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Two typical species (Citrus reticulate and Conyza canadensis) from riparian buffer strips in the Danjiangkou Reservoir were selected to evaluate the soil nitrogen mineralisation characteristics of single leaf and/or root treatments and to examine whether the interactive effects between leaves and root mixed treatments existed under laboratory incubation conditions. We measured the rate of nitrogen mineralisation of the plants on days 1, 3, 7, 14, 21, 31, 41, 51, and 61. The main results were summarised as follows:1) the laboratory incubation experiment had three stages, the first (1-7 days) comprised soil microbial adaptation, the content of mineral nitrogen was markedly increased in the second stage (7-41 days), and became steady in the final stage (41-61 days); 2) ANOVA strongly indicated that C. reticulate leaf treatment (GL) was correlated to C. canadensis leaf treatment (PL) in the whole incubation (P<0.05), but C. reticulate root treatment (GR) was not correlated to C. canadensis root treatment (PR) in the second and third stages (P>0.05). There was a strong correlation between GL and GR and PL and PR (except at day 41) in the plants; 3) For single treatments, only GL promoted soil net N mineralisation, and GL+PL and GL+PR in mixed treatments, whereas others had no effect; and 4) the Pearson method and PCA demonstrated the total N of plant was the most important plant chemical property. In conclusion, the plant chemical properties played a key role in the net N mineralisation and the existence of interactive effects between mixed treatments depended on the plant chemical properties and incubation conditions.
The content of soil aggregates can be used to characterize the stability of soil structure and reflect the change trend of soil quality. In this study, the effects of 4 kinds of land use, namely, wetland, woodland, farmland, and grassland, on soil aggregate content and stability were analysed in the 0-20 cm soil layer, and the spatial heterogeneity of large particle size aggregates was analysed to simulate the distribution by spatial interpolation. The results showed that the destruction rate of farmland soil aggregates was the maximum at 46.98%, but that of woodland was the minimum at 26.36%. On the basis of the content of soil water stable aggregate, and mean weight diameter and geometric mean diameter of aggregate particles, the strength of soil structure stability was found to be wetland > woodland > farmland > grassland; all 4 kinds of land use resulted in significant differences in soil aggregate stability (P<0.05), and the difference between the wetland and grassland was the most significant. Wetland soil structure was the best, followed by woodland and farmland; grassland showed the least stable soil structure. The results of this study can provide a reference basis for the evaluation of desertification degree and zoning management in the Liaohe River basin.
It is important to develop and utilise saline-alkali land for protecting, improving the quality, and increasing the area of cultivated land. This research adopts the conventional analytical method for estimating organic matter and available nutrient content, alkalization, and ion composition in the soil of West Liaohe Basin at depths of 0-5, 5-15, 15-30, and 30-50 cm, across eight vegetation. Nutrient content in saline-alkali soil differed among the eight ecological landscapes studied. Organic phosphorus content was higher in saline-alkali land growing corn, and Leymus chinensis and Setaria viridis. Similar or relatively low nutrient content, but significant difference among the soil profile layers was found in Chloris virgata and Suaeda glauca landscapes, and in bare land(P<0.01). The characteristics differed significantly among the four soil layers (P<0.01). The pH, ESP, and salinity were generally low in the four soil layers of areas growing L. chinensis and S. viridis. Na+, CO32-, and HCO3- content were very high within a depth of 0-5 cm S. glauca covered and bare landscapes. CO32- and HCO3-content were lower on saline-alkali land that grew corn, L. chinensis and S. viridis. There were significant differences in the ion composition among four soil layers of same ecological landscape (P<0.01). Bare landscapes develop when the salinity of soil reaches a certain level. In conclusion, the present study can provide atheoretical basis for reasonable restoring salinized land.
We conducted a two-year field experiment to investigate the effects of three fertilizers, each with different N∶P ratio, on soil pH and stoichiometry characteristics. Our results showed that, when compared to the control, N input (when in excess of 30 g·m-2) significantly decreased soil pH when both N and P were added. However, N input (when in excess of 10 g·m-2) also decreased soil pH when only nitrogen was added, and the value was much lower than that when treatments included addition of both N and P. Moreover, comparing to high N and low phosphate input, the low nitrogen and high phosphate input significantly decreased the concentrations of macroelements (K, Ca, and Mg), microelements (Fe, Mn, Cu, and Zn), as well as toxic elements (Al and Mn), and also decreased the soil N∶P. This is possibly due to P limited in this area, and high P low N inputs mitigate P limited on plant growth, simultaneously increased other nutrients uptake by plant, resulting in the decrease of nutrients in soil. Therefore, based on the available soil nutrients and the amount of nitrogen that is being added, appropriate addition of phosphate can mitigate the influence of nitrogen deposition on soil pH and stoichiometry characteristics.
