Relationship of species diversity between overstory trees and understory herbs along the environmental gradients in the Tianshan Wild Fruit Forests, Northwest China

In forest ecosystems, interactions between overstory trees and understory herbs play an important role in driving plant species diversity. However, reported links between overstory tree and understory herb species diversity have been inconsistent, due to variations in forest types and environmental conditions. Here, we measured species richness(SR) and diversity(Shannon-Wiener(H') and Simpson's(D) indices) of overstory trees and understory herbs in the protected Tianshan Wild Fruit Forest(TWFF), Northwest China, to explore their relationships along the latitudinal, longitudinal, elevational, and climatic(current climate and paleoclimate) gradients in 2018. We found that SR, and H' and D diversity indices of overstory trees and understory herbs exhibited a unimodal pattern with increasing latitude and elevation(P<0.05) and negative associations with longitude(P<0.01). Along the climatic gradients, there were U-shaped patterns in SR, and H' and D diversity indices between trees and herbs(P<0.05). SR, and H' and D diversity indices for overstory tree species were positively associated with those for understory herbs(P<0.01). These findings indicate that overstory trees and understory herbs should be protected concurrently in the TWFF to increase effectiveness of species diversity conservation programs.

Changes in the relationship between species richness and belowground biomass among grassland types and along environmental gradients in Xinjiang, Northwest China

The association between biodiversity and belowground biomass(BGB) remains a central debate in ecology.In this study, we compared the variations in species richness(SR) and BGB as well as their interaction in the top(0–20 cm), middle(20–50 cm) and deep(50–100 cm) soil depths among 8 grassland types(lowland meadow, temperate desert, temperate desert steppe, temperate steppe desert, temperate steppe, temperate meadow steppe, mountain meadow and alpine steppe) and along environmental gradients(elevation, energy condition(annual mean temperature(AMT) and potential evapotranspiration(PET)), and mean annual precipitation(MAP)) based on a 2011–2013 survey of 379 sites in Xinjiang, Northwest China.The SR and BGB varied among the grassland types.The alpine steppe had a medium level of SR but the highest BGB in the top soil depth, whereas the lowland meadow had the lowest SR but the highest BGB in the middle and deep soil depths.The SR and BGB in the different soil depths were tightly associated with elevation, MAP and energy condition;however, the particular forms of trends in SR and BGB depended on environmental factors and soil depths.The relationship between SR and BGB was unimodal in the top soil depth, but SR was positively related with BGB in the middle soil depth.Although elevation, MAP, energy condition and SR had significant effects on BGB, the variations in BGB in the top soil depth were mostly determined by elevation, and those in the middle and deep soil depths were mainly affected by energy condition.These findings highlight the importance of environmental factors in the regulations of SR and BGB as well as their interaction in the grasslands in Xinjiang.

The Effect of Long-term Grazing Sheep in the Cotton Stubble on the Blood Biochemicals and Free Gossypol Residues

The objective of this study was to investigate the effect of long-term grazing sheep in cotton stubble on variation of biochemistry components and free gossypol residual in the blood. The survey found that 15% ewe of grazing group suffered miscarriage or premature birth,compared with the captive group ewes without this phenomenon. Blood test result shows that the free gossypol concentration in serum of grazing group was significantly higher than in indoor captive feeding group( P < 0. 01). In order to ensure the health of sheep grazing on cotton stubble and improve breeding rate,there is a need to do further reasonable research of grazing and feeding methods.

Effects of Dietary Supplement of Fermented Tomato Pomace on Dry Matter Intake and Nutrient Apparent Digestibility of Dairy Cows

This study was carried out to evaluate the effects of replacing corn silage with ensiled tomato pomace on dry matter intake and apparent digestibility of diets.Eight close up dry Holstein cows were used in 2 × 2 Latin square design.The animals were fed control(0% tomato pomace silage) and experimental(10% corn silage replaced by tomato pomace silage) diets.The result showed that dry matter intake in experimental group was 9.77 ± 0.44 kg/d,which was significantly higher than in control group(p < 0.05).Dry matter digestibility in experimental and control group was 73.9% and 70.2%,respectively,but there was no difference between two groups(p > 0.05).The substitution of tomato pomace silage in diet was associated with an increase of dry matter intake,dietary supplement of ensiled tomato pomace without any adverse effect on their health performance.

