Late Succession Research Articles

Evaluation of the potential of bryophytes to support seedlings development on waste rocks: a mesocosm study.

Revegetating waste rocks is essential for re-establishing a functional ecosystem, but it poses significant challenges. Nutrient-poor soil and high exposure to elements cause high seedling mortality in the first year. Survival can be increased by amending soil with organic matter before plantation to improve water retention and nutrient availability. However, this method comes with high environmental and economic costs. Using mesocosms, we tested the use of bryophytes as an alternative to improve seedling survival due to their ability to create a beneficial microclimate with improved soil humidity and increased nutrient availability, especially through biological nitrogen fixation. Two bryophyte species (Racomitrium canescens (Hedw.) Brid., an early succession, and Pleurozium schreberi (Brid.) Mitt., a late succession species) were evaluated with three higher plant species (Pinus banksiana, Rhododendron groenlandicum, and Populus balsamifera) planted in waste rocks. We further evaluated two distinct techniques for the application of bryophytes on waste rocks: evenly spreading fragments on the soil surface and regrouping the fragments around the higher plant stem. Results showed that R. canescens fixed significantly more nitrogen than P. schreberi on waste rock. On the contrary, P. schreberi released more nitrogen into the soil than R. canescens, likely due to higher mortality and nutrient loss during drying/rewetting cycles. While the short-term impact of bryophytes on seedlings was limited in this 6-month experiment, results suggest that bryophytes have the potential to support higher plants in the challenging conditions of waste rock revegetation by increasing nitrogen supply to seedlings.

Large wildfires alter the potential capacity of fire-prone Mediterranean pine forests to provide wild edible mushrooms over the long term

Projected trends of intensified wildfires due to climate warming and fuel-load accumulation are expected to significantly alter fungal diversity, but we know little about how these changes will impact ecosystem services. We aimed to analyze how large wildfires alter the capacity of fire-prone Mediterranean ecosystems dominated by Pinus pinaster Ait. to deliver the provisioning ecosystem service of mushroom production throughout the post-fire succession. We assessed this at early (<10 years), medium (10-20 years), and late (>20 years) stages after fire, compared to an unburned forest. Our results evidenced that large wildfires significantly reduced the capacity of these forests to provide mushroom harvesting opportunities. This adverse effect was most pronounced in the first few years after wildfire but persisted even after 20 years of post-fire succession. The total fungal species richness, abundance, diversity, and productivity at the post-fire successional stages remained lower than in the unburned forest, failing to reach their pre-fire levels even after two decades. However, the presence of commercially valuable edible fungal species, along with their species richness and productivity, began to recover in the medium and late stages after fire. In the immediate aftermath of the fire, saprotrophic fungal species dominated, while mycorrhizal species became more prevalent during the medium and late stages of secondary succession. Additionally, the abundance and productivity of mycorrhizal species in the late succession stage approached those found in the unburned forest. Soil pH and biochemical variables (microbial biomass C and β-glucosidase enzymatic activity) were key drivers of changes in species composition along the successional stages. This knowledge is essential to guide management solutions aimed at reducing ecosystem service loss and increasing resilience to the new scenario of extreme large wildfire events at shorter fire-free intervals, especially in southern Europe.

Companion interference and symbiotic matching phenomenon occurred in saline-alkali habitats

Salinization has emerged as a worldwide concern hampering the progression of agriculture and husbandry. Arbuscular mycorrhizal (AM) fungi, which abundantly distributed in the Songnen Plain, was considered to possess great potential for combating salinity. To elucidate the relationship between AM fungal community and saline-alkali ecological remediation, a 70-days pot experiment, with the soil in the late succession stage of Songnen saline-alkali habitat was taken as substrate, the dominant plant in the latter as research object, and the rhizosphere soil from three stages as inoculants, was conducted. Simultaneously, Chloris virgate was cultivated to ascertain the accompanying role on mycorrhizal effects and soil improvement. The results revealed that AM fungi effectively regulated the botanical morphogenesis, photosynthesis, osmotic concentration, and antioxidant enzymatic activity under saline-alkali conditions. Specifically, the net photosynthetic rate increased by 1.11–2.44 μmol·(m2)−1·s−1, and the total root length grew by 41.15–148.98 cm after inoculation. Furthermore, the soil salinization and nutrient sequestration were modulated by AM fungi, and that leaded to a notable reduction in soil pH by 0.3 %-1.64 % and an increase in nitrogen content by 52.17 %-118.84 %. In a comprehensive assessment, the utmost ecological advantage appeared in the group inoculated AM fungi procured from the identical stage as the host, with a peak mycorrhizal dependency of 2.93. Additionally, despite enhancing salinization restoration compared to the non-companion group, the associated plants reduced the mycorrhizal dependency of neighbour by a range of 27.04–51.46 %, and significantly decreased the dry weight by 0.09–0.28 g. These results confirmed the occurrence of symbiotic matching phenomenon in saline-alkali habitats and suggested that the mechanism should be considered as utilizing AM fungi for ecological restoration. However, the introduction of companion should be cautious due to their complex effects.

