scholarly journals Effects of forest conversion and seasonal changes on the assembly of bacterial and fungal communities in tropical forests

2021 ◽  
Author(s):  
G Lan ◽  
Bangqian Chen ◽  
Zhixiang Wu ◽  
Chuan Yang ◽  
Xicai Zhang
Keyword(s):  
Community Assembly ◽  
Bacterial Communities ◽  
Seasonal Changes ◽  
Rainy Season ◽  
Tropical Rainforest ◽  
Dry Season ◽  
Fungal Communities ◽  
Forest Conversion ◽  
Rubber Plantation ◽  
Soil Microbial

To date, few studies have assessed the impact of forest conversion or seasonal changes on soil microbial community assembly. To fill this research gap, 16S rRNA and ITS gene sequences were used to evaluate the effects of forest conversion and seasonal changes on the assembly of bacterial and fungal communities using 260 soil samples collected from tropical rainforest and rubber plantation sites across Hainan Island, South China. A majority (~60%) of observed OTUs conformed with neutral model expectations, indicating that neutral processes were important for the assembly of soil microbial communities. For bacterial communities, the NST (normalized stochasticity ratio) was higher in the tropical rainforest (0.746 in the dry season, 0.684 in the rainy season) versus rubber plantation sites (0.647, 0.584), regardless of season. Thus, forest conversion decreased the importance of stochasticity for soil bacterial community assembly. For fungal communities, rubber plantation communities showed greater stochasticity (NST = 0.578) than rainforest communities (NST = 0.388) in the dry season, but the reverse was true in the rainy season (NST = 0.852 for rubber plantations; NST = 0.978 for rainforest). Both the NST results and structural equation modeling showed that bacterial communities were more stochastic in the dry season, while fungal communities were more stochastic in the rainy season; the effects of seasonal changes on assembly therefore differed between bacterial and fungal communities. More importantly, forest conversion did not have a direct impact on the assembly of bacterial or fungal communities, but exerted indirect effects via soil pH and soil AK.

scholarly journals Network complexity of rubber plantations is lower than tropical forests for soil bacteria but not fungi

2021 ◽  
Author(s):  
Guoyu Lan ◽  
Chuan Yang ◽  
Zhixiang Wu
Keyword(s):  
Network Structure ◽  
Tropical Rainforest ◽  
Soil Microbial Communities ◽  
Hainan Island ◽  
Past Research ◽  
Forest Conversion ◽  
Rubber Plantation ◽  
Microbial Composition ◽  
Rubber Plantations ◽  
Soil Microbial

Abstract. Soil microbial communities play a crucial role in ecosystem functioning. Past research has examined the effects of forest conversion on soil microbial composition and diversity, but it remains unknown how networks within these communities respond to forest conversion such as when tropical rainforest are replaced with rubber plantations. In this study, we used Illumina sequencing and metagenome shotgun sequencing to analyze bacterial and fungal community network structure in a large number of soil samples from tropical rainforest and rubber plantation sites in Hainan Island, China. Our results showed only a few shared network edges were observed in both bacterial and fungal communities, which indicates that forest conversion altered soil microbial network structure. We found a greater degree of network structure and a larger number of network edges among bacterial networks in samples from tropical rainforest compared to samples from rubber plantations. The difference was especially pronounced during the rainy season and indicates that rainforest bacterial networks were more complex than rubber plantation bacterial networks. However, rubber plantations soil fungal networks showed more higher links and higher network degree, suggesting that forest conversion does not reduce fungal network complexity. We found that some groups of Acidobacteria were keystone taxa in our tropical rainforest soils, while Actinobacteria were keystone taxa in rubber plantation soils. In addition, seasonal change had a strong effect on network degree, the complexity of soil bacterial and fungal network structure. In conclusion, forest conversion changed soil pH and other soil properties, such as available potassium (AK) and total nitrogen (TN), which resulted in changes in bacterial and fungal network composition and structure.

scholarly journals Historical land use has long-term effects on microbial community assembly processes in forest soils

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Ernest D. Osburn ◽  
Frank O. Aylward ◽  
J. E. Barrett
Keyword(s):  
Land Use ◽  
Microbial Community ◽  
Community Assembly ◽  
Soil Microbial Communities ◽  
Fungal Communities ◽  
Long Term Effects ◽  
Soil Microbial ◽  
Historical Land Use ◽  
Microbial Community Assembly

