scholarly journals Microbial contribution to post-fire tundra ecosystem recovery over the 21st century

2021 ◽  
Author(s):  
Nicholas J. Bouskill ◽  
Zelalem Mekonnen ◽  
Qing Zhu ◽  
Robert Grant ◽  
William Riley
Keyword(s):  
Nutrient Cycling ◽  
21St Century ◽  
Mechanistic Model ◽  
Terrestrial Ecosystem ◽  
Soil Nutrient ◽  
Ecosystem Recovery ◽  
Saprotrophic Fungi ◽  
Complex Interactions ◽  
Microbial Functional Groups ◽  
Tundra Ecosystem

Abstract Tundra ecosystems have experienced an increased frequency of fire in recent decades, and this trend is predicted to continue throughout the 21st Century. Post-fire recovery is underpinned by complex interactions among microbial functional groups that drive nutrient cycling post-fire. Here we use a mechanistic model to demonstrate an acceleration of the nitrogen cycle post-fire driven by changes in niche space and microbial competitive dynamics. We show that over the first 5-years post-fire, fast-growing bacterial heterotrophs colonize regions of the soil previously occupied by slower-growing saprotrophic fungi. The bacterial heterotrophs mineralize organic matter, releasing organic and inorganic nutrients into the soil. This pathway outweighs new sources of nitrogen and facilitates the recovery of plant productivity. We broadly show here that while consideration of distinct microbial metabolisms related to carbon and nutrient cycling remains rare in terrestrial ecosystem models, they are important when considering the rate of ecosystem recovery post-disturbance and the feedback to soil nutrient cycles on centennial timescales.

scholarly journals Core Microbiota in Agricultural Soils and Their Potential Associations with Nutrient Cycling

mSystems ◽  
2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Shuo Jiao ◽  
Yiqin Xu ◽  
Jie Zhang ◽  
Xin Hao ◽  
Yahai Lu
Keyword(s):  
Nutrient Cycling ◽  
Microbial Ecology ◽  
Eastern China ◽  
Habitat Preferences ◽  
Soil Nutrient ◽  
Rice Soils ◽  
Core Microbiota ◽  
Continental Scale ◽  
The Core ◽  
Ecological Roles

ABSTRACT Revealing the ecological roles of the core microbiota in community maintaining and soil nutrient cycling is crucial for understanding ecosystem function, yet there is a dearth of continental-scale studies on this fundamental topic in microbial ecology. Here, we collected 251 soil samples from adjacent pairs of maize and rice fields at a continental scale in eastern China. We revealed the major ecological roles of the core microbiota in maintaining complex connections between bacterial taxa and their associations with belowground multinutrient cycling. By identifying the habitat preferences of the core microbiota, we built a continental atlas for mapping the spatial distributions of bacteria in agro-soils, which helps forecast the responses of agricultural ecosystems to anthropogenic disturbance. The multinutrient cycling index for maize and rice soils was related to bacterial α-diversity and β-diversity, respectively. Rice soils exhibited higher bacterial diversity and closer bacterial cooccurrence relationships than maize soils. In contrast to the macro- or microecological latitudinal richness patterns in natural terrestrial ecosystems, the bacteria in maize soils showed higher richness at high latitudes; however, this trend was not observed in rice soils. This study provides a new perspective on the distinct bacterial biogeographic patterns to predict the ecological roles of the core microbiota in agro-soils and thus helps manage soil bacterial communities for better provisioning of key ecosystem services. IMPORTANCE Disentangling the roles of the core microbiota in community maintaining and soil nutrient cycling is an important yet poorly understood topic in microbial ecology. This study presents an exploratory effort to gain predictive understanding of the spatial atlas and ecological roles of the core microbiota. A systematic, continental-scale survey was conducted using agro-soils in adjacent pairs of maize (dryland) and rice (wetland) fields across eastern China. The results indicate that the core microbiota play major ecological roles in maintaining complex connections between bacterial taxa and are associated with belowground multinutrient cycling. A continental atlas was built for mapping the bacterial spatial distributions in agro-soils through identifying their habitat preferences. This study represents a significant advance in forecasting the responses of agricultural ecosystems to anthropogenic disturbance and thus helps manage soil bacterial communities for better provisioning of key ecosystem services—the ultimate goal of microbial ecology.

