Table of Content

20 January 2016, Volume 25 Issue 1

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Orginal Article

Analysis of vegetation dynamics using GIMMS NDVI3g in the Three-Rivers Headwater Region from1982 to 2012

DU Jia-Qiang, JIAERHENG·Ahati, ZHAO Chen-Xi, FANG Shi-Feng, LIU Wei-Ling, YIN Jun-Qi, YUAN Xin-Jie, XU Yan-Da, SHU Jian-Min, HE Ping

2016, 25(1):  1-12.  DOI: 10.11686/cyxb2015111

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The Three-Rivers Headwater Region (TRHR) refers to the source area of the Yangtze River, Yellow River and Lancang River, an important water resource. Vegetation activities in this region are closely related to water and ecological security in China. As a critical component of terrestrial ecosystems, vegetation has become one of the important issues in global climate change. Numerous case studies have been conducted on vegetation dynamic trends over relatively short study periods however, few long-term studies from the 1980s to recent years have been completed because the normalized difference vegetation index (NDVI) datasets limited. Additionally there are few quantitative analyses of the consistency of vegetation trends over time. In this study, the latest GIMMS NDVI3g datasets from 1982 to 2012 were used to identify any spatiotemporal patterns in vegetation changes over the growing season and seasonal NDVI at regional, biome and pixel scales in the TRHR. To explore the change process linear regression over progressively longer periods from the initial year of the study was applied to detect vegetation growth changes in TRHR. At the regional scale, although a positive trend of growing season and seasonal NDVI were found during past three decades, there were two distinct periods with opposite trends in spring NDVI, a significant increase and a significant decrease before and after 1998, respectively. As the study period increases, the rates of NDVI increase in the spring and summer growing season markedly reduced, but in autumn the NDVI increased. However, significant NDVI increases were found in most seasons. The season and period with significant trend in NDVI differed among vegetation types. Significant increases in NDVI were observed in spring during the first few periods for coniferous forest and shrub and in spring and summer during the first few periods for desert and meadow areas. The difference in persistence of NDVI trends caused variation in the contribution of seasonal vegetation activity to plant growth. During the first few periods, the largest NDVI increase and the largest contribution were generally found in spring and in summer, respectively. During the last few periods, both the largest NDVI increase and contribution were found in autumn. It can be inferred that increases in NDVI during the growing season was mainly due to both the earlier start of vegetation growth and accelerated vegetation activity during previous periods and from both the accelerated vegetation growth and a delay in the end of the growing season during latter periods.

Vegetation phenology dynamics and its response to climate change on the Tibetan Plateau

MA Xiao-Fang, CHEN Si-Yu, DENG Jie, FENG Qi-Sheng, HUANG Xiao-Dong

2016, 25(1):  13-21.  DOI: 10.11686/cyxb2015089

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We extracted vegetation phenology parameters (start, end and duration of the growing season) using GIMMS NDVI remote sensing data from 1982-2005 from the Tibetan Plateau and analyzed the spatial distribution and inter-annual variation of vegetation phenology in order to explore the mechanisms of the response of phenology to climate change. The spatial distribution of vegetation phenology was closely related to hydrothermal conditions on the Tibetan Plateau. Along a transect running from the southeast to the northwest, the start of the growing season was gradually delayed, the end of growth season advanced while the length of growing season reduced. The inter-annual variability of the start and the end of the growing season tended to increase while that of the growing season length decreased. Elevation plays an important role in the regional heterogeneity of phenology, but a boundary was identified at approximately 3400 m altitude. Below 3400 m phenology fluctuated irregularly with altitude whereas above 3400 m phenology was closely associated with altitude. Based on climate data from meteorological stations, the relationship between vegetation phenology and the key meteorological factors under the different grassland types were analyzed; the results show that temperature is more important to the change of vegetation phenology than precipitation on the Tibetan Plateau.

Spatial-temporal variation of vegetation phenology and their relationships with vegetation degradation in a Qinghai Lake watershed

LI Guang-Yong, JIANG Cui-Hong, CHENG Tao, ZHANG Hao-Ran, CHEN Zhan-Tao

2016, 25(1):  22-32.  DOI: 10.11686/cyxb2015210

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This paper presents a threshold method to examine the vegetation phenology in a Qinghai Lake watershed based on a time-series analysis of a MODIS EVI dataset from 2000 to 2014 using 16-day intervals. The spatio-temporal variation of vegetation phenology and the relationship with vegetation degradation were also analyzed. The results showed that the beginning of the vegetation growing season (BGS) occurred from mid-April to mid-June and the end of growing season (EGS) from mid-August to mid-October; growing season (GS) was between 100 to 150 days. The BGS spatial pattern was embodied by a transition from southeast to northwest; vertical zonation in the mountainous region showed a contrary trend in EGS and GS. Spatio-temporal variation of vegetation phenology at the whole watershed level showed spatial heterogeneity under climate change, but mean BGS trends were not pronounced during the study period. EGS was advanced approximately 6.4 days and GS prolonged by 8.9 days. Vegetation phenology was also affected by vegetation degradation. BGS tended to be later when vegetation flourished and advanced when vegetation was degraded. The relationship between annual EGS date and vegetation degradation was relatively complex. EGS and vegetation degradation were significantly negatively correlated indicating EGS was earlier where the vegetation was in good condition.

