Dominant Functional Groups Research Articles

Plant Phenology of High-Elevation Meadows: Assessing Spectral Responses of Grazed Meadows

Groundwater-dependent ecosystems are biologically diverse and productive ecosystems but constitute a small fraction of total land area in semiarid regions. Efforts to link remotely sensed data from satellite-based platforms to measurements of vegetation structure and function at smaller spatial scales have increasingly received attention, due to the need to manage diverse landscapes at scales relevant to management. In the semiarid western United States, grazing is a dominant land use and meadows can receive a high degree of grazing pressure. In this study we examined satellite-based and near-surface imagery to determine if they were useful in assessing grazed systems with different grazing management. We compared meadows that were chronically grazed by feral horses in conjunction with periodic cattle grazing to a meadow managed and grazed by cattle only. We examined the agreement between near-surface digital cameras (PhenoCams) and satellite-based indices of greenness and production for meadows in the Central Great Basin, United States. We also verified them with field-collected data on percent foliar cover by dominant functional groups. There was strong agreement between the Landsat normalized difference vegetation index and PhenoCam Green Chromatic Coordinate (GCC) (Pearson's r ≥ 0.61). Gross primary production modeled using Landsat satellite imagery and integrated over the growing season had a strong linear relationship with GCC integrated over the growing season (R2 = 0.89). Furthermore, despite differences in spatial and temporal resolution, integrated metrics from both platforms were able to discern differences in grazing pressure. Meadows with chronic feral horse grazing plus 3 mo of livestock grazing had reduced integrated gross primary production and GCC in comparison with a meadow that had short-term grazing (for 2 mo) by livestock only. The ability to detect differences in grazed systems from PhenoCams and satellite platforms provides important tools for quantifying the effects of grazing in groundwater-dependent ecosystems.

Decay stages and meteorological factors affect microbial community during leaf litter in situ decomposition

• Decay stages and meteorological factors affect leaf litter’s microbial community.• Bacteria and fungi were mainly affected by OC, TN, pH, and water content of leaf litter.• Bacterial (6.6) and fungal (3.6) Shannon indexes were the largest after 125 days.• Microbial diversity and decay stage directly regulated the litter mass-loss rate.Litter microorganisms play a crucial role in the biological decomposition in forest ecosystems; however, the coupling effect of meteorological and substrate changes on it during the different stages of leaf decomposition in situ remains unclear. Hence, according to meteorological factors dynamics, a one-year field litter of Quercus wutaishanica in situ decomposition experiment was designed for four decay stages in a warm temperate forest. Microbial community composition was characterized using Illumina sequencing of fungal ITS and bacterial 16S genes. Bacterial (6.6) and fungal (3.6) Shannon indexes were the largest after 125 days’ litter decomposition (October). The relative abundance of Acidobacteria after 342 days and Bacteroidetes after 125 days were 3 and 24 times higher than after 31 days, respectively. Some non-dominant species (bacteria: Firmicutes, Planctomycotes, and Verrucomicrobia; fungi: Chytridiomycota and Glomeromomycota) may be absent or present at different decomposition stages due to litter properties or meteorological factors. Chemoheterotrophy and aerobic-chemoheterotrophy were the dominant bacterial functional groups, and the dominant fungal functional groups were saprotrophs, pathotrophs, and symbiotrophs. Precipitation and relative humidity significantly affected bacteria. Temperature, sunlight intensity, and net radiation significantly affected fungi. Besides, among the relative contributions of changes in bacterial and fungal community structure, leaf litter properties alone explained the variation of 5.51% and 10.63%. Microbial diversity and decay stage directly affected the litter mass-loss rate, with meteorological factors (precipitation, relative humidity, air temperature, and sunlight intensity) being indirect. Our findings highlight the importance of microbial diversity for leaf litter decomposition and the influence of meteorological factors.