In order to evaluate soil and water conservation status in the restored grasslands in “Grain for Green” history in the hilly-gully region of Loess Plateau, wheatgrass and switchgrass plots were studied. The scouring experiments were carried out in a laboratory to simulate soil detachment by concentrated flow under six slopes (S=17.36%~42.26%) and discharges (Q=1.0~2.5 L·s-1). Soil rill erodibility (Kr) was estimated by WEPP model. The seasonal dynamics of soil rill erodibility under wheatgrass and switchgrass vegetation were studied during the growing season. Soil rill erodibility under wheatgrass in the hilly-gully region of Loess Plateau varied significantly with season (P<0.05), revealing a significant decline during the growing season. In contrast, soil rill erodibility under switchgrass cover had no clear seasonal dynamics during the growing season (P>0.05). Kr values in wheatgrass plots varied from 0.002 1 to 0.022 4 s·m-1. Soil rill erodibility in switchgrass displayed a pattern of seasonal dynamics, including an initial increase, followed by decline. Kr values in switchgrass plots varied from 0.003 2 to 0.021 9 s·m-1. The seasonal dynamics of soil rill erodibility of wheatgrass and switchgrass were affected by seasonal changes in soil cohesion, water-stable aggregate content, and grass root density. Significant negative correlation between soil rill erodibility and soil cohesion, water-stable aggregate content, and grass root density were found. In addition, the dynamics of change in soil rill erodibility of wheatgrass and switchgrass plots could be predicted based on with soil cohesion and grass root density. The growth of grass root system and the seasonal change in soil cohesion emerged as the main factors affecting the dynamics of soil rill erodibility of the restored grasslands in the hilly-gully region of Loess Plateau. Soil rill erodibility of the two types of grasslands showed significant negative correlation with soil cohesion and water-stable aggregate content, which are important parameters for simulating the dynamics of soil rill erodibility of the restored grasslands in this region.
85 soil samples under different land use pattern were collected from 17 provinces in China.Then each soil sample was added with cornstalk and cultivated under natural condition for 90 d in order to understand the dynamics and motivation of soil organic matter (SOM) after the cornstalk addition.The results showed that the original land use pattern significantly affected SOM of soil samples with stalk.63.5% soil samples had shown an increase of SOM,while SOM of 36.5% soil samples decreased,which indicates that cornstalk addition did not necessarily lead to SOM increasing within a short period of time. SOM of 88% soil samples from crop dry land had increased while it decreased all samples from paddy soils, and SOM in soils from forest lands and vegetable fields did not have obvious trend. After cornstalk addition, the number of cultivable bacteria, fungi and actinomycetes of all soil samples increased in the following orders:paddy field> forest> vegetable>crop dry land, and fungi>actinomycetes>bacteria. According to phospholipid fatty acids (PLFA), the smaller bacteria/fungi and G+/G-, the more stable soil micro-ecosystem is; the smaller A/B,ios/anteiso and C/A are, the more unstabilitythe environment in soilis. PLFA analysis shows that soil micro-ecosystem stability increases in the following series:paddy field,crop dry land, forest land and vegetable land; the environmental and soil nutrient stress increases in the following series:vegetable land,crop dry land, forest land and paddy field. Therefore, paddy field had the worst soil micro-ecosystem stability and suffered the most nutrient and environment stress than all the other soils in this study.
