Forest Ecology and Management最新文献

Understanding the role of biocrust-forming mosses in soil recovery after wildfires is necessary for assessing the resilience of managed ecosystems. The purpose of this study was to investigate the mid-term impacts of two contrasting post-fire management strategies on soil recovery in eucalypt plantations in north-central Portugal, where a high cover of biocrust-forming mosses developed post-fire, contributing to erosion control. Six years after a wildfire, we examined the legacy effects of salvage logging and two rates of mulch application using logging residues (a standard rate of 8.0 Mg ha^-1 and a reduced rate of 2.6 Mg ha^-1) on soil properties, and explored the interaction between moss biocrusts and forest management practices on soils. Our findings reveal the resilience of soils to physical disturbance after logging operations, with no persistent negative effects on their physicochemical properties. Although forest residue mulches showed minimal influence on soils after six years, an interesting interaction with moss biocrusts was observed. In the absence of moss cover, direct contact of wood residues with soil at the standard mulch rate promoted higher nutrient content and biochemical activity, potentially attributed to accelerated decomposition processes. Regardless of the management applied, our study highlights the role of moss biocrusts in improving soil aggregation and biochemical processes in the mid-term. However, the severe water repellency observed in these soils may have impeded further biocrust expansion. Understanding the implications of forest management practices on soil recovery after wildfires is imperative for guiding strategies aimed at promoting ecosystem recovery and resilience in fire-prone managed forest ecosystems.

European forests have been influenced by human interventions for millennia. Many formerly traditional forest management practices have been lost due to changes in technology and attitudes. One commonly used practice was charcoal burning, remnants of which have remained in the forests for hundreds of years. We aimed to evaluate the differences between abandoned remnants of charcoal mounds and their surroundings in terms of soil-dwelling fauna and to compare them with old-growth forests in reserves of the Czech Republic. Our primary focus was on four macroarthropod taxa: centipedes, millipedes, terrestrial woodlice and symphylans. We discovered that charcoal mounds did not significantly differ from control forest patches regarding species richness and rigidity but varied in species composition and functional traits. In comparison, forest reserves were significantly richer in species, hosted less adaptable taxa, higher functional traits and exhibited different species compositions with the same number of shared species with charcoal mounds and controls. We found that the addition of charcoal residuals from traditional forest management can enrich pedobiodiversity – old, abandoned charcoal mounds within forests can enhance the biodiversity of relatively species-poor soils. Nevertheless, these residuals cannot match the biodiversity found in undisturbed old-growth forests. However, stand-scale biochar application in plantation forests could be a promising biodiversity strategy that mimics this traditional forest management practice.

Selective logging, a common disturbance in mixed-species and uneven-aged forests, can cause substantial collateral stand damage and tree mortality. Here we explore damage patterns and some mechanisms that increase post-harvest tree mortality in a selectively logged subtropical Atlantic Forest in Argentina. We investigate the spatial relations of felled and damaged trees through spatial point pattern analysis and evaluate the relationships between mortality and different endogenous (size - diameter at breast height: DBH; and wood density: WD) and exogenous (damage and neighboring basal area: NBA) factors. The permanent plots were logged in 1999, and the fates of all pre-logging live trees ≥10 cm DBH were evaluated 20 years later. Of the monitored 3973 trees, 381 with damaged concentrated within 10.5 m of felled tree stumps. Over the next twenty years mean mortality was higher and more variable for damaged than undamaged trees (47 % ± 10 % SE and 39 % ± 2 % SE, respectively), and the presence of damage interacted with the other analyzed factors. For undamaged trees, the probability of mortality declined with DBH and NBA but not with WD. For damaged trees, instead, the probability of mortality was related to an interaction between DBH, WD, and NBA. For damaged trees <30 cm DBH, mortality increased with WD and NBA, whereas for damaged trees ≥30 cm DBH, mortality peaked at both extremes of the WD range. For these large trees with low WD, the probability of mortality decreased with NBA, whereas for trees with high WD, the opposite was observed. Our findings suggest that selective logging affects the dynamics of forests by spatially concentrating damage and may alter subsequent tree deaths. This could have, long-term effects on forest structure. Increases in logging intensity would increase overall damage and spatially isolate trees (i.e., lower NBA), rendering them more vulnerable to wind damage and other external factors. Increased tree mortality will reduce forest carbon stocks and thereby jeopardize global efforts to mitigate climate change.

