Aims The temperate grasslands in Inner Mongolia, representing a great diversity in vegetation types (desert steppe, typical steppe and meadow steppe) and function groups (grass/herb, legume/non-legume), are ideal places to test the hypothesized functional trait relationships among plant organs. Our main objective in this study was to test whether plant functional traits vary in a coordinated fashion both within and across organs.

Methods Based on the field observation during July and August in both 2006 and 2007, we measured suites of ecophysiological traits of 42 grassland species from 19 sites in Inner Mongolia. The longitude of the study region ranges from 112.82° to 120.12° (E), and the latitude ranges from 41.76° to 49.89° (N). N and P concentrations, N:P ratios of leaves, stems, reproductive structures, fine roots (diameter < 1 mm) and coarse roots (diameter > 1 mm) as well as tissue density of leaf and fine root and specific leaf area/specific root length were determined.

Important findings At both population and interspecific level, N and P concentrations were positively correlated within each organ. Specific leaf area was negatively correlated with leaf N and P concentrations and tissue density at the population level but not at the interspecific level. Specific root length was negatively related to fine root tissue density at population level. Plants with low leaf or fine root tissue density had leaves or fine roots with high N concentrations and large specific leaf area or specific root length. N and P concentrations as well as N: P ratios were also consistently correlated across all organs, but no correlation between specific leaf area and specific root length was observed. At the population level there existed a weak negative correlation between leaf and fine root tissue density while at interspecific level this relationship disappeared. Grasses had lower N and P concentrations than herbs in leaves, reproductive structures and roots, but not in stems. Legumes had higher N concentrations than non-legumes in all organs, but they showed no significant differences in P concentrations.

Aims Leaf N and P stoichiometry has been widely studied at the species level in both aquatic and terrestrial ecosystems, however, it lacks research at the community level. Since the ecological stoichiometric characteristics could play important roles in connecting different levels of ecological studies and former studies mainly focused on the individual level, in this study, we try to figure out the pattern of foliar N and P at the community level of grassland ecosystems in Qinghai-Tibetan Plateau. Additionally, we also try to find out the relationships between community level leaf N, P and site climate factors.

Methods Leaf samples were collected from 47 research sites in Qinghai-Tibetan Plateau at the end of the growing season yearly from 2006 to 2008. We measured the leaf N concentrations by using an elemental analyzer and the leaf P concentration based on a molybdate/stannous chloride method. Climate data of annual mean temperature and annual mean precipitation (65 national standard stations) between 2006 and 2008 were used to interpolate into gridded data with a resolution of 1 km × 1 km through the tchebycheffian spline function.

Important findings Leaf N, P concentrations and N:P ratios at the community level over the southern part of Qinghai-Tibetan Plateau were 23.2 mg·g^-1, 1.7 mg·g^-1 and 13.5, respectively. Significant inter-annual differences were presented in leaf N, P concentrations and N:P ratios. Mean annual temperature was strongly correlated with leaf N, P and N:P ratios. Besides, the correlations between climate factors and leaf N, P, N:P ratios were generally consistent with the previous results found at the global scale. Our results suggest that the high variation in leaf P concentration and its strong correlation with environmental factors reveal that, to some extent, stoichiometric traits at the community level are adaptive to local environmental conditions.

Aims Homeostasis constrains the elemental composition of individual species within narrow bounds no matter the chemical composition of the environment or the resource base. Our objective was to determine the dynamics of leaf stoichiometry during the growth period of plants and the optimum time for stoichiometry study.

Methods We monitored leaf N, P stoichiometry of Scirpus mariqueter, Carex scabrifolia and Phragmites australis, the dominant species in Hangzhou Bay coastal wetlands, at different growth stages from May to October 2007.

Important findings Leaf N, P stoichiometry of the Scirpus, Carex and Phragmites species showed differences: 7.41-17.12, 7.47-13.15 and 6.03-18.09 mg·g^-1 for N, 0.34-2.60, 0.41-1.10 and 0.35-2.04 mg·g^-1 for P, and 7.19-30.63, 11.58-16.81 and 8.62-21.86 for N:P ratios, respectively. The arithmetic means for the three species were (11.69 ± 2.66), (10.17 ± 1.53) and (11.56 ± 3.19) mg·g^-1 for N, (0.93 ± 0.62), (0.74 ± 0.23) and (0.82 ± 0.53) mg·g^-1 for P, and 16.83 ± 8.31, 14.53 ± 3.91 and 16.49 ± 5.51 for N:P, respectively, but there was no significant difference of N, P stoichiometry (p > 0.05). It showed high N, P concentrations at the early stage of growth because of small biomass and then decreased greatly with leaf expansion during the fast growth period, increased as leaf growth became stable and decreased again with leaf senescence. Leaf N:P was low at the early stage of growth and then increased, decreased strongly at the fast growth period, and became stable after leaf maturation.

