Aims The French-Swiss School of phytosociology, also known as the Braun-Blanquet School, is prevalent in Europe and is one of the most influential schools in vegetation science. Here we gave a short introduction of the history of the French-Swiss School, its fundamental theory and the field practice. The development of the school can be divided into four periods: establishment (1910-1943), development (1945-1980), transition (1980-1990), and integration (1990-). The school gives emphasis on the importance of field practice, species interactions and community dynamics, and the critical role of character species or diagnostic species in vegetation studies. The school also emphasizes that the main attribute of plant community is species composition, and has developed a detailed workflow of field inventory and vegetation classification. Using the association as the basic unit, it builds a rigorous and formal system for vegetation classification. And the school has the strong compatibility in theory and technique. All these advantages are served as the basis of the development of current vegetation ecology. In addition, we identified several improvements needed or challenges of the school, including the definition of character species and association, data integration and transformation, and the linkage with eco-physiognomic vegetation classification. Finally, we gave a short introduction to the history of the French-Swiss School in China, and discussed its potential to elevate the current vegetation research in China.

Aims Shrubs play important roles in both forest and bushland ecosystems. This study aims to identify the adaptative strategies of shrubs in different habitats by analyzing the differences in functional traits of shrubs grown in understory of forest communities and in two bushlands.
Methods Nine functional traits for leaves and twigs were measured on samples collected from the dominant shrub species in 24 plots distributed in three contrasting habitats: forest understory, low mountain bushes, and bushes on the mountaintop, in Beishan Mountain of Jinhua, Zhejiang Province. The overall differences among habitats, inter- and intra-specific variations, and differences between life forms in the functional traits of shrubs were tested by statistical analysis.
Important findings The nine plant traits differed for shrubs grown in the three habitats. The shrubs in forest understory had higher leaf area (LA) and specific leaf area (SLA), lower leaf dry-matter content (LDMC), leaf tissue density (LTD) and twig tissue density (TTD), while those in low mountain bushes had greater leaf thickness (LT) and LTD, smaller SLA and twig dry-matter content (TDMC), compared with shrubs from bushes on the mountaintop. The inter- and intra-specific variation coefficients of SLA, twig diameter (TD), TTD, and TDMC were greatest in shrubs of the forest understory, whereas the inter- and intra-specific variation coefficients of SLA, LDMC, TDMC, and TTD were smallest in ​​shrubs of low mountain bushes. Among different life forms, the understory evergreen shrubs had significantly higher LT, LTD, and LDMC, and lower SLA, than that of deciduous shrubs. The differences in LT and SLA between evergreen and deciduous shrubs of the mountaintop bushes were the same as the understory shrubs, but the differences in LTD and LDMC were reversed. Species and its interaction with habitat are the major factors affecting the shrub traits. In short, compared to the shrubs from bushes, the understory shrubs in forest communities form a series of trait combinations with greater LA and SLA, and smaller LTD, TTD and LDMC for faster growth in order to adapt to the understory environment with less light and stronger competition; this is a quick investment-return (resource acquisitive) strategy. Shrubs from low mountain bushes and the mountaintop bushes are associated with a series trait combinations with greater LT, LTD, LDMC and TTD, and smaller LA, SLA for storing more nutrients and growing slower; this is a slow investment-return (resource conservative) strategy. Different combinations of shrub functional traits and their various life strategies can provide guidance to the ecological restoration of degraded vegetation in the subtropical region of China.

Aims An analysis of the variations in leaf traits of different tree species contributes to the understanding of plant community structures.
Methods This study explored the effect of the light environment on leaf traits at different canopy heights in a typical mixed broadleaved-Korean pine forest. We measured the leaf mass per area (LMA), leaf thickness (LT), leaf dry matter content (LDMC), chlorophyll content (CCI), leaf carbon content (C), mass-based and area-based nitrogen content (N_mass and N_area), and mass-based and area-based phosphorus content (P_mass and P_area) for 15 broad-leaved tree species in this forest.
Important findings We found that the LMA of Fraxinus mandschurica and Populus ussuriensis in the upper canopy were significantly higher than that in the lower canopy, but no significant vertical changes were detected in other species within the canopy. The CCI of Betula platyphylla increased from the lower to upper canopy. In contrast, the CCI of Ulmus japonica in the upper canopy was significantly higher than that in the middle canopy. The N_mass of Fraxinus mandschurica in the middle canopy was significantly higher than that in the upper canopy. These results indicated that the variations in leaf traits within the canopy were different among species. The LMA was positively correlated with the LT and LDMC in all three canopies, but the correlations of other trait combinations were only significant in one or two canopies. The results suggest that the leaves of Populus davidiana and Populus ussuriensis tend to adopt survival strategies involving lower photosynthetic ability, nutrient concentrations, and respiratory rates, while the leaves of Phellodendron amurense and Maackia amurensis tend to be located at the other end of the economics spectrum with contrasting trait values. Differences in species response to light may alter leaf morphological and chemical traits in canopy layers, and hence contribute to community assembly and species coexistence.

