Contamination and source-specific health risk assessment of soil heavy metals in the middle and upper reaches of the Heihe River Basin of China.

Anthropogenic activities drive heavy metal contamination in soil, making source-specific apportionment essential for managing health risks in rapidly urbanizing areas. This study focuses on the novel task of quantifying health risks from specific sources of heavy metal contamination and visualizing the spatial patterns of human activities' impact on heavy metal contamination and health risks. It combined multiple analytical techniques, including pollution indices, health risk assessments, and bivariate local indicators of spatial association analysis.

Nitrogen availability in soil controls uptake of different nitrogen forms by plants.

Nitrogen (N) uptake by plant roots from soil is the largest flux within the terrestrial N cycle. Despite its significance, a comprehensive analysis of plant uptake for inorganic and organic N forms across grasslands is lacking. Here we measured in situ plant uptake of 13 inorganic and organic N forms by dominant species along a 3000 km transect spanning temperate and alpine grasslands.

Loss of taxonomic and functional diversity and decrease in primary productivity with nitrogen enrichment after a long-term release from grazing in an alpine grassland.

Moderate grazing can sustain high species diversity and productivity. However, nitrogen enrichment often reduces species richness while promoting primary productivity, which contradicts the traditional understanding of the positive effect of plant diversity on productivity. Whether the responses of diversity and productivity to N enrichment on a long-term scale conform to those on short-term scale.

Characterization of the complete chloroplast genome sequence of wetland macrophyte (Typhaceae).

is an important wetland macrophyte native to the eastern parts of Asia and Oceania. Herein, the complete chloroplast genome of this species was assembled and characterized using whole-genome next-generation sequencing. The complete chloroplast genome showed a circular genome of 160,969 bp size with 36.

Soil respiration and its Q response to various grazing systems of a typical steppe in Inner Mongolia, China.

Background: As one of the important management practices of grassland ecosystems, grazing has fundamental effects on soil properties, vegetation, and soil microbes. Grazing can thus alter soil respiration (Rs) and the soil carbon cycle, yet its impacts and mechanisms remain unclear.

Methods: To explore the response of soil carbon flux and temperature sensitivity to different grazing systems, Rs, soil temperature (ST), and soil moisture (SM) were observed from December 2014 to September 2015 in a typical steppe of Inner Mongolia under three grazing systems: year-long grazing, rest-rotation grazing, and grazing exclusion.

The effects of changes in water and nitrogen availability on alien plant invasion into a stand of a native grassland species.

Plant invasions are a major component of global change, but they may be affected by other global change components. Here we used a mesocosm-pot experiment to test whether high water availability, nitrogen (N) enrichment and their interaction promote performance of three invasive alien plants (Lepidium virginicum, Lolium perenne and Medicago sativa) when competing with a native Chinese grassland species (Agropyron cristatum). Single plants of the three invasive and the one native species were grown in the center of pots with a matrix of the native A.

Nitrogen acquisition by plants and microorganisms in a temperate grassland.

Nitrogen (N) limitation is common in most terrestrial ecosystems, often leading to strong competition between microorganisms and plants. The mechanisms of niche differentiation to reduce this competition remain unclear. Short-term (15)N experiments with NH4(+), NO3(-), and glycine were conducted in July, August and September in a temperate grassland to evaluate the chemical, spatial and temporal niche differentiation by competition between plants and microorganisms for N.

Microbial properties explain temporal variation in soil respiration in a grassland subjected to nitrogen addition.

The role of soil microbial variables in shaping the temporal variability of soil respiration has been well acknowledged but is poorly understood, particularly under elevated nitrogen (N) deposition conditions. We measured soil respiration along with soil microbial properties during the early, middle, and late growing seasons in temperate grassland plots that had been treated with N additions of 0, 2, 4, 8, 16, or 32 g N m(-2) yr(-1) for 10 years. Representing the averages over three observation periods, total (Rs) and heterotrophic (Rh) respiration were highest with 4 g N m(-2) yr(-1), but autotrophic respiration (Ra) was highest with 8 to 16 g N m(-2) yr(-1).

Effect of rainfall interannual variability on the biomass and soil water distribution in a semiarid shrub community.

The dynamics of biomass and soil moisture in semiarid land is driven by both the current rainfall and the ecosystem memory. Based on a meta-analysis of existing experiments, an ecosystem model was used to calculate the effect of the rainfall interannual variability on the pattern of biomass and soil moisture in a shrub community. It was found that rainfall interannual variability enabled shrubs to be more competitive than grasses, and to maintain the dominant role over a longer time.

Carbon sequestration in two alpine soils on the Tibetan Plateau.

Soil carbon sequestration was estimated in a conifer forest and an alpine meadow on the Tibetan Plateau using a carbon-14 radioactive label provided by thermonuclear weapon tests (known as bomb-(14)C). Soil organic matter was physically separated into light and heavy fractions. The concentration spike of bomb-(14)C occurred at a soil depth of 4 cm in both the forest soil and the alpine meadow soil.

[Population structure and distribution pattern of rare plant communities in Houhe Nature Reserve].

An investigation on the size structure and spatial pattern of 26 major tree species with a diameter at breast height (DBH) > or = 5 cm was made on a 1 hm2 fixed plot in the mixed evergreen and deciduous broad-leaved forest in Houhe National Nature Reserve of Central China. The results showed that 7 populations of the 26 species, i.e.

[Fractal properties of the spatial pattern of rare and endangered plant populations in Houhe Nature Reserve in Hubei: Box-counting dimension].

The fractal properties of the spatial distribution pattern of 4 dominant plant populations and 7 rare and endangered plant populations were reflected through the box-counting dimensions. The results showed that the box-counting dimensions of 4 dominant populations ranged between 1.346 and 1.