Aims Studies on the relationship between leaf and fine root traits provide insights into interactions among plant functional traits, plant strategy for resource acquisition and mass partitioning, and predictive models for fine root traits. Our main objectives were to test if leaf and fine root traits vary in a coordinated pattern in typical temperate grassland and to determine to what extent inter- and intra-specific leaf and fine root traits exhibit structural and functional convergence.

Methods During July and August 2006, we measured nitrogen (N) and phosphorus (P) concentrations, N:P ratios of leaves and fine roots (diameter < 2 mm), specific leaf area and specific root length of 65 grassland species in Xilin River Basin, Inner Mongolia. We statistically analyzed correlations between leaf and fine root traits among and within species.

Important findings At the inter-specific level, N concentrations, P concentrations and N:P ratios of leaves and fine roots were significantly correlated, while specific leaf area and specific root length showed a weak relationship. Species from different functional groups differ in the correlation pattern. In dicotyledons there was a strong correlation between leaf and fine root N concentrations, but not in P concentrations. In contrast, monocotyledons had a positive relationship between leaf and fine root P concentrations, but not N concentrations. Observed inter-specific correlations between above and belowground traits weakened or disappeared when examined at the intra-specific level. Thus, leaf and fine root traits were generally correlated among species, while correlations were weak within species.

Aims Much research is being done on plant nutrients and stoichiometry. Our purpose was to reveal the effects of grazing on plant nutrients and stoichiometry in a typical steppe of Inner Mongolia of China.

Methods We studied nutrient content of C, N and P and their ratio in soil and leaves of dominant plants in three adjacent sites: fenced since 1983 and 1996 and unfenced. We employed the stoichiometric approach and assessed the effects of grazing on spatio-temporal patterns of nutrient cycling between plants and soil in restoration succession of degenerate steppes.

Important findings Both total soil nutrient content and the ratio of the soil total nitrogen and soil total phosphorus (STN:STP) were lower in overgrazed plant communities compared to fenced plant communities at different levels of restoration. Conversely, the ratio of soil organic carbon and STN (SOC:STN) was higher in overgrazed plant communities. The total organic carbon content (TOC) of most plants was higher in fenced communities and lower in grazed communities and was positively correlated with time since community restoration began. However, the content of total nitrogen (TN) and total phosphorus (TP) in plants was higher in fenced communities than that in grazed communities. Both TN and TP correlated negatively with time since restoration began and positively with the degree of degradation due to overgrazing. TP had a larger range in values compared to TN. The stoichiometry ratios of nitrogen and phosphorus (N:P) and carbon and nitrogen (C:N) in leaves were the lowest in grazed communities and correlated negatively with the degree of degradation. These communities had less total N than total P; however, this pattern was reversed in fenced communities, where sometimes both N and P were limiting. We propose that stoichiometry ratios in dominant plant species can serve as indicators of direction of plant succession in this typical steppe.

Aims Little is known about constrained ratios of carbon, nitrogen, and phosphorus (C:N:P) in terrestrial ecosystems. Our objective was to examine the C:N:P stoichiometry and its relationship with N and P resorption in evergreen broad-leaved forests (EBLF), evergreen coniferous forests (CF) and deciduous broad-leaved forests (DF) at the regional scale.

Methods The study was conducted in Tiantong National Forest Park (29°52′ N, 121°39′ E), Zhejiang Province, eastern China. To estimate foliar and litter C:N:P ratios and N and P resorption efficiencies, we quantified the C, N and P concentrations in leaf and litterfall in EBLF, CF and DF. We used type II regression slopes (reduced major axis, RMA) to determine whether C:N:P stoichiometry varied across gradients of forest production and nutrients.

Important findings The C:N:P ratios in EBLF, CF and DF were 758:18:1, 678:14:1 and 338:11:1 in fresh leaves and 777:13:1, 691:14:1 and 567:14:1 in litterfall, respectively. The foliar C:N ratio was highest in CF, intermediate in EBLF and lowest in DF, while the foliar C:P and N:P ratios were highest in EBLF, intermediate in CF and lowest in DF. In contrast, the litterfall C:N and C:P ratios were higher in EBLF than in CF and DF, and there were no significant differences of N:P ratio among forests. The type II regression slope for N vs. P in leaves of overall plants was statistically >1, suggesting an increasing investment of N with increasing of P in fresh leaves. In contrast, the slope for N vs. P in litterfall approximated 1. N resorption in EBLF was significantly higher than in CF and in DF, but the highest P resorption was observed in DF. Although foliar N:P ratios indicated that EBLF was P limited, DF was N limited and CF was both N and P limited, the nutrient resorption efficiency did not respond with relatively high N resorption in EBLF and high P resorption in DF. We concluded that the relative higher resorption of N and P before leaf abscission could be an inherent property of plants, but was not a mechanism thought to have evolved to conserve nutrients in environments with limited N or P supply.

