in Italy and their association with declining oak trees

Soil‐borne species of Phytophthora were isolated from 19 of 30 examined oak forest areas in Italy. The frequency of isolated Phytophthora spp. (35.2%) was significantly correlated with soil pH and longitude of the sites. Eleven Phytophthora species were detected. Phytophthora cambivora, P. cinnamomi and P. cactorum were recovered from sites in central and southern Italy whereas P. quercina was isolated in the northern and central part of the country. Phytophthora citricola occurred all over Italy. Phytophthora quercina was the only species significantly associated with declining oak trees.     

Distribution of Armillaria species in upland Ozark Mountain forests with respect to site,overstory species composition and oak decline

Armillaria root disease is a contributing factor to oak decline in the Ozark Mountains of central USA. We have identified Armillaria gallica, Armillaria mellea, and Armillaria tabescens in Quercus‐Carya‐Pinus forests of the region. Presence/absence patterns of each Armillaria species as well as all possible Armillaria species combinations were analysed by contingency tables and/or stepwise logistic multiple regressions with principal characteristics of the studied sites and forest stands, both quantitative and qualitative: geographic land‐type association, bedrock type, landform position, slope direction (aspect), soil type and soil surface stone cover, down woody debris, abundance and basal area of woody vegetation and decline mortality by species. Most decline mortality consisted of two red oak species (section Erythrobalanus, Quercus coccinea and Quercus velutina), which also were most sensitive to Armillaria infection. Site characteristics related to the distributions of Armillaria species and decline mortality were also related to the preponderance of Q. coccinea and Q. velutina, regional vegetation history (i.e. conversion of Pinus echinata stands to hardwoods), and the different strategies of territory acquisition and spread of the Armillaria species involved. The presence of A. gallica may reduce the activity of more virulent Armillaria species.     

Carbon concentrations and carbon storage capacity of three old-growth forests in the Sila National Park,Southern Italy

Old-growth forests play a key-role in reducing atmospheric carbon dioxide(CO₂) concentrations by storing large CO₂ amounts in biomass and soil over time.This quantifies the carbon pool into different forest compartments in three Mediterranean old-growth forests of Southern Italy populated by Pinus laricio,Fagus sylvatica and Abies alba.Ecosystem carbon pools have been assessed per compartment,i.e.,living trees,dead wood,litterfall(foliar and woody),roots and 0-20 cm topsoil...     

Requirements and biological aspects of Fusarium eumartii and its possible role in oak decline in North-eastern Italian oak forests

To determine a possible role of Fusarium eumartii in oak decline in different zones of Italy some requirements (temperature, substrates, pH) and some biological aspects (ability to produce phytotoxic metabolites, and pathogenicity) were studied in vitro and by inoculation tests on oak seedlings.     

Effects of slope and canopy trees on light conditions and biomass of dwarf bamboo under a coppice canopy

Dwarf bamboo, Pleioblastus chino, grows extensively in abandoned coppice woodlands on the Kanto Plain in central Japan and suppresses other understory plants. In order to clarify the factors determining the growth of P. chino, we considered the effect of light conditions under a coppice canopy and examined its relationship with slope aspect, slope angle, and basal area of the trees. The relative photon flux density under the canopy was highly correlated with canopy coverage (R ² = 0.97). The light conditions under the canopy were almost the same at all sites in the summer leafy season regardless of the stand type, while they were remarkably different among the sites and depended on the basal area of evergreen trees in the winter leafless season. The biomass of P. chino on the forest floor was described by the equation: y = 3.18 x ₁ – 0.05 x ₂ + 3.11 (R ² = 0.77, P < 0.01), where y is the log-transformed value of P. chino biomass (gdrymassm^–2), x ₁ is cos at solar noon at the winter solstice, and x ₂ is the canopy coverage during the winter leafless season. is the angle between the suns rays and the normal to the surface and changes with slope aspect and angle. We concluded that light conditions under the canopy in the leafless season had a great effect on P. chino biomass, and that the basal area of evergreen trees and slope characteristics can provide useful guidelines in the control and management of P. chino.     

