Influence of experimental treatments on mean acorn root length and seedling height (cm) at the end of the experiment.

<p>Means with the same letter are not significantly different from each other (P>0.05 ANOVA followed by Scheffe test). Error lines represent ± standard deviation of the mean. The legend is the same as described for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047682#pone-0047682-g003" target="_blank">Figure 3</a> above.</p

The mean absolute emergence rates of root and shoot from sharp tooth oak with five mechanical scarification treatments.

<p>Data were the emergence rate every seven days. The legend is the same as described for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047682#pone-0047682-g003" target="_blank">Figure 3</a> above.</p

The effect picture of growth condition of Chinese cabbage seeds.

<p>The seeds were watered by distilled water (CK) and 80% methanol extracts from embryo, cotyledon and pericarp of sharp tooth oak acorns.</p

Profile of acorn measurement.

<p>L-Length, PL- Package length, D- Diameter, CSD- Cup scar diameter.</p

The consequent length of roots and shoots from sharp tooth oak acorns following five different mechanical scarification treatments.

<p>Data were calculated using germinant acorns to divide by all tested seeds, then multiplied by 100%. CK – the control, RS – removing the cup scar, RP – removing the pericarp, HC – removing pericarp and cutting off 1/2 of the distal end of the cotylendon, TC - removing pericarp and cutting off 2/3 of the distal end of the cotylendon.</p

The schematic diagram of different mechanical treatments of sharp tooth oak acorn.

<p>The schematic diagram of different mechanical treatments of sharp tooth oak acorn.</p

Germinating, rooted and irresponsive percentage of sharp tooth oak acorns in 137 days.

<p>Error lines represent ± standard deviation of the mean.</p

Dissolved inorganic N deposition and the ratio of NH₄⁺-N/NO₃^--N during the entire growing season at the 12 experimental sites.

<p>Dissolved inorganic N deposition and the ratio of NH₄⁺-N/NO₃^--N during the entire growing season at the 12 experimental sites.</p

Seasonal and Spatial Variations of Bulk Nitrogen Deposition and the Impacts on the Carbon Cycle in the Arid/Semiarid Grassland of Inner Mongolia, China

<div><p>Atmospheric nitrogen (N) deposition is an important component that affects the structure and function of different terrestrial ecosystem worldwide. However, much uncertainty still remains concerning the magnitude of N deposition on grassland ecosystem in China. To study the spatial and temporal patterns of bulk N deposition, the levels of N (NH₄⁺-N and NO₃^--N) concentration in rainfall were measured at 12 sites across a 1200 km grassland transect in Inner Mongolia, China, and the respective N deposition rates were estimated. The inorganic N deposition rates ranged from 4.53 kg N ha^-1 to 12.21 kg N ha^-1 with a mean value of 8.07 kg N ha^-1 during the entire growing season, decreasing steadily from the eastern to the western regions. Inorganic N deposition occurred mainly in July and August across meadow steppe, typical steppe, and desert steppe, which corresponded to the seasonal distribution of mean annual precipitation. A positive relationship was found between inorganic N deposition and mean annual precipitation (R² = 0.54 ~ 0.72, <i>P</i> < 0.0001) across the grassland transect. Annual estimation of inorganic N deposition was 0.67 Pg yr^-1 in Inner Mongolia, China based on the correlation between N deposition rates and precipitation. N deposition was an important factor controlling aboveground biomass and ecosystem respiration, but has no effect on root biomass and soil respiration. We must clarify that we used the bulk deposition samplers during the entire sampling process and estimated the dissolved NH₄⁺-N and NO₃^--N deposition rates during the entire growing season. Long-term N deposition monitoring networks should be constructed to study the patterns of N deposition and its potential effect on grassland ecosystem, considering various N species, i.e., gaseous N, particle N, and wet N deposition.</p></div

Seasonal variations of inorganic N concentrations in three different steppe types, i.e., meadow steppe, typical steppe, and desert steppe across the grassland transect during the entire growing season.

<p>Seasonal variations of inorganic N concentrations in three different steppe types, i.e., meadow steppe, typical steppe, and desert steppe across the grassland transect during the entire growing season.</p