查看更多>>摘要：Rodents are ubiquitous seed predators in nature and their size-related seed choice plays an important role in the plant's community structure. However, to understand how size-related seed predation by rodents affects plant recruitment, it is fundamental to predict seed and seedling response to rodent predation. We assessed the interactive effects between seed size and rodent exclusion on seed germination and early seedling survival of Quercus serrata in 10 subtropical forested islands in Thousand Island Lake, China. We found that rodent exclusion significantly improved the proportion of seed germination but not for early seedling survival. The proportion of seed germination in rodent-accessed plots was lower than rodent-exclosure plots and such reduction was strengthened by seed size. The proportion of early seedling survival was similar in both treatments and both increased with seed size. Our study found a significant size-related seed choice by rodents at the seed germination stage and showed that seeds would experience conflicting selective pressures across life stages in the early recruitment. Our findings highlight that size-dependent seed use by rodents is a key biotic factor to limit the oak early recruitment.
查看更多>>摘要：Spatial variations of maximum canopy height are key indicators of many ecosystem processes such as aboveground biomass and productivity. With rapid advances in remote sensing techniques, such as airborne laser scanning (ALS), we can now measure canopy height, tree density, and canopy gaps from local to large scales. But these data are yet to be fully exploited for a better understanding of canopy height variations in relation to fine topographical heterogeneities and neighborhood conditions at the landscape level (>100 km2). In this study, we analyzed ALS data to extract spatial variations in canopy height and topographic features for a forest-dominated area of 230 km2 in Kyoto, Japan. The study area spanned an elevational range from 70 to 1000 m a.s.l and included four forest types, i.e., cedar or cypress plantations (PL), natural evergreen needle leaf forests (ENF), deciduous broadleaved forests (DBF), and evergreen broadleaved forests (EBF). PL had a greater mean canopy height than ENF, both of which were taller than DBF and EBF. Canopy height exhibited a hump-shaped relationship with elevation with the peak value at mid-altitude (461-560 m) in all forest types. Canopy height was greater by 5-10 m in the concave valleys than on the convex slopes and ridges. Trees were taller at greater distances from forest gaps and with lower tree density in the neighborhood. Local tree density, distance from the nearest canopy gap, and topographic curvatures were the most significant predictors in the best-fitted model (Random Forest: R2 = 0.41). The analytical approach developed in this study provides a useful tool for planning proper land use and maintaining a healthy forest stand at the regional scale.
查看更多>>摘要：Eucalyptus plantations are already planted in or expanding to water-limited regions with a high risk of severe drought. In future drier and more variable climate including extreme events, the ability of trees to recover after severe droughts emerges as a crucial for the sustainability of forest plantations. An original experiment involving 80% reduction in throughfall was set up in Brazil to gain insight into the responses of Eucalyptus grandis trees to prolonged (3-year) extreme water deficit and the ability of this species to recover following water stress. Our study focused on the changes in basal area, stem radius, and total height measured by high-temporal resolution dendrometers and periodical surveys of trees affected by 80% throughfall reduction (treatment group) and in a control group. The differences in basal area, stem radius, and total height growth rate were compared between groups over (i) 37 months of 80% throughfall reduction and (ii) 31 months following the end of 80% throughfall reduction. The correlations among growth rates, stem radius fluctuations, and meteorological variables in each group were determined to gain insights into the trees' responses to environmental conditions and stem water status.
Divoll, Timothy J.Aldrich, Stephen P.Haulton, G. ScottO'Keefe, Joy M....