The area of urban green-land is expanding dramatically as a strategy to counter rapid urbanization. Urban green-land ecosystems with plantations as their main vegetation type have great potential to sequester atmospheric carbon. Continuous measurements of CO2 flux were made using eddy covariance technique, from January 2014 to January 2016, in Fuzhou City to quantify the seasonal dynamics of net ecosystem CO2 exchange (NEE) and its responses to environmental factors. Gross ecosystem productivity (GEP), ecosystem respiration (Re), and net ecosystem productivity (NEP=–NEE) showed strong seasonal pattern, with CO2 uptake dominating during the growing season from April to November, and a respiratory release of CO2 dominating during the non-growing season. Ecosystem respiration (Re) had a positive relation with GEP and gross primary productivity, and the fitting line was less than 1, with the straight intercept not zero, which shows that the balance of urban green-land ecosystem was greatly influenced by the precipitation and distribution of precipitation during the growing season. An exponential equation of the net carbon exchange to simulate the soil temperature (Ta) showed that NEE increased exponentially with the Ta, and the interpretation ratio was more than 80％. GEP increased exponentially with the Ta, and there was no optimum temperature, i.e., the highest temperature had no inhibitory effect on the GEP. NEP decreased with increasing Ta, when Ta 5.0 ℃, but increased when Ta 5.0 ℃. NEE and photosynthetically active radiation (PAR) meet the optimal hyperbolic relationship when PAR 350 μmol·(m2·d)–1, where the ecological system breathing was greater than the photosynthetic production, and when PAR 500 μmol·(m2·d)–1, where the ecosystem carbon uptake was saturated. The ecosystem quantum yield (α) and maximum photosynthesis (Amax) showed apparent seasonal patterns, both peaking in July. Correlation analysis showed that the NEE residuals for different months were negatively correlated with rainfall and positively correlated with Ta and vapour pressure deficit. The present results could contribute to the carbon budget of urban ecosystems and help create carbon-oriented management strategies for sustainable urban development under global climate change.
This paper aimed to study the characteristics of land cover change and the impact of human activities on potential natural vegetation (PNV) in the arid region of Central-East Asia. This information is of great significance for the protection of the ecological environment and the rational use of land resources. Firstly, the study simulated the distribution of PNV in the arid region of Central-East Asia based on meteorological data and a CSCS model. Secondly, the study analysed the land cover change based on the 2001-2013 MODIS land cover datasets. Finally, we studied the variation characteristics of human occupancy intensity on PNV. The results showed that:1) the PNV in the arid region of Central-East Asia included potential forestland, potential grassland, potential tundra, and potential desert; 2) the shrubland increased dynamically in Central Asia, the croplands expanded significantly in the arid region of China, and the areas of shrubland and grassland in the middle and west of Mongolia decreased; 3) the human occupancy increased in the study area. The human occupancy proportion of the study area was notably increased by 1.45% from 2010 to 2013. The human occupancy proportion of the potential grassland showed the largest increase (2.88%) from 2009 to 2013 and the human occupancy proportion of the potential forest showed the largest increase (6.99%) from 2001 to 2005; 4) in the North Kazakhstan Tri-State(Солтүстiк Казакстаноблысы,Акмолаоблысы,Костанайоблысы), migration was the major factor that affected PNV, as the human occupancy proportion increased by 11.38% from 2006 to 2013; in the arid regions of Hulunbuir and Shanxi, agricultural development was the main factor for increased human occupancy, which increased by 6.62% and 17.64%, respectively, from 2001 to 2013.
Heavy metal ATPases HMA2 mediated Cd long-distance transport plays important roles in the distribution and detoxification of Cd2+ in plants. However, the molecular mechanism underlying Cd2+ long-distance transport in Iris lactea remains unknown. Total RNA was extracted from the roots of I. lactea to obtain a fragment of IlHMA2 by RT-PCR. Then RNAi expression vector pARTG1G2 with inverted repeats of HMA2 driven by the promoter CaMV35S was constructed based on the intermediate vector pHANNIBAL and the plant expression vector pART27 by restriction enzyme digestion and ligation. Moreover, the recombinant plasmid was transformed into agrobacterium GV3101 by freezing and thawing method, and then was transformed into I. lactea to obtain IlHMA2-RNAi lines. This would be a good basis for clarifying the IlHMA2 mediated Cd2+ long distance transport in the adaptation of I. lactea to Cd2+ contaminated environments.
