Mixed Quercus Research Articles

Predicted Spatial Distribution of the Eastern Spotted Skunk (Spilogale putorius) in Virginia Using Detection and Non-Detection Records

The geographic distribution of a species is a fundamental component in understanding its ecology and is necessary for forming effective conservation plans. For rare and elusive species of conservation concern, accurate maps of predicted occurrence are particularly problematic and often highly subjective. Spilogale putorius (Eastern Spotted Skunk) populations have experienced large declines since the 1940s. Their elusive behavior and perceived rarity result in low detection probability when using conventional methods for sampling small mammals. Low detection probability often causes uncertainty as to where Eastern Spotted Skunks could be a management concern. We modeled the distribution of predicted occurrence of Eastern Spotted Skunks using verifiable occurrence and non-detection records obtained throughout Virginia from 2010 to 2020. Occurrence data consisted of trapping records reported to the Virginia Department of Wildlife Resources, incidental photo-verified reports of sightings and road-killed animals, and remote-camera detections. Non-detections were presumed at baited remote-camera locations following intense survey efforts. We fit predicted occurrence models using generalized linear modeling in an information-theoretic framework using the package ‘stats’ in Program R. Our results incidated a greater probability of presence from the Blue Ridge westward, increasing with slope steepness along northeastern- to southeastern-facing slopes and decreasing with slope steepness along southeastern- to southwestern-facing slopes. Emergent rock outcrops prominent along northeastern slopes offer ample protective rocky cover, whereas mixed Quercus spp. (oak), Kalmia latifolia (Mountain Laurel), and Rhododendron maximum (Rosebay Rhododendron) forest communities along southern-facing slopes provide suitable areas of cover, both of which are critical for spotted skunk survival and reproductive success. Our analysis provides insight into the relationships between landscape features and Eastern Spotted Skunk distributions across Virginia. Understanding these relationships is critical for the effective management and conservation of this vulnerable species.

Fuel Modelling Characterisation Using Low-Density LiDAR in the Mediterranean: An Application to a Natural Protected Area

Fuel structure and characteristics are important to better understand and predict wildfire behaviour. The aim of the present study was to develop a methodology for characterising fuel models using low-density and free LiDAR data that facilitate the work of managers of protected territories. Field inventories were carried out in order to understand the characteristics of the stand and the variables that fuel models must include. This information, together with the use of the intensity and structure provided by LiDAR, was used to perform statistical analyses. The linear regressions obtained to characterise the stand of the mixed Quercus spp.–Pinus ssp.-dominated stand had an R2 value ranging from 0.4393 to 0.66. While working with low-density LiDAR data (which has more difficulties crossing the canopy), in addition to the obtained results, we performed the statistical analysis of the dominant stand to obtain models with R2 values ranging from 0.8201 to 0.8677. The results of this research show that low-density LiDAR data are significant; however, in mixed stands, it is necessary to only use the dominant stratum because other components generate noise, which reduces the predictive capacity of the models. Additionally, by using the decision tree developed in combination, it is possible to update the mapping of fuel models in inaccessible areas, thereby significantly reducing costs.

The presence of shade-intolerant conifers facilitates the regeneration of Quercus petraea in mixed stands

Positive productivity-diversity relationships, pest-effect mitigation and increased resilience and stability maintain an ongoing interest for mixed stands in forestry. However, how mixing species affects forest regeneration is yet to be further explored.We used data from the French National Forest Inventory (from 2006 to 2016) to model Quercus petraea (Matt.) Liebl regeneration cover in pure and mixed Quercus petraea stands; we included the effects of abiotic and biotic factors as well as mixture. We hypothesized that the characteristics of the companion species would prevent or facilitate the regeneration of oak.Quercus petraea regeneration cover in this study responded negatively to total canopy cover and herbivory pressure. Mean July potential evapotranspiration (PET), mean December maximal temperature and soil pH are variables whose spatial variations over a given territory structure regeneration cover; all three of these variables have optimum values. Quercus petraea regeneration cover is linked to the proportion of Quercus petraea in the canopy layer in all mixed stands, except when the oak is mixed with shade-intolerant conifers: in this case, Quercus petraea regeneration is enhanced. The shade tolerance of admixed broadleaved species did not affect the Quercus petraea regeneration. This suggests that oak regeneration was facilitated with a shade-intolerant coniferous companion species due to better light transmittance through the crown or the competitive advantage of Quercus petraea over coniferous shade-intolerant species.These results are of interest for oak mixtures since Quercus petraea regeneration cover benefits from mixtures with shade-intolerant conifers and is at least equal to that of pure stands.