Rumen Degradability and Post-ruminal Digestion of Nitrogen and Amino acids by Cows Grazing Temperate Pasture

This experiment was conducted to evaluate nutrient digestion in the rumen and flow to the duodenum of steers grazed on orchardgrass( Dactylis glomerata L.,OG) or meadowfescue( Festuca pratensis Huds.,MF.) pastures located on northern part of Japan without supplement. Fifty-two digestion trials were carried out grazing Holstein steers fitted with cannulas in the rumen,duodenum and distal ileum in the three years. The pastures were divided into several paddocks,and the steers grazed each paddock for a day and allowed double of dry requirements the grazing cattle. The pre-grazing herbage mass did not significantly differ between pastures but the crude protein( N × 6. 25) content of herbage ranged from 19. 3% to 27. 5% on OG pasture and from 20. 0% to 32. 8% on MF pasture. Total N and AA-N intake did not differ but the degradability of dietary nitrogen in the rumen( RDN) was higher in MF than in OG pasture. The ratio of RDN to OM truly digested in the rumen was negatively related to the apparent N absorption in the rumen,and it was suggested that the amount of apparent N absorption in the rumen would be positive when the ratio was above 25 g / kg. Non-ammonia nitrogen( NAN) and AA-N flows to the duodenum of steers were lower in MF than in OG pasture. Duodenal AA flows were more linked to duodenal NAN flows and accounted for approximately 60% of duodenal NAN flows. The proportion of methionine and lysine slightly increased in the duodenal flows compared with the consumed AA,but a comparison between the essential AA composition of milk and the lean tissue indicated that duodenal digesta was most limiting in methionine,lysine,arginine,and histidine,and that deficiencies of arginine and histidine for milk production were relatively small.

Spatio-temporal patterns of drought in North Xinjiang, China, 1961–2012 based on meteorological drought index

Drought, which is one of the most frequently occurring severe hazards with long time scales and cov- ering wide geographical areas, is a natural phenomenon resulting in significant economic losses in agriculture and industry. Drought is caused by an imbalance between the inputs of and the demand for water which is insufficient to meet the demands of human activities and the eco-environment. As a major arid and semi-arid area and an important agricultural region in Northwest China, North Xinjiang （NX） shows great vulnerability to drought. In this paper, the characteristics of inter-annual and seasonal drought were analyzed in terms of drought occurrence and drought coverage, by using the composite index of meteorological drought and the data of daily precipitation, air temperature, wind speed, relative humidity and sunshine duration from 38 meteorological stations during the period 1961-2012. Trend analysis, wavelet analysis and empirical orthogonal function were also applied to investigate change trend, period and regional characteristics, respectively. In NX, annual and seasonal drought occurrence and drought coverage all showed a decreasing trend that was most significant in winter （with rates of-0.26 month/10a and -15.46%, respectively）, and drought occurrence in spring and summer were more frequent than that in autumn and winter. Spatially, drought was severe in eastern regions but mild in western regions of NX. Annual and seasonal drought occurrence at 38 meteorological stations displayed decreasing trends and were most significant in ＂Shi- hezi-Urumqi-Changji＂, which can help to alleviate severe drought hazards for local agricultural production and improve human livelihood. NX can be approximately classified into three sub-regions （severe drought region, moder- ate drought region and mild drought region）, which were calculated from annual drought frequencies. The cross wavelet transform suggested that SOl （Southern Oscillation Index）, AOI （Arctic Oscillation Index）, AAOI （Antarctic Oscillation Index）, PAOI （Pacific/North American Oscillation Index） and NAOI （North Atlantic Oscillation Index） have significant correlation with the variation of drought occurrence in NX. To prevent and mitigate the occurrence of drought disasters in NX, agricultural and government managers should pay more attention to those drought events that occur in spring and summer.