Theoretical and empirical studies have suggested that climate, soils, and topography are the primary drivers of aboveground biomass in forests. Yet, the direct effects of these drivers may be mediated by indirect effects, such as species diversity and structural diversity. This study investigates the relationships between climate, topography, soil fertility, species diversity, structural diversity, and aboveground biomass (AGB) using Structural Equation Modeling (SEM) to distinguish indirect and direct causal relationships. We conducted this study in longleaf pine (Pinus palustris)-dominated forests in the southeastern United States (SEUS), using United States Department of Agriculture Forest Service inventory data from 2015 to 2019. The longleaf pine ecosystems of the SEUS are of great importance due to their rich biodiversity and unique ecological functions, but they also provide an opportunity for scientific studies across a large ecological gradient because they exist across a wide range of edaphic conditions. However, studies in longleaf pine have primarily focused on stand structure, regeneration processes, prescribed fire practices, and groundcover restoration, leaving a knowledge gap regarding AGB in this ecosystem. We hypothesized that (1) climate, topography, and soil fertility would influence AGB through positive indirect effects; (2) structural diversity rather than species diversity would strongly mediate the response of AGB to climate, topography, and soil fertility; and (3) species diversity and structural diversity would be positively correlated, with structural diversity positively impacting AGB across coarse scale ecological gradients. Structural diversity could be important in predicting AGB because it reflects the horizontal complexity of the forest stand. Our results show that mean annual temperature and slope had considerable direct negative and positive impacts on AGB, respectively. Additionally, soil fertility, elevation, and precipitation indirectly impacted AGB by affecting species diversity. Specifically, AGB decreased in highly fertile soils, whereas elevation and precipitation led to an increase in tree species diversity. Structural diversity had a direct positive influence on AGB, while species diversity played an indirect role by promoting structural diversity. While there are diverse objectives for managing longleaf pine, management that promotes high levels of stand structural diversity may strengthen the stock of longleaf pine forest AGB, which could be especially important in the face of changing climatic conditions. Our findings emphasize the importance of integrating climate resilience and carbon storage goals into forest management practices.

Cacao is the most important agricultural product in the southern region of Bahia state, Brazil, with 70 % of its production occurring under the traditional agroforestry where cacao is mostly shaded by native trees. This traditional system allows to reconcile the production with the maintenance of the portion of original biodiversity. However, increased deforestation and intensified agroforestry management aimed at boosting productivity may impact the diversity of native species and the services they provide. In this context, our aim was to disentangle the role of landscape forest cover and the local vegetation complexity on predation of caterpillars and herbivory of cacao plants located in agroforestry systems. The study was conducted across 18 cacao agroforest sites in southern Bahia located in landscapes with different amounts of forest cover. We assessed predation rate using dummy caterpillars, sampling understory birds and arthropods and collected leaves of cacao trees to analyze damage by herbivory. We also measured shading levels and the abundance of cacao trees in each agroforestry. Predation pressure on dummy caterpillars was positively influenced by the abundance of total predators and the level of landscape forest cover and negatively by the number of cacao trees. Even so, we found no evidence that landscape, local features or the actual invertebrate assemblages (predators or herbivores) influenced the cacao leaf damage. The findings highlight the multifaceted interactions between ecological factors, predation pressure, and leaf damage within cacao agroforestry systems.

Addition of nitrogen (N) to forest soil may alter wood decay rates and fungal community structure and richness. In a northern Sweden Pinus sylvestris L. forest, two levels of ammonium nitrate were applied annually from 1971 to 2008. In 2007 we initiated an investigation into wood decay (assessed through mass loss) and fungal responses using stakes of trembling aspen (Populus tremuloides Michx.) and loblolly pine (Pinus taeda L.) wood installed at different soil depths in plots where zero (N0), low (34 kg; N1), or high (68 kg; N2) levels of N were applied. Stakes were located either horizontally on the surface of the organic horizon, at the interface between the mineral and organic horizons, or vertically in the mineral soil. For litter and mineral soil, fertilizer treatment was not significant for any soil chemical or physical property. Overall, pine and aspen wood stake mass loss was less than 35 % three years after deployment. Notably, the N1 treatment had the most pronounced effect on wood decay, and significantly accelerated aspen decomposition at the organic horizon surface in the second and third years. Analysis of fungal DNA extracted from the wood stakes revealed fluctuations in fungal richness and community composition depending upon stake location and duration since deployment. Fungal richness was notably higher in surface aspen stakes under N0 and N1 treatments and in surface pine stakes under N0 in the second year, though richness generally decreased with time as stake decay increased. Fungal community composition also varied by stake location and time since deployment. These results indicate that prolonged N addition can affect fungal richness, which may in turn affect wood decomposition rates. Further research is needed to clarify the nature and persistence of long-term soil N-addition effects on organic matter decomposition and soil microbial communities.