土壤微生物群落对麻栎-刺槐混交林凋落物分解的影响

以麻栎-刺槐混交林和麻栎纯林为研究对象，采用野外定点采样、室内分析与高通量测序的方法，对凋落物分解过程中土壤微生物菌群多样性特征及其对凋落物分解速率的影响进行了研究。结果表明：（1）麻栎-刺槐混交林凋落物的分解速率高于麻栎纯林。两种林分凋落物有机碳（TOC）、全氮（TN）发生释放，全磷（TP）发生积累-释放的过程。（2）两种林分土壤细菌优势类群为放线菌门（Acidobacteria）、变形菌门（Proteobacteria）、酸杆菌门（Actinobacteria）和疣微菌门（Verrucomicrobia），土壤真菌优势类群为担子菌门（Basidiomycota）、子囊菌门（Ascomycota）和被孢霉门（Moritierellomycota）。（3）凋落物分解过程中，麻栎-刺槐混交林土壤微生物菌群丰富度指数和菌群多样性指数变化范围小于麻栎纯林。（4）凋落物分解速率与土壤细菌菌群丰富度指数和菌群多样性指数呈显著正相关，与土壤真菌菌群丰富度指数呈显著正相关。土壤微生物群落对麻栎-刺槐混交林和麻栎纯林凋落物分解速率具有重要影响，研究结果为深入开展混交林土壤微生物多样性对凋落物分解的影响研究提供理论依据。;Forest ecosystems are an important part of the terrestrial ecosystem. In forest ecosystems, the plants transmit carbon, nitrogen, phosphorus and other nutrients to the soil in the form of litter. Soil microorganisms, as the main decomposers of litter, affect the energy flow and material circulation of forest ecosystems. This paper took the mixed Quercus acutissima Carruth. and Robiniapseudoacacia L. forest (QR), as well as pure Quercus acutissima Carruth forest (QAC) as research objects. The field fixed-point sampling, indoor analysis, and high-throughput sequencing methods were used to study the characteristics of soil microbial diversity and their effects on the litter decomposition rate. The results were as follows: (1) The litter decomposition rate of QR was higher than that of QAC, the litter decomposition rate of QR was 0.70, and the litter decomposition rate of QAC was 0.62. During the litter decomposition of the two forest stands (QR and QAC), total organic carbon (TOC) and total nitrogen (TN) were released, but total phosphorus (TP) was accumulated first and then released. (2) The two forest stands had the same dominant soil microbial communities, the dominant soil bacterial communities were Actiobacteria, Proteobacteria, Actinobacteria and Verrucomicrobia, and the dominant soil fungi communities were Basidiomycota, Ascomycota and Mortierierellomycota. (3) During the litter decomposition of the two forest stands, the variation range of the soil microbial community richness index and diversity index of QR was smaller than that of QAC. The bacterial community richness index (Chao1 index and ACE index) and community diversity index (Shannon index and Simpson index) of QR and QAC showed a trend of first increasing and then decreasing. The fungal community richness index of QR showed a trend of first decreasing and then increasing, and the fungal community diversity index showed a gradually decreasing trend. The fungal community richness index of QAC showed a gradually decreasing trend, and the fungal community diversity index showed a trend of first decreasing and then increasing. (4) The litter decomposition rate was significantly positively correlated with the soil bacterial community richness index and diversity index, while significantly positively correlated with the soil fungal community richness index. The soil microbial community had an important influence on the litter decomposition rate of QR and QAC. The research results are helpful to understand the relationship between the litter decomposition rate and soil microbial communities in mixed forests, and provide theoretical basis for the research of the influence of soil microbial diversity on litter decomposition in mixed forests.