Feasibility study of fabricating 20 nm resolution dielectric Fresnel zone plates with ultrahigh aspect ratio for EUV optics

EUV light optics are either reflective or diffractive due to the substantial absorption characteristics by almost all materials. Despite great successes in manufacturing integrated circuit chips, reflective EUV optics are still unfriendly to small-to-medium enterprise (SME) because of the enormous costs. Recently, diffractive EUV optics has come to the light in hopes to be able to establish manufacturing nanoscale products and inspecting nanoscale structures. Diffractive zone plates with high resolution in EUV wavelengths are urgently needed. This paper reports our latest success in developing 20 nm resolution zone plates for focusing and imaging in the EUV and soft X-ray regions. It firstly discusses the diffraction efficiency of FZPs tailored for 13.5 nm wavelength to decide the essential height of the zone plate. Then, Monte Carlo simulation method was used to figure out the achievable zone plate parameters by high-resolution electron beam lithography (EBL). Finally, this work systematically explored the viability of nanofabricating top-tier 20 nm resolution hydrogen silsesquioxane (HSQ) zone plates with the duty cycle ratio nearing 1:1 and the aspect ratio approaching 13:1 on 50 nm thick Si3N4 membranes.

Impacts of oxbow lake evolution on sediment microbial community structure in the Yellow River source region

Oxbow lake formation and evolution have significant impacts on the fragile Yellow River Basin ecosystem. However, the effects of different oxbow lake evolutionary stages on sediment microbial community structure are not yet understood comprehensively. Therefore, microbial community structure in three stages of oxbow lake succession, namely, lotic lake (early stage), semi-lotic lake (middle stage), and lentic lake (late stage), was investigated in the present study in the Yellow River Basin on the Qinghai-Tibet Plateau. Amplicon sequencing was employed to reveal differences in microbial community diversity and composition. The bacterial and fungal communities in sediment were significantly different among the three succession stages and were driven by different environmental factors. In particular, bacterial community structure was influenced primarily by nitrate-nitrogen (N), microbial biomass phosphorus, and total carbon (C) and organic C in the early, middle, and late stages, respectively. Conversely, fungal community structure was influenced primarily by ammonium-N in the early stage and by moisture content in the middle and late stages. However, the predicted functions of the microbial communities did not exhibit significant differences across the three succession stages. Both bacteria and fungi were influenced significantly by stochastic factors. Homogeneous selection had a high relative contribution to bacteria community assembly in the middle stage, whereas the relative contributions of heterogeneous selection processes to fungal community assembly increased through the three stages. As succession time increased, the total number of keystone species increased gradually, and the late succession stage had high network complexity and the highest network stability. The findings could facilitate further elucidation of the evolution mechanisms of oxbow lake source area, high-altitude river evolution dynamics, in addition to aiding a deeper understanding of the long-term ecological evolution patterns of source river ecosystems.

Testing effects of bottom-up factors, grazing, and competition on New Zealand rocky intertidal algal communities.

