Search

Plant root variations and their relations with soil moisture and nutrient supply have been well documented for many species, while effects of drought, combined with extreme poor soil nutrients, on plant roots remain unclear.Herein, we addressed root vertical distributions of two typical xerophyte semishrub species, Artemisia sphaerocephala and A. intramongolica, and their relations with soil moisture, total soil nitrogen and carbon contents in arid Hunshandake desert, China. The two species experienced similar light regimes and precipitation, but differed in soil moisture and soil nutrients.Root vertical distribution patterns (e.g., coarse root diameter, root depth and root biomass) differed considerable for the two species due to high heterogeneity of soil environments. Coarse and fine root biomasses for A. intramongolica, distributed in relatively moist fixed dunes, mainly focused on surface layers (94%); but those for A. sphaerocephala dropped gradually from the surface to 140 cm depth. Relations between root traits (e.g., diameter, root biomass) and soil moisture were positive for A. intramongolica, but those for A. sphaerocephala were negative.In general, the root traits for both species positively correlated with total soil nitrogen and carbon contents. These findings suggest that both soil moisture and poor soil nutrients were the limiting resources for growth and settlement of these two species., The root traits for Artemisia sphaerocephala and A. intramongolica were positively correlated with total soil nitrogen and carbon contents. These findings indicate that both soil moisture and poor soil nutrients were the limiting resources for growth in these two species.

The impacts of banning wild spat collection are crucial for the future development of the Zhikong scallop fishery. Failure to the quantitative analysis of economic impacts obstructs the understanding of policy performance. Using key parameters extracted from the data and information through field research, we estimate the financial losses in spat collection, mariculture, and processing sectors. Our results show that the local ban should spark a chain reaction on the national Zhikong scallop fishery and potentially cause substantial economic consequences. The decreasing profitability and growing negative externalities of traditional mariculture are the main reasons for the local government to overhaul its marine development strategy. These findings have implications for some problems in the current marine management system or, from a more positive perspective, the crisis of the Zhikong scallop fishery providing China an opportunity to accelerate reforms for sustainable mariculture.

In nitrogen (N)-limited temperate regions, winter is an important period of N accumulation. The accumulated N is released during snowmelt and thawing, and the availability peaks in early spring. However, the early-spring dynamics of specific N forms (i.e., ammonium NH4+ and nitrate NO3−) in temperate grasslands are still not fully understood. Here, we added 15NH4+ and 15NO3− (equivalent to 150 mg 15N m−2) to the soils of a meadow steppe and a typical steppe in northern China immediately after snowmelt, then quantified the retention dynamics of 15NH4+ and 15NO3− in soils, microbes, and plants over the subsequent growing season. Approximately 70% of the added 15N tracers were initially retained within the soil−microbe−plant systems in both temperate grasslands. In early spring, much 15N was immobilized in soils and microbes, while little had been taken up by plants. During the subsequent growing season, approximately 45% of the 15N was rapidly lost by the soils and microbes, but plant 15N acquisition gradually increased. Although soils and plants retained similar levels of 15NH4+ and 15NO3− during the growing season, soil microbes retained more 15NH4+ than 15NO3−. Different plant taxa had distinct 15N acquisition capacities: perennial grasses and forbs accumulated the 15N tracers rapidly, while annuals did not. Perennial grasses were effective immobilizers of the 15NH4+, whereas forbs were effective immobilizers of the 15NO3−. These findings provided evidence of the substantial retention of early-spring N over the following growing season in temperate grasslands, regardless of the vegetation type and N form. However, it was clear that the dynamics of early-spring 15NH4+ and 15NO3− differed within the soil−microbe−plant systems.

Island tourism is an important part of marine tourism and has developed into an important part of international tourism consumption. The island tourism environment is the foundation for the sustainable development of island tourism. This paper takes Koh Lan as the research area to conduct a questionnaire survey among international tourists to understand their perception of the tourism environment of the island based on descriptive analysis and cross-analysis. The results show that tourists in the tourism environment of the island have obvious behavioral characteristics. 66.7% of the tourists are interested in the island through friends and networks; 76.9% of them travel together with their families and friends more than once; more than 56% of them stay for one day causing the low willingness of these tourists; the homestay is the favorite accommodation option for those who choose to stay; 51.5% of tourists choose to eat at the hotel, and 92.7% of visitors spend less than US $500; 24.2% of the time is used to visit Tawaen Beach, which is the most popular tourist attraction on the island; visitors of different ages and genders have different preferences when choosing travel activities; beach leisure is a favorite activity for tourists. The study evaluates tourists' satisfaction with the tourism environment of the island. More than 90% of the tourists expressed satisfaction with the experience of visiting the island. This evaluation reflects the deficiencies and directions for improvement of the tourism environment of the island and provides inspiration for the development of international island tourism.