Response of taxonomic and functional diversity to disturbance severity in temperate hardwood forests

AbstractAims:Quantify changes in taxonomic and functional diversity (FD) and identity to determine if responses to a disturbance severity gradient follow a “colonization/competition” hypothesis: diversity will (a) increase with disturbance severity as more open conditions favor species with traits linked to colonization; and (b) become more similar between regeneration and overstorey layers as environmental filtering favors species with traits linked to increasing competition for light.Location:North Carolina, USA.Methods:Taxonomic (richness [S], evenness [E], and Shannon diversity [H′]) and functional diversity (richness [FRic], evenness [FEve], and dispersion [FDis]) and identities were calculated for regeneration and overstorey before and after restoration treatments: control (CONT); “undesirable” subcanopy stems removed via herbicide (HERB); repeated burning (RRXF); and timber harvest followed by burning (HARV).Results:In the overstorey, HARV affected taxonomic and FD. In HARV, S and H′ were lower than in other treatments. At high levels of species richness, FEve was lower in HARV than in HERB and RRXF. Similarly, at high levels of species richness, FDis was greater in HARV than other treatments. In the regeneration layer, taxonomic and FD did not differ across treatments during any of the post‐treatment years. In the regeneration stratum, HARV increased the means of traits associated with rapid post‐disturbance establishment, carbon capture, and maximum height. Greater dissimilarity in composition between the overstorey and regeneration suggests stronger treatment effects on regeneration in HARV than less severe treatments.Conclusion:Patterns do not support the hypothesis that taxonomic diversity increases with disturbance severity or decreases with time after disturbance in the regeneration layer. Of the restoration treatments tested in this study, only HARV affected aspects of functional identity of the regeneration stratum; even so, FD remained unchanged. In mixed Quercus forests, functional identity rather than taxonomic or FD may provide insight into nuanced effects of restoration treatments on ecosystem function.

Contrasting species decline but high sensitivity to increasing water stress on a mixed pine–oak ecotone

Abstract Forest decline under environmental stress is expressed by regeneration failure and accelerated mortality in all ontogenic stages at the population level. Characterizing functional traits and mechanisms that best capture species decline and mortality is essential to assess forest dynamics. We analysed sensitivity to increasing water stress in two species with different water‐use strategies on a mixed Quercus pyrenaica–Pinus sylvestris forest where adult pines express vulnerability to climate change but oaks do not. We compared the dynamics of radial growth, wood δ13C and sapwood non‐structural carbohydrates (NSCs) in response to drought at different time‐scales in both species and two age cohorts in pine. Both species were very sensitive to water stress, which influenced trait phenotypic plasticity at short‐ and long time‐scales. Water‐use strategy in pines of both ages was more conservative than in the more drought‐tolerant oak. Both species showed negative growth trends despite increasing intrinsic water‐use efficiency. Recent growth of pines is slower than it was in the past. Carbon isotope discrimination trends in young pines suggested increasing leaf gas exchange constraints. NSCs were far from depletion in both species and all pine ages. Intra‐ and inter‐annual NSC variability was higher in oaks than in pines and in soluble sugars (SS) than in starch. SS were lowest in young pines. Sensitivity of NSCs to contrasting climatic years was low in pines, and NSC levels mostly remained homeostatic for this species. The sensitivity to climate expressed suggests different C allocation strategies, with less coupling between radial growth and current‐year photosynthesis in young pines. Synthesis. Pines expressed negative responses to increased water stress regardless of age, showing rising gas exchange constraints through tighter stomatal control of water losses than oaks. Young pines showed similar functional responses to water stress than old pines in decline, which suggests species‐level vulnerability and could be regarded as early warning signals anticipating mortality in pines. Yet, given the high sensitivity to drought also expressed by the non‐declining oak, it would have been difficult to unequivocally disentangle species decline based only on the functional traits analysed.