Phytoplankton community structure and water ecological assessment in the Three Gorges Reservoir

2020年是长江禁渔开局之年,三峡库区作为长江的重要生态屏障,其水生态环境健康对长江大保护的实施具有重要意义。本文于2020年8月、11月及2021年1月、4月在三峡库区干支流共设置19个断面探究浮游植物群落结构特征,并利用生物量、多样性指数、综合营养状态指数和浮游植物Q指数等多种评价方法评价三峡库区水生态健康并分析其影响因素。结果表明:(1)三峡库区共鉴定出浮游植物8门105属266种,年平均丰度为6.4×10⁴ cells/L,年平均生物量为0.038 mg/L。不同季节优势种组成不同,变异直链藻(Melosira varians Agardh)、骨条藻(Skeletonema spp.)、脆杆藻(Fragilaria spp.)为全年优势种。(2)三峡库区共划分24个功能群,B、D、MP、S1、P、Y为优势功能群。RDA分析表明,电导率、总氮、化学需氧量、总磷、pH、总溶解性固体与三峡库区四季功能群呈现显著关系。(3)相较于丰度、生物量和多样性水质评价结果,浮游植物Q指数更适用于三峡库区水生态评价,显示三峡库区干流水生态环境总体较好,但春、夏两季支流浮游植物丰度、生物量显著升高和浮游植物Q指数的降低在一定程度上影响了干流水生态健康,成为三峡库区面临的主要风险。因此更应充分做好支流水华监测、预警,充分利用干流水生态调度,保障三峡库区水生态环境健康。;The year 2020 is the first year of the 10-year fishing ban in the Yangtze River. As an important ecological barrier of the Yangtze River, the water ecological environment health of the Three Gorges Reservoir (TGR) is of great significance to the implementation of the Yangtze River protection. Nineteen sites were set in the main and tributaries of the TGR in year 2020 (August and November) and 2021 (January and April) to explore the composition of phytoplankton community, and multiple assessment methods such as biomass, diversity index, comprehensive trophic status index and phytoplankton Q index were used to evaluate the water ecological health of the TGR area and analyze its influencing factors. The results showed that: (1) The 266 taxa of phytoplankton belonging to 105 genera in 8 phyla were identified,the average annual density was 6.4×10⁴ cells/L and an average annual biomass was 0.038 mg/L. The composition of dominant species varied seasonally. Melosira varians Agardh, Skeletonema spp. and Fragilaria spp. were the dominant species all year round. (2) The phytoplankton in the TGR was classified into 24 functional groups, of which B, D, MP, S1, P and Y were the dominant functional groups. Redundant analysis showed that Cond, total nitrogen, COD, total phosphorus, pH and total dissolved solid were the main environmental factors affecting the functional groups in the TGR. (3) Compared with the assessment results of density, biomass and the diversity of water quality, phytoplankton Q index were more suitable for the assessment of water ecology in the TGR. Results showed that the water ecological environment of the main stream in the TGR area was generally good. However, the significant increases of the density, biomass and the decrease of phytoplankton Q index in spring and summer tributaries would affect the water ecological health of the main stream to a certain extent, which had become the main risks for the TGR area. Therefore, we should make full use of the monitoring and early warning of tributary bloom and take advantage of the water ecological dispatch of the main stream to ensure the water ecological environment health of the whole TGR area.

Bottom-up and top-down effects on codetermination of the dominant phytoplankton functional groups in Lake Erhai

Bottom-up and top-down effects on codetermination of the dominant phytoplankton functional groups in Lake Erhai

Insights into the profile of soil fungal diversity in Thailand

Soil fungi are diverse and abundant organisms. However, our knowledge of the global diversity and distribution of soil fungi is limited. This study uses the Global Soil Mycobiome Consortium (GSMc) dataset to explore the assortment of soil fungi in Thailand. The study aimed to evaluate the diversity and richness of soil fungi in Thailand, identify the dominant fungal taxa and functional groups present in Thai soils, and examine the impact of land use and fire on the diversity of soil fungi in Thailand. We identified 18,209 OTUs, of which Ascomycota and Basidiomycota were the most abundant in all land conditions. We also found that ectomycorrhizal and soil saprotrophs were primary lifestyles, accounting for around 20%. Our results provide novel insights into the diversity and distribution of soil fungi in Thailand and contribute to understanding soil fungal ecology in tropical regions. The paper also invites collaboration to explore this ecosystem further.