Aims Plant or biomass stoichiometry can be used to distinguish biological entities (genes, cells, organisms, etc.) based on element composition. Our objective was to determine the stoichiometry characteristics and examine nutrient limitation in evergreen broad-leaved forest, coniferous and broad-leaved mixed forest and coniferous forest.

Methods We determined C, N, P stoichiometry of leaves of 19 dominant trees of 16 taxa in three forest types at the Pearl River Delta Forest Ecosystem Research Station, Guangdong Province, South China.

Important findings Leaf stoichiometry showed large variations: C ranged from 434 to 537 mg·g^-1, N from 6.8 to 23.0 mg·g^-1, P from 0.56 to 2.10 mg·g^-1, C:N from 21.22 to 70.74, C:P from 227.14 to 844.64 and N:P from 5.26 to 20.91. Leaf N, P, C:N and C:P were linearly correlated (p < 0.01). Leaf C, C:P and N:P (weighted average ± standard deviation: (517.85 ± 35.96), (727.47 ± 231.52) and (15.71 ± 3.76) mg·g^-1, respectively) were the highest in coniferous forest, followed by mixed forest (509.47 ± 19.38, 553.01 ± 152.32 and 10.93 ± 1.89, respectively) and evergreen broad-leaved forest (481.59 ± 18.35, 412.19 ± 200.91 and 9.46 ± 4.28, respectively), and a reverse sequence was detected for leaf P content. The sequence for N content was coniferous forest ((12.20 ± 5.65) mg·g^-1) > evergreen broad-leaved forest ((11.50 ± 4.24) mg·g^-1) > mixed forest ((10.51 ± 5.22) mg·g^-1) and for C:N was mixed forest (51.35 ± 13.65) > coniferous forest (47.40 ± 15.85) > evergreen broad-leaved forest (45.59 ± 14.70), and higher nutrient use efficiency was discovered in three forest types. Several evergreen broad-leaved trees and evergreen broad-leaved forest had shortages of N.

Aims Nitrogen (N) and phosphorus (P) are two key elements of life and are major limiting nutrients in many ecosystems across the world. The balance of N and P has become the focal point of global change ecology and biogeochemistry, especially as aggravated by atmospheric nitrogen deposition. Although N:P stoichiometry has proved useful in studies of nutrient limitation, biogeochemical cycles, forest succession and degraded land, little is known about it in lower subtropical forest succession. Therefore, our objective is to better understand nutrient controlling factors of plant-soil interaction and reveal interactions of N and P to provide insight and theoretical fundamentals for forest management.

Methods We measured total N and P of organs of dominant species and different soil layers in three forests in Dinghushan Biosphere Reserve, Southern China: pine forest (PF, early successional stage), pine and broad-leaved mixed forest (MF, middle stage) and monsoon evergreen broad-leaved forest (MEBF, advanced stage).

Important findings Soil N content in the 0-10 cm soil layer increased with succession; values in PF, MF and MEBF were 0.440, 0.843 and 1.023 g·kg^-1, respectively. The largest value of P content in the same layer was in MF (0.337 g·kg^-1); the values in PF and MEBF were 0.190 and 0.283 g·kg^-1, respectively. Plant foliage N and P content decreased with succession; the largest values for roots were in MF, and the values in PF equaled those in MEBF. Soil N:P ratio in the 0-10 cm layer significantly increased with succession; 2.3, 2.5 and 3.6, respectively. The N:P ratio of various plant organs also increased with succession, and the value in foliage was close to that in roots; the foliage N:P ratios were 22.7, 25.3 and 29.6, respectively. We discussed the characteristics of N:P ratios in soil and plants of the lower subtropical forest ecosystem, the law of N:P ratios in soil and plants in successional series, and the limiting effect of P on the lower subtropical forest ecosystem.

Geocarpy and amphicarpy are two special types of fruiting modes in angiosperms, and they occur mostly in terrestrial herbaceous plants. Geocarpous and amphicarpous species often occur in unstable habitats, where water or light is limiting, soil disturbance is frequent and environmental fluctuations are high. These two types of fruiting modes are important plant ecological adaptations that evolved via natural selection. The adaptive advantages of geocarpy include high survivorship of offspring in the favorable parental microhabitats, maintenance of seed viability in extreme environments, escape from herbivory and damage by fire and increase length of the developmental period of fruits. Amphicarpy is ecologically significant in that it reduces competition among siblings within the population, maintains and increases the size of the population in situ and increases the adaptability and evolutionary plasticity of the species. Thus, these two fruiting modes are considered adaptive strategies of species to biotic and abiotic factors of the environment. However, their potential evolutionary disadvantages include limitation of seed or fruit dispersal, influence on gene transfer and thus population genetic structure and increase of population fragmentation and of reproductive costs, all of which can greatly impact the distribution of species, population increase, migration, fitness and life history evolution. Geocarpy has been reported in about 24 families and 57 genera and amphicarpy in 13 families and 34 genera of angiosperms. Moreover, both types of fruiting modes occur in species of Asteraceae, Brassicaceae, Fabaceae and Scrophulariaceae. Phylogenetically, geocarpy occurs in the magnoliids, monocots and eudicots and amphicarpy in both monocots and eudicots, but neither mode has been reported in the basalmost angiosperms (ANITA clades).