Changing characteristics and influencing factors of the soil microbial community during litter decomposition in a mixed Quercus acutissima Carruth. and Robinia pseudoacacia L. forest in Northern China

Soil microorganisms play an important role in the decomposition of litter. There stand structure and in-forest microenvironment of mixed forests and pure forests are different, and whether these differences affect the soil microbial community structure and further affect litter decomposition needs further research. In this paper, a mixed Quercus acutissima Carruth. and Robinia pseudoacacia L. (QR) forest and a pure Quercus acutissima Carruth. (QAC) forest were studied to analyse the compositions and influencing factors of soil bacterial and fungal communities during litter decomposition. Through field sampling and quantitative analysis performed in a laboratory, the results of this research were as follows: (1) During litter decomposition, the litter decomposition rate of the QR forest was higher than that of the QAC forest. (2) The dominant bacteria were Acidobacteria, Proteobacteria and Actinobacteria, and the dominant fungi were Basidiomycota and Ascomycota in the QR and QAC forests. (3) For litters decomposed from May to November, the soil bacterial alpha diversity index (richness index and evenness index) showed an increasing trend and the soil fungal alpha diversity index showed a decreasing trend in the QR and QAC forests, but the changes in the QR forest were smaller than those in the QAC forest. (4) Redundancy analysis (RDA) showed that the soil bacterial community structure was different between the QR and QAC forests, and the soil temperature, soil moisture, litter TN, C:N ratio, and N:P ratio were important factors affecting the soil microbial community structure. The results indicate that mixed forests have a more stable microbial alpha diversity index and that the TN, C:N ratio and N:P ratio of litter have important effects on soil microbial community structure; therefore, mixed forests should be given more priority in ecological restoration, and nitrogen regulation must be given attention during forest management.

From Climatic to Anthropogenic Drivers: A Multi-Proxy Reconstruction of Vegetation and Peatland Development in the French Jura Mountains

A 4 m core was extracted from the center of a peatland located in the Drugeon valley (France). Thirteen radiocarbon dates were used to build a robust age model. Testate amoebae were used for reconstructing mire surface wetness. High-resolution pollen analysis of the sequence reconstructed 9 millennia of development of the peatland and its surrounding vegetation. During the early/middle Holocene (9500 to 5800 cal BP), warm conditions led to high evapotranspiration and low water levels. The vegetation history is characterized by the development of a Pinus and a mixed Quercus forest. From 5800 cal BP, testate amoebae show wetter conditions, indicating the onset of the cooler Neoglacial period. The cooling is also evidenced by the development of Abies and Fagus trees, replacing the oak forest. The first indicators of human impact appear at about 4800 cal BP, and indicators of farming activity remains very rare until ca. 2600 cal BP, at the beginning of the Iron Age. The development of the peatland responded to climatic fluctuation until 2600 cal BP, after which human impact became the main driver. The last millennium has been characterized by sudden drying and the spread of pine on the peatland.

Litter decomposition in pure and mixed Quercus and Fagus stands as influenced by arthropods in Belgrad Forest, Turkey