Kentucky bluegrass (Poa pratensis) is widely used as the turfgrass for city landscaping in the north of China, and drought is the main factor limiting the growth of turfgrass. Typically, plants exhibit a compensation or growth stimulating effect after drought and re-watering. Therefore, study on regulated deficit irrigation methods of Kentucky bluegrass in Lanzhou is very important. In this study, we conducted repetitive treatments of ‘drought-rewatering-drought-rewatering’ during the growth season of Kentucky bluegrass, which is widely planted in Lanzhou. We analysed the evapotranspiration, turf quality, physiological index, and water consumption pattern of the turfgass during different seasons to determine the optimum irrigation. The following treatments were performed:control, 70%-80% field water holding capacity (FWC); treatment Ⅰ, 65%~56% FWC; treatment Ⅱ, 55%~46% FWC; treatment Ⅲ, 45%~36% FWC; treatment Ⅳ, 35%~26% FWC; treatment Ⅴ, 25%~16% FWC. The results showed that during spring and autumn, the treatment Ⅰ had no significant effect on the analysed indexes of Kentucky bluegrass, whereas the treatments Ⅱ and Ⅲ significantly changed all indexes, and the treatments Ⅳ and Ⅴ resulted in increases of all indexes. The treatment Ⅱ had significant effects on the analysed indexes of Kentucky bluegrass during summer, but complete recovery was noted after rewatering, while in the other treatments, the indexes were more greatly altered and complete recovery was difficult even after rewatering. Therefore, the minimum irrigation limit for Kentucky bluegrass grown in Lanzhou is 40% FWC in spring and autumn and 50% FWC in summer.
To investigate the ecological adaptability of wild flower under different shade conditions and seek appropriate shading proportions, the effects of different light intensity (full light, 25%, 50%, 70% shading) were tested on the growth and physiological and biochemical characteristics of 10 species of wild ornamental plants around Lanzhou City. The results showed that water content increased with the increase of shading on Hypecoum erectum and Caltha palustris. The dry weight of Anemone rivularis was higher in 75% shading, and the difference was significant compared with the other treatments (P<0.05). Soluble sugar content decreased with increasing shading on Clematis florida, and chlorophyll content of P. anserine, H. erectum, Geum aleppicum, and C. palustris increased with increasing shading. The content of MDA was significantly higher than other treatments (P<0.05) under full light condition in F. orientalis, H. erectum, and C. palustris. Similarly, MDA contents of Anaphalis sinica and G. aleppicum in 75% shading were higher than other treatments. To sum up, full light was more suitable for the growth of A. sinica, P. chinensis, C. florida and A. vitifolia; P. anserine, A. rivularis, F. orientalis, H. erectum, and G. aleppicum could endure moderate shading; C. palustris was suitable for growing under shading condition.
To test the tactics of resource allocation, pollinator abundance, and mating system, the reproductive allocation characters of three species of the family Gentianaceae [Gentianopsis paludosa (selfing), Gentiana farreri (outcrossing with high insect visit frequencies), and Swertia przewalskii (outcrossing with low insect visit frequencies)], were tested at the same habitat in the eastern Qinghai-Tibetan Plateau. The results showed that the P/O ratios differ significantly among these three species. The P/O ratio of G. paludosa was significantly lower than that of the other two cross-fertilized species, and the P/O ratio of S. przewalskii was significantly lower than that of G. farreri. Reproductive allocation differed significantly among the three species. G. paludosa had a higher reproductive allocation than that in the two cross-fertilized species, and the reproductive allocation of G. farreri was higher than that in S. przewalskii. The reproductive allocations of the two cross-fertilized species G. farreri and S. przewalskii were negatively correlated with their respective individual sizes, whereas G. paludosa did not reveal any relationship between these two parameters. The results indicated that mating system and pollinator abundance might influence resource allocation characteristics. Although the reproductive biomass of the three species was positively correlated with their individual size, the reproductive allocation of the self-fertilized species was significantly higher than that in the two cross-fertilized species. In addition, its high reproductive allocation was not affected by individual size. It appeared that the high reproductive allocation might be caused by reproductive assurance, which in turn might reduce the reproductive cost in the self-fertilized species.