Aims To analyse the feasibility of space-for-time method in predicting phenology shifts of Plantago asiatica and Taraxacum mongolicum on the Qinghai-Xizang Plateau, as well as revealing the phenological changes of the two herbaceous plants under climate warming.
Methods The observed phenological data for Plantago asiatica and Taraxacum mongolicum from 10 sites on the Qinghai-Xizang Plateau during 2002-2011, as well as the meteorological data (i.e., daily mean air temperature) were collected. First, multiple linear regression models were bulit between geographic factors (longitude, latitude and altitude) and phenological events/annual mean temperature at different altitude gradients. Then, the longitude and latitude were kept to be unchanged, and the unary linear regression models between phenological events/annual mean temperature and altitude were built. Finally, the altitude was used as the “bridge” to indicate the relationship between the change of phenological events and the change of annual mean temperature.
Important findings The temperature decreased with the increasing altitude (R² > 0.89, p < 0.05), illustrating that changes of altitude gradients can be used to substitute for changes of annual mean temperature. The change in the simulated phenological events of the two herbaceous plants all showed a strong dependence on the change of altitude (R² > 0.70, p < 0.05), which contributed the most among the geographic factors. Strong dependences were observed between the simulated phenological events and the simulated annual mean temperature (R² > 0.93, p < 0.05), showing that phenological events could be predicted by the annual mean temperature with the space-for- time method. For Plantago asiatica, the first leaf date (FLD) and the first flowering date (FFD) occurred earlier with increasing annual mean temperature as 5.1 and 5.4 days per ℃, respectively, while the common leaf coloring date (LCD) occurred later as 4.8 days per ℃. The FLD and FFD of Taraxacum mongolicum advanced by 6.5 days and 7.8 days per ℃ of increase in the mean annual temperature while the LCD delayed by 6.7 days per ℃.

Aims A variety of plant species can release soil water which is absorbed from wet soil layers to the dry soil layers during the period when transpiration rate is low (hydraulic lift). The purpose of this study is to explore the phenomenon of hydraulic lift for the mixed sowing combinations of two leguminous forages with gramineous forage, uncover the inter-specific relationship between forages with deep and shallow roots and provide theoretical basis for the establishment of mixed grassland.
Methods A split-root pot experiment was conducted outdoors. Two leguminous forages Medicago sativa and Astragalus laxmannii were sowed individually or sowed with a gramineous forage (Secale cereal ‘Dongmu 70’) with proportions of 3:7, 5:5 and 7:3. While the soil water content was measured continuously, deuteroxide (D₂O, D% > 99.9%) tracing technique was adopted to test the occurrence of hydraulic lift and to calculate the lift water quantity.
Important findings The yield of S. Cereal ‘Dongmu 70’ in mixed sowing with A. laxmannii was higher than that with M. sativa. The yield of AC2 (Medicago sativa:gramineae being 5:5) and BC3 (A. laxmannii : gramineae being 7:3) was higher than other mixed sowing proportions in the same mixed sowing combination. There was a significant difference in the average daily water lift during the whole growth period among different single sowing or mixed sowing combinations. The lift water amount for a given leguminous forage was higher in mixed sowing combinations than in single sowing combinations. A. laxmannii displayed higher daily water lift quantity regardless of single sowing or mixed sowing. The average daily water lift of BC2 (A. laxmannii : gramineae being 5:5) was significantly higher than other combinations. Hydrogen stable isotope ratio (δD) of soil water in upper and bottom pots significantly increased after treated with deuteroxide tracer. The values of soil water δD in the upper pot, xylem water δD, whole plant carbon isotope discrimination (Δ¹³C) and yield of Secale cereal ‘Dongmu 70’ have provided the evidence that the water status or yielding performance of S. cereal ‘Dongmu 70’ in the combinations of BC1 (A. laxmannii : gramineae being 3:7) and AC2 was better than other mixed combinations. This study validated the hypothesis that the phenomenon of hydraulic lift occurred when the deep-rooting leguminous and gramineous forages with shallow root were sown together. The water lift by the tested leguminous forages has been absorbed by their neighboring gramineous forage.

