Forest Ecology and Management最新文献

Vauhkonen (2024) showed concerns mainly regarding the analyses and used models in our study on forest management effects on the spatial distribution of willow tits (Kumpula et al., 2023). The idea in this study was to figure out if forest management practices (clear-cuttings and thinnings) have effect on the decreasing willow tit population. We used long-term breeding data of willow tits collected in Oulu which was combined with spatial environmental data with GIS (Geographic Information System) methods. Here we answer the criticism, explain some inaccuracies of our study and point out with more detailed analyses of nearest neighbour distances (NNdist) of willow tits that the forest management practices indeed are related to decreasing willow tit population density.

The rhizosphere, a critical interface involving soil, plant roots, and microorganisms, plays a vital role in the feedback processes between plants and soil, especially under phosphorus (P) limiting conditions typical of subtropical forests. This study used a chronosequence design to investigate first-fourth successive planting rotations of Chinese fir (Cunninghamia lanceolata) plantations in Fujian Province, China, with stands around 17 years old. We employed a modified P fractionation assay and metagenomic sequencing to explore P cycling in the rhizosphere across different plantation rotations. Rhizosphere labile P concentrations increased significantly in the fourth rotation, alongside a consistent upward trend in moderately labile P throughout successive plantings. Conversely, stable P and residual P concentrations declined during successive plantings, signaling a shift toward more accessible P forms. From metagenomic analyses, the proportion of P transport processes (transportation of phosphonate, phosphate, and inorganic phosphate) gradually increased. Notably, abundances were significantly higher in the rhizosphere soil of the fourth Chinese fir planting rotation of the K01126 gene (involved in phosphate ester mineralization), the phnD gene (associated with phosphonate transport), functional genes related to the solubilization of inorganic phosphate, such as pqqB, pqqC, pqqE, and ppa, and the phoB gene (linked to P-starvation response regulation). The results indicate that functional microbes of the rhizosphere, dominated by Proteobacteria and Acidobacteria, are instrumental in changing P cycling processes during successive plantings. The successive planting rotations of Chinese fir plantations significantly and positively impacted on the gene abundance related to the activation and uptake of P in the rhizosphere. Based on these insights, specific strategies, such as regular monitoring and application of phosphate fertilizer and adjusting rotation timing based on the soil rhizosphere P status, and incorporating native broad-leaved tree species are suggested to promote efficient P cycling, thus supporting sustainable forest management practices.

Tropical forests play a critical role in the global carbon cycle, storing 40–55 % of terrestrial plant carbon and significantly contributing to primary productivity. However, uncertainties persist in estimating carbon stocks and fluxes, exhibiting variation across the Neotropics, Africa, and Asia tropical forest regions. Despite hosting some of the most densely sampled forests, significant uncertainties persist in biomass and forest carbon stock estimates in the Neotropics. Although the Southwestern Amazon (SWA) forests span over 20 million hectares, no specific biomass or above- and below-ground carbon model has been calibrated for this region thus far. In our study, we conducted direct forest inventories in the SWA to address the following question: Do the allometric patterns, biomass, and carbon stocks observed in the Southwestern Amazon differ from those found in other regions of the Amazon or Pantropical? Our research reveals substantial differences in water and carbon content, biomass stocks, above- and below-ground oven-dry biomass ratios, and allometric patterns between SWA forests and other Amazonian and Pantropical forests. We have demonstrated that these differences result in overestimations of forest biomass when applying allometric equations developed for other Amazonian and Pantropical regions to the open forests of Southwestern Amazonia. This overestimation can reach up to 37 % when using equations from the eastern Amazon, and between 26 % and 46 % depending on the applied Pantropical equation. The use of an inappropriate factor for the root-to-shoot ratio in the Southwestern Amazon (SWA) can lead to overestimates of belowground oven-dry biomass by up to 20 %. To reduce uncertainties related to estimates of forest carbon stock and flux in Neotropical forests, it is necessary to enhance the density of direct biomass measurements, particularly in southwestern Amazonia.

Wildfires are predicted to increase in frequency and severity with climate change but detailed understanding of their influence on forest wildlife is lacking for many species. Wildfires vary in their extent and severity among landscapes, limiting generalisations about impacts from a single wildfire. We investigated post-wildfire persistence in the threatened exudivorous yellow-bellied glider (Petaurus australis) in south-eastern Australia. The widespread occurrence of wildfires in the ‘Black Summer’ of 2019–20 enabled populations in three landscapes (90–160 km apart) to be studied. This species has a slow life history (one young per year and >1 year to mature) so post-fire recovery is predicted to be slow. We conducted repeat surveys over 3 years post-fire in each landscape at 25–29 sites that were occupied pre-wildfire. All survey sites were burnt in two landscapes but only 40 % were burnt in the third. We estimated declines in occupancy of 13 %, 40 % and 66 % in burnt forest. The factors driving the variation in decline appear to be a combination of fire severity and the abundance of very large (≥80 cm) hollow (i.e. cavity) -bearing trees that serve as den sites. The implications of this study are that the impacts of wildfires on populations of tree-hollow dependent species can be expected to vary in different landscapes as a consequence of fire severity, rainfall deficit and logging history. Our study suggests the importance of ensuring populations are conserved across a wide geographic gradient, and the value of very large hollow-bearing trees rather than simply the number of any hollow-bearing trees.

