Ju-Ying Huang’s research while affiliated with Ningxia University and other places

Salt stress has become a major threat to plant growth. Arbuscular mycorrhizal fungi (AMF) are considered as bioameliorators and can modulate plant growth in various ways. However, few studies have addressed whether AMF could mediate the detrimental effects of salinity on Ligustrum vicaryi plants. In this study, inoculated (colonization with two AMF, Rhizophagus intraradices (Ri) and Funneliformis mosseae (Fm), alone and in combination) and non-inoculated (NM) L. vicaryi plants were subjected to three levels of NaCl salinity (0, 50 and 200 mM NaCl) to examine the interactive effects on the growth, chlorophyll fluorescence parameters and biochemical parameters of plants in a greenhouse experiment. The results showed that salinity stress had significanlty decreased the total dry weight of L. vicaryi plants. However, with Ri inoculation, the total dry weight, Fv/Fm, Yield, qP, the nutrient contents of P, K⁺, Mg²⁺, Zn²⁺, the K⁺:Na⁺ ratio and soluble protein content were considerably increased, while tissue Na⁺ content and shoot:root Na⁺ ratio were decreaed under saline conditions. It is suggested that mycorrhizal fungi can alleviate the detrimental effects of salt stress on L. vicaryi plants. Furthermore, the results also provide evidence that the mediation of N, Ca²⁺, Zn²⁺, Mg²⁺ and soluble protein content would be probably the main mechanism underlying salt tolerance in mycorrhizal plants.

Soil samples from four vegetation mini-patches (Artemisia scoparia, Glycyrrhiza uralensis, Sophora alopecuroides, Astragalus melilotoides) in a desert steppe in central Ningxia were collected. Soil physico-chemical properties including soil particle-size distribution, organic matter, pH, EC, total N, total K, total P of three depths were measured. The fractal dimension of particle size distribution characteristics of soils derived from four different vegetation mini-patches and their correlations with soil physico-chemical properties were examined. The results showed that patch vege-tation distribution affected the distribution of soil particle size, with the A. melilotoides mini-patch being the highest (D=2.51) and G. uralensis mini-patch being the lowest (D=2.46). There were significant positive correlation between fractal dimensions and the contents of clay and silt, and nega-tive correlation between fractal dimensions and sand content. Fractal dimensions were positively correlated with pH value and EC, negatively correlated with the contents of soil organic matter and total N, and had no correlation with the contents of soil total K and total P. The patchy vegetation distribution had potential trends of salinization and degradation.

The serious negative impacts on local ecosystem alongside caused by expressway construction activities were analyzed. Based on theory of ecosystem services value and CBA(cost benefit analysis), the influence on and the damage to the ecosystem alongside by expressways construction are discussed and calculated in currency. Combined with comprehensive consideration of engineering cost, a scheme of minimum total cost was searched out through mathematical model to obtain the optimal scheme. The real purpose is to offer explicit economic information to management decision making during expressway construction, and make people realize that economic benefit brought by expressway construction have to be paid out by immense environmental cost and social cost. Which can help decision maker consider environmental cost and select right route.

Changes in precipitation can influence soil water and nutrient availability, and thus affect plant nutrient conservation strategies. Better understanding of how nutrient conservation changes with variations in water availability is crucial for predicting the potential influence of global climate change on plant nutrient-use strategy. Here, green-leaf nitrogen (N) and phosphorus (P) concentrations, N- and P-resorption proficiency (the terminal N and P concentration in senescent leaves, NRP and PRP, respectively), and N- and P-resorption efficiency (the proportional N and P withdrawn from senescent leaves prior to abscission, NRE and PRE, respectively) of Leymus chinensis (Trin.) Tzvel., a typical perennial grass species in northern China, were examined along a water supply gradient to explore how plant nutrient conservation responds to water change. Increasing water supply at low levels (< 9000 mL/year) increased NRP, PRP and PRE, but decreased green-leaf N concentration. It did not significantly affect green-leaf P concentration or NRE. By contrast, all N and P conservation indicators were not significantly influenced at high water supply levels (> 9000 mL/year). These results indicated that changes in water availability at low levels could affect leaf-level nutrient characteristics, especially for the species in semiarid ecosystems. Therefore, global changes in precipitation may pose effects on plant nutrient economy, and thus on nutrient cycling in the plant-soil systems.

Nitrogen (N) resorption from senescing leaves is an important mechanism of N conservation for terrestrial plant species, but changes in N-resorption traits over wide-range and multi-level N addition gradients have not been well characterized. Here, a 3-year N addition experiment was conducted to determine the effects of N addition on N resorption of six temperate grassland species belonging to three different life-forms: Stipa krylovii Roshev. (grass), Cleistogenes squarrosa (T.) Keng (grass), Artemisia frigida Willd. (semishrub), Melissitus ruthenica C.W.Wang (semishrub and N-fixer), Potentilla acaulis L. (forb) and Allium bidentatum Fisch.ex Prokh. (forb). Generally, N concentrations in green leaves increased asymptotically for all species. N concentrations in senescent leaves for most species (5/6) also increased asymptotically, except that the N concentration in senescent leaves of A. bidentatum was independent of N addition. N-resorption efficiency decreased with increasing N addition level only for S. krylovii and A. frigida, while no clear responses were found for other species. These results suggest that long-term N fertilization increased N uptake and decreased N-resorption proficiency, but the effects on N-resorption efficiency were species-specific for different temperate grassland species in northern China. These inter-specific differences in N resorption may influence the positive feedback between species dominance and N availability and thus soil N cycling in the grassland ecosystem in this region.