We review the structural diversity and evolutionary significance of a type of highly modified stamen that is lever-like or spurred and can function as lever during pollination. Evolutionary changes of the androecium in stamen number and morphology often take place during floral evolution, shifting from pollen production to new functions. Lever-like stamens have been described in several subfamilies of Lamiaceae and six genera of Zingiberaceae. There are two types. One is derived from connective elongation and is largely structured by two parallel developed stamens; it occurs in the Lamiaceae, typically Salvia. The other is modified from one developed stamen and occurs in the Zingiberaceae. Both types have a similar role in pollination in that pollinators have to push the lower arm of the staminal lever into the corolla tube for nectar and consequently load pollen on their backs; this is widely regarded as a mechanism of facilitating crossing-pollination and can affect reproductive success via precise pollination, pollen dispensing, etc. These stamens independently originated and evolved in different taxa. For example, there have been three independent evolutions in Salvia, and this has been presumed a key innovation driving species’ radiation within the genus. Future research is needed at the levels of both macro- and micro-evolution to fully understand evolutionary and ecological significance of lever-like stamens.

Photosynthate allocation is influenced by both environmental and biological factors. This paper reviews recent advances in the mechanism of photosynthate allocation and its controls at individual and community/ecosystem levels in order to improve understanding of plant responses to global change. At the individual level, more photosynthate will be allocated to roots under conditions of high light, low water and low nutrient availabilities. The effect of increased atmospheric carbon dioxide concentration on photosynthate allocation depends on soil nitrogen availability. The root mass fraction (RMF) will increase under low nitrogen and is unchanged under high nitrogen. At the community/ecosystem levels, photosynthate allocation is insensitive to environmental change. The RMF decreases with increasing stand age. The functional equilibrium hypothesis (optimal partitioning) can explain the regulation of photosynthate allocation in response to environmental change, the source-sink relationship can reflect the effect of ontogeny on photosynthate allocation and the allometric relationship provides an important theoretical baseline prediction to disentangle the effects of plant size and environmental variation on photosynthate allocation. Research is needed on 1) the fraction of photosynthate allocated to respiration at the ecosystem level, 2) accurate estimation of belowground biomass and belowground net primary productivity (BNPP), 3) comparative study of photosynthate allocations between young and mature forests and between field and greenhouse experiments, 4) effects of multiple factors and their interactions on photosynthate allocation at the ecosystem level and 5) cooperative effects of ontogeny and environmental factors on the regulation of photosynthate allocation.

Aims Ecological restoration is one of the most active and key activities in contemporary ecology. But, it has been translated in Chinese as “ecological recovery”. By means of checking its English meaning and evolved processes, it is suggested that, instead of “recovery”, change it in Chinese as “ecological reestablishment”. Because ecological restoration must involve human intention or agency, it is fundamentally about assisted recovery that works to accelerate natural processes. But, in case where ecological processes have worked unassisted or something that can happen by nature itself without human agency, the term, “recovery” should be used.

Important findings There are at least three time scales for natural recovery and ecological restoration. They are the geologic period scale (10³, 10⁶, 10⁹ a), ecosystem regeneration and succession scale (10, 10², 10³ a), and ecological restoration scale (1, 10, 10² a). The 1st and 2nd scale are time scales for natural recovery, they are 10-10²-10³times longer than ecological restoration periods. Humans could not over-scaled depending on the capacity of natural recovery. The incompatibility of natural recovery and restoration in time scales is the basic cause of why natural recovery cannot meet the ecological demands of human society. The author raises doubt to the statement of “put the natural recovery as the major objective”, and “transfer the major objective from the ecological restoration to natural recovery”. The author beliefs that to shift responsibility of restoration onto nature itself and recovery at long-last recovery is the logic of lazybones and unwilling to be responsible. That is violation of the acknowledged global environmental truth that “who destroys who should compensate; who pollutes who should eliminate; who enjoys, who should pay”. Besides recovery and restoration natural ecosystems, designed ecological solutions will go beyond restoring a past ecosystem, but creat a kind of coupled natural-artificial ecosystems that will be part of a future sustainable world.