Windstorms are natural factors in vegetation dynamics, but their intensity is increasing and undermines the forest resilience. Post-event interventions depend on forest types and management purposes. To promote mixed stands that are less susceptible to windthrow than monocultures, natural tree regeneration is usually recommended. However, wild ungulates attracted by the increased food supply in the new clearings can influence the secondary succession and slow down vegetation recovery. The impact of ungulate pressure on secondary successions in blowdown areas is still poorly known, especially in Mediterranean areas, which is particularly vulnerable to climate stressors. We investigated this topic using a monospecific silver fir (Abies alba) forest of artificial origin in the Apennines as a model system. The forest was left to natural succession after a severe windthrow in 2015, offering the opportunity to establish an ungulate exclosure experiment to analyse vegetation changes over six years. For the whole plant community, cover and height, α-diversity (species richness, Shannon and evenness indexes), and species composition were recorded yearly, together with tree seedling density, in open and fenced plots at increasing distances from the forest edge. Ecological and functional traits (proportion of light-demanding and forest specialists, endo-/epi-zoochorous species), and life-forms of the community samples were also analysed. Overall, we found that ungulates significantly influenced the dynamic trajectories of secondary succession. The effects on plant cover and diversity were negative and increased with distance from the forest edge. The presence of ungulates favoured generalist species and endozoochorous taxa. However, distance from the forest edge strongly reduced the latter effect. The average density of tree seedlings was overall high (ca. 10,000/ha), but it was strongly reduced by ungulates for three deciduous species and A. alba, the most browsed species. Natural recolonization after windthrow in Apennine pure silver fir stands may favour the formation of mixed, less susceptible forests, but the current ungulate pressure slows down this process, especially in the areas furthest from the forest edge.

Nitrogen (N) serves as the primary limiting nutrient for plant growth in the majority of terrestrial ecosystems. However, the effect of long-term N addition on root N acquisition, in particular the seasonal dynamics, is still not well understood. In a 19-year N addition experiment on plantations of ectomycorrhizal tree species Larix gmelinii (larch) and arbuscular mycorrhizal tree species Fraxinus mandshurica (ash), we determined root morphological, chemical and mycorrhizal traits, as well as soil properties. Concurrently, we used a field isotopic hydroponic method to measure root uptake rates of NH₄⁺, NO₃^-, and glycine in the early, mid and late growing season. Following N addition, mycorrhizal colonization rates in both species were reduced in early and late growing season. Root tissue density was reduced but specific root length and area were increased in ash under N addition across growing seasons, however, no significant differences in these traits were found in larch. Under N addition, both species showed lower uptake rates of all N forms and the total N than the controls throughout the growing season, except for the glycine-uptake of larch in early growing season. N addition did not modify the N-uptake preference in both species, but the contributions of specific N form to the total N varied with seasons. Collectively, referring to the framework of “root economics space”, these two species particularly ash showed greater reliance on the “do-it-yourself” strategy for N acquisition under long-term N addition, although the degree of which somewhat varied with season. Seasonal dynamics in root N-uptake rates of ash were mainly related to soil temperature and moisture, rather than soil N properties, showing less direct impact of N addition. Our findings provide deep insights into the effect of N deposition on root N acquisition strategy and related functions of forest ecosystem.