AbstractLand use change has long-term effects on the structure of soil microbial communities, but the specific community assembly processes underlying these effects have not been identified. To investigate effects of historical land use on microbial community assembly, we sampled soils from several currently forested watersheds representing different historical land management regimes (e.g., undisturbed reference, logged, converted to agriculture). We characterized bacterial and fungal communities using amplicon sequencing and used a null model approach to quantify the relative importance of selection, dispersal, and drift processes on bacterial and fungal community assembly. We found that bacterial communities were structured by both selection and neutral (i.e., dispersal and drift) processes, while fungal communities were structured primarily by neutral processes. For both bacterial and fungal communities, selection was more important in historically disturbed soils compared with adjacent undisturbed sites, while dispersal processes were more important in undisturbed soils. Variation partitioning identified the drivers of selection to be changes in vegetation communities and soil properties (i.e., soil N availability) that occur following forest disturbance. Overall, this study casts new light on the effects of historical land use on soil microbial communities by identifying specific environmental factors that drive changes in community assembly.

scholarly journals Micro-aggregation of a pristine grassland soil selects for bacterial and fungal communities and changes in nitrogen cycling potentials

2021 ◽  
Author(s):  
Christoph Keuschnig ◽  
Jean Martins ◽  
Aline Navel ◽  
Pascal Simonet ◽  
Catherine Larose
Keyword(s):  
Particle Size ◽  
Nitrogen Cycling ◽  
Bacterial Communities ◽  
Soil Microbial Communities ◽  
Microbial Interactions ◽  
Fungal Communities ◽  
Supernatant Fraction ◽  
Soil Microbial ◽  
Microbial Analysis

Microbial analysis at the micro scale of soil is essential to the overall understanding of microbial organization and interactions, and necessary for a better understanding of soil ecosystem functioning. While bacterial communities have been extensively described, little is known about the organization of fungal communities as well as functional potentials at scales relevant to microbial interactions. Fungal and bacterial communities and changes in nitrogen cycling potentials in the pristine Rothamsted Park Grass soil (bulk soil) as well as in its particle size sub-fractions (PSFs; > 250 µm, 250-63 µm, 63-20 µm, 20-2 µm, < 2 µm and supernatant) were studied. The potential for nitrogen reduction was found elevated in bigger aggregates. The relative abundance of Basidiomycota deceased with decreasing particle size, Ascomycota showed an increase and Mucoromycota became more prominent in particles less than 20 µm. Bacterial community structures changed below 20 µm at the scale where microbes operate.Strikingly, only members of two bacterial and one fungal phyla (Proteobacteria, Bacteroidota and Ascomycota, respectively) were washed-off the soil during fractionation and accumulated in the supernatant fraction where most of the detected bacterial genera (e.g., Pseudomonas, Massilia, Mucilaginibacter, Edaphobaculum, Duganella, Janthinobacterium and Variovorax) were previously associated with exopolysaccharide production and biofilm formation.Overall, the applied method shows potential to study soil microbial communities at micro scales which might be useful in studies focusing on the role of specific fungal taxa in soil structure formation as well as research on how and by whom biofilm-like structures are distributed and organized in soil.

scholarly journals Seasonal Changes in the Intertidal and Subtidal Algal Communities of Extremely and Moderately Polluted Coastal Regions of Sanya Bay (Hainan Island, China)

2019 ◽  
Vol 7 (4) ◽  
pp. 93
Author(s):  
Eduard A. Titlyanov ◽  
Tamara V. Titlyanova ◽  
Hui Huang ◽  
Anna V. Scriptsova ◽  
Huili Xu ◽  
...  
Keyword(s):  
Species Diversity ◽  
Seasonal Changes ◽  
Rainy Season ◽  
Hainan Island ◽  
Dry Season ◽  
Polluted Area ◽  
Algal Communities ◽  
Intertidal Zones ◽  
Polluted Sites ◽  
Sanya Bay