Global climate change is predicted to stimulate primary production and consequently increases litter inputs. Changing precipitation regimes together with enhanced litter inputs may affect plant community composition and structure, with consequent influence on diversity and ecosystem functioning. Responses of plant community to increased precipitation and belowground litter addition were examined lasting 5 years in a semiarid temperate grassland of northeastern China. Increased precipitation enhanced community species richness and abundance of annuals by 16.8% and 44%, but litter addition suppressed them by 25% and 54.5% after 5 years, respectively. During the study period, perennial rhizome grasses and forbs had consistent negative relationship under ambient plots, whereas positive relationship between the two functional groups was found under litter addition plots after 5 years. In addition, increased precipitation and litter addition showed significant interaction on community composition, because litter addition significantly increased biomass and abundance of rhizome grasses under increased precipitation plots but had no effect under ambient precipitation levels. Our findings emphasize the importance of water availability in modulating the responses of plants community to potentially enhanced litter inputs in the semiarid temperate grassland.

At the species level, plants can respond to climate changes by changing their leaf traits; however, there is scant information regarding the responses of morphological, physiological and anatomical traits of plant functional types (PFTs) to aridity. Herein, the leaf traits of five PFTs representing 17 plant species in temperate grasslands were examined along a large-scale aridity gradient in northeastern China. The results show that leaf thickness in shrubs, perennial grasses and forbs increased with heightened aridity. Trees increased soluble sugar content, but shrubs, perennials and annual grasses enhanced proline accumulation due to increasing aridity. Moreover, vessel diameter and stomatal index in shrubs and perennial grasses decreased with increasing aridity, but stomatal density and vascular diameter of five PFTs were not correlated with water availability. In conclusion, divergences in adaptive strategies to aridity among these PFTs in temperate grasslands were likely caused by differences in their utilization of water resources, which have different temporal and spatial distribution patterns. Leaf traits of shrubs and perennial grasses had the largest responses to variability of aridity through regulation of morphological, physiological and anatomical traits, which was followed by perennial forbs. Trees and annual grasses endured aridity only by adjusting leaf physiological processes.

There have been debates on the driving factors of C4 plant expansion, such as PCO2 decline in the late Micocene and warmer climate and precipitation at large-scale modern ecosystems. These disputes are mainly due to the lack of direct evidence and extensive data analysis. Here we use mass flora data to explore the driving factors of C4 distribution and divergent patterns for different C4 taxa at continental scale in China. The results display that it is mean annual climate variables driving C4 distribution at present-day vegetation. Mean annual temperature is the critical restriction of total C4 plants and the precipitation gradients seem to have much less impact. Grass and sedge C4 plants are largely restricted to mean annual temperature and precipitation respectively, while Chenopod C4 plants are strongly restricted by aridity in China. Separate regression analysis can succeed to detect divergences of climate distribution patterns of C4 taxa at global scale.

Elucidating the driving factors among-population divergence is an important task in evolutionary biology, however the relative contribution from natural selection and neutral genetic differentiation has been less debated. A manipulation experiment was conducted to examine whether the phenotypic divergence of Leymus chinensis depended on climate variations or genetic differentiations at 18 wild sites along a longitudinal gradient from 114 to 124°E in northeast China and at common garden condition of transplantation. Demographical, morphological and physiological phenotypes of 18 L. chinensis populations exhibited significant divergence along the gradient, but these divergent variations narrowed significantly at the transplantation. Moreover, most of the phenotypes were significantly correlated with mean annual precipitation and temperature in wild sites, suggesting that climatic variables played vital roles in phenotypic divergence of the species. Relative greater heterozygosity (HE), genotype evenness (E) and Shannon-Wiener diversity (I) in western group of populations suggested that genetic differentiation also drove phenotypic divergence of the species. However, neutral genetic differentiation (FST = 0.041) was greatly lower than quantitative differentiation (QST = 0.199), indicating that divergent selection/climate variable was the main factor in determining the phenotypic divergence of the species along the large-scale gradient.