The Cotton Stalk and Its Utilization as Ruminant Feed Resource in Xinjiang

Two separate experiments were carried out: the first one involved a study of the chemical and some intrinsic feed characteristics of raw cotton stalk( CS) and the efficiency of chemical,biological treatments on the improvement of the feed value of CS. CS was treated with chemical treatment by mixing 3% Ca( OH)2( CS + Ca),3% urea( CS + U),3% urea +3% Ca( OH)2( CS + Ca + U). Moreover,CS was treated with biological treatment by inoculation of either Lentinus edodes( CS + Po) or Pleurotus ostreatus( CS + Pl) or crushing CS by adding minor ingredient processed into pellet feed,samples from all treatment were analyzed for the nutrients,In vitro dry matter digestibility( INDMD) and free gossypol detoxification rate. The second investigated was the use of crushed or granulation CS as a test feed followed by voluntary feed intake and preference test with sheep. CS + Ca + U treatment can reach up the CP and IVDMD to 9% and 36%,respectively. CS + Po decreased the fiber component and improved CP content and IVDMD. The free gossypol content declined and the free gossypol detoxification rate reached more than 50%. By feeding sheep under the same level of concentrate and corn silage,the voluntary feed intake and daily weight gain in granulation group is higher than in crushing group( P < 0. 05). Crushing CS by adding minor ingredient processed into a pellet feed was best in terms of improved nutritional quality,feed intake and preference,and it was safe and practical method that can be widely used in sheep production systems,to promote the CS feed utilization in similar areas.

Water-use efficiency in response to simulated increasing precipitation in a temperate desert ecosystem of Xinjiang, China

Water-use efficiency（WUE） is a key plant functional trait that plays a central role in the global cycles of water and carbon. Although increasing precipitation may cause vegetation changes, few studies have explored the linkage between alteration in vegetation and WUE. Here, we analyzed the responses of leaf WUE, ecosystem carbon and water exchanges, ecosystem WUE, and plant community composition changes under normal conditions and also under extra 15% or 30% increases in annual precipitation in a temperate desert ecosystem of Xinjiang, China. We found that leaf WUE and ecosystem WUE showed inconsistent responses to increasing precipitation. Leaf WUE consistently decreased as precipitation increased. By contrast, the responses of the ecosystem WUE to increasing precipitation are different in different precipitation regimes： increasing by 33.9% in the wet year（i.e., the normal precipitation years）and decreasing by 4.1% in the dry year when the precipitation was about 30% less than that in the wet year.We systematically assessed the herbaceous community dynamics, community composition, and vegetation coverage to explain the responses of ecosystem WUE, and found that the between-year discrepancy in ecosystem WUE was consistent with the extent to which plant biomass was stimulated by the increase in precipitation. Although there was no change in the relative significance of ephemerals in the plant community, its greater overall plant biomass drove an increased ecosystem WUE under the conditions of increasing precipitation in 2011. However, the slight increase in plant biomass exerted no significant effect on ecosystem WUE in 2012. Our findings suggest that an alteration in the dominant species in this plant community can induce a shift in the carbon-and water-based economics of desert ecosystems.

Effect of Addition of Dried Beet-pulp on Silage Fermentation Quality of Fish Waste Inoculated with Lactic Acid Bacteria

[Objective] This study was to further enhance previous research in finding appropriate methods for preservation and utilization of fish waste.[Method]Fresh fish waste（head and viscera）from arabesque greenling（Pleurogrammus azonus）was mixed with dried beet-pulp and beet molasses at a ratio of 70：20：10 on fresh matter basis,respectively.These were inoculated with /without a commercial inoculant of Lactobacillus plantarum and ensiled at room temperature for 15,30,60 and 90 days.Fermentation quality and chemical composition of the silages were evaluated and a feeding trial conducted using hen layers with fish waste silage replacing 25% of a commercial formulated diet on dry matter basis.[Result] The concentration of lactic acid in the silages tended to increase with extension of the ensiling period and was significantly（P 〈 0.05）enhanced by the inoculant.The pH declined from 6.5 to around 4.4 during the first 15 days of the ensiling period and did not change much thereafter.The non-protein nitrogen（NPN）content increased two folds after 15 days in all silages relative to the material but the rate of volatile basic nitrogen（VBN）to total nitrogen（TN）was less than 10%.Feed intake and egg production was similar with replacement of 25% of the commercial formulated diet with fish waste silage.