Aims The pattern of plant biomass allocation represents the plant response to the environment and is accompanied by every stage of plant life history. So it is closely related to the growth and development of plants. There have been reports on the size dependence of plant biomass allocation, but few studies have reported on its responses to different phenological phase.
Methods In this study, Nitraria tangutorum in Ulan Buh Desert was used as the research object. The biomass of different organs (root, layering, newborn stem, older stem, leaf and reproductive organ) in the flowering, fruiting and vegetative growth stages in two consecutive years of 2016 and 2017 were measured. The significant differences of slope and intercept of the fitted equation with Standardized-major-axis were respectively used to discuss the varied size dependence and the biomass allocation in different phenological phase or ages, especially between the aboveground and belowground biomass and between the support and assimilation organs.
Important findings The results showed that the effect of reproductive allocation on biomass allocation pattern of N. tangutorum is mainly reflected in the scale of relative biomass allocation (36.00%) rather than the extent of size dependence (16.67%). The reproductive growth has a greater impact on the biomass allocation pattern of newborn stems, which changes the size dependence extent among different phenological phases, but the trend is inconsistent. The reproductive growth increases the scale of relative biomass allocation to leaves and reduces that to older stems, but did not change their extent of size dependence. The biomass allocation rate in the belowground part of N. tangutorum increased with the accumulation of its biomass, but the reproductive allocation slightly decreased this rate. Nitraria tangutorum exhibited a higher rate of biomass allocation to supporting organs as plant biomass increases. Over time it is more likely for biomass to be allocated to assimilating organs.

Aims Nutrient availability is an external factor that affect the growth of seagrasses. However, the demand for and absorption of different forms of nitrogen and phosphorus by different tissues of seagrasses are unclear. In this study, the uptake of nitrogen and phosphorus by Zostera marina was studied to determine the nutrient uptake kinetics. The objectives of this research are to: 1) investigate the absorption characteristics of ammonia nitrogen, nitrate nitrogen and phosphorus in Z. marina; 2) evaluate the differences in absorption between the different forms of nitrogen; and 3) analyse the differences in absorption between the different tissues of Z. marina.
Methods Equipment was used to separate the aboveground and belowground tissues of Z. marina. Six concentration levels of ammonia nitrogen, nitrate nitrogen and phosphorus were established to experimentally test the uptake kinetics of nutrients by Z. marina. The nutrient concentrations in different parts of seawater column were measured to determine the nutrient changes and calculate the kinetic characteristics of nutrient uptake.
Important findings 1) The absorption of ammonia nitrogen, nitrate nitrogen and phosphorus by Z. marina was consistent with the characteristics of saturated absorption kinetics. The relationship between the absorption rate and the nutrient concentrations in water could be described by the Michaelis-Menten equation. 2) The maximum absorption rate (V_max) of ammonia nitrogen by Z. marina (52 μmol·g^-1·h^-1) was significantly higher than that of nitrate nitrogen (39 μmol·g^-1·h^-1). 3) Both aboveground and belowground tissues of Z. marina could absorb nutrient, but the V_max of leaves (aboveground tissues) for ammonia nitrogen, nitrate nitrogen and phosphorus absorption were 43.1, 30.5 and 15.6 μmol·g^-1·h^-1, respectively, which were 2.6-fold, 1.2-fold and 6-fold higher than the corresponding V_max of belowground tissues. The results show that the absorption capacity of Z. marina for ammonia nitrogen is higher than that for nitrate nitrogen, and the absorption of nitrogen and phosphorus may depend primarily on the aboveground tissues (leaves). The results provide a theoretical basis for the study of the mechanisms of nitrogen and phosphorus uptake and utilization by Z. marina and the evaluation of marine ecological impacts.

Aims Arbuscular mycorrhizal fungi (AMF) form symbiotic relationships with most terrestrial plants, contributing to the nutrient uptake of host plants. While little is known on how rhizospheric microorganisms affect the relationships between AMF and host plants under nutritional stress. We hypothesize that AMF may compete for nutrients with host plants in extremely nutrient-limited environments, such as nitrogen deficient habitats, and nitrogen-fixing bacteria will alleviate the competition.
Methods In order to test our hypotheses, we grew Solidago canadensis plants under nitrogen deficient treatments. We inoculated plants with AMF and a nitrogen-fixing bacterium to test the relationships among the host plant and microorganisms.
Important findings Under the lowest nitrogen level (0.025 mmol·L^-1 N of ammonium nitrogen), the growth of S. canadensis was more restricted with AMF colonization, suggesting competition between AMF and the host. However, with the inoculation of nitrogen-fixing bacterium, AMF colonization was promoted and plant growth was increased. These results indicate that nitrogen-fixing bacteria could moderate the competition for nutrients between AMF and their host under nitrogen deficiency. This study improves our understanding of the invasion mechanisms of alien plants, where they interact with different microorganisms under extreme nutrient stress.