Insights from the Niger Delta Region, Nigeria on the impacts of urban pollution on the functional organisation of Afrotropical macroinvertebrates

Anthropogenic activities, including urbanisation and industrialisation threaten stream ecological integrity, ecosystem community structure and ecosystem functioning of rivers and streams worldwide. However, developing sustainable monitoring strategies for ecological health remains a critical challenge in Africa. We examined the effects of urban disturbance on macroinvertebrate Functional Feeding Groups in selected streams in the Niger Delta Region of Nigeria. We sampled 11 sites between 2008 and 2012 and grouped into three site groups (Site groups 1 > 2 > 3). The groups represent an increasing gradient of urban pollution. Our result showed that urban-induced disturbances affected physicochemical variables in the study area (PERMANOVA; p < 0.05), with nutrients NO2-N, PO4-P, and electrical conductivity being significantly higher in impacted Site group 3 (ANOVA, p < 0.05). Predators and gatherers were the most dominant Functional Feeding Group recorded in the study area, while shredders were the least abundant macroinvertebrate Functional Feeding Groups. The multivariate RLQ analysis revealed that shredders, predators, and scrapers were tolerant of urban pollution, whereas gatherers were sensitive to increasing urban pollution. Overall, macroinvertebrates Functional Feeding Groups responded differentially to urban pollution in the Niger Delta Region. Identifying pollution indicator Functional Feeding Groups is seen as an important step towards developing a reliable, low-cost tool for riverine monitoring of urban pollution effects in Africa.

Potential of silica from water treatment sludge modified with chitosan for Pb(II) and color adsorption in sasirangan waste solution

Water treatment sludge (WTS) still contains a lot of silica oxide (SiO2) as much as 43.12-66.90% by weight and can act as an adsorbent to be applied to the treatment of Sasirangan wastewater. Silica extraction from WTS was carried out by microwave-assisted leaching, which - compared to conventional extraction - had several advantages including high extraction yields, fast, uniform, and more selective processing time. In addition, Sasirangan liquid waste is a by-product of the dyeing process of Sasirangan cloth, which still contains heavy metals in amounts exceeding the quality standard. This study aims to extract silica from WTS by microwave-assisted leaching process to synthesize silica modified by chitosan (Si-Kit) as an adsorbent to reduce Pb(II) from Sasirangan wastewater, and to obtain a kinetic model of the adsorption process. The silica from microwave-assisted leaching process (Si-MaL) and Si-Kit adsorbents were characterized using FTIR and SEM. The results showed that the dominant functional groups of Si-Kit included Si-O-Si, Si-O-C stretching vibrations, and stretching vibration of C=N showing that the condensation between aldehyde groups and amino groups occurred to form base after the addition of glutaraldehyde. The SEM images showed that Si-MaL and Si-Kit adsorbent obviously increased in particle size with the presence of visible particles of homogeneous granules and large pores. The removal efficiency percentage of Pb(II) and color occurred at 6% w/v adsorbent weight and 70 min was 87.20% and 61.87% respectively. Meanwhile, the adsorption kinetics of Pb(II) and color followed the zero order kinetics model at weight variation of 6%-w/v based on the value of R2 close to one and the adsorption capacity of Pb(II) ion and color were 12.01 mg g-1 and 467 mg g-1, respectively.

Temporal-spatial distribution and ecological evaluation of macroinvertebrate functional feeding groups in Yongding River Basin