Arthropod assemblages and decomposition rates were compared in the litter of pure and mixed Quercus (Quercus petraea L.) and Fagus (Fagus orientalis L.) stands. Litter was sampled on a monthly basis for 1 year and stored in litterbags of different mesh sizes. The experimental objective was to test the effect of mesh size on litter decomposition, decomposition rates of litter, and diversity of the invertebrate fauna between the two types of stands. Decomposition rates were measured by filling three fiber litterbags of different mesh sizes with pure Quercus litter (3 g) left in the pure Quercus stand, and litterbags with Fagus litter (3 g) were left in the pure Fagus stand. Mixed litter samples were prepared by mixing of equal amounts of each litter in the same litterbag and leaving them in the mixed stand. The residual mass of litter from the pure Quercus stand was significantly lower in fine- and coarse-mesh bags than in the medium-mesh bags in pure the Fagus stand. Carbon and nitrogen levels in the pure Quercus litter were significantly different among the mesh sizes at the end of the incubation period. Macroarthropods from 27 taxa were collected from pitfall traps every month. Their relative numbers differed significantly between the pure and mixed-stand litter samples. Litter-dwelling Isotomidae (Collembola) and Mesostigmata (Acarina), and soil-dwelling Mesostigmata were the most numerous in the mixed stand. It is significant that the abundance of macroarthropods contributed to the mass loss of litter in both the medium and coarse mesh sizes in the mixed stand, but did not significantly affect the mass of litter in the pure stands. In the mixed stand, there was a negative correlation between litter mass loss and total number of microarthropods in all mesh sizes. Mixed-stand litter decomposed more slowly than pure-stand litter.

Alley cropping with strawberries: Two case-studies in Romania

The paper focuses on the use of alley cropping, an arable agroforestry system comprising rows of trees planted with a companion crop grown in the alleyways between the rows, in two sub-compartments (81B%: 0.75 ha, elevation 715 m asl; 81E: 3.4 ha, elevation 735 m asl) artificially regenerated at 1.80 m x 1.60 m spacing in the south-east of Transylvania (Romania) in 1997 (81B%) and 2003 (81E). The climate (Dfbx, specific to low and middle mountains) and soil (luvisol, of moderate fertility for pure or mixed Quercus petraea stands) are only moderately favourable to strawberry culture. The rows of tree species consists of Quercus rubra, Acer pseudoplatanus, Prunus avium (81B%), and Quercus petraea, Fagus sylvatica, Acer pseudoplatanus, and Larix decidua (81E). Strawberries (variety Elsanta,) were planted at 60 x 60 cm spacing in two pure rows in-between the tree rows as well as within the rows of planted trees. Both plantations were fenced, with manual topsoil hoeing up to four times a year, lighly fertilized (N, P, K complex) and chemically protected against browsing and pests.
 Strawberry rotation (six years, of which five years - two to six - with fruit production) was longer than the one (maximum three years) recommended in pure crops. Strawberry production reached the maximum level in years 3 or 4.
 Under the local conditions, the alley cropping with strawberries had demonstrated to be a viable alternative to the 'classical' monocropping system in terms of (a) survival rate of plants (over 95 per cent), (b) initial height growth of plants (very quick, resulting from reduced competition with grasses and naturally regenerated forest trees such as pioneer species), (c) establishment of a new forest culture, the full forest cover being achieved immediately after the end of strawberry production, as well as (d) economics (early and relevant revenue from the crop).

Regeneration dynamics, population structure, and forest composition in some ridge forests of the Western Himalaya, India

ABSTRACTThe present study aimed to analyze the regeneration dynamics, population structure, and forest composition in some ridge forests of the Western Himalaya to elucidate the impact of climate change. The highest species richness (trees, 17; saplings, 16; seedlings, 16) was recorded in mixed Rhododendron arboreum forest. The maximum tree density (737 ± 25.93 trees ha−1; mixed Quercus floribunda); sapling density (5342 ± 587.54 saplings ha−1; mixed Quercus semecarpifolia), and seedling density (71,429 ± 26,632.29 seedlings ha−1; mixed Cedrus deodara) were recorded in forests of higher altitudes. The mean basal cover values in these forests oscillated between 39.21 ± 1.53 m2 ha−1 (mixed Quercus leucotrichophora) to 87.65 ± 15.45 m2 ha−1 (mixed Abies pindrow). The highest Shannon index value (0.51 ± 0.05) and species evenness (0.36 ± 0.02) for trees were recorded in mixed Rhododendron arboreum forest. Some species like Betula utilis, Myrica esculenta, Ficus rumphii, Ilex dipyrena, Quercus floribunda, Litsea elongata, Symplocos paniculata, and Abies spectabilis were noticed as new recruiters (recent invaders) in new habitats, which may change the future forest composition. This study revealed that ridge forests of the Bhagirathi catchment area were in transition phase at middle altitudes. Mixed Quercus floribunda forest was observed to be the youngest regenerating forest; however, mixed Abies pindrow forest was the most mature old-growth forest.