Top-down and bottom-up factors and their interaction highlight the interdependence of resources and consumer impacts on food webs and ecosystems. Variation in the strength of upwelling-mediated ecological controls (i.e., light availability and herbivory) between early and late succession stages is less well understood from the standpoint of influencing algal functional group composition. We experimentally tested the effect of light, grazing, and disturbance on rocky intertidal turf-forming algal communities. Studies were conducted on the South Island of New Zealand at Raramai on the east coast (a persistent downwelling region) and Twelve Mile Beach on the west coast (an intermittent upwelling region). Herbivory, light availability, and algal cover were manipulated and percent cover of major macroalgal functional groups and sessile invertebrates were measured monthly from October 2017 to March 2018. By distinguishing between algal functional groups and including different starting conditions in our design, we found that the mosaic-like pattern of bare rock intermingled with diverse turf-forming algae at Twelve Mile Beach was driven by a complex array of species interactions, including grazing, predation, preemptive competition and interference competition, colonization rates, and these interactions were modulated by light availability and other environmental conditions. Raramai results contrasted with those at Twelve Mile Beach in showing stronger effects of grazing and relatively weak effects of other interactions, low colonization rates of invertebrates, and light effects limited to crustose algae. Our study highlights the potential importance of an upwelling-mediated 3-way interaction among herbivory, light availability, and preemption in structuring contrasting low rocky intertidal macroalgal communities.

Changes in soil microbe-mediated carbon, nitrogen and phosphorus cycling during spontaneous succession in abandoned Pb[sbnd]Zn mining areas

The mechanism through which soil microorganisms mediate carbon and nutrient cycling during mine wasteland restoration remained unknown. Using soil metagenome sequencing, we investigated the dynamic changes in soil microbial potential metabolic functions during the transition from biological soil crusts (BSC) to mixed broad-conifer forest (MBF) in a typical PbZn mine. The results showed soil microorganisms favored carbon sequestration through anaerobic and microaerobic pathways, predominantly using efficient, low-energy pathways during succession. Genes governing carbon degradation and aerobic respiration increased by 19.56 % and 24.79 %, respectively, reflecting change toward more efficient and intensive soil carbon utilization in late succession. Nitrogen-cycling genes mediated by soil microorganisms met their maximum influence during early succession (sparse grassland, SGL), leading to a respective increase of 75.29 % and 76.81 % in the net potential nitrification rate and total nitrogen content. Mantel and correlation analyses indicated that TOC, TN, Zn and Cd contents were the main factors affecting the soil carbon and phosphorus cycles. Soil AP content emerged as the primary influencer of genes associated with the nitrogen cycle. These results shed light on the dynamic shifts in microbial metabolic activities during succession, providing a genetic insight into biogeochemical cycling mechanisms and underscoring crucial factors influencing soil biogeochemical processes in mining regions.

Rhizosphere assembly alters along a chronosequence in the Hallstätter glacier forefield (Dachstein, Austria).

Rhizosphere microbiome assembly is essential for plant health, but the temporal dimension of this process remains unexplored. We used a chronosequence of 150 years of the retreating Hallstätter glacier (Dachstein, Austria) to disentangle this exemplarily for the rhizosphere of three pioneer alpine plants. Time of deglaciation was an important factor shaping the rhizosphere microbiome. Microbiome functions, i.e. nutrient uptake and stress protection, were carried out by ubiquitous and cosmopolitan bacteria. The rhizosphere succession along the chronosequence was characterized by decreasing microbial richness but increasing specificity of the plant-associated bacterial community. Environmental selection is a critical factor in shaping the ecosystem, particularly in terms of plant-driven recruitment from the available edaphic pool. A higher rhizosphere microbial richness during early succession compared to late succession can be explained by the occurrence of cold-acclimated bacteria recruited from the surrounding soils. These taxa might be sensitive to changing habitat conditions that occurred at the later stages. A stronger influence of the plant host on the rhizosphere microbiome assembly was observed with increased time since deglaciation. Overall, this study indicated that well-adapted, ubiquitous microbes potentially support pioneer plants to colonize new ecosystems, while plant-specific microbes may be associated with the long-term establishment of their hosts.

Differences in soil chemistry between early and late succession of oak-hornbeam forest after grassland abandonment

Changes in C and nutrient cycling during succession are well studied, however, results can be contrasting for different nutrients and successional sequences. We analyzed soil chemical differences between early and late succession of oak-hornbeam forest. Late forest succession efficiently retained plant-available P, and total Mn, Zn, Fe, Cu, and Ni pools in the soil, as their concentrations were similar to those of early-successional grasslands. Available K, soil organic C, and organic matter content, as well as C:N and C:S ratios were higher in late than in early succession. Soil organic N and S concentrations did not differ between the stages.

Succession of microbial community composition and secondary metabolism during marine biofilm development.