Variability of Soil Salinity at Multiple Spatio-Temporal Scales and the Related Driving Factors in the Oasis Areas of Xinjiang,China

Located in the inland arid area of central Asia, salt-affected farmlands take up one third of the total irrigated land area in Xinjiang of Northwest China. Spatio-temporal variability of soil salinity and the underlying mechanism are fundamental problems challenging the sustainability of oasis agriculture in China. In this study, the data of total dissolved solids(TDS) measured for soil samples collected from 27 representative study areas in the oasis areas of Xinjiang were analyzed and the coefficient of variation(CV) and stratification ratio(SR) of TDS were used to describe the lateral and vertical soil salinity variations, respectively. Weekly, monthly,and annual changes in soil salinity were also summarized. Results showed that the top(0–20 cm) soil salinity was highly variable(CV> 75%) for most studied areas. Lateral variation of soil salinity was significantly correlated with the sampling interval; as a result, a maximum sampling interval of 0.9 m was found for reducing evaluation uncertainty. The top 0–20 cm soil salt accounted for about25.2% of the total salt in the 0–100 cm soil profile. The stratification ratio values(the ratio of TDS at the 20–40 cm depth to that at the 0–20 cm depth) were mostly smaller than 1 and on average 0.92, illustrating that the top 0–20 cm soil contained slightly more salt and a considerable amount of salt still existed in subsurface and deep horizons. Irrigation reduced top soil salinity by 0.52 g kg-1, or14.6%, within the first week. On average, the relative range of soil salinity, calculated to indicate monthly changes in soil salinity, was58.2% from May to September. A 27-year experiment indicated that cultivation increased soil salinity by 44.4% at a rate of 0.14 g kg-1year-1. At small spatio-temporal scales, soil salinity variation was mainly affected by anthropogenic factors, such as irrigation and land use. However, natural factors, including groundwater, topography, and climate conditions, mainly influenced soil salinity variation at large spatio-temporal scales. This study displayed the highly variable nature of soil salinity in space and time. Those driving factors identified in this study could provide guidelines for developing sustainable agriculture in the oasis areas and combating salinization in arid regions of China.

Characteristics of water erosion and conservation practice in arid regions of Central Asia:Xinjiang,China as an example

Located in the inland arid area of Central Asia and northwest China,Xinjiang has recently received heightened concerns over soil water erosion,which is highly related with the sustainable utilization of barren soil and limited water resources.Data from the national soil erosion survey of China(1985-2011)and Xinjiang statistical yearbook(2000-2010)was used to analyze the trend,intensity,and serious soil water erosion regions.Results showed that the water erosion area in Xinjiang was 87.6
103 km^(2) in 2011,mainly distributed in the Ili river valley and the northern and southern Tian Mountain.Soil erosion gradient was generally slight and the average erosion modulus was 2184 t/(km^(2) a).During the last 26 years,the water erosion area in Xinjiang decreased by 23.2%,whereas the intensity was still increasing.The driving factors from large to small impact included:population boom and human activities4vegetation degradation4rainfall and climate change4topography and soil erodibility4tectonics movement.Soil water erosion resulted in eco-environmental and socioeconomic losses,such as destroying farmland and grassland,triggering floods,sedimentation of reservoirs,damaging transportation and irrigation facilities,and aggravating poverty.A landscape ecological design approach is suggested for integrated control of soil erosion.Currently,an average of 2.07×10^(3) km^(2) of formerly eroded area is conserved each year.This study highlighted the importance and longevity of soil and water conservation efforts in Xinjiang,and offered some suggestions on ecological restoration and combating desertification in arid regions of Central Asia.&2015 International Research and Training Center on Erosion and Sedimentation and China Water and Power Press.Production and Hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).

Effects of Enclosure on Plant and Soil Restoration in the Junggar Desert

Enclosure is commonly used in the restoration of degraded grasslands.However,the effects of enclosure on grassland plant and soil restoration remain controversial,particularly in deserts.To assess the effects of enclosure on desert plants and soil properties,using high throughput sequencing,the differences between plants and soil were systematically analyzed before and after enclosure construction.The soil organic carbon,total nitrogen and total phosphorus contents of the three desert flora increased and decreased,but the difference was not significant;enclosure increased plant height,coverage,aboveground biomass,and species richness by 58.99%,59.35%,33.29%,and 51.21%,respectively,in a Seriphidium transiliense formation;by 15.49%,33.52%,20.85%,and 5.13%,respectively,in a Haloxylon persicum formation;and by 83.80%,31.51%,76.66%and 33.33%,respectively,in an Anabasis salsa formation.For soil bacteria,enclosure significantly increased the average number of operational taxonomic units and Shannon-Wiener index by 12.74% and 2.92%,respectively,under S.transiliense formation and by 17.08% and 3.17%,respectively,under H.persicum formation.However,enclosure had no significant effect on the average number of operational taxonomic units or Shannon-Wiener index under A.salsa formation.Enclosure significantly increased desert plants,soil bacterial diversity,and desert plant community productivity;however,the increase in soil nutrient content was not significant.These results demonstrate that enclosure is effective for restoring desert ecosystems but may have little effect on the soil nutrient content.

