European Journal of Forest Research最新文献

Pinus pinaster is a very important species for the Galician wood industry. A genetic breeding program was started in the 1980s to select plus trees based on growth and straightness. In this study, we estimated genetic parameters, juvenile-mature correlations and genetic gains in basic density (BD) and the dynamic modulus of elasticity (MOE_d) in Galician breeding families, as well as their relation to volume, straightness, and tree slenderness. All traits were measured at a tree age of 12 years in three half-sib progeny trials. Wood quality traits were also measured at 24 years in two other trials. All progeny trials followed a randomized complete block design and the data were analyzed using several mixed-model approaches. The individual heritability of MOE_d remained stable at both ages (~ 0.39) but decreased with age for BD (from 0.44 at age 12 to 0.24 at age 24). The high juvenile-mature correlations (0.51 for BD, 0.57 for MOE_d) observed support the viability of early selection for both traits at 12 years. Both wood quality traits correlated positively with each other and weakly with volume, straightness and tree slenderness. Selecting a minimum number of the best families, based on volume or any wood quality trait, would generate genetic gains for the selecting trait and prevent genetic losses of non-selecting traits. We also identified specific families showing positive genetic gains for all traits. The research indicates that either or both of these wood quality traits could be included as new selection criteria in the Galician breeding program.

Growth and yield (G&Y) of forest plantations can be significantly impacted by maladaptation resulting from climate change, and assisted migration has been proposed to mitigate these impacts by restoring populations to their historic climates. However, genecology models currently used for guiding assisted migration do not account for impacts of climate change on cumulative growth and assume that responses of forest population to climate do not change with age. Using provenance trial data for interior lodgepole pine (Pinus contorta subsp. latifolia Douglas) and white spruce (Picea glauca (Moench) Voss) in western Canada, we integrated Universal Response Functions, representing the relationship of population performance with their provenance and site climates, into top height curves in a G&Y model (Growth and Yield Projection System, GYPSY) to develop population-specific climate sensitive top height curves for both species. These new models can estimate the impact of climate change on top height of local populations and populations from a range of provenances to help guide assisted migration. Our findings reveal that climate change is expected to have varying effects on forest productivity across the landscape, with some areas projected to experience a slight increase in productivity by the 2050s, while the remainder are projected to face a significant decline in productivity for both species. Adoption of assisted migration, however, with the optimal populations selected was projected to maintain and even improve productivity at the provincial scale. The findings of this study provide a novel approach to incorporating assisted migration approaches into forest management to mitigate the negative impacts of climate change.

As an essential nutrient, Nitrogen (N) availability is fundamental in evaluating forest productivity, and as such, understanding the effects of changing atmospheric N inputs in forest ecosystems is of high significance. While most field experiments have been employing ground fertilization as a method to simulate N deposition, two experimental forest sites in Italy have adopted the more advanced canopy N application approach. Here we present findings from a case study of wood core analyses of predominantly pure, even aged, Sessile oak (Quercus petraea L.) and European beech (Fagus sylvatica L.) forest stands, treated with either below or above canopy N fertilization, comparing between the two simulation pathways of increased N deposition. The potential effects of elevated N availability on total ring width, mean ring density, and their corresponding earlywood and latewood fractions are examined. Our results indicate inconclusive effects of the treatments on the ring width traits of both Q. petraea or F. sylvatica, although basal area increment patterns appeared to be affected divergently between the species and treatments. Mean and earlywood, but not latewood, densities on the other hand, exhibited a decrease in certain years of the treatment period in Q. petraea as result of the above canopy N application only, whereas F. sylvatica wood density showed no clear response to any of the treatments. Thus, we are describing distinct reactions of the two broadleaved species to the different experimental N deposition approaches, discussing potential growth patterns under increased N availability, and emphasizing the importance of considering wood density in assessments of tree biomass accumulation and essentially Carbon storage capacities.

Deadwood is a key component of nutrient cycling in natural tropical forests, serving as a globally important carbon storage and habitat for a high number of species. The conversion of tropical forests to agriculture modifies deadwood pools, but we know little about deadwood dynamics in forests recovering from human disturbance. Here we quantified the volume and diversity of coarse woody debris (CWD, ≥ 7 cm diameter) and the mass of fine woody debris (FWD, < 7 cm) along a chronosequence of natural forest recovery in the lowlands of the Ecuadorian Chocó region. We sampled forest plots ranging from 1–37 years of recovery post-cessation of agricultural use as either cacao plantation or cattle pasture, as well as actively managed cacao plantations and cattle pastures, and old-growth forests. In contrast to our expectation, we found no significant increase in deadwood volume with recovery time. The diversity in size, decay stage and type of CWD increased along the recovery gradient, with no effect of previous land use type. The mass of FWD increased overall across the recovery gradient, but these results were driven by a steep increase in former pastures, with no change observed in former cacao plantations. We suggest that the range of sizes and decomposition stages of deadwood found in these two major tropical agricultural systems could provide suitable resources for saproxylic organisms and an overlooked carbon storage outside old-growth forests. Our estimates of deadwood in agricultural systems and recovering forests can help improve global assessments of carbon storage and release in the tropics.

