Microbiota responses to mutations affecting NO homeostasis in Arabidopsis thaliana.

Interactions between plants and microorganisms are pivotal for plant growth and productivity. Several plant molecular mechanisms that shape these microbial communities have been identified. However, the importance of nitric oxide (NO) produced by plants for the associated microbiota remains elusive.

Effects of environmental changes on soil respiration in arid, cold, temperate, and tropical zones.

Soil respiration (R) is projected to be substantially affected by climate change, impacting the storage, equilibrium, and movement of terrestrial carbon (C). However, uncertainties surrounding the responses of R to climate change and soil nitrogen (N) enrichment are linked to mechanisms specific to diverse climate zones. A comprehensive meta-analysis was conducted to address this, evaluating the global effects of warming, increased precipitation, and N enrichment on R across various climate zones and ecosystems.

Alder expansion stimulates nitrogen oxide (NO) emissions from southern Eurasian permafrost peatlands.

Nitrogen oxides (NO) play an important role for atmospheric chemistry and radiative forcing. However, NO emissions from the vast northern circumpolar permafrost regions have not been studied in situ due to limitations of measurement techniques. Our goals were to validate the offline analytical technique, and based on this, to widely quantify in situ NO emissions from peatlands in the southern Eurasian permafrost region.

Antagonistic effect of mercury and excess nitrogen exposure reveals provenance-specific phytoremediation potential of black locust-rhizobia symbiosis.

Interaction of different environmental constrains pose severe threats to plants that cannot be predicted from individual stress exposure. In this context, mercury (Hg), as a typical toxic and hazardous heavy metal, has recently attracted particular attention. Nitrogen (N)-fixing legumes can be used for phytoremediation of Hg accumulation, whereas N availability could greatly affect its N-fixation efficiency.

Differences of nitrogen metabolism in date palm (Phoenix dactylifera) seedlings subjected to water deprivation and salt exposure.

Drought and salt exposure are among the most prevalent and severe abiotic stressors causing serious agricultural yield losses, alone and in combination. Little is known about differences and similarities in the effects of these two stress factors on plant metabolic regulation, particularly on nitrogen metabolism. Here, we studied the effects of water deprivation and salt exposure on water relations and nitrogen metabolites in leaves and roots of date palm seedlings.

Short term effects of climate change and intensification of management on the abundance of microbes driving nitrogen turnover in montane grassland soils.

Montane grasslands in Europe are exposed to increasing temperatures twice as fast as the global average. Changes in climatic conditions are possibly accompanied by an increase in land use intensity, caused by a prolongation of the vegetation period and the need to improve productivity. Therefore, the investigation of combined effects of climate change and land use intensity is needed to further implement agricultural management strategies.

Foliar traits of sessile oak (Quercus petraea Liebl) seedlings are largely determined by site properties rather than seed origin.

Due to climate change, sessile oak (Quercus petraea) seedlings experience an increasing risk of drought during regeneration of forest stands by management practices. The present study was aimed at elucidating the potential of sessile oak seedlings originating from sites with different aridity and nitrogen (N) supply to acclimate to contrasting water availability. For this purpose, a free-air cross-exchange experiment was conducted between a dry and a humid forest stand with high and low soil N contents, respectively, during two consecutive years differing in aridity before harvest.

A single Thaumarchaeon drives nitrification in deep oligotrophic Lake Constance.

Ammonia released during organic matter mineralization is converted during nitrification to nitrate. We followed spatiotemporal dynamics of the nitrifying microbial community in deep oligotrophic Lake Constance. Depth-dependent decrease of total ammonium (0.

Nitrogen turnover and NO/N ratio of three contrasting tropical soils amended with biochar.

Biochar has been reported to reduce emission of nitrous oxide (NO) from soils, but the mechanisms responsible remain fragmentary. For example, it is unclear how biochar effects on NO emissions are mediated through biochar effects on soil gross N turnover rates. Hence, we conducted an incubation study with three contrasting agricultural soils from Kenya (an Acrisol cultivated for 10-years (Acrisol10); an Acrisol cultivated for over 100-years (Acrisol100); a Ferralsol cultivated for over 100 years (Ferralsol)).

N-fixing black locust intercropping improves ecosystem nutrition at the vulnerable semi-arid Loess Plateau region, China.

The Loess Plateau in northwestern China constitutes one of the most vulnerable semi-arid regions in the world due to long-term decline in forest cover, soil nutrient depletion by agricultural use, and attendant soil erosion. Here, we characterize the significance of N-fixing Robinia pseudoacacia L. and non-N-fixing Juglans regia L.

Foliar nitrogen metabolism of adult Douglas-fir trees is affected by soil water availability and varies little among provenances.

The coniferous forest tree Douglas-fir (Pseudotsuga menziesii) is native to the pacific North America, and is increasingly planted in temperate regions worldwide. Nitrogen (N) metabolism is of great importance for growth, resistance and resilience of trees. In the present study, foliar N metabolism of adult trees of three coastal and one interior provenance of Douglas-fir grown at two common gardens in southwestern Germany (Wiesloch, W; Schluchsee, S) were characterized in two subsequent years.

Disentangling gross NO production and consumption in soil.

The difficulty of measuring gross NO production and consumption in soil impedes our ability to predict NO dynamics across the soil-atmosphere interface. Our study aimed to disentangle these processes by comparing measurements from gas-flow soil core (GFSC) and NO pool dilution (NOPD) methods. GFSC directly measures soil NO and N fluxes, with their sum as the gross NO production, whereas NOPD involves addition of NO into a chamber headspace and measuring its isotopic dilution over time.

