Background
Forests play a crucial role in absorbing CO
2
from the atmosphere. 55% of the carbon in terrestrial ecosystems is stored in forests, with the majority of forest carbon stored in soil. To ...better understand soil organic carbon (SOC) of forests and to access interventions that affect their SOC concentration, we conducted a comparative analysis between natural and planted forests. Forest interventions refer to the actions taken by humans to manage, protect, or transform forests, and can be divided into two main categories: environmental intervention and anthropogenic intervention. This study focused on the effects of different interventions on SOC in natural and planted forests by reviewing a total of 75 randomized controlled trials in the global literature and extracting a total of 15 different interventions.
Results
Through network meta-analysis, we found that natural forests have 22.3% higher SOC than planted forests, indicating their stronger carbon storage function. In natural forests, environmental interventions have a stronger impact. SOC is significantly influenced by forest age, fertilization, and elevation. In planted forests, however, anthropogenic interventions have a stronger impact. Pruning branches and fertilization are effective interventions for planted forests. Furthermore, forest degradation has a significantly negative impact on SOC in planted forests.
Conclusion
Overall, interventions to enhance soil carbon storage function differ between natural and planted forests. To address global climate change, protect biodiversity, and achieve sustainable development, it is imperative to globally protect forests and employ scientifically sound forest management practices. Regarding natural forests, the emphasis should be on comprehending the effects of environmental interventions on SOC. Conversely, concerning planted forests, the emphasis should be on comprehending the effects of anthropogenic interventions.
Functional diversity is considered a key link between ecosystem functions and biodiversity, and forms the basis for making community diversity conservation strategies. Here, we chose a subtropical ...forest community in China as the research object, which is unique in that other regions of the world at the same latitude have almost no vegetation cover. We measured 17 functional traits of 100 plant species and calculated seven different functional diversity indices, based on functional richness, evenness, and divergence. We found that most functional diversity and species diversity indices significantly differed with plant habit. There was a significant positive correlation among functional richness indices. However, functional divergence indices, multidimensional functional divergence (FDiv), and Rao’s quadratic entropy index (RaoQ) were significantly negatively correlated, and RaoQ and functional divergence indices (FDis) were uncorrelated. The correlations between three types (richness, evenness, and divergence) of functional diversity indices and three species diversity indices were different. Lineage regression results generally showed that three functional richness indices (Average distance of functional traits (MFAD), Functional volume (FRic) and Posteriori functional group richness (FGR)) were increased with three species diversity indices (species richness (S), Shannon-Wiener index (H) and Pielou index (E)). The functional evenness index (FEve) decreased with species richness (S), Shannon-Wiener index (H) and increased with species evenness (Pielou index (E)), but the change trends were small. All three types of functional diversity indices declined with altitude, although altitude had a weak influence on them. Other environmental factors affected the functional diversity of the community. Here, soil total phosphorus (TP) was the most critical environmental factor and the convex had the least effect on functional diversity in our subtropical forest community. These results will contribute to our understanding of functional diversity in subtropical forests, and provide a basis for biodiversity conservation in this region.
This paper studies the problem of shield tunnels laterally passing through piles based on in situ tests and numerical methods. The effects of vertical load, pile–tunnel distance, and tunnel-cover ...depth on the horizontal displacement and the bending moment of adjacent piles were investigated. The results show that the shield tunnel induced adjacent pile displacement toward the tunnel side near the tunnel axis, and the soil below and above the tunnel axis constrained the pile, displacing toward the tunnel side. The maximum values of the horizontal displacement and bending moment were at the tunnel axis. The vertical load on the cap had little influence on the horizontal response of the pile. The main influence area induced by shield construction was located within 1.5 times the tunnel diameter. The maximum horizontal displacement and maximum bending moment were reduced by 36–45% and 45–78% on the far pile due to the shading effect induced by the near pile. The tunnel-cover depth had a significant influence on the distribution patterns of the horizontal displacement and the bending moment. The positions of the maximum horizontal displacement and the maximum bending moment moved downward with increases in tunnel-cover depth. The maximum horizontal displacement and bending moment increased with increases in tunnel-cover depth.
The spatial dispersion of individuals in a species is an important pattern that is controlled by many mechanisms. In this study we analyzed spatial distributions of tree species in a large-scale (20 ...ha) stem-mapping plot in a species-rich subtropical forest of China. O-ring statistic was used to measure spatial patterns of species with abundance > 10. Qo_ io, the mean conspecific density within 10 m of a tree, was used as a measure of the intensity of aggregation of a species. Our results showed: (1) aggregated distribution was the dominant pattern in the plot. The percentage of aggregated species decreased with increased spatial scale. (2) The percentages of significantly aggregated species decreased from abundant to intermediate and to rare species. Rare species was more strongly aggregated than common species. Aggregation was weaker in larger diameter classes. (3) Seed traits determined the spatial patterns of trees. Seed dispersal mode can influence spatial patterns of species, with species dispersed by both modes being less clumped than species dispersed by animal or wind, respectively. Considering these results, we concluded that seed dispersal limitation, self-thinning and habitat heterogeneity primarily contributed to spatial patterns and species coexistence in the forest.