At the end of the rainy season in 2016 and at the end of the dry season in 2017, we conducted a floristic study of marine macrophytic algae in the intertidal and subtidal zones in moderately and heavily polluted areas at Luhuitou reef, Sanya Bay, Hainan Island, China. A total of 109 species of marine macrophytes were found during these samplings. At the end of the rainy season, 72 species of macrophytes (50% reds, 19% browns, and 31% greens) were found. At the end of the dry season, we found and identified 92 species of macrophytes (46% reds, 20% browns, and 34% greens). Seasonal changes in species diversity, species composition, and the structure of algal communities at differently polluted sites exhibited common features as well as specific characteristics. By the end of the dry season, the diversity of macroalgal species was increased, and the composition of dominant and accompanying species of macrophytes in polydominant communities was changed in moderately and heavily polluted areas. Seasonal changes in the marine flora of differently polluted areas were characterized by specific features as follows: Less changes in species diversity of heavily polluted area compared with moderately polluted area during the change from the rainy season to the dry season; significant increase in the biomass of green algae and their projective coverage in the middle and low intertidal zones of heavily polluted sites in the dry season; and the increase in the numbers of mono- and bidominant communities in the middle and low intertidal zones of heavily polluted sites by the end of the dry season.

scholarly journals Effects of seasonal upwelling on hydrography and mesozooplankton communities in a Pacific tropical cove off Colombia

2019 ◽  
Vol 67 (4) ◽  
Author(s):  
Bellineth Valencia ◽  
Alan Giraldo ◽  
Marisol Rivera-Gómez ◽  
Vanessa Izquierdo ◽  
Andrés Cuellar-Chacón
Keyword(s):  
Water Column ◽  
Seasonal Changes ◽  
Rainy Season ◽  
Physiological Stress ◽  
Dry Season ◽  
Coastal Zones ◽  
Subsurface Waters ◽  
Northern Pacific ◽  
Field Campaigns

Introduction: The effects of seasonal upwelling on the conditions of the water column and mesozooplankton communities are poorly understood in the coastal zones of the Eastern Tropical Pacific (ETP), despite the important role of upwelling events in the modulation of productivity in these zones. Objective: To evaluate the influence of seasonal upwelling over the Panama Bight on the structure of the water column and mesozooplankton communities in a tropical cove of the ETP. Methods: Hydrographic data and mesozooplankton samples were collected during four field campaigns in Ensenada de Utría (December 2011, February 2012, October 2013, and February 2013), an estuary located in the Northern Pacific coast of Colombia. Non-parametric and multivariate analyses were used to evaluate seasonal differences in the environmental and biotic variables. Results: Surface waters were warm (> 25 °C) and presented low salinities (< 30) throughout the study period. In contrast, subsurface waters were colder (< 20 °C), saltier (> 33), and presented low dissolved oxygen concentrations (< 2.0 ml l-1) during the dry season (January - March), whereas the water column was homogeneous during the rainy season (April - December). Despite the seasonal changes in the environmental conditions, the expected enhancement in the productivity of the system during the dry season (i.e., higher biomass and abundance of the mesozooplankton) only occurred in February 2012. Contrary to expectations, ichthyoplankton abundance was higher during the rainy season, when the assemblage was dominated by the larvae of anchovy (Cetengraulis mysticetus) and an unidentified Gobiidae. Conclusions: The entrance of upwelled waters into Ensenada de Utría is an important factor modulating the seasonal changes observed in the water column. However, there is high interannual variability in the response of mesozooplankton communities to the upwelling events. Because upwelled waters are oxygen-depleted and more acidic, the entrance of upwelled waters into Ensenada de Utría could be causing physiological stress to the benthic and pelagic organisms inhabiting the deepest zones of the cove. This condition may worsen in the future given the predicted increase of deoxygenation and ocean acidification due to climate change.

scholarly journals Effects of tropical rainforest conversion to rubber plantation on soil quality in Hainan Island, China

2021 ◽  
Author(s):  
Rui Sun ◽  
Guoyu Lan ◽  
Chuan Yang ◽  
Zhixiang Wu ◽  
Banqian Chen ◽  
...  
Keyword(s):  
Land Use ◽  
Soil Properties ◽  
Soil Quality ◽  
Tropical Rainforest ◽  
Hainan Island ◽  
Tropical Rainforests ◽  
Forest Conversion ◽  
Rubber Plantation ◽  
Cellulose Decomposition ◽  
Rubber Plantations

