Ornelas, Adelia Carla SantosProvidello, AlexandraSoares, Marcio RobertoViani, Ricardo Augusto Gorne...
9页
查看更多>>摘要：Investigating the impact of silvicultural practices on tropical forest restoration plantations is highly relevant, as there is a growing global demand for large-scale ecological restoration. The objective of this study was to test the hypothesis that native trees respond positively to the intensification of fertilization and weed control in a forest restoration plantation on a site previously used as cropland in the Atlantic Forest region of Brazil. We carried out a study with 22 native tree species, 11 of which were classified as shade species and the other 11 classified as diversity species. We implemented a randomized experimental design in a split-plot design, with six replicates of four treatments: intensive weed control (glyphosate spraying every 3 months) with and without fertilization, and non-intensive control (mechanical control every 6 months), with and without fertilization. We performed fertilization by supplying the site with 53 kg ha(-1) of nitrogen, 35 kg ha(-1) of phosphorus, and 51 kg ha(-1) of potassium. We evaluated individual tree crown areas and increments in basal diameter and height 16 months after planting. In general, growth varied more among species than in weed control and fertilization treatments. Overall, the method of controlling weeds did not influence tree growth, but interacted with species for all growth variables. Fertilization increased tree diameter increment, and interacted with species, leading to diameter and height increments; however, most of the species did not respond to fertilization. Contrary to our expectations and previous findings, silvicultural intensification did not promote higher overall tree growth, probably because the restoration planting was conducted on a cropland with decades of intensive management, which increased soil fertility and reduced weed abundance through periodical maintenance prior to restoration planting. Our results highlight the importance of considering local and historical conditions to decide whether and when management intensification is required to accelerate tree growth in tropical forest restoration plantations.
查看更多>>摘要：The soil seed bank (SSB) in forests is a key indicator of their resilience after disturbances. Despite the growing interest in describing patterns of SSB and understanding potential processes underpinning those patterns, we still know little about SSB patterns and drivers in semi-deciduous tropical forests. Using the regeneration emergence method, we assessed the patterns of SSB (i) across four vegetation types with variable intensity of past human disturbances: typical dense forest - degraded dense forest - young preforest fallow - old preforest fallow, and (ii) in relationships to soil depth (0-5 cm, 5-10 cm, 10-15 cm, 15-20 cm) in a protected tropical semi-deciduous dense forest in Benin, West-Africa. The standing vegetation (adults and regeneration) data and soil samples were collected using a systematic sampling of 60 plots of 10 m x 10 m in the four vegetation types. Herbaceous plants dominated (67% - 78%) the SSB. From the SSB, five tree species emerged: Ceiba pentandra (L.) Gaertn., Dialium guineense Willd., Ficus sur Forssk., Leucaena leucocephala (Lam.) De Wit, and Lonchocarpus sericeus (Poir.) Kunth. Regarding tree species, the total densities of germinated seeds (seeds.m(-2)) were higher in typical dense forest (28.00 +/- 7.22) and young preforest fallow (16.67 +/- 7.07) than in old preforest fallow (10.00 +/- 6.75) and degraded dense forest (8.89 +/- 3.81). When only tree species were considered, the SSB was more diverse and dense in typical dense forest than in other vegetation types suggesting negative effect of past human disturbances on SSB. The similarity of the species composition between the SSB and the surrounding vegetation was low (Jaccard's similarity index ranged from 0 to 17.64%, indicating that the majority of tree species in the surrounding vegetation were absent in the SSB. This study highlighted a need of planting effort of native tree species to restore degraded areas.