Understanding the role of dominant species in structuring the distribution of neighbor species is an important part of understanding community assembly, a central goal of ecology. Phylogenetic ...information helps resolve the multitude of processes driving community assembly and the importance of evolution in the assembly process. In this study, we classified species in a 20-ha subtropical forest in southern China into groups with different degrees of phylogenetic relatedness to the dominant species Castanopsis chinensis. Species surrounding individuals of C. chinensis were sampled in an equal area annulus at six spatial scales, counting the percent of relatives and comparing this to permutation tests of a null model and variance among species groups. The results demonstrated that dominant species affected their relatives depending on community successional stage. Theory would predict that competitive exclusion and density-dependence mechanisms should lead to neighbors that are more distant in phylogeny from C. chinensis. However, in mature forests distant relatives were subjected to competitive repulsion by C. chinensis, while environment filtering led to fewer distant species, regardless of scale. A variety of biological and non-biological factors appear to result in a U-shaped quantitative distribution determined by the dominant species C. chinensis. Scale effects also influenced the dominant species. As a dominant species, C. chinensis played an important role in structuring the species distributions and coexistence of neighbor species in a subtropical forest.
The evolutionary mechanisms underlying the biogeochemical niche conservatism in forests remain incompletely understood. Here we aimed to determine how the strengths of biogeochemical niche ...conservatism vary among elements and between life forms. We measured leaf concentrations of basal elements (C, N, P, K, Ca, and Mg) in a wide range of life forms in a subtropical montane evergreen broad‐leaved forest. We found that differences in life forms such as evergreen/deciduous woody species and herbaceous/woody species significantly affected leaf elemental composition. The significant phylogenetic signal was present in leaf C, N, K, and Mg concentrations but absent in leaf P and Ca concentrations in all species. These contrasting strengths of biogeochemical niche conservatism were best generated by Ornstein–Uhlenbeck processes toward optima. Woody species were evolutionarily selected to show lower optimal leaf N, P, and K concentrations and higher optimal leaf C, Ca, and Mg concentrations than herbaceous species. The number of optima varied from the least in leaf C concentration to the most in leaf Ca concentration, suggesting the stronger convergent evolution of leaf Ca concentration. The positions of optima toward the tips were more selected in woody species, suggesting the more frequency of species‐specific adaptations in woody species. The positions of optima were also selected at the nodes towards the species groupings from certain life forms (e.g., the group of 12 Polypodiales ferns in leaf Ca evolution and the group of three evergreen Theaceae species in leaf P evolution) that were converged to present similar leaf elemental composition. During the evolution of biogeochemical niche, strong correlations were found among leaf C, N, P, and K concentrations and between leaf Ca and Mg concentrations. In conclusion, the strengths of biogeochemical niche conservatism can vary among elements and between life forms due to the different tempo and mode of Ornstein–Uhlenbeck processes.
Our results show that biogeochemical niche conservatism relates to plant species diversification and life form evolution in subtropical forest plants. Furthermore, the strengths of biogeochemical niche conservatism varying among elements and between life forms might be mostly determined by the tempo and mode of OU processes.
The spatial dispersion of individuals in a species is an important pattern that is controlled by many mechanisms. In this study we analyzed spatial distributions of tree species in a large-scale (20 ...ha) stem-mapping plot in a species-rich subtropical forest of China. O-ring statistic was used to measure spatial patterns of species with abundance >10. Ω₀₋₁₀, the mean conspecific density within 10 m of a tree, was used as a measure of the intensity of aggregation of a species. Our results showed: (1) aggregated distribution was the dominant pattern in the plot. The percentage of aggregated species decreased with increased spatial scale. (2) The percentages of significantly aggregated species decreased from abundant to intermediate and to rare species. Rare species was more strongly aggregated than common species. Aggregation was weaker in larger diameter classes. (3) Seed traits determined the spatial patterns of trees. Seed dispersal mode can influence spatial patterns of species, with species dispersed by both modes being less clumped than species dispersed by animal or wind, respectively. Considering these results, we concluded that seed dispersal limitation, self-thinning and habitat heterogeneity primarily contributed to spatial patterns and species coexistence in the forest.
A widely used veterinary antibiotic tylosin is associated with a fast increase in the prevalence of genes for macrolide resistance. Therefore, there are growing concerns of its potentially adverse ...effects on natural ecosystems, and a study on the sorption of tylosin is an important step in this direction. As a weak base, prior studies pointed out that cation exchange was the main sorption mechanism for tylosin in soil, and minerals were important factors in influencing the sorption. However, the ionic effect on the tylosin sorption process on minerals has not been systematically conducted. In this study, the sorption of tylosin on pure clay minerals was investigated in different ionic strength solutions. Moreover, the interlayer interaction of tylosin on different types of montmorillonite was preliminarily studied. All of the sorption data were fitted with the Langmuir-Freundlich-Hill sorption model. The results showed that the variation tendency of tylosin sorption capacity on montmorillonite and kaolinite were nearly the same. The sorption capacity of tylosin at different ionic strengths decreased with the order: 0.008 M > 0.051 M > 0.108 M > 0.508 M. In different ion solutions, the sorption capacity of tylosin decreased in the following order: K
+
> Na
+
> Ca
2+
Mg
2+
. However, the sorption of tylosin on montmorillonite at low initial concentration of tylosin displayed a different tendency. When the initial concentration of tylosin was low, its sorption capacities on montmorillonite at different ionic strengths decreased with the order: 0.051 M 0.108 M > 0.008 M > 0.508 M. For different ionic solutions, the sorption of tylosin decreased in the order of Mg
2+
Ca
2+
> K
+
> Na
+
. The cation effect on tylosin sorption in the interlayers of montmorillonite was also investigated. The sorption of tylosin on different montmorillonites decreased in the order of Ca-montmorillonite > Na-montmorillonite > K-montmorillonite. These indicated that the hydration of inorganic ions influenced the sorption of tylosin. The results provide a more comprehensive understanding about the sorption of tylosin on minerals.