Hyperaccumulator plants are recognized as promising phytoremediation candidates owing to their ability to accumulate substantial heavy metal ions without obvious signs of poisoning. Two ecotypes of Sedum alfredii (hyperaccumulating, HE and non-hyperaccumulating, NHE) were employed for hydroponic experiments with a modified culture solution. The chlorophyll content, photosynthetic parameters, and chlorophyll fluorescence characteristics were analysed. The results indicated that the chlorophyll a (Chla) and chlorophyll b (Chlb) content of the HE plants significantly decreased (P<0.05) by 46.91% and 43.09%, respectively, compared with non-Cd treated samples after stress for 7 days, whereas the Chla and Chlb contents of NHE were significantly decreased by 50.9% and 49.98%, respectively. Under the stress, the decrease in net photosynthetic rate (Pn) in HE was less than that in NHE. The Pn of HE was 31.97% less than that of the control and 50.69% less in NHE; both changes were statistically significant. The transpiration rate (Tr) of HE decreased by 50.58% after stress for 4 days and then increased, whereas the Tr of NHE decreased by 60.47% after stress for 1 day and then increased. The initial fluorescence (F0) of HE increased promptly and then decreased, whereas the F0 of NHE gradually increased during stress for 4 days. The maximum fluorescence (Fm) in HE was always higher than NHE. The actual photochemical efficiency (ΦPSII), photochemical quenching coefficient (qP), and apparent photosynthetic electron transport rate (ETR) of HE firstly decreased and then increased, whereas the ΦPSII and ETR of NHE were stable after a decrease. The non-photochemical quenching coefficient (NPQ) of HE gradually increased, whereas NPQ and qP tended to be stable. Thus, the response of the two ecotypes of Sedum to cadmium treatment was completely different. This study also investigated the physiological responses of the two S. alfredii ecotypes to cadmium stress, which would provide further evidence for the HE S. alfredii restoration of soil cadmium pollution.
To understand the genetic diversity distribution and genetic background of different Stylosanthes species, 60 accessions from 6 species were evaluated by cluster analysis and principal component analysis based on 17 phenotype traits. The results showed that banner stripe had the highest Shannon diversity index, followed by stem growth habits and stem indumentum. Plant height had the highest variation coefficient, followed by leaf width and petiole length. Clustering analysis demonstrated that 60 accessions were classified into 2 groups. Group I included 7 accessions of Stylosanthes capitata, 10 accessions of S. macrocephala, 7 accessions of S. hamata and 11 accessions of S. humilis, and group II included 8 accessions of S. gracilis and 17 accessions of S. guianensis. This study could provide useful information for selecting fine germplasm and improving breeding efficiency of Stylosanthes.
Seed vigor of 10 seed samples in Medicago sativa was determined by standard germination test, just germination test, cold germination test, and electrical conductivity test. We found that the 10 seed samples fell into three classification levels based on germination percentage and vigor index in the standard germination test. Under the just germination test, the 10 seed samples could be classified into 6 different levels based on radicle emergence with count time from 24 to 28 h after the beginning of incubation. Under the cold germination test, the seed samples could also be classified into 6 different levels based on vigor index and germination potential. Under the electrical conductivity test, the seed samples could be classified into 7 different levels. Thus, the electrical conductivity test was the most sensitive method for M. sativa seed vigor evaluation, followed by just germination test and cold germination test. The standard germination test was not suitable for seed vigor evaluation.
In order to select alfalfa (Medicago sativa) varieties adapted to drip irrigation cultivation in northern Xinjiang areas, and provide the basis for theories of drip irrigation cultivation techniques in artificial forage planting applications, we studied the effects of drip irrigation cultivation techniques on 13 alfalfa varieties appropriate for cultivation in the northern Xinjiang area. The results showed that Magnum Ⅶ, WL319HQ, and SK3010 easy planting were successful varieties under the conditions of drip irrigation, while Longmu 806 and Longmu 801 were not. Results for yield characteristics showed that the 4010 hay had the highest yield, and had high cold resistance but low light and temperature sensitivity, and it was most appropriate for drip irrigation cultivation in local areas. The SK3010 variety had high cold resistance, which made it suitable for cold areas. The WL343HQ and WL319HQ varieties grew slower before the winter season and were inappropriate for irrigation cultivation. The Magnum Ⅶ, WL363HQ and WL354HQ hay yield was equal to Suntory (Control). The 4010, Magnum Ⅶ, WL363HQ and WL354HQ varieties were more suitable for planting in a drip irrigation cultivation mode.
To address Leymus chinensis grassland degradation and dramatic productivity decline in Songnen Plain, we designed experiments with 20 and 30 cm spacing with 5, 10, and 15 cm deep root cuttings based on the L. chinensis clone growth ability characteristics. We analysed the height, density, biological diversity, quantity, and quality characteristics of L. chinensis community. The result showed that all root cutting treatments had different influences on the growth of L. chinensis. The root cutting depths of 5 and 10 cm significantly improved the height and density of L. chinensis and reduced the community diversity index (P<0.05); the 5 cm deep root cutting also showed the best growth improvement of L. chinensis. From these results, we concluded that suitable root cutting treatments can improve the growth of L. chinensis and add value to the management of L. chinensis grassland.