Assessment of forest vegetation and anthropogenic pressure in Ramgarh region of Uttarakhand, West Himalaya

Forest is a complex system, consisting of distinct forest communities, and status of any forest can be recognized by analysing its vegetation. For vegetation analysis phytosociological analysis is the best approach. The present study was carried out at 8 different sites of Ramgarh region using different phytosociological parameters. The results of this study revealed, on the basis of IVI, that five major vegetation types viz. Pinus roxburghii, Quercus leucotrichophora, mixed broad leaved, Quercus floribunda and Rhododendron arboreum were dominating this region. The distribution of most of the tree species was random and there was no species having good regeneration status at any site of the region. It was also observed that the anthropogenic disturbance is changing the species richness and diversity of the region. Thus, the conservation and management of these sites are important for the sustainability of forests in the region.

Thinning alters the early-decomposition rate and nutrient immobilization-release pattern of foliar litter in Mediterranean oak-pine mixed stands

Leaf litter decomposition is a major pathway for nutrient recycling and a chief factor controlling ecosystem primary productivity. The aim of this study was to analyze the effect of forest thinning on the early-stage foliar decomposition rate and nutrient immobilization-release pattern in a mixed Quercus pyrenaica-Pinus pinaster forest growing in the western Mediterranean basin. Two thinning treatments, differing in the intensity of canopy reduction, were compared with a control (unthinned) situation. Oak leaves showed faster decomposition rates than pine needles in unthinned plots. Intense canopy reduction (40% of basal area removed) reduced decomposition rates in both species whereas intermediate reduction (25% of basal area removed) increased decomposition of needles to a rate similar to that of oak leaves. C and N transfer from N-rich to N-poor foliar litter was not detected, indicating a marginal role of canopy reduction in this process. A decoupling of the decomposition rate from immobilization-release pattern was found for mobile elements (K and Mg) at intermediate levels of canopy cover whereas Ca dynamics indicated that pine needles had not started the lignin-mediated degradation phase two years after incubation. We finally hypothesized that strong reductions of canopy cover in dry Mediterranean sites might have an aridification effect on litter decomposition.

Spatial Autoregressive Models for Stand Top and Stand Mean Height Relationship in Mixed Quercus mongolica Broadleaved Natural Stands of Northeast China

The relationship of stand top and stand mean height is important for forest growth and yield modeling, but it has not been explored for natural mixed forests. Observations of stand top and stand mean height can present spatial dependence or autocorrelation, which should be considered in modeling. Simultaneous autoregressive (SAR) models, including spatial lag model (SLM), spatial Durbin model (SDM) and spatial error model (SEM), within nine spatial weight matrices were utilized to model the stand top and stand mean height relationship in the mixed Quercus mongolica Fisch. ex Ledeb. broadleaved natural stands of Northeast China, using ordinary least squares (OLS) as a benchmark model. The results showed that there was a high linear relationship between stand top and stand mean height and that there was a positive spatial autocorrelation pattern in model residuals of OLS. Moreover, SEM and SDM performed better than OLS in terms of reducing the spatial dependence of model residuals and model fitting, regardless of which spatial weight matrix was used. SEM was better than SDM. SLM scarcely reduced the spatial autocorrelation of model residuals. Among nine spatial matrices in SEM, rook contiguous matrix performed best in model fitting, followed by inverse distances raised to the second power (1/d2) and local statistics model matrix (LSM).