We investigated community structure of macroinvertebrate, water environment factors, hydrological factors at 23 sampling sites of the Yongding River basin from spring 2017 (April) to autumn 2017 (November). We analyzed the composition, spatial and temporal distribution of the macroinvertebrate functional feeding groups, as well as their responses to changes in riverine habitat. A total of 78 macroinvertebrate species were identified, with 52, 50 and 53 macroinvertebrate species in spring, summer and autumn respectively. The dominant functional feeding groups were gather-collectors, followed by predators, while the proportion of scrapers, filter-collectors and shredders were extremely low. Dominant species in the three seasons were all gather-collectors, including Orthocladius, Rheotanytarsus, Cricotopus in spring, Glyptotendipes in summer, and Polypedilum, Chironomus, Orthocladius in autumn. Results of redundancy analysis showed that the functional feeding groups of macroinvertebrate community structure were mainly influenced by water temperature, flow velocity, salinity, and total phosphorus in spring, by total phosphorus, dissolved oxygen, conductivity and flow capacity in summer, and by total phosphorus and dissolved oxygen in autumn. Total phosphorus had positive correlation with gather-collectors in all three seasons, indicating that the functional feeding groups of macroinvertebrates were affected by water pollution. The evaluation based on the metrics of functional feeding groups showed that: 1) in terms of material cycle, primary productivity of Guishui River were significantly higher than other regions, and that in autumn were significantly higher than other seasons. The secondary productivity and decomposition capacity of Yanghe River were significantly higher than other regions, and those in spring were significantly higher than other seasons. The autotrophy/heterotrophy of Yanghe River was significantly lower than other regions, and that in spring were significantly higher than other seasons. 2) The longitudinal transport capacity of Sanggan River was significantly higher than other regions, and that in autumn was significantly higher than other seasons. 3) The lateral input capacity of Guishui River was significantly higher than other regions, and that in summer was significantly higher than other seasons.

Physico-Chemical Properties and Deposition Potential of PM2.5 during Severe Smog Event in Delhi, India.

The present work studies a severe smog event that occurred in Delhi (India) in 2017, targeting the characterization of PM2.5 and its deposition potential in human respiratory tract of different population groups in which the PM2.5 levels raised from 124.0 µg/m3 (pre-smog period) to 717.2 µg/m3 (during smog period). Higher concentration of elements such as C, N, O, Na, Mg, Al, Si, S, Fe, Cl, Ca, Ti, Cr, Pb, Fe, K, Cu, Cl, P, and F were observed during the smog along with dominant organic functional groups (aldehyde, ketones, alkyl halides (R-F; R-Br; R-Cl), ether, etc.), which supported potential contribution from transboundary biomass-burning activities along with local pollution sources and favorable meteorological conditions. The morphology of individual particles were found mostly as non-spherical, including carbon fractals, aggregates, sharp-edged, rod-shaped, and flaky structures. A multiple path particle dosimetry (MPPD) model showed significant deposition potential of PM2.5 in terms of deposition fraction, mass rate, and mass flux during smog conditions in all age groups. The highest PM2.5 deposition fraction and mass rate were found for the head region followed by the alveolar region of the human respiratory tract. The highest mass flux was reported for 21-month-old (4.7 × 102 µg/min/m2), followed by 3-month-old (49.2 µg/min/m2) children, whereas it was lowest for 21-year-old adults (6.8 µg/min/m2), indicating babies and children were more vulnerable to PM2.5 pollution than adults during smog. Deposition doses of toxic elements such as Cr, Fe, Zn, Pb, Cu, Mn, and Ni were also found to be higher (up to 1 × 10-7 µg/kg/day) for children than adults.

Pattern and drivers of soil fungal community along elevation gradient in the Abies georgei forests of Segila mountains, Southeast Tibet

Soil fungi are a diverse group of organisms extremely crucial to forest nutrient cycling and carbon (C) storage. The elevational pattern of soil microbial diversity has been widely studied, but how soil properties, elevation, and their association affect fungal community in subalpine forests remain to be explored. Here, soil fungal community diversity was investigated using high-throughput sequencing along an elevation gradient (3500–4300 m a.s.l.) in the Abies georgei var. smithii forests, a typical subalpine forest type in the Segila Mountains of Southeast Tibet. Elevation significantly affected the soil properties. Available phosphorus (P), total nitrogen (N), and soil organic C (SOC) increased whereas pH decreased with elevation. A U-shaped pattern for fungal diversity was found in topsoil while a slight monotonically decreasing pattern in subsoil layer across the elevation gradient. Basidiomycota, Ascomycota, and Mortierellomycota were the top three dominant phyla, and ectomycorrhizal fungi were the dominant functional fungi group in the A. georgei forest soils. Significant negative correlations were observed between fungal OTUs richness and NO 3 - ( r = −0.431, p < 0.01), indicating that soil N availability is an important factor for fungal diversity. Based on redundancy analysis, soil factors explained 32.1% of the total variations in composition structure of fungal community. Soil pH, moisture, and fertilities (i.e., SOC, TN, TP, NO 3 - ) were independent factors affecting the fungal community composition. Collectively, the alterations in soil environmental factor across elevations are essential in shaping the soil fungal diversity and community composition in the A. georgei forests in Segila Mountains, Southeast Tibet. • Elevation significantly increased soil organic C and nutrients while decreased pH. • Topsoil fungal richness showed a U-shaped pattern with increasing elevation. • Ectomycorrhizal fungi (EcM) were the dominant functional group across elevation. • NO 3 - was the prominent driving factor on fungal diversity in the A. georgei forests.