Fine roots play a pivotal role in terrestrial carbon and nutrient cycling. However, our knowledge on drivers of fine-root biomass (FRB) and productivity (FRP) focus on functional traits, biodiversity and abiotic factors, while less attention on allometric constraints, an indispensable driver of organism biomass allocation. We measured FRB (FRP) for 24 plots using 216 soil cores (ingrowth cores) from four forest types (birch, oak, larch and pine) on a warm-temperate mountain of north China, and investigated leaf, stem and fine-root functional traits, stand factors, diversity indices and soil property. We tested the allometric relationships among FRB, FRP, aboveground biomass (AGB), leaf biomass and functional traits, and examined how allometry, size-dependent growth strategy, the mass-ratio and complementarity effects affected FRB and FRP directly and indirectly. There was a stable allometric relationship between FRP and FRB at both the soil-core and plot levels, and the former supporting the predicted exponent for leaves (= 1) of the metabolic scaling theory. Contrary to common observations, both FRB and FRP at plot scale showed negative (or non-significant) relationships with aboveground (or leaf) biomass. Instead, higher AGB led to more conservative growth strategies, which led to lower FRB, and thus lower FRP due to allometric constraints. Root traits (mass-ratio effect) showed the strongest direct effect on FRB, while diversity index (complementarity effect) and soil fertility revealed relatively weak effects. FRP was strongly driven by allometry (FRB) and soil nitrogen, while functional traits and diversity index affected FRP via FRB instead of directly. The complementarity effect on FRP may be overestimated if FRP–FRB allometry was not considered in multivariate analyses. Our results are not conflict with the positive correlations of FRB (FRP) with AGB or leaf biomass reported by large-scale studies, but together suggest contrasting changes of growth strategies with tree size versus climate, which may affect aboveground–root relationship simultaneously. We also suggest to carefully test allometric relationships to better understand how complementarity versus mass-ratio effect, stand factors and environment, together affect fine-root dynamics.

In forest management, merging stand structural diversity with carbon storage is essential for resilience and climate mitigation. This study assesses (1) how structural diversity in stands of spruce (Picea abies (L.) H. Karst.), pine (Pinus sylvestris L.), beech (Fagus sylvatica L.), and oak (Quercus robur L. and Quercus petraea (Matt.) Liebl.) in Central Europe varies with age, site quality, and applied thinning grade; (2) these factors' impact on carbon stock; and (3) the link between structural diversity and carbon stock. Analyzing 26 long-term thinning experiments, we used the Gini coefficient of tree heights to measure structural diversity and species-specific biomass functions for carbon stock assessments. Our results show that structural diversity, highest in beech and spruce, decreases with stand age and on richer sites. Thinning enhances structural diversity in spruce and beech but reduces it in pine and oak. Unthinned or only moderately thinned mature spruce and beech stands outperform pine and oak in carbon stock (200–300 vs. 100–150 Mg C ha⁻¹). C- and D&E-grade thinning halves carbon stock. A decrease in vertical layering with increased carbon storage varies across species. Given the same carbon stock, thinning from above maintains structural diversity in spruce and beech, while non-thinning or thinning from below promotes structural diversity in pine and oak. Based on the current silvicultural practice reflected by the NFI data of Germany, we argue that reduced thinning in previously D&E-grade thinned stands may slightly reduce their structural diversity. However, a suspension or reduction of thinning would strongly improve carbon storage (+ 100–200 Mg C ha⁻¹) in the next 3–5 decades. We discussed options for reconciling structural diversity and carbon storage by silvicultural management of the four considered species in Central Europe.

Climate change is expected to intensify drought in the Mediterranean region. Previous studies indicate that tree species mixing may reduce the water stress. Our study investigates the response to past drought events of four co-occurring Mediterranean species: Pinus pinea L. (stone pine), Pinus pinaster Ait. (maritime pine), Juniperus thurifera L. (Spanish juniper) and Quercus ilex L (holm oak). The study was performed at an interannual scale, both in monospecific and mixed stands. Annual tree ring widths data measured on increment cores and stem discs obtained from 281 trees were used to quantify the responses to drought events using complementary resilience indices. Additionally, we assessed tree intra- and inter-specific competition impact over the past 25 years. We fitted and compared generalised linear mixed models to determine the influence of species identity, stand composition as intra-specific and inter-specific competition on complementary resilience indices and annual basal area increment. The co-existence with other species enhanced the resistance to drought of the stone pine as the resilience capacity of the Spanish juniper. Conversely, maritime pine’s drought resistance declined considerably in mixed stands. Notably, only the anisohydric species Spanish juniper and holm oak were able to return to pre-disturbance growth rates after the drought. The influence of competition on tree growth was found to differ according to the hydrological conditions of each year and varied based on the specific source of competition. Our study showed that mixed stands in the Spanish Northern Plateau, especially with holm oak and Spanish juniper, are more resilient to prolonged droughts due to spatio-temporal complementarity and subsequent competition reduction. That is another reason for which such composed mixed stands should be promoted in the arid conditions of the Spanish Northern Plateau.

