*Recent studies have highlighted a direct, fast transfer of recently assimilated C from the tree canopy to the soil. However, the effect of environmental changes on this flux remains largely unknown. *We investigated the effects of drought on the translocation of recently assimilated C, by pulse-labelling 1.5-yr-old beech tree mesocosms with (13)CO(2). (13)C signatures were then measured daily for 1 wk in leaves, twigs, coarse and fine root water-soluble and total organic matter, phloem organic matter, soil microbial biomass and soil CO(2) efflux. *Drought reduced C assimilation and doubled the residence time of recently assimilated C in leaf biomass. In phloem organic matter, the (13)C label peaked immediately after labelling then decayed exponentially in the control treatment, while under drought it peaked 4 d after labelling. In soil microbial biomass, the label peaked 1 d after labelling in the control treatment, whereas under drought no peak was measured. Two days after labelling, drought decreased the contribution of recently assimilated C to soil CO(2) efflux by 33%. *Our study showed that drought reduced the coupling between canopy photosynthesis and belowground processes. This will probably affect soil biogeochemical cycling, with potential consequences including slower soil nitrogen cycling and changes in C-sequestration potential under future climate conditions.

Drought effects on allocation of recent carbon: From beech leaves to soil CO2 efflux

Preferential flows and soil moistures on a Benggang slope: Determined by the water and temperature co-monitoring

Restoration of semi-natural grassland communities
involves a combination of (1) sward disturbance to
create a temporal window for establishment, and (2)
target species introduction, the latter usually by seed
sowing. With great regularity, particular species
establish only poorly. More reliable establishment
could improve outcome of restoration projects and
increase cost-effectiveness. We investigated the
abiotic germination niche of ten poorly establishing
calcareous grassland species by simultaneously
exploring the effects of moisture and light availability
and temperature fluctuation on percentage germina-
tion and speed of germination. We also investigated
the effects of three different pre-treatments used to
enhance seed germination – cold-stratification, osmo-
tic priming and priming in combination with gibberellic
acid (GA 3 ) – and how these affected abiotic
germination niches. Species varied markedly in width
of abiotic germination niche, ranging from Carex flacca
with very strict abiotic requirements, to several species
reliably germinating across the whole range of abiotic
conditions. Our results suggest pronounced differ-
ences between species in gap requirements for
establishment. Germination was improved in most
species by at least one pre-treatment. Evidence for
positive effects of adding GA 3 to seed priming
solutions was limited. In several species, pre-treated
seeds germinated under a wider range of abiotic
conditions than untreated seeds. Improved knowledge
of species-specific germination niches and the effects
of seed pre-treatments may help to improve species
establishment by sowing, and to identify species for
which sowing at a later stage of restoration or
introduction as small plants may represent a more
viable strategy.

/pdf/the-germination-niches-of-grassland-species-targeted-for-476pgyybmw.pdf

The germination niches of grassland species targeted for restoration

To identify the key indicators for salt tolerance evaluation of Salix matsudana Koidz, we explored the relationship of ion absorption and distribution with chlorophyll, fluorescence parameters (leaf performance index, maximum photochemical efficiency), and photosynthetic gas parameters (net photosynthetic rate, transpiration, stomatal conductance, intercellular carbon dioxide concentration) under salt stress. We established 4 treatment groups and one control group based on salinity levels of NaCl hydroponic solutions (171, 342, 513, and 684 mm). The Na+/K+, Na+/Ca2+, chlorophyll fluorescence, and photosynthetic parameters of leaves were measured on the 1st, 3rd, 5th, 8th, 11th, and 15th days to analyze the correlations of chlorophyll, chlorophyll fluorescence and photosynthetic parameters to the ion distribution ratio. The results showed that (1) The ratio of the dry weight of roots to leaves gradually increased with increasing salt concentration, whereas the water content of leaves and roots first increased and then decreased with increasing time. (2) The content of Na+, Na+/K+, and Na+/Ca2+ in roots and leaves increased with increasing salt stress concentration and treatment time, and the difference gradually narrowed. (3) Ca2+ was lost more than K+ under salt stress, and Na+/Ca2+ was more sensitive to the salt stress environment than Na+/K+. (4) Because the root system had a retention effect, both Na+/K+ and Na+/Ca2+ in roots under different NaCl concentrations and different treatment times were higher than those in leaves, and Na+/Ca2+ was much higher than Na+/K+ in roots. (5) Na+/K+ had a higher correlation with fluorescence parameters than Na+/Ca2+. Among them, Na+/K+ had a significantly negative correlation with the maximum photochemical efficiency, and the correlation coefficient R2 was 0.8576. (6) Photosynthetic gas parameters had a higher correlation with Na+/Ca2+ than with Na+/K+. Among them, significantly negative correlations were noted between Na+/Ca2+ and Gs as well as between Na+/Ca2+ and E under salt stress. The correlation between Na+/Ca2+ and Gs was the highest with a correlation coefficient of 0.9368. (7) Na+/K+ and Na+/Ca2+ had no significant correlation with chlorophylls. Na+/Ca2+ was selected as a key index to evaluate the salt tolerance of S. matsudana Koidz, and the results provided a reference for analyzing the relationship between ion transport and distribution for photosynthesis.