Invasion of Winter Moth in New England: Effects of Defoliation and Site Quality on Tree Mortality

Widespread and prolonged defoliation by the European winter moth, Operophtera brumata L., has occurred in forests of eastern Massachusetts for more than a decade and populations of winter moth continue to invade new areas of New England. This study characterized the forests of eastern Massachusetts invaded by winter moth and related the duration of winter moth defoliation estimated using dendrochronology to observed levels of tree mortality and understory woody plant density. Quercus basal area mortality in mixed Quercus and mixed Quercus—Pinus strobus forests in eastern Massachusetts ranged from 0–30%; mortality of Quercus in these forests was related to site quality and the number of winter moth defoliation events. In addition, winter moth defoliation events lead to a subsequent increase in understory woody plant density. Our results indicate that winter moth defoliation has been an important disturbance in New England forests that may have lasting impacts.

Overstory succession in a mixed Quercus petraea–Fagus sylvatica old growth forest revealed through the spatial pattern of competition and mortality

Old-growth forests are often looked at as a reference for naturalness. Analyzing their successional pathways can provide valuable information on the main drivers of succession in the absence of anthropogenic influence. This knowledge could then prove particularly useful for the maintenance of mixed species stands as a management option to counteract potential changes in forest functions under foreseen climate scenarios. The study was conducted in an old growth Quercus petraea–Fagus sylvatica forest in the Runcu Grosi Natural Reserve, western Romania. Main goals of the research were to assess the structure of the old growth forest and understand how the spatial pattern of the two species is shaped by their competitive relationship. We wanted to figure out if the spatial relationship between Q. petraea and F. sylvatica is different between trees belonging to different layers, and how a possible difference can influence their successional dynamics. To accomplish these tasks, living and dead (both standing and lying) trees were mapped in four 0.56ha plots. The relationship between trees, considering species, vegetative and social status, was analysed through univariate and bivariate point pattern analyses. Spatial structure based on tree size was investigated with Moran’s correlograms and a local indicator of spatial association. The spatial relationship between understory and canopy trees was also assessed using crown cover data to test for differences among the species.The upper layer is dominated by Q. petraea, whereas F. sylvatica was the only species in the suppressed one. The high amount of deadwood was mostly due to oak contribution. F. sylvatica living trees presented a clumped structure, while Q. petraea exhibited a random pattern. F. sylvatica dead trees showed instead repulsion to living ones. Suppressed trees were clumped at all distances, whereas trees belonging to dominant and intermediate strata were randomly distributed. Repulsion was found between the two species in the dominant layer. Beech recruitment occurred more frequently outside the canopy of dominant trees. Those beeches established under dominant tree showed a preference for oak cover.The succession from oak-dominated to beech-dominated stands has already reached an advanced stage in this old growth forest. The two species competitive interactions are mostly driven by their different shade tolerance and crown plasticity. Quercus–Fagus mixed stands like the Runcu-Grosi one should be preserved to maintain forest diversity and enhance forest resilience. Oak decline could be reduced by the occurrence of natural disturbances, together with active management that should be promoted to reduce beech competitive pressure.

Influence of Soil Organic Carbon and Total Nitrogen of Soil under Different Plant Communities in Central Yunnan

By the field investigation and laboratory analysis methods, through research the characteristics of SOC, TN in soil of mixed Pine and Quercus, Nepalensis, Bayberry bushes, Pinus Yunnanensis and Abandoned Land in central Yunnan. It resulted that different plant communities took little impact on the soil physical properties, besides the soil moisture was remarkable, the bulk density and soil porosity effect is not prominent. The content of nutrients in different plant communities shows that vegetation abundant soil is more rich than vegetation sparse soils, and in 0~10 ㎝ SOC and TN content is higher than in 10~20 ㎝. Then by the study the C: N ratio in the soil, it showed that relative to the accumulation of TN, different communities in favour of the process SOC accumulation. The C: N ratio as follows: Abandoned land > Pinus Yunnanensis > mixed Pine and Quercus > Bayberry bushes > Nepalensis, so that revealed the ratio of C and N take negative correlation with their decomposition rate.