In nature, secondary metabolites mediate interactions between microorganisms residing in complex microbial communities. However, the degree to which community dynamics can be linked to secondary metabolite potential remains largely unknown. In this study, we address the relationship between community succession and secondary metabolism variation. We used 16S and 18S rRNA gene and adenylation domain amplicon sequencing, genome-resolved metagenomics, and untargeted metabolomics to track the taxons, biosynthetic gene clusters, and metabolome dynamics in situ of microorganisms during marine biofilm succession over 113days. Two phases were identified during the community succession, with a clear shift around Day 29, where the alkaloid secondary metabolites, pseudanes, were also detected. The microbial secondary metabolite potential changed between the phases, and only a few community members, including Myxococotta spp., were responsible for the majority of the biosynthetic gene cluster potential in the early succession phase. In the late phase, bryozoans and benthic copepods were detected, and the microbial nonribosomal peptide potential drastically decreased in association with a reduction in the relative abundance of the prolific secondary metabolite producers. Conclusively, this study provides evidence that the early succession of the marine biofilm community favors prokaryotes with high nonribosomal peptide synthetase potential. In contrast, the late succession is dominated by multicellular eukaryotes and a reduction in bacterial nonribosomal peptide synthetase potential.

The confinedness of undergrowth Picea obovata and Abies sibirica (Pinaceae) to tree-related microhabitats and their development features at various phases of post-fire succession in green-moss dark coniferous forests in the Northern Pre-Urals

Forest ecology frequently explores the role of microsite mosaics in forest communities for the regeneration of forest-forming tree species. The present study aims to find out whether the ontogenetic structure and differentiation of Siberian spruce (Picea obovata) and Siberian fir (Abies sibirica) undergrowth plants by the plant vitality are associated with their occurrence on various microsites. The study has been carried out in the Pechora-Ilych State Nature Biosphere Reserve, Russia. In green-moss fir-spruce forests, 23 temporary sample plots were established, including 1) forest communities of the intermediate phase of post-fire succession (in areas where fires happened in 1850–1900) and 2) forest communities of the late phase (in areas where there were no fires, at least since the mid-XIX century). On the study plots, P. obovata and A. sibirica undergrowth individuals were recorded indicating ontogenetic state, vitality and microsite substrate for each plant. Using the Z-criterion, a comparison of the occurrence frequencies (%) of various undergrowth groups of P. obovata and A. sibirica on various microsites has been carried out, i.e. within each species and between the studied species, as well as at each phase of post-fire succession and between the phases. The analysis showed that, in communities of both succession phases in both species, undergrowth plants of ontogenetic state im2 occurred on deadwood logs less frequently than the undergrowth plants of the earlier ontogenetic state im1. At the same time, in both species on the flat ground surface an opposite occurrence trend for these ontogenetic states was revealed. In communities of the late succession phase, A. sibirica undergrowth plants of the ontogenetic state im2 and normal vitality occurred on a flat ground surface within inter-crown sites more frequently than plants of reduced and low vitality. A comparison between the species showed that in forest communities of both succession phases, A. sibirica undergrowth plants of im1 and im2 ontogenetic states more frequently occupy flat ground surface than deadwood logs, whereas P. obovata undergrowth plants more frequently grow on deadwood logs than on the flat ground surface. In addition, in communities of the intermediate succession phase, A. sibirica undergrowth is more likely than P. obovata to be found in the under-crown sites (especially on a flat ground surface). In communities of the late succession phase, A. sibirica undergrowth more often grows in under-crown sites on the near-trunk elevations of living trees. In both species, 40–50% of im2 plants of low vitality grow in inter-crown sites. To clarify the influence of the microsite mosaics on the regeneration processes in the studied forests, more detailed and large-scale studies are further needed, which will allow us obtaining more representative samples of undergrowth plants at various ontogenetic states.