Phytoplankton Community Structure and Its Relationship with Environmental Factors in Nanhai Lake

In order to determine the characteristics of phytoplankton community structure in Nanhai Lake in Baotou City and its relationship with environmental factors, water and phytoplankton samples were collected and composition and biomass were investigated at six sites in the spring, summer, and autumn of 2021. This article used correlation analysis and redundancy analysis (RDA) combined with the community turnover index (BC) to analyze the phytoplankton functional groups. The results showed that 7 phyla and 68 genera of phytoplankton were identified in the water body, of which Chlorophyta, Bacillariophyta, Cyanobacteria, Chrysophyta, Euglenophyta, Cryptophyta, and Pyrrophyta accounted for 34%, 32%, 16%, 6%, 4%, 4%, and 3%, respectively. The phytoplankton in the water body was classified into 23 functional groups, of which MP and D functional groups were the long−term dominant functional groups, indicating that the habitat is a turbid water body. The ecological state index (Q) value ranged from 1.94 to 3.13, with an average value of 2.74. The comprehensive nutritional index (TSIM(∑)) was between 49.32 and 52.11, with an average value of 51.72, indicating that Nanhai Lake was in a mesotrophic state. Correlation analysis and redundancy analysis (RDA) showed that multiple nutrients, transparency (SD), chemical oxygen demand (COD), water temperature (WT), and Chlorophyll a (Chl−a) were the main environmental factors affecting the biomass of dominant functional groups in the water body. The study showed the characteristics of the functional groups of algae in a precious urban lake in arid and semi−arid areas of China and their relationship with environmental factors (physical and chemical indicators, anions and cation ions, and heavy metal ions), and provided a scientific basis for its water quality evaluation.

Catalytic Effect of Alkali Metals on the Gasification Dissolution Reaction and Deep Reaction Behavior of Metallurgical Cokes.

In this paper, the deep reaction behaviors of tamping and top-charging cokes with different K2CO3 and Na2CO3 contents were investigated and the evolution of the functional group structure and the carbon structure of coke with the extension of the deep reaction was clarified. The results showed that the deep reaction gasification of coke steadily increased with the K2CO3 and Na2CO3 content. However, the catalytic effect of different contents of K2CO3 seemed to be stronger than that of different contents of Na2CO3. Meanwhile, the catalytic effect of alkali metals on the gasification reaction of tamping coke was more significant. The gasification dissolution of coke gradually decreased from the outside to the inside of the particle with the extension of the deep reaction, while the catalytic effect of K2CO3 and Na2CO3 seemed to be more dramatic on surface of the coke particle. In contrast, the gasification dissolution reaction on the surface of tamping coke was more severe; consequently, the surface pore area of tamping coke was much higher than that of top-charging coke. According to the variations in the functional group structure of cokes, aromatic hydrocarbon gradually became the dominant functional group in the coke structure with the extension of the deep reaction. The above variation led to a gradual decrease in the reactivity of coke, though the decomposition reactions of oxygen-containing functional groups in coke were promoted to some extent by the addition of K2CO3. With the extension of the deep reaction of coke, amorphous carbon was gradually transformed into sequential carbon.

