A new brood-pollination mutualism between Stellera chamaejasme and flower thrips Frankliniella intonsa.

BACKGROUND: Brood pollination mutualism is a special type of plant-pollinator interaction in which adult insects pollinate plants, and the plants provide breeding sites for the insects as a reward. To manifest such a mutualism between Stellera chamaejasme and flower thrips of Frankliniella intonsa, the study tested the mutualistic association of the thrips life cycle with the plant flowering phenology and determined the pollination effectiveness of adult thrips and their relative contribution to the host's fitness by experimental pollinator manipulation. RESULTS: The adult thrips of F. intonsa, along with some long-tongue Lepidoptera, could serve as efficient pollinators of the host S. chamaejasme. The thrips preferentially foraged half-flowering inflorescences of the plants and oviposited in floral tubes. The floral longevity was 11.8 ± 0.55 (mean ± se) days, which might precisely accommodate the thrips life cycle from spawning to prepupation. The exclusion of adult thrips from foraging flowers led to a significant decrease in the fitness (i.e., seed set) of host plants, with a corresponding reduction in thrips fecundity (i.e., larva no.) in the flowers. CONCLUSIONS: The thrips of F. intonsa and the host S. chamaejasme mutualistically interact to contribute to each other's fitness such that the thrips pollinate host plants and, as a reward, the plants provide the insects with brooding sites and food, indicating the coevolution of the thrips life cycle and the reproductive traits (e.g., floral longevity and morphology) of S. chamaejasme.

Yak and Tibetan sheep trampling inhibit reproductive and photosynthetic traits of Medicago ruthenica var. inschanica.

Livestock grazing affects grassland stability, resilience, and productivity owing to trampling, foraging, and excretion. Over time, trampling influences a wide range of grassland components and can have lasting effects. Trampling helps maintain grassland health but may also cause its degradation. In a field experiment over two growing seasons, we simulated yak and sheep trampling at different intensities and investigated their effects on the reproductive and photosynthetic characteristics of Medicago ruthenica var. inschanica in a Tianzhu alpine meadow in Gansu Province, China. Our results show that simulated trampling inhibited the asexual and sexual reproduction and growth of M. ruthenica. The root surface area, root volume, root biomass, pod length, pod number per unit area, number of seeds per pod, thousand-seed weight, and seed yield were significantly reduced under simulated trampling in the upper 30 cm of soil (P < 0.05) but were not reduced in the deeper soil layers (> 30 cm). Light trampling by both yak and Tibetan sheep promoted photosynthesis, while heavy trampling by both species inhibited photosynthesis. Yak trampling inhibited photosynthesis more than Tibetan sheep trampling, and overall, the adverse effects of yak trampling on asexual and sexual reproduction and growth of M. ruthenica were greater than those of Tibetan sheep trampling. Thus, the effect of yak trampling is greater than the effect of trampling by Tibetan sheep, where the different trampling intensities of yak and Tibetan sheep can result in direct but varied influences on grasslands, potentially leading to grassland differentiation.

[Spatio-temporal variation of water yield and its response to precipitation and land use change in the Yellow River Basin based on InVEST model]. / 基于InVESTæ¨¡åž‹çš„é»„æ²³æµåŸŸäº§æ°´é‡æ—¶ç©ºå˜åŒ–åŠå ¶å¯¹é™æ°´å’ŒåœŸåœ°åˆ©ç”¨å˜åŒ–çš„å“åº”.

Yellow River Basin is an important water conservation and ecological barrier area, the study of water supply service in which is of great significance to the high-quality development and ecological environment protection. Based on the Invest InVEST model and the method of scenario analysis, we analyzed the temporal and spatial patterns of water yield in the Yellow River Basin in recent 20 years (1995-2015) with land use and cover, meteorological and soil data as inputs. We examined the impacts of precipitation change and land use change on water yield and their impacts on water yield. The results showed that water yield depth had average growth of 24.34 mm from 1995 to 2015. The high water yield area located in the west and southwest, and the low water yield area located in the northwest. The change of deep spatial pattern was not evident. Among the three grade basins in the Yellow River Basin, the river basin above Longyangxia, with the highest water yield of about 11.7 billion m3·a-1, was the main water yield area of the Yellow River Basin. The river basin from Lanzhou to Hekou had the lowest water yield, with a value of 44 million m3·a-1. The average water yield depth of permanent glacier and snow land was the largest in the whole basin. Grassland was the main contributor to the total water yield of the whole basin, providing 62.6% of the total water yield. Land use/cover change had moderate effect on water yield.