Environmental impact of mechanical site preparation on mineral soils in Sweden and Finland — a review

Mechanical site preparation (MSP) is deliberate soil disturbance which is undertaken to improve the conditions for forest regeneration. Disc trenching and mounding are the dominant MSP practices currently used in Sweden and Finland. In this paper, the impacts of MSP on the soil, water quality, greenhouse gas (GHG) emissions and ground vegetation of mineral soil sites in Sweden and Finland are reviewed. The practices considered are patch scarification, mounding, inverting, disc trenching, and ploughing, which together represent a wide range of soil disturbance intensity. The environmental effects of MSP in this region have not been studied extensively. The environmental impact of MSP derives from the process of creating microsites which involves horizontal and/or vertical redistribution of soil and soil mixing. This typically affects decomposition, element circulation and leaching, vegetation coverage and uptake of nutrients and water, and possibly erosion and sediment exports. Following disc trenching or mounding the effects on GHG emissions appear to be minor over the first two years. For a few years after disc trenching concentrations in soil water collected below ridges are higher than that below furrows for some elements (e.g., NO3-, NH4+, Mg2+, and total or dissolved organic C). The physical and chemical effects of ploughing remain detectable for several decades. There is little evidence about how the effects of forestry activities in upland areas on soil-water chemistry are transferred to adjacent surface water bodies, including what role streamside discharge areas play. MSP increases the tree biomass C store and may increase the total ecosystem C store. The impact of MSP on the cover and abundance of ground vegetation species depends on the composition of the original plant community, MSP intensity, and the establishment rate of different species. Species cover generally seems to decline for late succession understory species, while pioneer and ruderal species can benefit from the microsites created. Areas containing lichens which are used for reindeer forage require special consideration. More research is needed on the environmental effects of MSP, particularly regarding its long-term effects. Further efforts should be made to develop efficient site-preparation practices which better balance the disturbance intensity with what is needed for successful regeneration.

Greta Gerwig’s Girlhood Trilogy

On the occasion of Barbie’s blockbuster summer, FQ columnist Caetlin Benson-Allott situates director Greta Gerwig’s latest success in relation to her previous two films, Little Women (2019) and Lady Bird (2017). All three films are female-centered coming-of-age stories, prompting Benson-Allott to read them as a trilogy. Doing so not only honors Gerwig’s achievement as an auteur, Benson-Allott suggests, but also generates important questions about what these films say about girlhood and middle-class white American women’s quest for autonomy and self-determination. Gerwig’s trilogy reveals an artist struggling to make sense of girl culture and the societal paradigms that impact it.

Tracking succession by means of 3D scans of plant communities in a glacier forefield to infer assembly processes

In primary successions, assembling plant communities are key for ecosystem functioning and stability. Often, plant successions are described on a taxonomic, functional and/or phylogenetic level, where species' identities, traits or evolutionary histories are considered. In this study, we exploited community features characterizing whole plant assemblages to capture emerging properties only available at the community level. Next to features aggregating over multiple plant species, we used a customized multispectral 3D plant scanner extracting digital community features as proxies for the frequency distribution of traits, productivity, prevalence of plant competition, and plant strategies and functions. Using these community features, we provide a comprehensive description of plant successions along glacier forefield. Additionally, we used a community feature‐based framework assessing the covariance of community feature dissimilarities and environmental dissimilarity to explore the mechanisms underlying plant community assemblies. Our data indicate a shift from fast‐growing and acquisitive, to slow‐growing and conservative plant strategies; increased productivity; higher competition between plant species; and an increasing contribution to the biogeomorphic stability along the successional gradient. Our results further indicate that stochastic processes dominate in early succession, whereas communities are mainly shaped by deterministic processes including environmental filtering and species interactions at late succession. We conclude that assessments of plant community features, facilitated by the use of field‐ready 3D scanners, provide complementary information to trait‐based approaches on the species level with implications for ecological processes.

Higher plant colonisation and lower resident diversity in grasslands more recently abandoned from agriculture