Abstract. Land-use changes can alter soil properties and thus affect soil quality. Our understanding of how forest conversion (from tropical rainforest to rubber plantations) affects soil properties and soil quality is limited. An ideal testing ground for analyzing such land-use change and its impacts is Hainan Island, the largest tropical island in China. Based on 21 soil physicochemical and biological properties, a soil quality index (SQI) employed principal component analysis to assess soil quality changes from the conversion of tropical rainforests to rubber plantations. The results showed that (i) soil available potassium, available phosphorus, microbial biomass carbon, cellulose decomposition, acid phosphatase, and urease were vital soil properties for soil quality assessment on Hainan Island. (ii) The SQI of rubber plantations decreased by 26.48 % compared to tropical rainforests, while four investigated soil properties (soil pH, total phosphorus, cellulose decomposition, and actinomyces) increased. (iii) The SQI of both the tropical rainforests and rubber plantations showed significant spatial differences, which, under tropical rainforests, was more sensitive to seasonal changes than those under rubber plantations. (iv) Structural equation modeling suggested that forest conversion directly impacted soil quality and, indirectly impacted soil qualities' spatial variation by their interaction with soil types and geographical positions. Overall, though the conversion of tropical rainforest to rubber plantation did not decrease all soil properties, the tropical rainforest with its high soil quality should be protected.

scholarly journals Differential Responses of Soil Bacterial and Fungal Community to Short-Term Crop Tree Management in a Larix gmelinii Plantation

Forests ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1411
Author(s):  
Li Ji ◽  
Jiangbo Yu ◽  
Xingzhe Zhang ◽  
Yue Liu ◽  
Lixue Yang
Keyword(s):  
Organic Carbon ◽  
Bacterial Communities ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Soil Fungi ◽  
Fungal Communities ◽  
Larix Gmelinii ◽  
Short Term ◽  
Soil Microbial ◽  
Soil Bacterial

Crop tree management (CTM) is a widely applicable silviculture technology that is used to improve the performance of individual trees. However, only little information is available about the effects of the CTM regime on the soil microbial community structure. We conducted a study to explore the effects of short-term (five years) CTM on the soil bacterial and fungal diversity, community composition, and structure in the 0–10 cm soil layer in a Larix gmelinii (Rupr.) Kuzen. plantation. We set out to investigate the differential response of bacterial and fungal communities to variations in soil properties mediated by short-term CTM. Compared with the control plots, the soil microbial biomass carbon and microbial biomass nitrogen in CTM increased significantly by 64.2% and 32.3%, respectively. CTM significantly promoted the content of soil organic carbon, dissolved organic carbon, and nitrate nitrogen, and reduced the content of dissolved organic nitrogen. CTM changed the Shannon and Simpson indices of soil fungi to a remarkable extent but had little effect on the α diversity of bacterial communities. The bacterial β diversity was more sensitive to CTM than fungi. The relative abundance of Verrucomicrobiae (the dominant class of soil bacteria) in CTM was significantly increased by 78.2%, while the relative abundance of Agaricomycetes (dominant class for soil fungi) was reduced by 43.3%. We observed a significantly increased number of unique OTUs for soil fungi in the CTM plots. Redundancy analysis showed that dissolved organic carbon, soil moisture, and total phosphorus content significantly affected the composition of bacterial communities, while soil dissolved organic nitrogen, C/N, and total phosphorus drove the high variation in fungal community composition. Overall, our results emphasize the divergent response of soil bacterial and fungal communities in Larix gmelinii plantations to short-term CTM. We must pay more attention to the functional role of soil microbiota in future forest management.

scholarly journals Vertical distribution, nutrient concentration and seasonal changes of fine root mass in a semi-deciduous tropical dry forest and in two adjacent pastures in the Western Llanos of Venezuela

2020 ◽  
Vol 8 (2) ◽  
pp. 93-104
Author(s):  
Ana Francisca González-Pedraza ◽  
Nelda Dezzeo
Keyword(s):  
Vertical Distribution ◽  
Seasonal Changes ◽  
Rainy Season ◽  
Nutrient Concentration ◽  
Fine Root ◽  
Tropical Dry Forest ◽  
Dry Season ◽  
Dry Forest ◽  
Nutrient Concentrations ◽  
Root Mass