Ayding Lake, located in the extreme arid region in Middle Asia, has a unique environment condition. Occluded terrain leads to high temperatures in summer. Currently, no studies have shown how this area is affected by Salicornia europaea. In this study, 3 sample plots with different water and population characteristics were selected and named plots A, B, and C. Plot A was a high terrain, with no water on the surface after April and low plant density. The surface of plot B was covered with water for a long period, and it had moderate plant density. The surface of plot C was covered with water during the early months of the year, and it had the highest plant density. We set 3 quadrats of 0.5 m×0.5 m in each plot. Each quadrat was investigated 1~2 times a month, and the plant density was counted 10 times. By using dynamic life table and correlation analysis, we studied the relationship between population change and temperature. The results showed that S. europaea populations grew before May. In all plots, the high mortality period for S. europaea populations was from May to June because of self-thinning triggered by increase in temperature and reductions in moisture and nutrients. The S. europaea populations of plots A and B showed a second high mortality period from July to August because of the extreme temperature of 43 ℃ for 43 days. The S. europaea population in plot A showed a third high mortality period in September because of high temperature and salt stresses caused by evaporation of soil moisture resulting in increased salt concentration. The plant mortality noted in plots A and B was significantly correlated with temperature. S. europaea population in plot C had only one period of high mortality, but this was not significantly correlated with temperature. This is because compared to plots A and B, plot C had more moisture and higher plant population density, which can relieve the stress of high temperature. The survival curves of plant populations in plots A and B belong to Deevey type Ⅲ, which show high mortality rates at the beginning of the year, but tend to become steady with time. The survival curve of plant population in plot C belongs to Deevey type Ⅱ, which shows the same mortality rate at all times in a year.
In this study, the widely distributed poisonous weed Achnatherum inebrians in a natural degraded grassland of Gansu Province, northwest China (both sides of the road in Dahe Township, Sunan County) was selected as the experiment material. Following a randomized block experimental design, we treated the experimental plots with glyphosate and heavy-duty harrow to compare their controlling effects on A. inebrians. Following this, high quality forages were selected to reseed these plots and growth improving technology were applied under field conditions. The results indicated that the 10% glyphosate treatment was able to control more than 98% of the A. inebrians, and the 150~190 g·667 m-2 of glyphosate treatment was economically appropriate. The controlling effect of heavy harrow on A. inebrians was more than 90%, and the 30 cm depth of heavy harrow was appropriate. The germination rate of reseeding combinations Ⅴ[(Elymus nutans 1 kg·667 m-2) + (Festuca rubra 0.5 kg·667 m-2) + (Poa pratensis 0.3 kg·667 m-2) + (Coronilla varia 0.2 kg·667 m-2)] and+Ⅵ [(E. nutans 1 kg·667 m-2) +(F. rubra 0.5 kg·667 m-2) + (P. pratensis 0.2 kg·667 m-2) + (C. varia 0.3 kg·667 m-2) ]under shallow tillage sowing, shallow tillage drilling and loosen the soil treatment were 85% and 73%, 91% and 87%, and 87% and 75%, respectively, which indicated combination Ⅴ and Ⅵ strong adaptability. When the reseeding depths were 0 cm and 4~8 cm, the germination rate and survival rate were lower when compared to 1~4 cm depth, indicating this was the most appropriate depth for reseeding. Compared with control treatment, the shallow tillage drilling and loosening the soil treatments for the reseeding combinations Ⅴ and Ⅵ effectively improved the soil nutrient status, and increased the grass height, density, and biomass and are worth applying in ecological restoration of degraded natural grassland.