8页
查看更多>>摘要：Bat populations face numerous threats, including the loss of forests in which they roost and forage. Present-day forests are commonly managed for timber harvesting, recreation, and wildlife. Understanding bat responses to forest management is crucial for balancing the conservation of endangered bats and forest restoration. We used radio telemetry to study nocturnal movements and habitat selection patterns of female and juvenile bats of two forest-dependent, federally listed bat species in an oak-dominated managed forest. We estimated foraging space use and assessed habitat selection for 33 northern long-eared bats (Myotis septentrionalis) and 25 Indiana bats (Myotis sodalis) from May to August 2014-2017 in south-central Indiana, USA. Myotis septentrionalis space use averaged 176 ha and bats selected water, historic thinning, and patch cuts (<= 4 ha) over other habitats, with all but one bat avoiding larger openings (>= 4-ha clearcuts). Myotis sodalis space use averaged 343 ha and bats selected 4-ha patch cuts, historic openings, and historic thinning over other habitats. In contrast to M. septentrionalis, one-third of the M. sodalis foraged over larger clearcuts, while two-thirds foraged over smaller openings and thinnings. We showed that bats were attracted to small regeneration harvests of varying structural ages. Forests maintained for a mix of mature stands, thinned stands, shelterwoods, small regenerative cuts (<7 ha), and small water sources should provide suitable foraging habitat for these endangered Myotis species, while also promoting forest regeneration.
Gowda, Juan H.Blackhall, MelisaShipley, LisaKitzberger, Thomas...
9页
查看更多>>摘要：Large herbivores prefer to consume plants with high concentration of digestible carbohydrates and protein, whereas fire spread is favored by foliage characteristics that induce rapid ignition and high radiant energy. We tested in eight Patagonian woody plants whether foliar traits that determine dry matter and nitrogen digestibility to browsing herbivores were related to four variables that determine their flammability. We found a negative relation between digestibility and flammability. Fiber content (i.e. Neutral and Acid Detergent Fiber), was positively related with heat emission, maximum temperature and flame duration, being negatively related to time to ignition. PCA indicated that digestibility was negatively related with all variables associated with flammability. Digestibility decreased throughout the growing season, whereas flammability showed no clear seasonal trend. Fiber content was correlated with time to ignition and maximum temperature during most of the growing season, except in late spring. We conclude that highly digestible plants are likely to be less flammable than fiber rich ones, and that fiber content may serve as an indicator of seasonal changes in flammability of foliage. Because leaf traits are likely to influence habitat selection and movement by herbivores as well as spread and severity of fires, further studies linking foliar shape variables and plant architecture with their chemical composition may improve current mechanistic models of herbivore and fire behavior.
查看更多>>摘要：The eco-cultural nature of ancient woods and forest landscapes in the UK is well-established. Furthermore, the loss of cultural knowledge and memories as traditional management reduced and in many cases ceased during the twentieth century presents challenges for site conservation and that of the eco-cultural resources. Additionally, both tangible and intangible cultural heritage of these landscapes are seriously threatened and cultural severance is a major driver of ecological change and species loss. This paper takes a regionally-based case-study of these eco-cultural landscapes and their biocultural resources as evidenced by archaeology, archival sources, oral histories, and ecological field survey. This information provides detailed time-lines for specific sites from Domesday to the twenty-first century. Finally, site assessment and evaluation, and practical management implementation are considered. Issues of lack of recognition of biocultural heritage and hence of inadvertent or unknowing damage are discussed. Lack of accepted evaluation processes or effective kite-marking for sustainable forest products presents significant problems.
Beals, Kendall K.Scearce, Alex E.Swystun, Alex T.Schweitzer, Jennifer A....
11页
查看更多>>摘要：It has been firmly established that oak regeneration benefits from prescribed burning and reduced competition with fire-intolerant tree species. Despite recommendations for research on the role of the microsite environment for oak regeneration, very little is known about the interacting effects of fire, soil, and surrounding plant community on oak establishment. We collected undisturbed and burned soil in the aftermath of a wildfire in Great Smoky Mountains National Park and used amplicon sequencing to identify differences in composition of bacterial and fungal communities between unburned and burned soils. To assess the effects of plant community, fire-induced shifts in soil microbial communities, and their interaction we conducted a glasshouse experiment and grew Quercus velutina seedlings in factorial treatments of plant neighbor (oak vs. pine seedling) and soil burn status (unburned vs. burned soil). Fire reduced the diversity of plant pathogenic and saprotrophic fungi and reduced the relative abundance of plant pathogenic fungi. Fire did not affect soil bacterial communities. Shifts in soil fungal community composition enhanced oak seedling root growth, but the effect of the soil microbiome was mediated by plant neighbor interactions. Seedling root growth was negatively correlated with diversity of pathogenic fungi. Root growth was enhanced in burned soil relative to unburned soil, but only when growing with a pine seedling neighbor as opposed to an oak seedling neighbor. Results from this study show that interactions between soil microbes and nearby plants can in part mediate oak seedling growth. As such, nuanced decisions that consider the ecological interactions of the microsite environment are needed to achieve desired outcomes for oak regeneration.