Tylosin sorption on three ion-exchanged montmorillonites indicated that hydrogen bond interactions were more important than cation exchange in the montmorillonite interlayer.
Habitat specialization has been considered as a primary factor in determining the distribution of species. In this study, we investigated species–habitat associations while controlling for spatial ...neighbourhood effects in a large-scale (20
ha) stem-mapping plot in a species-rich subtropical forest of China. Habitat specialization was measured by topographic variation and its effects on species distributions were modelled at three different spatial scales (10×10, 20×20 and 25×25
m
2) using log-linear regression models and randomization tests. Our results showed: (1) 83% of the species were related to at least one or more topographic variables. Among them, 66%, 60%, 65% and 70% were closely dependent on slope, aspect, elevation and convexity, respectively. (2) Topographic variables have much stronger non-linear (quadratic and cubic) effects on species distributions than linear effects. (3) The effects of topographic heterogeneity on the distribution of shrubs species are smaller than on the distribution of canopy species, and smaller effects were also found in less abundant species. (4) There was a strong neighbourhood effect on species distribution: In 85% of the species, abundance in a focal quadrat was significantly correlated with abundance in the neighbour quadrats. We conclude that habitat specialization plays an important role in maintaining the diversity of this species-rich subtropical forest.
Die Habitatspezialisierung wurde bisher als primärer Faktor angesehen, der die Verbreitung von Arten bestimmt. In dieser Studie untersuchten wir die Arten-Habitat-Assoziationen unter Berücksichtigung der räumlichen Nachbarschaftseffekte in einer großflächigen (20
ha) Stammkartierungs-Probefläche in einem artenreichen, subtropischen Wald in China. Die Habitatspezialisierung wurde über die topografische Variation gemessen und ihre Effekte auf die Artenverteilung wurden auf drei räumlichen Skalen (10×10, 20×20 und 25×25
m
2) modelliert indem log-lineare Regressionsmodelle und randomisierte Tests verwendet wurden. Unsere Ergebnisse zeigten: (1) 83% der Arten standen in Beziehung zu mindestens einer oder mehr topographischen Variablen. Unter ihnen waren 66% eng mit der Steigung, 60% mit der Ausrichtung, 65% mit der Höhe und 70% mit der Konvexität korreliert. (2) Topographische Variablen hatten wesentlich stärkere nicht-lineare (quadratische und kubische) als lineare Effekte auf die Artenverteilung. (3) Die Effekte der topographischen Heterogenität auf die Verteilung der Buscharten waren geringer als auf die Verteilung der Kronendacharten. Es wurden ebenfalls geringere Effekte auf die weniger häufigen Arten festgestellt. (4) Es gab einen starken Effekt der Nachbarschaft auf die Artenverteilung: 85% der Arten waren signifikant mit ihrer Häufigkeit in den Nachbarflächen korreliert. Wir schließen daraus, dass die Habitatspezialisierung eine wichtige Rolle dabei spielt, die Diversität in diesen artenreichen subtropischen Wäldern zu erhalten.
Plasmonic Pd nanosheets have been emerging as promising materials for application in near-infrared （NIR） photothermal therapy （PTT） of cancer. However, animal in mice studies indicated that the ...original synthesized poly（vinylpyrrolidone） （PVP）-protected small Pd nanosheets （Pd-PVP） and some further surface-modified small Pd nanosheets such as Pd-PEG（SH） easily accumulated in reticuloendothelial system （RES） organs （liver, spleen, etc.） and were difficult to be cleared from these organs quickly. In the work, we surprisingly found that glutathione （GSH） could promote the clearance of surface-modified small Pd nanosheets （e.g. Pd-PVP, Pd-PEG（SH） and Pd-GSH） from the RES organs efficiently. The effects of GSH on the biodistribution and clearance of different surface-modified Pd nanosheets were investigated. Our results indicated that these surface-modified Pd nanosheets with or without GSH added caused no morbidity at target primary organs, and GSH can promote the clearance of different surface-modified Pd nanosheets in the order of Pd-PVP ≈ Pd-PEG（SH）〉Pd-GSH. This study suggests that glutathione could be an attractive reagent for promoting nanomaterials eliminated from the reticuloendothelial systems （RES）.
PDF