With the objective to contribute to a better understanding of ecological consequences of deforestation on the below-ground system in the Western Llanos of Venezuela, we evaluated the vertical distribution, nutrient concentration and seasonal changes of total fine root mass (FRM) (<2 mm diameter) in a semi-deciduous tropical dry forest and in 2 adjacent pastures of Cynodon nlemfuensis: a young pasture (YP, 5 years old) and an old pasture (OP, 18 years old) in the Obispo municipality, Barinas State. This evaluation included measurements at the end of the rainy season, during the dry season and during the subsequent early rainy season in 2005/2006. Highest FRM was recorded during the dry season, which probably indicates a plant water-stress response mechanism. The highest proportion (63‒88%) of FRM was concentrated in the 10–20 cm soil layer at all studied sites, probably due to a higher nutrient and moisture content at that depth. Non-significant differences (P>0.05) were observed in the total concentrations of organic carbon, nitrogen, phosphorus, calcium and magnesium in the FRM in soils supporting forest, OP and YP at the evaluated depths. Non-significant changes in the total FRM and nutrient concentrations were observed between the sampling periods and the 3 study sites. YP soils showed a slight increase in FRM that could be associated with the root growth of secondary vegetation, which is considered a weed and is periodically removed. Our results suggest that the land use change from tropical forest to pastures has not significantly affected the mass of fine roots and their carbon and nutrient concentrations. Further studies are needed to determine if these findings apply to other ecosystems.

Prevalence and seasonal changes in the gastro-intestinal helminths of Nigerian goats

1996 ◽  
Vol 70 (4) ◽  
pp. 329-333 ◽  
Author(s):  
C.O. Nwosu ◽  
A.F. Ogunrinade ◽  
B.O. Fagbemi
Keyword(s):  
Seasonal Changes ◽  
Rainy Season ◽  
Dry Season ◽  
Intestinal Helminth ◽  
Helminth Parasites ◽  
Cysticercus Tenuicollis ◽  
Large Numbers ◽  
Oesophagostomum Columbianum ◽  
Faecal Samples ◽  
First Time

AbstractA total of 120 gastro-intestinal tracts and 960 faecal samples were examined to assess the prevalence and seasonal changes in the gastro-intestinal helminth parasites of Red Sokoto (maradi) goats slaughtered at Ibadan between May 1991 and April 1992. Egg types of strongyles, Strongyloides, Trichuris, Skrjabinema, Dicrocoelium and Moniezia were encountered in 93%, 83%, 44%, 0.9%, 2.3% and 31% of the faecal samples respectively. However, only strongyle, Strongyloides and Trichuris eggs occurred in large numbers and were more common during the rainy season than in the dry season. The parasites recorded and their prevalences were Haemonchus contortus (90.0%), H. ovis (5.0%), Strongyloides papillosus (80.8%), Trichostrongylus colubriformis (78.3%), T. axei (69.2%), Trichuris ovis (72.5%), T. globulosa (38.3%), Oesophagostomum columbianum (67.5%), Cooperia curticei (58.3%) Gaigeria pachyscelis (40.8%), Skrjabinema ovis (5.0%), Nematodirus battus (5.8%), Moniezia expansa (29.2%), M. benedeni (10.0%), Paramphistomum spp. (5.0%) and Cysticercus tenuicollis (33.3%). Haemonchus ovis is reported for the first time in Nigeria. Mixed infections were most prevalent. Young goats were more commonly infected and had higher worm counts than adult goats. Only Haemonchus, Trichostrongylus, Strongyloides and Cooperia spp. occurred in large numbers. Irrespective of the age of the goats, higher worm counts were generally encountered during the rainy season than in the dry season. The results are discussed in relation to the control of helminthiasis in grazing animals in Nigeria.

scholarly journals Composition and seasonal variation of the ichthyofauna from upper Rio Paraguaçu (Chapada Diamantina, Bahia, Brazil)

2007 ◽  
Vol 50 (4) ◽  
pp. 663-672 ◽  
Author(s):  
Alexandre Clistenes de Alcântara Santos ◽  
Érica Pellegrini Caramaschi
Keyword(s):  
Seasonal Variation ◽  
Seasonal Changes ◽  
Rainy Season ◽  
Multivariate Analyses ◽  
Dry Season ◽  
The Other ◽  
Chapada Diamantina ◽  
Number Of Species ◽  
Abiotic Variables

The aim of this work was to characterize the composition of the ichthyofauna of the upper course of the Rio Paraguaçu. Two excursions were carried out, one in the dry season, and the other in the rainy season, with 36 localities sampled. A total of 63 species were collected. Multivariate analyses indicated that abiotic variables such as the channel order and altitude were the main influences on the number of species present. The number of species in each excursion was equivalent in the two seasons, suggesting that seasonal changes have little influence on the ichthyofauna of this area.

Sign in / Sign up

Export Citation Format

Share Document