查看更多>>摘要：Understanding the dynamic relationships between water uptake patterns and forest management in plantations is important for predicting the impacts of climate change and tailoring forest restoration to mitigate potential impacts. However, the water uptake patterns of overstory trees and associated drivers in plantations with different management practices are poorly understood. In this study, analyses of stable isotopes (delta H-2 and delta O-18), in addition to a MixSIAR model, were applied to assess the water uptake patterns of Pinus massoniana Lamb. under four forest management measures (no thinning: NTN; understory removal: USR; light-intensity thinning: LIT; and heavy-intensity thinning: HIT) under three rainfall events (8.9 mm, 13.3 mm and 67.7 mm) in the Three Gorges Reservoir Area in China. A random forest model and variation partitioning analysis were further used to identify the effects of tree and soil properties on the water uptake patterns of overstory trees. The results indicated that P. massoniana in the NTN and USR stands mainly derived water from deep soil, whereas P. massoniana in the HIT stand absorbed more water from surface soil. P. massoniana in the LIT stand consistently used deep soil water after 8.9 mm of rainfall, and preferred to use shallow soil water after 67.7 mm of rainfall. This result suggested that P. massoniana in the LIT stand has a more competitive advantage over that in the HIT stand through consistent uptake of deep soil water following light rainfall; however, this strategy is more conducive to avoid excessive consumption of deep soil water than the strategies used in the NTN and USR stands as it allows the extraction of shallow soil water following heavy rainfall. The different water uptake patterns of P. massoniana among the four treatments were mainly attributed to differences in tree properties, including leaf biomass, fine root biomass density, and leaf water potential. Overall, light-intensity thinning may be a suitable forest management practice to optimize the water use strategies of P. massoniana to cope with the changes in precipitation pattern.
Chen, XinliHisano, MasumiTaylor, Anthony R.Chen, Han Y. H....
14页
查看更多>>摘要：Soil carbon (C) plays an important role in mediating global climate change and sustaining environmental condition. Although experimental studies primarily from grasslands revealed the positive effects of plant diversity on soil C storage, there is uncertainty about the directions and magnitudes of tree diversity and soil C relationships in natural forests. Using Canada's National Forest Inventory data from temperate to boreal forests, we examined the relationships between soil C stocks and tree functional diversity and identity, and how these relationships varied along environmental gradients (i.e., biomes, mean annual temperature, climate moisture index, and soil drainage). In contrast to the results from grassland experiments, we found a negative relationship between tree diversity and soil C stocks in temperate forests and a nonsignificant relationship in boreal forests. Moreover, soil C stocks increased with functional diversity in moist and poorly drained sites, but decreased in dry and welldrained sites within the temperate forest biome. Within the boreal biome, soil C stocks increased with functional diversity in warm climates, but decreased in cold climates. Our findings at the macro-ecological scale indicated that the positive effects of plant diversity might be the highest at the boreal-temperate forests' ecotone. In addition, within the temperate biome, tree communities with higher leaf nitrogen, phosphorus content and specific leaf area were associated with greater mineral horizon soil C stocks, especially in warm or well-drained sites. Our finding of the abiotic context-dependent relationships between soil C stocks and tree functional diversity and identity can guide forest management across different environmental conditions.
Best, KatherineHaslem, AngieMaisey, Alex C.Semmens, Kristin...