In order to explore the effects of air nitrogen deposition on alpine meadows, four nitrogen levels (N0, 0; N5, 14.3 g·m-2; N10, 28.6 g·m-2; N20, 57.1 g·m-2) were established in alpine meadows in the eastern Tibetan Plateau, and the biomass and species diversity for each level were measured after three consecutive years of nitrogen addition. The aboveground biomass increased from N0 to N20, reaching the maximal value at N20. Regarding the spatial pattern, the aboveground biomass showed a trend of upward shift, that is, the plants grew taller. The belowground biomass increased initially but decreased afterwards as nitrogen addition increased, peaking at N10, and it showed a trend of shifting towards topsoil (0-10 cm depth). Among the three functional groups (grass, sedge and forbs), aboveground biomass of grass increased from N0 to N20, peaking at 20, and so did the ratio between the aboveground biomass and total aboveground biomass of grass. In addition, plant species diversity decreased gradually as nitrogen addition increased. In conclusion, nitrogen addition exerted an evident influence on the structure of alpine meadows.
To explore the effect of fallow on weed community and species diversity in farm ecosystem, species composition and diversity were investigated in the interior, field bund, and drainage ditch of continuous rice-wheat and rice-fallow systems. The results showed that, 1) 64 species (58 genera belonging to 28 families) were distributed in continuous rice-wheat system with 39.1% perennial plants, while 76 species (32 families belonging to 68 genera) were distributed in rice-fallow system with 52.6% perennial plants; 2) Fallow significantly increased species richness (P=0.021)and Shannon-Wiener diversity index(P=0.006), but the difference of Simpson dominance index and Pielou evenness (P=0.318)index were not significant(P=0.844), between the two systems; 3) The species index in field bund were higher than that in interior and drainage ditch of both systems, which showed the importance of non-crop habitats for maintaining biodiversity, but no significant differences were found between the margin and interior of rice-fallow system; 4) The results of DCA clearly reflected the distribution range of various community types. Almost all rice-wheat communities were separated from rice-fallow communities, and community composition were similar between interior and field bund in the fallow period. These results reveal that fallow can reduce the difference of species composition between crop and non-crop habitats and effectively improve the plant biodiversity level of farm ecosystem.
In order to develop a roughage source for rabbits, the nutritive value of sun-cured whole plants of Daheishan (Coix lacryma-jobi cv. Daheishan) was determined. The plant was bred by the Maize Research Institute of Sichuan Agricultural University. Twenty-four healthy, 42-day-old French IRA rabbits with the same genetic background and similar weight (1 107.00±98.42) g were randomly assigned to two groups (12 each per group). All rabbits were housed individually in single wire metabolism cages that allowed separation of faeces and urine. The rabbits were fed two diets:basal (100% basal diet) and test (85% basal diet plus 15% whole plant of Daheishan). The experimental duration was for 11 d (7 d of adaptation period, and 4 d of collection period). After the study period, in vivo digestion test was performed. The results showed that the dry matter (DM) content of whole plants of Daheishan was 88.46%. The contents of gross energy (GE), crude protein (CP), crude fibre (CF), neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), nitrogen free extract (NFE), ether extract (EE), crude ash (Ash), calcium (Ca), and total phosphorus (TP) of the DM were 16.94 MJ·kg-1, 13.46%, 29.58%, 62.57%, 42.05%, 7.01%, 31.20%, 1.02%, 13.19%, 1.21%, and 0.20%, respectively. The Arg, His, Ile, Leu, Met, Lys, Phe, Thr, and Val contents were 0.47%, 0.15%, 0.37%, 0.74%, 0.14%, 0.41%, 0.46%, 0.45%, and 0.49%, respectively. For growing rabbits, the total tract apparent digestibilities of DM, GE, CP, CF, NDF, ADF, ADL, EE, Ash, Ca, and total P of whole plant of Daheishan were 31.67%, 30.02%, 60.09%, 4.55%, 10.26%, 0.80%, 29.21%, 54.68%, 38.17%, 58.84%, and 6.25%, respectively. DE was 5.69 MJ·kg-1 DM. In addition, the total tract apparent digestibilities of Arg, His, Ile, Leu, Met, Lys, Phe, Thr, and Val were 89.98%, 87.16%, 82.54%, 84.31%, 72.40%, 83.77%, 83.63%, 75.81%, and 83.84%, respectively. These results indicated that sun-cured whole plants of Daheishan had particularly higher crude protein and calcium contents than other contents. Fibre composition was reasonably high, and thus, this plant had a high nutrient digestibility in growing rabbits; Daheishan also had high amino acid content. Therefore, from the perspective of chemical composition and digestibility of nutrients, the whole plant of Daheishan can be used as roughage in rabbit production.