SEASONAL VARIATION OF PHYTOPLANKTON FUNCTIONAL GROUPS IN TUYEN LAM RESERVOIR, CENTRAL HIGHLANDS, VIETNAM

Seasonal changes in freshwater phytoplankton assemblages at Tuyen Lam Reservoir in the Central Highlands of Vietnam were classified into 23 functional groups based on physiological, morphological, and ecological characteristics. A total of 168 species were recorded during 10 surveys from 2015 to 2019 at 7 sampling sites, with Chlorophyta dominating in number of species. Phytoplankton abundance varied from 0.18×105 to 21.2×105 cells/L during the study period, mainly due to cyanobacteria. Seven of the 23 functional groups were considered to be dominant (relative density &gt; 5%). The dominant functional groups were groups M and G in the dry season and groups M, G, P, and E in the rainy season. Group M (Microcystis aeruginosa) was the most common in both seasons, while group P (Closterium, Staurastrum, Aulacoseira), group E (Dinobryon, Synura), and group G (Sphaerocystis, Eudorina) were more common in the rainy season. The Shannon diversity index (H¢) showed that phytoplankton communities were relatively diverse and that most of the study sites were lightly polluted. However, the ecological status has deteriorated at some locations due to the overgrowth of group M, leading to eutrophication in this reservoir. This study highlights the usefulness of functional groups in the study of seasonal changes in phytoplankton dynamics. Functional groups are applied for the first time at Tuyen Lam Reservoir and can be used to predict early-stage cyanobacterial blooms in future studies.

Comparison of RSM and ANFIS modeling techniques in corrosion inhibition studies of Aspilia Africana leaf extract on mild steel and aluminium metal in acidic medium

In this work, the predictive capabilities of response surface methodology (RSM) and adaptive neuro fuzzy inference systems (ANFIS) in modeling aluminum (Al) and mild steel corrosion inhibition by Aspilia Africana (A. Africana) were comparatively analyzed. Phytochemical and Fourier Transform Infrared Spectroscopy (FTIR) characterization of A. Africana leaf extract indicated that the inhibitor possessed high value flavonoids, Tannins and dominant functional groups necessary for promoting sustainable corrosion inhibition. While statistical parameters verified the applicability of RSM and ANFIS techniques in modeling the corrosion inhibition of Al and mild steel, error indices illustrated the dominance of ANFIS (R2 = 0.9917) and RSM (R2 = 0.9905) in predicting the inhibition efficiency of Al and mild steel, respectively. Analysis of variance (ANOVA) showed that acid concentration (F-value = 191.23) was the most influential process parameter in the modeling of Al corrosion inhibition process, while A. Africana inhibitor concentration presented an F-value of 160.5 to maintain its superior position among other factors in the modeling of mild steel corrosion inhibition. ANFIS coupled genetic algorithm optimization (ANFIS-GA) of Al corrosion inhibition was validated to be 80% at HCl conc. of 0.7 M, inhibitor conc. of 0.59 g/L and immersion time of 6.2 h. Similarly, mild steel corrosion inhibition process was optimized using RSM-GA and validated to be 77.3% efficiency (HCl conc. = 0.5 M, inhibitor conc. = 0.37 g/L and time of 4.8 h). Post optimization characterization using electrochemical studies demonstrated close agreement with inhibition efficiency obtained by gravimetric technique. Furthermore, polarization studies indicated that A. Africana leaf extract acted as a mixed type inhibitor in the corrosion process of Al and mild steel species.

Intra-annual growing season climate variability drives the community intra-annual stability of a temperate grassland by altering intra-annual species asynchrony and richness in Inner Mongolia, China.