The natural disturbance model for ecosystem management of timber harvesting promotes the emulation of natural disturbance regimes in the patterns of tree removal. Wildfire is a prominent natural disturbance in boreal forests of western Canada, frequently removing most of the tree canopy from patches of 500–10,000 ha in stand-replacing events. However, fire suppression, coupled with a spatial pattern of timber harvesting dominated by small patch cuts of 10–160 ha, have changed the spatial scale of younger stands away from scales within which boreal organisms evolved. In two regions (Sub-Boreal Spruce biogeoclimatic zone of central British Columbia and Liard Basin of southeast Yukon), we tested the hypothesis that different spatial scales of stand-replacing forest disturbance (wildfire and timber harvesting) result in different amplitudes of change in abundance of snowshoe hare, a keystone boreal forest mammal for which mid-seral stand conditions provide optimal habitat. Landscapes with large patches (>2000 ha) of mid-seral forest following stand-replacing disturbance supported consistently and often significantly more hares, with wider amplitude in cyclic fluctuation, than small patches (20–200 ha) of mid-seral habitat and than mature forest landscapes. Densities of hares high enough to support reproduction by Canada lynx (a specialist hare predator) only occurred in landscapes disturbed at the scale of a moderate to large-sized wildfire (1000 – 10,000 ha). Landscapes unaffected by stand-replacing disturbance for at least 80 years (i.e. mature forests) supported very few hares and without cyclic fluctuations. We recommend that the recent pattern of cutting dominated by small patches (20–200 ha) be shifted to include many larger patches (2000–5000 ha). This can happen with incremental, contiguous patch cutting over a period of years short enough that the completed patch will supply high quality, mid-seral habitat for at least the period of one hare cycle (10 y). In designing relatively large patches, mature green tree retention would be desirable for various values, but would be best as small stands of mature forest dispersed within large patch cuts, similar to the legacy of fire. Silviculture (reforestation and stand tending) should create and sustain a mix of conifer and deciduous regeneration in the mid-seral stands. Emulating spatial patterns of stand-replacing natural disturbance appears necessary to sustain snowshoe hare cycles when most fires are suppressed in intensively managed western Canadian boreal forests.

Climate models forecast a significant reduction in average precipitation and an extension of the dry period over the coming decades, which will likely influence the biogeochemical processes of the Brazilian savanna (i.e. Cerrado). However, studies about the fate of soil nutrient availability in this biome remain scarce. We conducted a field-based experimental rainfall reduction in three Cerrado ecotypes, namely an open savanna (OS), a woodland savanna (WS), and an intermediate savanna (IS), to assess its effects on soil organic matter, total phosphorus, microbial biomass nitrogen, dissolved organic nitrogen and inorganic nitrogen (NH₄⁺-N and NO₃^--N) pools in dry and rainy seasons for two consecutive years. Despite sharing common soil origins and climatic conditions, these ecotypes showed contrasting levels of soil organic matter as well as phosphorus and nitrogen pools. The WS showed higher soil fertility with organic matter levels of 11.19 %, P levels of 2.54 mg Kg⁻¹, and NO₃^--N levels of 2.15 mg Kg⁻¹, compared to the OS, which had organic matter levels of 7.04 %, P levels of 0.65 mg Kg⁻¹, and NO₃^--N levels of 1.49 mg Kg⁻¹. The IS showed intermediate values, with organic matter levels of 8.94 %, P levels of 0.65 mg Kg⁻¹, and NO₃^--N levels of 1.93 mg Kg⁻¹. Seasonal patterns considerably influenced soil nutrient content, with higher soil inorganic nitrogen levels typically found during the rainy season and higher soil phosphorous levels during the dry season, although these patterns varied among ecotypes. Soil organic matter, dissolved organic nitrogen, and microbial biomass nitrogen exhibited greater sensitivity to the experimental reduction in rainfall compared to soil phosphorus and inorganic nitrogen. However, this sensitivity varied across ecotypes and seasons, with a particularly strong effect observed in the IS and during the rainy season. Our findings suggest that the effects of climate change in the Cerrado might strongly vary among seasons and the different ecotypes, highlighting the need for more comprehensive experimental studies in the different ecotypes to fully understand future nutrient dynamics in the Cerrado.

Human activities can substantially alter forest structure, consequently affecting forest animal communities. An important effect on bat behavior is given by canopy discontinuities like clearings or trails: while the former act as foraging sites, the latter are known to be used by bats to move inside the forest. For this reason, we can expect trails to have a strong influence on bat activity, with differences determined by the species' flying abilities. Here we assess the impact of trails on a local bat community by quantifying the effect of trails’ characteristics on the activity of bat species in relation to their wing morphology. We collected paired acoustic data and environmental variables along trails and in internal areas of a forest in central Italy. We modelled the activity levels of three bat guilds differing in wing morphology and identified the species mostly responsible for the observed compositional dissimilarity in between trails and internal zones by adopting a multivariate approach. Trail width and tree’s diameter were the main drivers of the observed differences between bat activity along trails and internal areas, but their effect differed among bat guilds. Edge and open-space foragers increased their activity along wider trails, while closed-space foragers showed an opposite trend; the latter also avoid trails in favor of internal areas especially when trees are larger. Four species yielded a significant contribution to the dissimilarity in activity levels between trails and internal areas, and namely Pipistrellus pipistrellus, Nyctalus noctula, Miniopterus schreibersii and Barbastella barbastellus. Our results show a clear effect of forest trails on bat activity, highlighting differences across functional groups in relation to trail characteristics. Furthermore, within guilds, not all species respond with the same intensity, suggesting differences in how different species are attracted to linear features and forest gaps. Overall, our results depict a complex interaction between forest trails and bat activity, suggesting that structural changes in forests can trigger diverse responses in bats. Future research on the topic may focus on assessing how such effects can affect bat communities at the landscape scale and longer time-scales.