Distribution and storage of soil organic and inorganic carbon under different ecological zones in Xinjiang,China

The objective of this study was to quantify both soil organic carbon(SOC)and soil inorganic carbon(SIC)stocks in different ecological zones in Xinjiang Region,the largest arid and semi-arid region in northwest China.The specific focus was on the vertical distributions of 641 typical soil profiles(0-100 cm).The study region covered five ecological zones:I-Altai/west Junggar;II-Junggar basin;III-Tianshan mountain;IV-Tarim basin;and V-Kunlun-Altun mountains.The zones are categorized by their specific geographical locations from north to south with terrains derived from mountains to basins.The data used in the study were obtained from the first(1960s)and the second(1980s)National Soil Surveys and partially from the field survey of this study conducted in 2013.The results suggest that there are 11.74 Pg SOC and 26.71 Pg SIC total stocks in the 0-100 cm surface soil over the entire study region.The distributions of SOC and SIC were found to be non-uniform.The Tianshan mountain zone has the highest SOC stock,followed by the Tarim basin,Kunlun-Altun mountains,Altai and west Junggar(Altai/west Junggar),and Junggar basin zones.In contrast,the Tarim basin zone had the highest SIC stock,followed by the Tianshan mountain,Kunlun-Altun mountains,Junggar basin,and Altai/west Junggar zones.The SOC content decreases gradually from northwest to southeast and from mountains to deserts;while the SIC content decreases gradually from south to north.The SOC and SIC contents also change with soil depth.Within a given ecological zone,the SOC content increased with increasing soil depth,peaked at about 20-40 cm,then it decreased with the bigger depths below 40 cm.The SIC contents increased gradually from 0 to 40 cm,and then decreased gradually with increasing soil depth over the 40-100 cm depth in all ecological zones except for the Tianshan mountain area.

Woody plant encroachment may decrease plant carbon storage in grasslands under future drier conditions

Aims Woody plants are widely distributed in various grassland types along the altitudinal/climatic gradients in Xinjiang,China.Considering previously reported change in carbon(C)storage following woody plant encroachment in grasslands and the mediating effect of climate on this change,we predicted that a positive effect of woody plants on plant C storage in semiarid grasslands may revert to a negative effect in arid grasslands.We first investigated the spatial variation of aboveground C(AGC)and belowground C(BGC)storage among grassland types and then tested our prediction.Methods We measured the living AGC storage,litter C(LC)and BGC storage of plants in two physiognomic types,wooded grasslands(aboveground biomass of woody plants at least 50%)and pure grasslands without woody plants in six grassland types representing a gradient form semiarid to arid conditions across Xinjiang.Important Findings Living AGC,LC,BGC and total plant C storage increased from desert to mountain meadows.These increases could also be explained by increasing mean annual precipitation(MAP)or decreasing mean annual temperature(MAT),suggesting that grassland types indeed represented an aridity gradient.Woody plants had an effect on the plant C storage both in size and in distribution relative to pure grasslands.The direction and strength of the effect of woody plants varied with grassland types due to the mediating effect of the climate,with wetter conditions promoting a positive effect of woody plants.Woody plants increased vegetation-level AGC through their high AGC relative to herbaceous plants.However,more negative effects of woody plants on herbaceous plants with increasing aridity led to a weaker increase in the living AGC in arid desert,steppe desert and desert steppe than in the less arid other grassland types.Under greater aridity(lower MAP and higher MAT),woody plants allocated less biomass to roots and had lower BGC and had a more negative impact on herbaceous plant production,thereby reducing vegetation-level BGC in the desert,steppe desert and desert steppe.In sum,this resulted in a negative effect of woody plants on total plant C storage in the most arid grasslands in Xinjiang.As a consequence,we predict that woody plant encroachment may decrease rather than increase C storage in grasslands under future drier conditions.