Understanding the factors that regulate the functioning of our ecosystems in response to environmental changes can help to maintain the stable provisioning of ecosystem services to mankind. This is especially relevant given the increased variability of environmental conditions due to human activities. In particular, maintaining a stable production and plant biomass during the growing season (intra‐annual stability) despite pervasive and directional changes in temperature and precipitation through time can help to secure food supply to wild animals, livestock, and humans. Here, we conducted a 29‐year field observational study in a temperate grassland to explore how the intra‐annual stability of primary productivity is influenced by biotic and abiotic variables through time. We found that intra‐annual precipitation variability in the growing season indirectly influenced the community intra‐annual biomass stability by its negative effect on intra‐annual species asynchrony. While the intra‐annual temperature variability in the growing season indirectly altered community intra‐annual biomass stability through affecting the intra‐annual species richness. At the same time, although the intra‐annual biomass stability of the dominant species and the dominant functional group were insensitive to climate variability, they also promoted the stable community biomass to a certain extent. Our results indicate that ongoing intra‐annual climate variability affects community intra‐annual biomass stability in the temperate grassland, which has important theoretical significance for us to take active measures to deal with climate change.

Burning the seed bank: Seed response of eight species to different fire intensities in Patagonian steppe

AbstractQuestionsFire intensity influences the soil seed bank in fire‐prone environments. The aim of this investigation was to study the effects of fire intensity on seed germination and seedling growth of native species which belong to three functional groups (grasses, shrubs, and fire ephemerals). We addressed the following questions: (1) How does fire intensity affect the seed germination and seedling growth of the functional groups? Are there differences among species within each functional group? (2) How do seed traits (shape, size, protection structures of seeds, and embryo position) influence the resistance to high temperatures? (3) What conclusions at the community level can we infer from our results?LocationNorthwestern Patagonian grasslands, Argentina.MethodsWe performed two experimental burns using different amounts of grassland biomass to simulate low and high fire intensities on sowed seeds of eight native species (four grasses, two shrubs, and two fire ephemerals). We calculated the frequency of seed germination, mean germination time, and estimated seedling growth by weighing the dry biomass (roots and leaves). We examined the relationship of seed mass, length, and shape to the percentage of seed germination in low‐ and high‐temperature treatments.ResultsBoth temperature treatments negatively affected the seed germination of all functional groups and species, except for the fire ephemeral Boopis gracilis with protected linear embryos. Among grasses, the presence of protective structures in Pappostipa speciosa seeds and of hairs in Poa lanuginosa seeds probably provides resistance to high temperatures. Root growth of seedlings of the grasses Pappostipa speciosa and Festuca pallescens was stimulated by high‐temperature treatment ensuring post‐fire establishment.ConclusionsOur results suggest that fire intensity influences the post‐fire seed germination and seedling growth of the three dominant functional groups of northwestern Patagonian grasslands. In addition, we can affirm that the species of these functional groups have adaptations to resist wildfires and are capable of exploiting post‐fire resources.

Phytoplankton biomass and community composition in three Texas estuaries differing in freshwater inflow regime

Because many estuaries worldwide are experiencing large-scale alterations in freshwater inflows due to climatic and human influences on watersheds, it is critical to understand ecosystem-level responses to freshwater inflow conditions and variability. This study compared environmental conditions and phytoplankton biomass/community composition among three Texas estuaries with differing freshwater inflow regimes to understand the impacts of freshwater inflow magnitude on phytoplankton communities. It was hypothesized that: 1) nutrient concentrations and phytoplankton biomass would be highest in San Antonio Bay (SA), the high inflow estuary and lower in Nueces-Corpus Christi Bay (NC) and Baffin Bay (BB) due to lower average inflows, and 2) the phytoplankton community would be dominated by large and/or fast-growing taxa in SA, with a greater fraction of small and/or slow-growing taxa in NC and BB. Highest inorganic nutrient concentrations were generally observed in SA, while high organic nutrient concentrations were found in BB. Chlorophyll a was relatively high in both SA and BB (mean 16.9–18.5 μg L−1) while phytoplankton biovolume was highest in BB. Despite distinct freshwater inflow, salinity and nutrient regimes, differences in phytoplankton community composition were less pronounced. Nano- or microplankton were the dominant size class of phytoplankton in each system, and diatoms were the dominant functional group, accounting for 27–49% of total biovolume on average. There were indications that the phytoplankton community was more diverse in SA, especially following inflow events, providing evidence that inflow may act as a disturbance that leads to greater phytoplankton diversity. Results from this study also showed that while freshwater inflow is important for nutrient delivery, low inflow estuaries such as BB are still susceptible to effects of eutrophication due to long residence times and nutrient retention/recycling. Overall, the differing responses of each of these ecosystems to freshwater inflow highlight the importance of system-specific management plans and consistent monitoring programs in coastal estuaries.