Sapling richness and composition in canopy gaps of a southern Appalachian mixed Quercus forest1

Canopy gaps create distinct microenvironments within the broader forest environment and provide a mechanism for regeneration and recruitment. In this study, we investigated patterns of sapling richness and composition in 40 canopy gaps in a secondary, mixed Quercus forest on the Cumberland Plateau in Tennessee. We found that sapling richness was high, with 34 species represented in canopy gaps. A species-gap area curve revealed that sapling richness increased steadily with gap sizes up to ca. 200 m2, but then tended to level off. While minor components in the main forest canopy, Acer saccharum, Fagus grandifolia, and Acer rubrum were the most widespread and abundant species in gaps. Our analyses of floristic composition using ordination (NMS) and randomization techniques (MRPP) clarified the mechanisms responsible for structuring patterns of gap composition and species-environment relationships, including the effects of individual factors (gap formation mechanism, gap size, aspect, and soils) and their collective impacts. Snag-formed gaps were smaller in size and most common on southern exposures with stony loam soils. Gaps formed by uprooted trees were larger and most common on north-facing slopes with shallow, gravelly loam soils. Gap composition varied along these gradients. Saplings of current canopy dominant genera (Quercus and Carya) were largely restricted to small gaps on xeric sites, suggesting that gap-phase succession will result in a transition from a Quercus–Carya system to one with a much stronger Acer–Fagus component.

Coltriciella sonorensis sp. nov. (Basidiomycota, Hymenochaetales) from Mexico: evidence from morphology and DNA sequence data.

Coltriciella sonorensis is described here as a new species from Mexico. It is characterized by pleuropodal, flabelliform basidiomes, rounded to elongated or daedaloid pores, a well-developed sub-hymenium, and oblong to cylindrical basidiospores, slightly attenuated towards the apex. The specimen was collected on soil in an open Quercus stand in mixed Quercus–tropical deciduous forest in the Sierra de Alamos–Rio Cuchujaqui Biosphere Reserve, Sonora, Mexico. From a phylogenetic perspective, the species appears to be related to C. oblectabilis, also occurring in Mexico.

Properties of humic acids in Mediterranean forest soils (Southern Italy): influence of different plant covering

The chemical and spectroscopic properties of humic acids (HAs) isolated from four litters and their corresponding underlying soils at three depths in a protected forest area in Southern Italy were investigated as a function of four different plant coverings: Quercus ilex L., mixed Carpinus betulus L. and C. orientalis Mill., Pinus halepensis L., and mixed Quercus trojana Webb. and Q. ilex L.. The forested site is a part of a calcareous plateau, characterized by homogeneous soils classified as Eutric Cambisols associated with Calcic Luvisols. The changes in the composition of HAs with soil depth have been evaluated on the basis of chemical (elemental and COOH groups) and spectroscopic analyses (E4/E6 ratio and FT IR spectra), and lignin-derived CuO oxidation products. A different distribution of the main elements was found in the various HAs which is apparently related to the type of humic acid-precursor biomolecules in the parent litters. The HAs isolated from soils under Q. ilex and mixed Carpinus species showed a slight increase in the C/H ratio and COOH content downward the soil profile, suggesting increasing aromatic polycondensation and humification degree with depth. On the contrary, no trend was observed for HAs from soils under Pinus halepensis L. and mixed Quercus species, indicating a partial incorporation of residues deriving from litter degradation into these HAs. Further, the content of lignin-derived phenols was higher in Pinushalepensis L. and mixed Quercus species layers, with the same trend measured for the corresponding HAs, thus confirming a lignin contribution related to the lignin type of plant covering.