The objective of this study was to investigate the effect of native grass diets on performance, fur density, and serum biochemical indexes in finished Rex rabbits. Thirty 110-day-old healthy Rex rabbits were randomly divided into 3 groups, with 10 rabbits in each group (half male and half female). Group Ⅰ was control, where the rabbits were fed a basal diet; Group Ⅰ rabbits were fed 85% basal diet+15% local native grass; and group Ⅱ rabbits were fed 70% basal diet+30% local native grass. The adaptation period was 7 days, and the treatment period was 30 days. The results showed that the body weight, average daily gain, average daily feed intake, and body condition score increased and that the ratio of feed to gain decreased in rabbits fed with experimental diets. Compared with the control, in group Ⅱ rabbits, animal body weight, average daily gain, average daily feed intake, and body condition score increased by 9.78%, 57.9%, 3.79%, and 7.38% (P0.05), respectively, and the ratio of feed to gain decreased by 9.4% (P0.05). Fur density increased when the rabbits were fed with experimental diets. Compared with the control group, in group Ⅱ rabbits, fur densities on the back, waist, and left and right shoulders increased 20.7%, 38.6%, 33.7% and 47.3% respectively (P0.05). The fur density on the buttocks increased by 12.9% (P0.05). The serum total protein and albumin contents increased 15% and 13%, respectively (P0.05), and the serum globulin also increased (P0.05). In summary, the performance of Rex rabbits can be improved by feeding native grass diet during the finishing period.
Grassland forms the main body of the land ecosystem and plays a pivotal role in the maintenance of the national ecological environment. Locust plagues commonly occur in Inner Mongolia grasslands and have caused serious damages to the grassland vegetation. In order to reduce losses, we analysed and summarised locust plagues and suggested strategies for the application of green control technologies on grasslands from 2006 to 2015. Accordingly, the locust plagues have decreased for six years from 2010 to 2015 in Inner Mongolia. Presently, locust plagues occur only as spots or slices of mid-density or low-density. The control effects by using Nosema locustae, Metarhizium acridum, Bacillus thuringiensis, azadirachtin, matrine, nicotine·matrine, herding chicken and duck, release of natural enemies of locusts, and ecological management have been excellent. The green control technologies have been refined, and the basic control strategies have been decided. Over the past few decades, the cumulative application areas using the green control technologies have increased to 7.333 million hectares. The application green control technologies has reduced the pasture direct economic benefit loss of 990 million CNY from 2006 to 2015 and resulted in remarkable ecological, economic, and social benefits. In order to resolve problems with production and achieve green and sustainable control, capital input must be increased, early warming system must be perfected, biological control needs to be strengthened, and additional scientific research must be reinforced.
Since the free settlement project was carried out, the life of a herdsman has undergone major changes. We investigated 459 households in three counties located in northern Xinjiang, China. We analysed the impact of livelihood capital of herdsmen on their life satisfaction by using ordered logit method, on the basis of sustainable livelihood framework and classification of herdsmen. The results show the following. First, regional spatial differences and type heterogeneity exist in household livelihood capital and life satisfaction. Second, the household livelihood capital index was the highest in Fuhai County among pure pastoral herders; the life satisfaction of herdsmen was the highest in Tacheng City, and purely pastoral household satisfaction was higher than that for part-time herding and non-herding households. Third, the household livelihood capital had a significant impact on life satisfaction. Among them, increases in physical capital, financial capital, and social capital were found to increase the life satisfaction of herdsmen, and increases in natural capital and human capital were found to decrease the life satisfaction of herdsmen. Finally, this study provides relevant policy proposals to increase the livelihood capital of herdsmen.
Feeding wild oat herb to livestock that typically feed on grass improves efficiency of roughage, maintains the protein percentage in milk, inhibits puerperal diseases and metabolic diseases in cows, thereby prolonging the life-span of cows, reducing feed cost, increasing milk yield and daily gain, and other aspects. Wild oat as feed is gradually being accepted and valued by livestock farmers. In recent years, the production of wild oat herb has increased significantly in China; the import quantity of wild oat is also increasing. This study analysed wild oat production and trade in China, as well as determined the future development characteristics and trend of wild oat production and trade. Based on ARMA model, we predicted the total production and import quality of wild oat. On the basis of our observations, we propose future trends of production and trade of wild oat and suggest policies for development of the wild oat production industry.