Fire disturbances and atmospheric nitrogen (N) deposition can significantly soil nutrient dynamics and plant nutrient uptake, thereby influencing on biogeochemical cycles within forest ecosystems. Despite these known effects, the combined impact of burning and N addition on leaf nutrient characteristics and the underlying mechanisms remains largely unexplored, particularly within forest ecosystems. This study presents a three-year field experiment designed to assess the responses of leaf N and phosphorus (P) concentrations, N:P ratios, and nutrient resorption in six dominant species (comprising two tree species and four understory species) to burning and N addition in a coniferous-broadleaved mixed forest located within a subtropical-warm temperate transition zone in Central China. The findings revealed that burning did not affect N concentrations in either green or senesced leaves, nor did it influence N or P resorption across any of the tree or shrub species. However, it did increase P concentrations in green leaves and reduce N:P ratios in shrub species. N addition elevated the N concentrations and N:P ratio in green and/or senesced leaves (with the exception of Quercus acutissima Carruth.), without affecting N or P resorption. These results suggest that shrubs enhanced P uptake due to increased soil P availability but maintain consistent internal P cycling (i.e., nutrient resorption) following low-severity fires. Additionally, most shrub species exhibited lower N:P ratios compared to tree species post-burning, indicating distinct nutrient requirements and fire responses based on life form. This study provides essential insights, demonstrating that burning mitigates P limitation on plant growth in subtropical–warm temperate ecotonal forests. Furthermore, the differential responses of leaf nutrient traits and associated stoichiometry across diverse life forms to environmental disturbances may influence plant diversity and community composition within these forests.

Laminated Root Rot caused by the fungal pathogen Coniferiporia sulphurascens is a damaging disease within many Douglas-fir forests of the Pacific Northwest of North America. Management of these forests in a changing climate and fire regime will require changes to silvicultural practices. A long-term study (ca. 30 years) in Oregon, USA provides an opportunity to investigate the effects of thinning on disease dynamics in an area of historically high laminated root rot incidence. The effects of three thinning prescriptions on tree mortality caused by C. sulphurascens were compared on ca. 160 ha within the Siuslaw National Forest. Observations were compared with predictions from the Forest Vegetation Simulator and its Western Root Disease Model extension. No significant effect of thinning treatment on mortality (p = 0.981), or annual basal area increment (p = 0.372) was observed. In contrast to observations, the Forest Vegetation Simulator over estimated growth, while the Western Root Disease Model extension was consistent with field measurements. Thinning treatments appear to have minimal impacts on laminated root rot induced mortality but also do not result in the expected increase in growth rate typically associated with a thinning treatment.

Climate change-related extreme drought events already have a significant impact on the productivity and mortality of Central European forests. European beech (Fagus sylvatica ssp. sylvatica), one of the most important European broadleaved species, has responded to such drought periods with increasing mortality and reduced volume increment. This has raised concerns about its suitability and adaptive capacity in relation to future climatic conditions and motivated the search for alternative tree species that are suitable for assisted migration into European beech forests. One of the candidates is the Oriental beech species complex (F. sylvatica ssp. orientalis), whose range extends from the Balkan to Iran and, at least in some parts of its range, grows under a warmer and drier climate. In order to evaluate whether Oriental beech is more drought tolerant, we compared the radial growth response to droughts between 1920 and 2018 of a total of 138 European and 122 Oriental beeches growing under identical site conditions in eight different locations in Germany and France. The species identity of all analysed trees was verified by microsatellite analyses, and the origin of the introduced Oriental beech was traced to the Greater Caucasus (7 stands) and the Black Sea coast (1 stand). The drought responses of radial growth were quantified using the indices resistance, resilience, and recovery as suggested by Lloret et al. (2011) and growth recovery time (GRT) (Thurm et al., 2016) and used as response variables in generalized linear mixed effect models.

Considering only the average radial growth response to severe and extreme drought events, both the different Lloret indices and the GRT did not show prominent difference between Oriental and European beech. However, the mixed model analyses, which also included interaction terms, revealed interspecific differences in drought tolerance, depending on the intensity and timing of the drought. In extreme summer drought years, values of resistance predicted by the mixed-effect models were significantly higher in Oriental beech than in European beech, whereas its resilience was only slightly better than in European beech, regardless of drought intensities. In contrast, Oriental beech was much more susceptible to spring drought with significantly weaker growth recovery and distinctly longer growth recovery times.

Based on these results, Oriental beech provenances from the Caucasus do not appear to be sufficiently more drought tolerant than European beech to justify an assisted migration approach to adapt Central European forests to climate change. To analyse the drought tolerance of Oriental beech more comprehensively, introduced trees representing other genetic clusters need to be analysed, as well as the effects of repeated drought events on growth and mortality.