/pdf/study-on-the-relationship-of-ions-na-k-ca-absorption-and-1xwdgggd.pdf

Study on the Relationship of Ions (Na, K, Ca) Absorption and Distribution to Photosynthetic Response of Salix matsudana Koidz Under Salt Stress

The invention relates to the technical field of rural sewage treatment equipment, and in particular relates to a kitchen sewage treatment device The kitchen sewage treatment device comprises a sewage collecting well and a reaction tank surrounding the sewage collecting well, wherein the bottom and the side wall of the sewage collecting well are water-tight structures; the reaction tank is provided with a fine sand layer, a geotextile and a gravel layer sequentially from top to bottom; moisture-proof herbaceous plants are planted on the fine sand layer; the bottom and the side wall of the reaction tank are water-tight structures; and moreover, the side wall of the sewage collecting tank is provided with a first water permeable hole communicated with the gravel layer, and the side wall of the reaction tank is provided with a second water permeable hole which is formed at the position of the fine sand layer and is higher than the first water permeable hole to prolong the retention time of kitchen sewage in the reaction tank and strengthen the effects, of fine sand and root systems of the moisture-proof herbaceous plants, of adsorbing and absorbing pollutants in the sewage, so that the sewage as much as possible is subjected to denitrification, the content of nitrate nitrogen in the sewage is reduced, the kitchen sewage is effectively treated in a centralized manner, and the pollution caused by the kitchen sewage to the environment is reduced

Kitchen sewage treatment device

The invention relates to a method for rapidly recovering vegetation of wasteland. The method uses deep ditching and shallow covering ways to sow awnless brome on the wasteland, and the awnless brome is managed and protected for 2-3 years to achieve vegetation recovery. The method has few actual operation steps, and is simple and feasible, low in cost, low in energy consumption, simple in process, and fast in effectiveness, and is convenient for practical application and popularization. After the technology is applied, vegetation coverage is high, and restoration effect is stable. Using the method to restore vegetation of the wasteland, the vegetation of the wasteland can be rapidly established in a short time, to form effective earth's surface cover degree. The method prevent soil nutrient from running off with water-wind erosion, increases soil, retains fertilizer and soil fertility, and reduces soil moisture evapotranspiration, increases water-holding capacity, and conserves water, so as to establish a friendly ecological environment in which wasteland vegetation covers effectively in a long time and ecosystem service function continuously develops.

Method for rapidly recovering vegetation of wasteland

The invention relates to a planting method for increasing the wintering rate of timothy grass in a cold region. The planting method includes the following steps of sowing, wherein soil preparation, deep ditching sowing, shallow covering after sowing and sowing fertilizer application are conducted; cutting and fertilizer application, wherein cutting is not conducted in the sowing year, and fertilizer is applied just one month before local first frost; irrigation, wherein if the manual irrigation requirement is met, irrigation is conducted once after each fertilizer application, frozen water and regreening water are irrigated when the winter daily average temperature is lower than zero DEG C and after spring regreening respectively, and if the manual irrigation requirement is not met, natural rainfall is used for irrigation. Timothy grass is planted in the north of China, the plant wintering rate is increased to 95% or more from the original value smaller than 35%, the effect is remarkable, and the technical bottleneck of difficult wintering in large-scale cultivation popularization of timothy grass in the north and even northeast region of China is broken through successfully.

Planting method for increasing wintering rate of timothy grass in cold region

Correctly quantifying the relationships between soil respiration and environmental factors and their sources of variability is essential to predict future carbon fluxes and climate feedback. Soil water conditions and soil temperature strongly affect soil respiration and the dynamics of soil organic matter. Despite this, simulation of soil respiration (Rs) based on soil temperature (Ts) and soil volumetric water content (θ) must still be improved, as demonstrated by its discrepant model performance among different seasons. With the objective of gaining a further understanding of the relationships of Rs with Ts and θ and providing an improved model to simulate Rs variations, we measured hourly Rs, Ts and θ using the chamber technique in artificial smooth brome grassland for analysis. We began by dividing the four seasons of a year according to the daily mean air temperature, followed by representing the seasonal variation of Rs, Ts and θ. We found that Rs correlated significantly with Ts in an exponential relationship and with θ in a parabolic relationship seasonally, where the determination coefficient of the Rs-θ relationship was significantly larger than that of the Rs-Ts relationship. We also discovered that the shape of the Rs-θ relationship was seasonally dependent because the optimal θ and the width of the peak Rs around the optimal θ were seasonally specific. Finally, by considering seasonality, the combinational simulation model explained more variation of soil respiration. Thus, seasonality should be considered for more reliable model simulations of soil respiration. These findings are relevant for more accurate predictions and modelling of soil respiration, particularly in temperate artificial grasslands with a continental monsoon climate, where the ‘Birch effect’ strengthens seasonality, and these findings further our understanding of changes in the rates of soil carbon losses as artificial grassland is established.

Pang Zhuo

Papers

Method for rapidly recovering vegetation of wasteland

Planting method for increasing wintering rate of timothy grass in cold region

Soil respiration simulation based on soil temperature and water content in artificial smooth brome grassland

Kitchen sewage treatment device

Seasonal pattern of stem radial growth of Salix matsudana and its response to climatic and soil factors in a semi-arid area of North China