查看更多>>摘要：Mediterranean forests are important sources of income for society and represent biodiversity hotspots, charac-terized by a mosaic of forest structures, from short-rotation even-aged stands to old-growth forests. However, such increased complexity requires forest management to balance timber production with biodiversity conser-vation at various spatial scales. This study investigated the impacts of forest structures and management alter-natives on the occurrence and richness of Tree-related Microhabitats (TreMs) - as proxies for forest biodiversity - in three Mediterranean forests in Italy. The generalized linear mixed model was applied to assess the relationship between a large set of forest structural parameters and the occurrence and richness of TreMs at the tree level, and resulted in an overall model accuracy higher than 80%. The same model was then implemented in hypothetical forest structures, resulting from no management, close-to-nature forestry and combined management system. Results show that at early developmental stages of the stand, no management slightly anticipates the occurrence of TreMs, while in mature forests, the combined forest management system effectively balances forest produc-tivity with biodiversity conservation. The close-to-nature management system is recommended for promoting TreMs richness. Such findings might be used to support sustainable forest management and valorise the multi-functional role of Mediterranean forests.
Rodriguez, S. A.Efron, S. T.Bucci, S. J.Scholz, F....
11页
查看更多>>摘要：Land use changes due to forestry activities can alter forest carbon (C) sequestration capacity by modifying vegetation structure and ecosystem functioning. The main objective of this study was to analyze aboveground net primary productivity (aNPP), through stem growth and litterfall production, and their feedback on soil C and nutrient contents, within a humid subtropical region. Two main forestry activities in NE Argentina were studied: selectively logged forests and Pinus taeda (loblolly pine) plantations for wood production. Well-preserved native forests were used as a control to compare the effects of interventions on the original subtropical forests. Despite differences in tree density and aboveground biomass among forests and pine plantation stands, the aNPP and total annual litterfall were similar across all ecosystems. However, litterfall quality and soil N content were substantially lower in pine plantations compared to both native forests. The labile soil C fractions were higher in pine plantations than native forests while no differences were observed in recalcitrant humic fractions across ecosystems. Overall, the results of this study suggest that man-made intervention in the structure of forest ecosystems does not necessarily result in degradation of aboveground ecosystem processes but had an impact on belowground processes and stocks in pine plantations, which has important implications for forest management.
查看更多>>摘要：Shrub encroachment is a global phenomenon occurring in a wide range of ecosystems, including in tree plantations, which is known to affect ecosystem functioning and productivity. Forest management in tree plantations (e.g. shrub clearing, tree thinning and pruning) often aims to increase wood and non-woody products yield while optimizing other ecosystems services such as carbon sequestration. However, little is known on the effect of shrub clearing on tree growth and tree water status in juvenile tree stands. Under climate change scenarios that predict increased frequency of extreme events such as droughts, management during the early stages of stand plantations may be crucial for its sustainability. This study aimed to explore the combined effect of shrub understorey removal and drought in two cork oak (Quercus suber L.) juvenile plantations, with similar stand age but distinct soil types and forest management, on tree water status, assessed through leaf water potential measurement, and on tree growth. The study was conducted during two consecutive years, including a drought year. Results revealed that the shrub understorey removal positively affected the physiological response of trees in both plantations but only affected tree growth (i.e. total height and leaf area) in the plantation with a higher tree density and shrub biomass. Shrub biomass and species composition most probably had a determinant effect on tree growth due to soil water competition. Our results emphasize the need for site-specific forest management during the early stages of cork oak plantation for maintaining its future sustainability and provision of ecosystem services.
NSTL
Elsevier