13页
查看更多>>摘要：The creation of mechanically carved tree cavities to provide supplementary shelter for hollow-dependent wildlife is increasingly popular in conservation management programs. However, there is limited empirical evidence quantifying how the features of their design and broader placement within the landscape influence use by target fauna. In this study, we took a multi-scale approach to investigating the use of chainsaw hollows (CHs) by a target native arboreal marsupial, Krefft's Glider Petaurus notatus. We hypothesized that Krefft's Gliders would respond to attributes of: (1) the CH itself; (2) the tree into which it was installed; and (3) the habitat within the reserve in which it was located. We monitored occupancy (over 2.7 years, using a pole camera) of 48 CHs installed in live Eucalyptus trees across multiple reserves in Melbourne, Australia, plus visitation (over ~3 months, using camera traps) to 40 of the CHs. Mixed models were used to relate the occupancy of CHs by Krefft's Gliders to field-collected data on various attributes of CHs at all three scales. From a total of 35,219 visitations across the 40 CHs, we recorded 13 native hollow-dependent species (five mammals, eight birds) visiting CHs. During 14 pole-camera inspections, Krefft's Glider occupied 60% of the 48 CHs at least once, with 4% used as maternal dens during breeding. Four exotic species were also recorded visiting and/or occupying CHs. Orientation and volume both significantly affected occupancy: Krefft's Gliders were more likely to occupy larger CHs, and those facing north and west (possibly related to microclimate). Tree-scale attributes did not affect occupancy, but Krefft's Gliders were more likely to occupy CHs further from reserve edges, and where local density of Black Wattles (Acacia mearnsii: an important food resource) and low vegetation cover (100-200 cm above ground) was increased. Our findings show that CHs can provide supplementary shelters for Krefft's Gliders when natural hollows are limited. Practitioners should consider both the physical characteristics of the cavity (e.g. volume) and the surrounding habitat (e.g. availability of foraging resources) to enhance the use of CHs by target species. The ongoing availability of CHs to target species will also be influenced by their use by exotic species, and potential for closure as woundwood grows. In an Australian context, a lack of knowledge about the specific features of natural hollows to which hollow-dependent fauna respond, means it is critical for policy and management to prioritize the retention of mature hollow-bearing trees.
查看更多>>摘要：Overbrowsing by highly abundant white-tailed deer (Odocoileus virginianus) negatively impacts the regeneration of the forest understory throughout the eastern United States. Deer management programs are often used by land managers to reduce deer densities and promote forest regeneration. This study examines the impact of a 15 -yearlong archery-based deer management program on the understory of a nature preserve in southern NY consisting of an old-growth hemlock and second-growth mixed hardwood forest. Vegetation plots were sampled every 3-5 years between 2004 and 2019, while deer density was estimated using camera trap survey data annually since 2009. Generalized mixed-effects models were used to determine the influence of deer density, forest type, canopy cover, and time on species richness, native stem density and total stem density. The most predictive models showed an increase in richness as time went on. Additionally, stem density had a negative relationship with deer density (i.e., stem density and species richness increased as deer density declined over time). For both native and total stem density, the highest-ranked model included only deer density as a predictor. Generally, woody species richness and stem density increased in the seedling ( 0.3 m tall) and sapling (0.3-0.9 m tall) size classes but remained relatively constant for the transgressive ( 0.9 m) size class over time and as deer density decreased. Many native species exhibited density increases in the smallest size classes, but black birch (Betula lenta), American beech (Fagus grandifolia), and mapleleaf viburnum (Viburnum acerifolium) were the only native species to increase in the transgressive (>0.9 m tall) class. Several non-native species, however, did increase in the transgressive size class since 2004. These results indicate that the forest has improved as a result of the DMP, but long-term recruitment of native species is still uncertain. The DMP has shown the potential to help restore woody regeneration but monitoring should continue to ultimately determine whether deer management can allow for true recruitment of native seedlings into the forest understory and canopy.
查看更多>>摘要：Oak (Quercus petraea (Matt.) Liebl. and Quercus robur L. grouped), European beech (Fagus sylvatica L.) and hornbeam (Carpinus betulus L.) are three major species of western and central European forests. When conditions are suitable for the three species, silvicultural management often favours oak because of its greater economic interest. Forest managers know that beech and hornbeam are strong competitors for oak during the regeneration phase, but the conditions that influence the relative success of the regeneration of the three species growing in mixture are still poorly characterised. The natural regeneration of the three species 20 years after canopy openings was studied based on 108 study sites established in 2001 in French forests impacted by the windstorms Lothar and Martin in 1999. In spring and summer 2018 and 2019, all saplings over 0.1 m in height were counted, species were identified and diameter at breast height (DBH) was measured for all saplings over 1.30 m. The height of the saplings with the highest and median DBH in each plot was recorded for each species. Mixed models were used to analyse the combined effects of former stand type, distance from the edge of the gap and soil conditions on species presence, sapling abundance, DBH and height. The modelling approach highlighted the preponderant role of the initial seed rain on the presence and sapling density of the three species compared to interspecific competition or distance from the edge. The two latter factors had a secondary effect on sapling DBH and height. Beech and hornbeam saplings were more abundant than oak saplings regardless of soil conditions (on average, 3097, 3063 and 344 saplings ha(-1), respectively), suggesting a strong competitive ability of these two species. Oak was present on 22% (43% for hornbeam and 68% for beech) of the studied plots, at a low density but with a height and DBH similar to that of beech or hornbeam. This result highlights the high dissemination capacity of beech and hornbeam, which prevents the establishment of a stand dominated by oak. When seeking to obtain oak-dominated stands in the lowlands of Europe, the abundance of beech and hornbeam can be a limiting factor that could lead to the disappearance of oak from large areas if no silvicultural operations are performed to promote it.