Abstract Rates of species colonisation and extirpation are increasing in plant communities world‐wide. Colonisation could potentially help compensate for, or compound, resident diversity loss that results from global environmental change. We use a multifactorial seed addition grassland experiment to examine relationships between plant colonisation, resident species diversity and key community assembly factors over 3 years. By manipulating colonist seed rate, imposing disturbance and examining abundance and diversity impacts of 14 formerly absent sown colonists in communities that varied in successional stage and time since agricultural abandonment, we were able to disentangle effects of global change factors (species introduction, novel disturbance and land use change) that are usually confounded. Evidence suggested that cover abundance of sown colonists was most strongly influenced by successional stage of recipient communities, though number of growing seasons was also important for the group of seven colonists with resource conservative ‘slow’ life history traits. Colonist type, seed rate and disturbance had weaker relationships with colonist cover. Factors affecting sown colonist cover were highly conditional. A negative relationship between plot‐level disturbance and colonist cover in early successional communities meant that, despite a positive relationship in late succession, colonisation was negatively related to disturbance overall, defying theoretical expectations. Non‐sown resident diversity was negatively related to colonist cover and positively related to successional stage. Resource acquisitive colonists with ‘fast’ life history traits appeared to limit cover of ‘slow colonists’ when the two groups were sown together, likely reflecting niche pre‐emption. Communities at earlier stages of succession had lower resident diversity and experienced higher levels of colonisation than communities at later stages of succession. Elevated colonisation and lower resident diversity both appeared to be symptoms of human‐induced land use change. However, results suggested that resource competition from plant colonists may also limit resident diversity in grasslands abandoned from agriculture more recently. Synthesis. Our findings point to the importance of resource availability and competition on plant colonisation and colonist impacts on residents. Although colonisation is potentially a source of biodiversity in the short term, our results suggest that plant colonists that reach high abundance may be a further threat to resident plant diversity in secondary grasslands recovering from a recent history of agriculture.

Drivers and mechanisms of spontaneous plant community succession in abandoned Pb[sbnd]Zn mining areas in Yunnan, China

The drivers and mechanisms underlying succession and the spontaneous formation of plant communities in mining wasteland remain largely unknown. This study investigated the use of nature-based restoration to facilitate the recovery of viable plant communities in mining wasteland. It was found that scientific analyses of spontaneously formed plant communities in abandoned mining areas can provide insights for nature-based restoration. A chronosequence (“space for time”) approach was used to establish sites representing three successional periods with six successional stages, and 90 quadrats were constructed to investigate changes in plant species and functional diversity during succession in abandoned PbZn mining areas. A total of 140 soil samples were collected to identify changes in soil properties, including plant nutrient and heavy metal concentrations. Then, this paper used structural equation models to analyze the mechanisms that drive succession. It was found that the functional diversity of plant communities fluctuated substantially during succession. Species had similar functional traits in early and mid-succession, but traits tended to diverge during late succession. Soil bulk density and soil organic matter gradually increased during succession. Total nitrogen (N), pH, and soil Zn concentrations first increased and then decreased during succession. Concentrations of Mn and Cd gradually decreased during succession. During early succession, soil organic matter was the key factor driving plant colonization and succession. During mid-succession, soil Zn functioned as an environmental filter factor limiting the rates of succession in mining wasteland communities. During late succession, soil bulk density and competition for nutrient resources contributed to more balanced differentiation among plant species. This thesis proposed that a nature-based strategy for the stabilization of abandoned mining lands could facilitate effective plant community restoration that promotes ecosystem services and functioning.

Efficacy and predictors of success on laryngomalacia surgery: experience from a tertiary pediatric care center in Brazil

ObjectivesLaryngomalacia is the most common congenital cause of stridor; the natural history of the disease runs through to complete resolution by the age of two. Severe cases are characterized by cyanosis, hypoxia, apnea, furcular and/or subcostal retractions, aspirations, pulmonary hypertension, and failure to thrive and must undergo surgery. This study aimed to evaluate the success rates of supraglottoplasty in our hospital and evaluate the predictive factors for surgical success. MethodsCohort study, prospectively planned. 75 patients undergoing endoscopic surgery from July 2007 to July 2016 were analyzed at the Santo Antônio Children’s Hospital. The primary outcome was percentage of surgical success, defined as the absence of respiratory symptoms or presence of a mild stridor without retractions on the first post-operative month (late success). The secondary outcomes were the early surgical success (absence of respiratory symptoms or presence of a mild stridor without retractions on the first post-operative day). Results39 (58.2%) were male, with an average of 4.9 months. Surgical success on the first day was 80.6% (n=54). At the end of the 1st month, surgical success was 88.6%, considering only those who completed assessment. Twenty-one (34%) presented comorbidities. Presence of comorbidities, pharyngomalacia and GERD were associated with a worse result on the 1st postoperative day, whereas, at the end of the first month, presence of comorbidities, concomitant injuries (tracheo and bronchomalacia) and pharyngomalacia were the predictive variables of surgery failure. ConclusionSupraglottoplasty has high rates of efficacy and low morbidity. The presence of comorbidities and pharyngomalacia has shown association with a worse early and late surgical outcome. Synchronous airway lesions predict a worse surgical result at the end of the first month. GERD was associated with obstructive symptomatology only in the 1st post-operative day. Level of evidenceLevel 3 of evidence, according to the “The Oxford 2011 Levels of Evidence” from Oxford Centre for Evidence-Based Medicine.