Effect of Drought and Recovery on Grazing Animal, Microbial, and Fungal Response in a Diverse Multi-Crop Rotation

2020 ◽  
Author(s):  
Douglas Landblom ◽  
Songul Senturklu
Keyword(s):  
Nutrient Cycling ◽  
Beef Cattle ◽  
Microbial Activity ◽  
Crop Rotation ◽  
Cover Crop ◽  
Crop Production ◽  
Microbial Respiration ◽  
Soil Nutrient ◽  
Soil Microbial ◽  
Animal Grazing

<p>Beef cattle grazing, soil microbial respiration, and Rhizobia spp. populations serve important roles in soil nutrient cycling and during periods of drought, when abnormal precipitation declines, forage production for animal grazing and performance are negatively impacted. Soil nutrient availability is essential for adequate crop production and extended drought reduces soil microbial activity and therefore nutrient cycling. During the 2017 growing season between April and October in the northern Great Plains region of the USA, effective precipitation for crop production and animal grazing was severely reduced due an exceptional drought as classified by the US Drought Monitor. At the NDSU – Dickinson Research Extension Center, Dickinson, North Dakota, USA, a long-term integrated system that includes yearling steer grazing within a diverse multi-crop rotation (spring wheat, cover crop, corn, pea-barley intercrop, and sunflower). Within the rotation of cash and forage crops, beef cattle graze the pea-barley, corn, and cover crop (13-specie) within the rotation and is being utilized to monitor the effects of animal, microbial and fungal activity over time and space in the crop and animal production system. Nitrogen fertilizer has been replaced in the system by soil microbial and fungal activity (Potential Mineralizable Nitrogen: 8.4 mg N/kg) such that for each 1% increase in SOM there is a corresponding increase of 18.8 kg of potential nitrogen mineralized per ha. Animal grazing days are severely reduced when precipitation is inadequate for soil microbial respiration to occur. What is even more concerning, when relying on microbial activity to supply plant nutrients, is recovery time for microbial activity to fully recover from exceptional drought as was the case in this research project. Compared to the 2016 crop production year that preceded the 2017 drought, cover crop (13-specie), pea-barley, and corn yields were reduced 86, 33, and 64% during the 2017 drought. This decline in crop production reduced the number of days of grazing by an average 50% and average daily gains were also reduced. Steer average daily gains were 1.05 0.95, and 0.83 kg/steer/day in 2017 when grazing pea-barley, corn, and cover crop, respectively. For this research that relies on soil derived plant nutrients soil analysis for microbial and Rhizobia spp. biomass began recovery in 2018 and continued into 2019 as evidenced by large percentage increases in organism biomass; however, complete production recovery did not occur by the end of the 2019 grazing season in which days of grazing were reduced compared to the 2016 grazing season. Biological animal, crop, microbial, fungal, and nutrient replacement recovery will be presented in the poster.</p>

The ecological effects of clear-cutting

1993 ◽  
Vol 1 (2) ◽  
pp. 121-144 ◽  
Author(s):  
Rodney J. Keenan ◽  
J. P. (Hamish) Kimmins
Keyword(s):  
Nutrient Cycling ◽  
Soil Nutrient ◽  
Ecological Impacts ◽  
Ecological Effects ◽  
Wood Production ◽  
Clear Cutting ◽  
Environmentally Sound ◽  
Definition Of ◽  
The Right ◽  
Slash Burning