Variation characteristics of different plant functional groups in alpine desert steppe of the Altun Mountains, northern Qinghai-Tibet Plateau.

In grassland ecosystems, the plant functional group (PFG) is an important bridge connecting individual plants to the community system. The grassland ecosystem is the main ecosystem type on the Qinghai-Tibet Plateau. Altun Mountain is located in the key grassland transcontinental belt of the northern Qinghai-Tibet Plateau. The composition and changes in the PFG in this ecosystem reflect the community characteristics in the arid and semi-arid extreme climate regions of the Plateau. The main PFGs were forbs and grasses, and the importance values (IVs) accounted for more than 50%. Plant species diversity of the community was influenced by the IV of the legumes, and the increase in legumes would promote the increase in plant community diversity. The C, N, and P contents of plant communities were mainly influenced by forbs and grasses, and the relationship between forbs and C, N, and P was opposite to that of grasses. However, under the influence of different hydrothermal conditions, forbs and grasses as dominant functional groups had a stronger correlation with community and soil nutrients. This indicates that the dominant PFGs (forbs and grasses) can dominate the C, N, and P contents of the community and soil, and legumes affect community composition and succession. In this study, we analyzed the changing characteristics of functional groups in dry and cold extreme environments and the difference in their impacts on community development compared with other grassland ecosystem functional groups.

Characteristic of soil fungal community and the influencing factors of Pinus massoniana forests in the Three Gorges Reservoir Region

Soil fungi are important components of belowground biodiversity and play important roles in soil carbon and nutrient cycling. We investigated fungal communities in the top soil (0-10 cm) of 22 Pinus massoniana forests in the Three Gorges Reservoir Region using high-throughput sequencing technique. We found that Ascomycota and Basidiomycota were the dominant fungi phyla, and Eurotiales, Russulales, and Tremellales were the most abundant fungi orders. The dominant functional groups in P. massoniana forests were saprophytic fungi, ectomycorrhizal fungi, and ericoid mycorrhizal fungi. Results of redundancy analysis showed that environmental variables but not spatial variables were the main drivers of soil fungal community structure across the 22 P. massoniana forests, which suggested that habitat filtering rather than dispersal limitation shaped soil fungal community structure. Aboveground biomass, soil conductivity, available phosphorus, soil bulk density, carbon to nitrogen ratio, nitrate concentration, and proportion of slit were the main factors explaining the variation in soil fungal community structure. It should be noted that the key factors influencing different fungal functional groups differed across forests.

Responses of pore structure parameters and functional group compositions of coals to irradiation power: implication to coalbed methane production via microwave irradiation

ABSTRACT Microwave irradiation could alter pores and surface chemistry properties of coal matrix, thereby affecting coalbed methane (CBM) production. The impacts of irradiation power on dominant pore structure parameters and functional group compositions of coals were elaborated in this study. The results show that the responses of micropore structure parameters of coals to irradiation depend on coal rank. Generally, micropore surface area and micropore volume of low-rank coals decrease after microwave irradiation. Moreover, a U-shaped trend exists between micropore parameters of low-rank coals and irradiation power. As for middle- and high-rank coals, micropore surface area and micropore volume increase after microwave irradiation. The irradiation power dependence of micropore parameters of middle-rank coal shows a decreasing trend, while that of high-rank coal shows an inverse U-shaped trend. Microwave irradiation decreases mesopores with diameter range of 2.00–32.00 nm for all coals, thereby reducing adsorption space of coal matrix for CH4. Besides, irradiation reduces C-O, C=O, and COOH of low-rank coals, while increases C-O and C=O of middle- and high-rank coals. Furthermore, microwave irradiation increases pyridine-N but decreases pyrrole/pyridone-N of all coals. Such alterations become pronounced with rising irradiation power. Overall, responses of pores and functional groups of coals to irradiation power rest with coal rank, therefore requiring further consideration in CBM production.