Tree species composition affects productivity and carbon dynamics of different site types in boreal forests

The objective was to analyse how differences in the initial proportions of tree species and site fertility affect carbon sequestration in living biomass and soil. We used the individual-based simulation model EFIMOD, which is able to simulate spatially explicit competition between trees for light and nutrients. Simulations were carried out for three site types with distinct initial stocks of soil nutrients. For each site, the 100-years undisturbed dynamics of monocultures and mixtures of three tree species (Betula pendula Roth, Pinus sylvestris L. and Picea abies (L.) H. Karst.) was predicted. Changes in the proportions of competing tree species were dependent on the fertility of the site: on poor sites, pine was the most competent species, while on rich sites, spruce increased its proportion during stand succession. Net primary production (NPP) and soil respiration were the highest in stands of two coniferous species and in stands with a high initial proportion of pine. Mixed stands were more productive than monocultures; the highest overyielding was observed with mixtures of two coniferous species. Simulated NPP and carbon stocks in all pools increased from poor to rich sites. The highest carbon stocks in standing biomass were observed for mixtures of conifer species and three-species mixtures; the greatest accumulation of forest floor occurred in stands with high proportions of pine.     

Patterns of litterfall and nutrient return at different altitudes in evergreen hardwood forests of Central Taiwan

Background

This study was designed to evaluate the internal nutrient cycling of litterfall in different elevation subtropical forests of Central Taiwan.

Methods

The litterfall of evergreen hardwoods at three elevations, specifically Mt. Peitungyen (2,078?m), Hui-Sun experimental forest (HSEF) (1,066?m), and Lienhauchi (782?m) in central Taiwan, was collected monthly using traps and sorted into leaves, twigs, reproductive litter, and miscellaneous material. In addition, the litter on the forest floor was collected trimonthly. All the samples were weighed and measured for C, N, P, K, Ca, and Mg concentrations and fluxes from March 2009 to February 2010.

Results

The annual litterfall productions were 6.58, 8.24, and 9.17?Mg?ha^?1?year^?1 at Mt. Peitungyen, HSEF, and Lienhauchi, respectively. At more than 60?%, leaves were the main component of the total litterfall. There was smallest decomposition constant (0.487) at Mt. Peitungyen. The nutrient fluxes increased as elevation decreased. The litterfall correlated positively with rainfall at Lienhauchi, with temperature at HSEF, and with temperature and rainfall at Mt. Peitungyen.

Conclusion

The annual litterfall decreased with an increase in elevation. The turnover rate was faster at HSEF than at Mt. Peitungyen. Thus, the forest managers should pay more attention to understand and monitor plant community responses to global warming and nutrient loss.     

Effect of different nitrogen and carbon sources and concentrations on the mycelial growth of ectomycorrhizal fungi under in-vitro conditions

Effect of different nitrogen and carbon sources and their concentrations in liquid media on the mycelial growth of six different ectomycorrhizal (ECM) fungal species was studied. Differences were found in the utilization of the different nitrogen and carbon sources between the fungal species. All the species showed better mycelial growth in the medium containing ammonium as nitrogen source. Growth was low in all species in medium in which nitrogen was supplied in nitrate form. All the ECM isolates investigated showed reduced growth in the medium containing maleic acid as the carbon source. The effect of glucose and di-ammonium hydrogen orthophosphate concentrations on mycelia growth of all the six fungal species was studied with ranges for glucose of 2–40 g/l, and for di-ammonium hydrogen orthophosphate of 2–20 g/l. Cortinarius fulvoconicus and Cortinarius flexipes showed maximal mycelial growth at a glucose concentration greater than 20 g/l. Suillus luteus, Scleroderma citrinum, Laccaria laccata, and Tricholoma aurantium showed maximal growth at a glucose concentration of 20 g/l. All six species showed maximal mycelial growth at 5–10 g/l of di-ammonium hydrogen orthophosphate concentration and with increased concentration mycelial growth in all species decreased.     

Silvicultural options in forests of the southern United States under changing climatic conditions

New Forests - Changing climatic conditions add a measure of uncertainty to sustainable forest management in forest ecosystems&nbsp;of the southern United States. Increasing temperatures and...