The leaf area index (LAI) is a crucial vegetation parameter that characterizes leaf sparsity and canopy structure, and the study of the spatial distribution pattern of the forest LAI and its environmental response can help to reveal the adaptive capacity of forest vegetation to climate change in semiarid areas. In this paper, a remote sensing inversion model of the LAI, which pertains to the forest ecosystem of Xinglong Mountain in the transition zone between the Qinghai‒Tibet Plateau and Loess Plateau, was established by combining an optical instrumentation method, a remote sensing inversion method, and a generalized additive model (GAM). The results showed that (1) the Meris terrestrial chlorophyll index (MTCI) linear regression model provided the greatest explanatory power for the LAI in the Xinglong Mountain forest, with R² = 0.88 and RMSE = 0.32. (2) The LAI was influenced mainly by the altitude, slope, profile curvature, aspect, planform curvature, temperature, precipitation, and evapotranspiration. According to the single-factor GAM, altitude (R² = 0.43) explained most of the total variation in the LAI, followed by precipitation (R² = 0.36). According to the multifactor GAM, the above influencing factors could explain 84.2% of the total variation in the LAI, which was significant (P < 0.001). (3) Interaction analysis revealed that the LAI was significantly influenced by the interaction between topographic and meteorological factors (P < 0.001). It was revealed that the topography of Xinglong Mountain is fragmented, the vertical band spectrum of vegetation is notable, and the forest LAI exhibits high spatial heterogeneity under the interaction between topographic and meteorological factors, reflecting the environmental response mechanism of vegetation growth in forest ecosystems in ecological transition zones.

Forest deadwood is an important carbon reserve, estimated to contain 8% of the total forest carbon. This type of woody debris is recognized as a source of carbon dioxide (CO₂), as the carbon is released back into the atmosphere by microbial decomposition. Production of methane (CH₄) and nitrous oxide (N₂O) has also been reported. In managed forests, logging residues form a major source of fine deadwood, but its role in the greenhouse gas exchange of forest ecosystems is poorly understood. We studied the greenhouse gas production of spruce and birch left-over fine woody debris and estimated the residence time of these residues at 18 spruce-dominated boreal forest sites in Central Finland. The study areas consisted of clear-cut forest stands, totally covering approximately 47 hectares, with logging residue ages varying between 0 and 10 years. The research was carried out over eight months from May to December 2019. We observed that CO₂ dominated the greenhouse gas production of the logging residues, with the production being regulated by air temperature, tree species, residue age, and wood moisture. Emission of CO₂ continued throughout the research period with a clear seasonal pattern. Production of CH₄ and N₂O was also observed, but not in climatically-relevant amounts. Deadwood half-life was estimated at 18 years for spruce and 9 years for birch. Our study demonstrates that logging residues form a mid-term carbon reserve and suggests that global warming could reduce the lifetime of the residues as a result of elevated and temperature-dependent CO₂ release in the studied Myrtillus type forest stands.

The increasing use of forest fuels poses risks to biodiversity. Lichens that grow on deadwood may be affected as fuel extraction removes their substrates. We surveyed deadwood and macrolichens on deadwood in two types of clearcuts: sites in which forest fuels, stumps and slash, had been extracted, and standard clearcut sites, i.e. control sites with no fuel extraction. Extraction sites had 52% lower deadwood volume (44.3 m³/ha vs. 21.4 m³/ha) and 36% less deadwood surface area. However, the negative impact of fuel extraction on macrolichen species richness was low: 21.4 and 16.9 species on average were found in control and extraction sites, respectively. We found a clear positive relationship between macrolichen species richness and the surface area of logs, which are usually not targeted by forest fuel extraction. Species composition varied more among extraction sites than control sites and differed between all the studied deadwood types. Species of Cladonia were associated with stumps, while species in the family Parmeliaceae were associated with logs. Slash was of negligible importance to macrolichens. Stumps may hold value, particularly if large-sized deadwood is otherwise not available. Thus, we conclude that the extraction of slash poses no threat to macrolichen diversity, whereas extensive extraction of stumps can cause losses in lichen diversity. The loss of coarse woody debris during forest fuel extraction has negative effects on lichen diversity and should be avoided.