Leaf Plasticity of the Subtropical Evergreen Tree Phoebe bournei Increases with Ontogeny in Response to Sun and Shade

Variation in shade tolerance is a primary mechanism driving succession in subtropical forests. However, little attention has been given to ontogenetic variation in light tolerance of late succession tree species such as Phoebe bournei. To investigate the differences in adaptive strategies between seedlings and saplings in response to sun and shade, we systematically studied the physiological and morphological leaf plasticity of P. bournei and how these variables are influenced by ontogeny. This study provided experimental evidence that leaf plasticity increases with the ontogeny of juvenile P. bournei adapting to the changing light resources. Investment in leaf construction increased with age and light resources in the evergreen P. bournei, as shown by leaf mass per unit area (LMA). Six-month-old seedlings lacked the adjustment of stomatal conductance (gs) and stomatal density responding to sun and shade. For seedlings, maintaining high gs under sun conditions increased stress risk instead of carbon gain. However, the leaves of 2-year-old saplings accumulated more soluble sugars and showed lower stomatal conductance and higher stomatal density under the sun than under shade conditions. The nonphotochemical quenching of sun leaves increased with plant age, indicating that the photoprotective capacity was enhanced with ontogeny. The leaf plasticity increasing along the ontogeny of juvenile P. bournei may contribute to the adaptation from shade to sun. Our study provides new insights into understanding the influence of ontogeny on shade responses of late succession trees in subtropical forests.

The effects of initiation season on succession patterns of benthic fouling organisms in coastal waters from two regions

Biofouling is the accumulation of organisms on artificial surfaces in the marine environment, with considerable ecological and economic effects. Thus, in-depth understanding of community succession is required to predict and combat this issue. However, various environmental factors, including temporal factors, can change the succession pattern. In this study, succession experiments were sequentially initiated during different seasons to verify the impact of initiation timing on the development and succession patterns of the fouling community. The initiation time (i.e., starting season for incubation) did not affect the succession pattern in Gunsan, whereas it did in Yeosu. Early and late succession in Gunsan were dominated by Ciona robusta and Mytilus galloprovincialis, respectively. This result is similar to the classical concept of succession. In contrast, bivalves, barnacles, and solitary ascidians were dominant in early succession and continued to colonize until late succession in Yeosu. Temporal factors had a substantial influence on the succession patterns of fouling organisms, depending on the presence or absence of dominant species. Further understanding of the impact of initiation timings on the succession of fouling organisms can enable prediction and control of community colonization, thereby reducing the ecological and economic impact of biofouling.

Niche and interspecific association of dominant tree species in karst forest of Junzi Mountain, Eastern Yunnan, China.

To understand the interspecific relationships of tree species in the karst forest of Junzi Mountain in Eas-tern Yunnan, we evaluated the niche and interspecific association of dominant tree species based on field survey plot data with the combining approaches of niche determination, χ2 test, association coefficient (AC), and Spearman rank correlation test. The results showed that the niche breadth of Quercus glaucoides was the largest and that of Juglans mandshurica was the smallest. The ranking of niche breadth was more consistent with the ranking of frequency than with that of importance values. The degree of niche overlap was generally low, with a mean value of 0.21, suggesting a low similarity in resource utilization among tree species. The overall association of dominant tree species was significantly positive, and the ratio of positive and negative association was 1.07, indicating that the communities were at a relatively stable and the late succession stage. The χ2 test and Spearman rank correlation test for tree dominant species showed that 65.3% species pairs were not significantly associated with each other, indicating a weak interspecific association. Both association coefficient (AC) and Spearman rank correlation coefficient showed significantly positive correlations with the corresponding niche overlap index. The species pairs of Q. glaucoides-Rhamnella martini, Viburnum propinquum-Zanthoxylum myriacanthum, Cladrastis delavayi-Carrierea calycina, Z. myriacanthum-C. delavayi had strong interspecific associations and wide ecological niches, thus may have potential application value in ecological restoration of karst region in eastern Yunnan and the vicinity areas.