[Responses of stoichiometric characteristics of rhizosphere soil to the degradation of alpine meadow.] / é«˜å¯’è‰ç”¸æ ¹é™ åœŸå£¤åŒ–å­¦è®¡é‡ç‰¹å¾å¯¹è‰åœ°é€€åŒ–çš„å“åº”.

This study aimed to understand the stoichiometric characteristics of carbon (C), nitrogen (N) and phosphorus (P) and soil nutrients in rhizosphere and non-rhizosphere soils and to obtain information on the status of soil and microbial nutrient limitation in degraded alpine meadow. We collected soil samples from rhizosphere (0-2 mm) of dominant plant species and non-rhizosphere (0-10 cm) of the alpine meadow with four different degraded degrees in the Qilian Mountains. We measured the concentration of C, N and P and extractable C, N, P (Ext-C, Ext-N, Ext-P), the activity and proportion of extracellular enzymes (ß-1, 4-glucosidase, ß-1, 4-N-acetylglucosaminidase, leucine aminopeptidase and acid phosphatase) involved in C, N, P cycles, as well as soil microbial biomass (MBC, MBN, MBP). The results showed that nutrient concentrations in the rhizosphere of dominant species was higher than that in non-rhizosphere. With the increases of degradation degree, soil C:N:P changed significantly, and resulted in a serious imbalance of C:N and severe N limitation. In the degraded alpine meadows, the ratio of log-transformed rhizosphere C-, N- and P-extracellular enzymes deviated from the 1:1:1 of global ecosystem, indicating that nutrient supply was mainly restricted by N and followed by P. The contents of soil total nutrients in degraded alpine meadow was relatively high, but the contents of soil available nutrients were low, which would hinder plant growth.

[Effects of Tongluo recipe on experimental diabetic peripheral neuropathy in rats].

OBJECTIVE: To investigate the effects of Tongluo Recipe (TLR), a compound Chinese herbal medicine, on experimental diabetic peripheral neuropathy in rats. METHODS: Diabetes was induced by streptozocin in rats. Eight weeks later, the diabetic rats were assigned to 3 groups according to different body weights: untreated group, low-dose TLR-treated group and high-dose TLR-treated group. Eight normal rats were assigned to normal control group. Systemic and sciatic nerve intrinsic antioxidant enzyme activities, lipid peroxide levels, hemorheology and sciatic nerve conduction velocity and ultrastructure changes were evaluated. RESULTS: Glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities were lower, and lipid peroxide levels were higher in plasma and sciatic nerve of the untreated group than those in the normal control group (P<0.05). Blood glucose and viscosity in the untreated group were higher than those in the normal control group. Sciatic nerve showed demyelination changes and decrease of conduction velocity. Vasa nervorum expanded and erythrocyte deposited in the capillary in the untreated group. TLR obviously improved sciatic nerve conduction velocity and ameliorated morphology changes, decreased blood viscosity, improved SOD and GSH-Px activities. CONCLUSION: TLR can obviously improve sciatic nerve function and ameliorate morphology changes in rats with diabetic peripheral neuropathy, probably through depleting free radical production, improving endothelial cell function and ameliorating hemorheology changes.

[Effects of strong solar UV-B radiation on photosynthesis and photosynthetic pigment contents of Saussurea superba on Qinghai-Tibet Plateau].

Taking the main companion species Saussurea superba in an alpine Kobresia humilis meadow on Qinghai-Tibet Plateau as test material, a UV-B exclusion experiment with UV-B excluding and UV-B transmitting filters was performed to study the effects of strong solar UV-B on the photosynthesis, photosynthetic pigments, and UV-B-absorbing compounds of S. superba, aimed to examine the adaptation capability of alpine plants to strong solar UV-B radiation. The removal of UV-B components from natural sunlight increased the net photosynthetic rate (P < 0.05) and PS II photochemistry efficiency of S. superba. The relatively increased leaf thickness under ambient UV-B could compensate the photo-oxidation of photosynthetic pigments, an inherent characteristic of alpine plants growing in intense UV-B. Short-term removal of UV-B radiation had no obvious effects on the UV-B-absorbing compounds, suggesting that these compounds in epidermal layer of S. superba could hardly be affected by the environment. It was concluded that the increase of photosynthetic pigment contents due to the enhancement of leaf thickness was a specious phenomenon, but the strong solar UV-B radiation on Qinghai-Tibet Plateau still had a potential negative impact on the photo-physiological processes in alpine plant S. superba.