查看更多>>摘要：The European oak bark beetle (Scolytus intricatus) has the potential to impact forest structures through its selection of certain trees. We investigated potential S. intricatus colonisation densities by setting up 150 trap trees and analysing them in 5-metre sections during a three-year period from 2014 to 2016 in a temperate forest in Slovakia, Central Europe. Understanding the population dynamics of S. intricatus and the drivers of its colonization density on trees is necessary if attempts to control or manage populations of S. intricatus in managed forests are to succeed. To explain the population dynamics of S. intricatus, ANOVA was used to assess the colonisation densities in the stem , and generalized linear mixed effect models (GLMMs) were used to analyse the main characteristics of the host trees and the meteorological variables. Structural equation modelling (SEM) was then used to explain the multitude of relationships among the predictor variables and bark beetle populations. Scolytus intricatus reached higher population levels under dry and warm conditions, when trees were prone to drought stress. The highest colonization densities at the trap trees occurred in May and June of 2014 and 2016; in 2015, the highest densities were reported in August and a second generation of S. intricatus was observed. This is unusual, as this species is usually univoltine, i.e. has one generation per year under Central European conditions. Population levels differed in different months during the 3-year study period, i.e. patterns of population dynamics and phenology are not repeating. The mixed-effects models demonstrated that the seasonal temperature influenced the occupation of trap trees by S. intricatus and that the lengths of the galleries were affected by the section surfaces. We conclude that environmental stress hastens the rate of drought stress in oak trees, resulting in faster population growth and higher survival of S. intricatus.
Thakur, ShinnyNegi, Vikram S.Dhyani, RupeshBhatt, I. D....
10页
查看更多>>摘要：Understanding patterns in forest communities and its driving factors play a critical role in ecological studies. In view of this, present study attempts to understand the role of environmental and anthropogenic factors towards shaping species diversity and composition along the altitudinal gradient (700-3800 m asl) in Indian western Himalaya. A total of 51 tree species (28 families) were recorded; Pinaceae (5) and Fagaceae (5) were the species rich families. alpha-diversity indices i.e., Margalef's richness index (R), Shannon index (HMODIFIER LETTER PRIME) and Simpson index showed a humped shaped distribution, whereas Evenness index (E) showed an inverted humped shaped distribution along the altitude range. Based on non-metric dimensional scaling (NMDS), four different community types were identified. Redundancy analysis (RDA) revealed a strong relationship of tree species composition with environmental (41.73% variation) and anthropogenic factors (17.35% variation). RDA further indicated that the bulk density (BD), disturbance index (DI), mean diurnal temperature range (Bio2) and solar radiation (SR) are significantly associated with sub-tropical (below 1200 m) and lower temperate forest (1200-1700 m) types. Likewise, soil organic carbon (SOC), precipitation of the driest quarter (Bio17) and pH were significantly associated with upper temperate (1700-2900 m), and subalpine forest composition (>2900 m). Both NMDS classification and RDA ordination clearly demonstrate spatial variability in composition of tree community and environmental properties.
NSTL
Elsevier