Clear-cutting is a controversial practice that is widely applied in forests managed for wood production in many parts of the world. This paper aims to provide an objective synthesis of the ecological effects of clear-cutting as a basis for more informed discussion of its merits and disadvantages. A definition of clear-cutting is put forward, and its place in modern productive forestry is described. Effects on microclimate, water, soil, nutrient cycling, and the diversity and composition of plant and animal species are reviewed. The effects of clear-cutting vary considerably depending on site conditions (such as climate, geology, and topography) and on the structure and composition of the forest, the extent and distribution of harvesting, the method used to extract the logs, and the length of time before the forest is removed again. However, it is evident that many of the ecological impacts commonly ascribed to clear-cutting, in fact, result from other stages of the wood-production process, such as the quality and intensity of roading, site preparation practices (such as mechanical disturbance or slash burning), and the intensity of control of noncrop vegetation. Situations where clear-cutting is inappropriate are described. It is argued that in the right situations, with appropriate safeguards, it is an environmentally sound practice that offers many advantages in terms of the production of wood fibre.Key words: clear-cutting, environmental impacts, microclimate, hydrology, soil, forest production, nutrient cycling, wildlife.

scholarly journals Religion in Europe in the 21st Century: The Factors to Take into Account

2006 ◽  
Vol 47 (2) ◽  
pp. 271-296 ◽  
Author(s):  
Grace Davie
Keyword(s):  
21St Century ◽  
Religious Life ◽  
World Order ◽  
Modern World ◽  
Complex Interactions ◽  
The Future ◽  
Changing Patterns ◽  
Take All

This article considers six factors that are currently shaping the religious life of Europe. These are the Judaeo-Christian heritage, the continuing influence of the historic churches, the changing patterns of church-going, new arrivals from outside, secular reactions and the growing significance of religion in the modern world order. Any assessment of the future of religion in Europe must take all of these into account, not least their mutual and necessarily complex interactions.

scholarly journals Annual mass drownings of the Serengeti wildebeest migration influence nutrient cycling and storage in the Mara River

2017 ◽  
Vol 114 (29) ◽  
pp. 7647-7652 ◽  
Author(s):  
Amanda L. Subalusky ◽  
Christopher L. Dutton ◽  
Emma J. Rosi ◽  
David M. Post
Keyword(s):  
Soft Tissue ◽  
Nutrient Cycling ◽  
Terrestrial Ecosystem ◽  
Dry Mass ◽  
River Ecosystem ◽  
Terrestrial Animal ◽  
The World ◽  
Connochaetes Taurinus ◽  
And Storage

The annual migration of ∼1.2 million wildebeest (Connochaetes taurinus) through the Serengeti Mara Ecosystem is the largest remaining overland migration in the world. One of the most iconic portions of their migration is crossing of the Mara River, during which thousands drown annually. These mass drownings have been noted, but their frequency, size, and impact on aquatic ecosystems have not been quantified. Here, we estimate the frequency and size of mass drownings in the Mara River and model the fate of carcass nutrients through the river ecosystem. Mass drownings (>100 individuals) occurred in at least 13 of the past 15 y; on average, 6,250 carcasses and 1,100 tons of biomass enter the river each year. Half of a wildebeest carcass dry mass is bone, which takes 7 y to decompose, thus acting as a long-term source of nutrients to the Mara River. Carcass soft tissue decomposes in 2–10 wk, and these nutrients are mineralized by consumers, assimilated by biofilms, transported downstream, or moved back into the terrestrial ecosystem by scavengers. These inputs comprise 34–50% of the assimilated diet of fish when carcasses are present and 7–24% via biofilm on bones after soft tissue decomposition. Our results show a terrestrial animal migration can have large impacts on a river ecosystem, which may influence nutrient cycling and river food webs at decadal time scales. Similar mass drownings may have played an important role in rivers throughout the world when large migratory herds were more common features of the landscape.

Interactions between plant growth and soil nutrient cycling under elevated CO2 : a meta-analysis

2006 ◽  
Vol 12 (11) ◽  
pp. 2077-2091 ◽  
Author(s):  
MARIE-ANNE De GRAAFF ◽  
KEES-JAN Van GROENIGEN ◽  
JOHAN SIX ◽  
BRUCE HUNGATE ◽  
CHRIS Van KESSEL
Keyword(s):  
Plant Growth ◽  
Nutrient Cycling ◽  
Elevated Co2 ◽  
Meta Analysis ◽  
Soil Nutrient ◽  
Soil Nutrient Cycling
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