Segregation of nitrogen use between ammonium and nitrate of ectomycorrhizas and beech trees.

Here, we characterized nitrogen (N) uptake of beech (Fagus sylvatica) and their associated ectomycorrhizal (EM) communities from NH and NO . We hypothesized that a proportional fraction of ectomycorrhizal N uptake is transferred to the host, thereby resulting in the same uptake patterns of plants and their associated mycorrhizal communities. N uptake was studied under various field conditions after short-term and long-term exposure to a pulse of equimolar NH and NO concentrations, where one compound was replaced by N.

An improved (15) N tracer approach to study denitrification and nitrogen turnover in soil incubations.

Rationale: Denitrification (the reduction of oxidized forms of inorganic nitrogen (N) to N2 O and N2 ) from upland soils is considered to be the least well-understood process in the global N cycle. The main reason for this lack of understanding is that the terminal product (N2 ) of denitrification is extremely difficult to measure against the large atmospheric background.

Methods: We describe a system that combines the (15) N-tracer technique with a 40-fold reduced N2 (2% v/v) atmosphere in a fully automated incubation setup for direct quantification of N2 and N2 O emissions.

Climate Change Impairs Nitrogen Cycling in European Beech Forests.

European beech forests growing on marginal calcareous soils have been proposed to be vulnerable to decreased soil water availability. This could result in a large-scale loss of ecological services and economical value in a changing climate. In order to evaluate the potential consequences of this drought-sensitivity, we investigated potential species range shifts for European beech forests on calcareous soil in the 21st century by statistical species range distribution modelling for present day and projected future climate conditions.

Climate change amplifies gross nitrogen turnover in montane grasslands of Central Europe in both summer and winter seasons.

The carbon- and nitrogen-rich soils of montane grasslands are exposed to above-average warming and to altered precipitation patterns as a result of global change. To investigate the consequences of climatic change for soil nitrogen turnover, we translocated intact plant-soil mesocosms along an elevational gradient, resulting in an increase of the mean annual temperature by approx. 2 °C while decreasing precipitation from approx.

Ectomycorrhizal Communities on the Roots of Two Beech (Fagus sylvatica) Populations from Contrasting Climates Differ in Nitrogen Acquisition in a Common Environment.

Beech (Fagus sylvatica), a dominant forest species in Central Europe, competes for nitrogen with soil microbes and suffers from N limitation under dry conditions. We hypothesized that ectomycorrhizal communities and the free-living rhizosphere microbes from beech trees from sites with two contrasting climatic conditions exhibit differences in N acquisition that contribute to differences in host N uptake and are related to differences in host belowground carbon allocation. To test these hypotheses, young trees from the natural regeneration of two genetically similar populations, one from dryer conditions (located in an area with a southwest exposure [SW trees]) and the other from a cooler, moist climate (located in an area with a northeast exposure [NE trees]), were transplanted into a homogeneous substrate in the same environment and labeled with (13)CO2 and (15)NH4 (+).

Effects of short term bioturbation by common voles on biogeochemical soil variables.

Bioturbation contributes to soil formation and ecosystem functioning. With respect to the active transport of matter by voles, bioturbation may be considered as a very dynamic process among those shaping soil formation and biogeochemistry. The present study aimed at characterizing and quantifying the effects of bioturbation by voles on soil water relations and carbon and nitrogen stocks.

Climate change induces shifts in abundance and activity pattern of bacteria and archaea catalyzing major transformation steps in nitrogen turnover in a soil from a mid-European beech forest.

Ongoing climate change will lead to more extreme weather events, including severe drought periods and intense drying rewetting cycles. This will directly influence microbial nitrogen (N) turnover rates in soil by changing the water content and the oxygen partial pressure. Therefore, a space for time climate change experiment was conducted by transferring intact beech seedling-soil mesocosms from a northwest (NW) exposed site, representing today's climatic conditions, to a southwest (SW) exposed site, providing a model climate for future conditions with naturally occurring increased soil temperature (+0.

Effects of Elevated Atmospheric CO2 on Microbial Community Structure at the Plant-Soil Interface of Young Beech Trees (Fagus sylvatica L.) Grown at Two Sites with Contrasting Climatic Conditions.

Soil microbial community responses to elevated atmospheric CO2 concentrations (eCO2) occur mainly indirectly via CO2-induced plant growth stimulation leading to quantitative as well as qualitative changes in rhizodeposition and plant litter. In order to gain insight into short-term, site-specific effects of eCO2 on the microbial community structure at the plant-soil interface, young beech trees (Fagus sylvatica L.) from two opposing mountainous slopes with contrasting climatic conditions were incubated under ambient (360 ppm) CO2 concentrations in a greenhouse.

Nitrous oxide emissions from soils: how well do we understand the processes and their controls?

Although it is well established that soils are the dominating source for atmospheric nitrous oxide (N2O), we are still struggling to fully understand the complexity of the underlying microbial production and consumption processes and the links to biotic (e.g. inter- and intraspecies competition, food webs, plant-microbe interaction) and abiotic (e.

Interspecific temporal and spatial differences in the acquisition of litter-derived nitrogen by ectomycorrhizal fungal assemblages.

The spatiotemporal dynamics of, and interspecific differences in, the acquisition of litter-derived nitrogen (N) by natural assemblages of ectomycorrhizal root tips are poorly understood. Small cylindrical mesh bags containing (15)N-labelled beech (Fagus sylvatica) leaf litter that permit hyphal but not root ingrowth were inserted vertically into the top soil layer of an old-growth beech forest. The lateral transfer of (15)N into the circumjacent soil, roots, microbes and ectomycorrhizas was measured during an 18-month exposure period.