Effects of stand density on the structure of soil microbial functional groups in Robinia pseudoacacia plantations in the hilly and gully region of the Loess Plateau, China.

Elucidating the responses of soil microbial functional groups to changes in stand density is crucial for understanding the sustainability of forest development. In this study, we obtained soil samples from Robinia pseudoacacia plantations of three different stand densities (low, middle, and high densities of 750, 1125, and 1550 trees ha, respectively) in the hilly and gully region of the Loess Plateau, China. We sought to determine the effects of stand density on the structure of soil microbial functional groups.

[Response of Soil Respiration Rates to Soil Temperature and Moisture at Different Soil Depths of Plantation in the Loess-Hilly Region].

It is of great significance to clarify the influence of soil temperature and moisture on soil respiration rate and its characteristics in ecologically fragile regions under the background of climate change for the accurate assessment and prediction of carbon budgets in this region. The average CO concentration and soil temperature and moisture at different soil depths (10, 50, and 100 cm) were measured using a CO analyzer and temperature and moisture sensors. The soil respiration rate was calculated using Fick's first diffusion coefficient method.

Rainfall pulse response of carbon fluxes in a temperate grass ecosystem in the semiarid Loess Plateau.

Rainfall pulses can significantly influence carbon cycling in water-limited ecosystems. The magnitude of carbon flux component responses to precipitation may vary depending on precipitation amount and antecedent soil moisture, associated with nonlinear responses of plants and soil microbes. The present study was carried out in a temperate grass ecosystem during 2013-2015 in the semiarid Loess Plateau of China, to examine the response of carbon fluxes to precipitation using the "threshold-delay" model.

Sap flow characteristics and responses to summer rainfall for and in the Loess hilly region of China.

As a major driving element of the structure and function of arid and semiarid ecosystems, rainfall is the essential factor limiting plant biological processes. To clarify the characteristics of transpiration and responses to summer rainfall, sap flow density () of and was monitored using thermal dissipation probes. In addition, midday leaf water potential (ψ) and leaf stomatal conductance () were also analyzed to determine water use strategies.

The coupling of leaf, litter, and soil nutrients in warm temperate forests in northwestern China.

The nutrient ecological stoichiometry of plants and soil is important for the growth and dynamics of species, but the stoichiometric relationships among leaf, litter, and soil remain poorly understood. We analyzed the carbon (C), nitrogen (N), and phosphorus (P) stoichiometry of the leaves, litter, and soil for 31 species at 140 sites in warm temperate forests in northwestern China to document the patterns of nutrient traits and their relationships with climatic factors. The average concentrations of C, N, and P in the combined forests were 462.

[C, N, P stoichiometric characteristics of tree, shrub, herb leaves and litter in forest community of Shaanxi Province, China].

A total of 121 sampling sites were selected to study the C, N, P stoichiometric characteristics among the leaves of tree, shrub, herb and the litter of the majority forest community of Shaanxi Province, China. We also studied their relationships with geographical factors. The results showed that C, N concentrations were highest in tree leaf, P concentration was highest in herb leaf, and the C, N, P concentrations were lowest in litter.

Temporal-Spatial Pattern of Carbon Stocks in Forest Ecosystems in Shaanxi, Northwest China.

The precise and accurate quantitative evaluation of the temporal and spatial pattern of carbon (C) storage in forest ecosystems is critical for understanding the role of forests in the global terrestrial C cycle and is essential for formulating forest management policies to combat climate change. In this study, we examined the C dynamics of forest ecosystems in Shaanxi, northwest China, based on four forest inventories (1989-1993, 1994-1998, 1999-2003, and 2004-2008) and field-sampling measurements (2012). The results indicate that the total C storage of forest ecosystems in Shaanxi increased by approximately 29.

[Storage and allocation of carbon and nitrogen in Pinus tabuliformis plantations on the south slope of the East Qinling Mountains, China].

The objective of this study was to study carbon and nitrogen storages and distributions in Pinus tabuliformis plantations along an age chronosequence of 8-, 25-, 35-, 42- and 61-year-old on the south slope of the East Qinling Mountains; China. Results showed that the carbon content and nitrogen contents ranged from 441.40 to 526.

[Storage and allocation of carbon and nitrogen in Robinia pseudoacacia plantation at different ages in the loess hilly region, China].

The 9-, 17-, 30- and 37-year-old Robinia pseudoacacia plantations in the loess hilly region were investigated to study the dynamics and allocation patterns of carbon and nitrogen storage. The results showed that the ranges of carbon and nitrogen contents were 435.9-493.

Chromatic dispersion correction in planar waveguide using one-layer volume holograms based on three-step exposure.

We propose a novel method to correct the chromatic dispersion in a planar waveguide with volume holograms fabricated by the three-step exposure technique. The 532 nm green laser is used to illuminate the holographic plate in three groups of different angles for achieving the desired holograms. When it is used in the planar waveguide, the chromatic dispersion of the original display can be corrected and an image with the real color can be obtained.

[Effects of artificial seabuckthorn forest on soil and water conservation in loess hilly region].

Seabuckthorn is regarded as a main eco-economical tree species, and plays an increasing important role in eco-environmental construction in Northwest, Northeast and North China. Our study on artificial seabuckthorn forest in loess hilly region showed that the average rainfall interception rate of 7-10 ages seabuckthorn canopy was 8.5%, and the litter layer of 5-10 ages seabuckthorn forest could intercept 0.

[Ecological benefits of artificial seabuckthorn stands in semi-arid hilly region of Loess plateauion soil- and water conservation and soil moisture].

There is a remarkable function on decreasing runoff and sediment in seabuckthorn and its mixed stands, but the effects on soil- and water conservation are different due to different structure and patterns of seabuckthorn and its mixed stands. The intensity of soil water use by seabuckthorn forest was different along with the month in growing season. In growing season, soil moisture in 0-500 cm layer was 5.