Vegetation changes in Otindag sand country during 2000-2014

YUAN Zhi-Hui, BAO Gang, YIN Shan, LEI Jun, BAO Yu-Hai, SA Chu-La

2016, 25(1):  33-46.  DOI: 10.11686/cyxb2015319

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MODIS NDVI collected during the growing season (from April to October) from 2000 to 2014 were adopted and integrated in this study to extract the time series characteristics of vegetation dynamics in Otindag sand country. The response of vegetation changes to climate data including temperature and precipitation recorded at fifteen meteorological stations were analyzed during 2000 to 2013 using annual and monthly time scales. The results revealed that regardless of the time scale (monthly or annual), the NDVI tended to increase over the 15-year observation period a result of climate and human activity Ecological restoration, indicating that ecological restoration work has produced benefits. The annual NDVI was correlated with precipitation (r=0.75), indicating that precipitation was the dominant factor in vegetation dynamics. With respect to spatial pattern, the NDVI in southern, central and northern fringe regions of the study area tended to increase but no obvious trends were observed in the central and some western areas of the region. Correlation between monthly average NDVI and climatic factors during the growing season showed that the response of vegetation change to temperature in April and May was strong, indicating that temperature was important in the early stages of the growing season. Correlation between NDVI and precipitation of the previous month were strongest from May to August revealing a hysteresis response of plant growth to rainfall. Shifting sand dunes showed the largest increase in NDVI while the smallest increase occurred in fixed sand dunes.

Spatial-temporal change in different vegetation growth of Xinjiang from 1982 to 2013

XU Yu-Feng, YANG Jing, LI Wei-Hong, FANG Gong-Huan, ZHANG Shu-Hua, DENG Hai-Jun, DONG Jie

2016, 25(1):  47-63.  DOI: 10.11686/cyxb2015073

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Based on a pixel scale linear regression model, we extended Advanced Very High Resolution Radiometer Global Inventory Modeling and Mapping Studies (AVHRR GIMMS) using MODIS normalized difference vegetation index (NDVI) data and constructed a time series of NDVI covering Xinjiang province from 1982 to 2013. We also analyzed the spatial-temporal changes in vegetation growth in different districts and correlated these changes with climate factors. NDVI increased significantly in the plain regions of northern and southern Xinjiang and in the mountainous region of southern Xinjiang, but decreased in the mountainous region of northern Xinjiang. Rainfall and minimum temperature were important factors in vegetation growth in Xinjiang. Vegetation was influenced by rainfall on the northern Xinjiang plain; crop growth was influenced by temperature, especially minimum temperature. On the southern plain vegetation growth was influenced by both rainfall and temperature and in the mountain regions by rainfall. Rainfall played a more important role in grassland compared to forest and cropland areas; rainfall has little influence on cropland because of the use of irrigation. Increasing rainfall and temperature promoted an increase in the NDVI while the degradation of vegetation in mountainous region of northern Xinjiang is influenced by a range of factors including climate change, fire, and the control of grazing pressure by fencing.

Spatial analysis of soil bulk density in Yili, Xinjiang Uygur Autonomous Region, China

ZHOU Li-Lei, ZHU Hua-Zhong, ZHONG Hua-Ping, YANG Hua, SUO Fei-Ya, SHAO Xiao-Ming, ZHOU Xing-Jie

2016, 25(1):  64-75.  DOI: 10.11686/cyxb2015249

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Currently, the study of soil bulk density of grassland is mainly focused on traditional statistical analysis based on survey data; studies using spatial pattern analysis of soil bulk density are limited. This paper attempted to apply multi-source data, which include field survey soil bulk density data, remote sensing data and meteorological data from 146 grassland sample plots to study the spatial analysis of soil bulk density in the Yili district, located at the northwest margin of Xinjiang Uygur Autonomous Region. Correlation analysis and regression analysis between the soil bulk density and elevation, annual average temperature, annual average precipitation, annual cumulative temperature above 10℃, wettability, and NDVI were examined. Subsequently regression analysis was undertaken using ArcGIS. There was a significant correlation between soil bulk density and elevation, annual average temperature, annual average precipitation, annual cumulative temperature above 10℃, wettability, and NDVI (P<0.01). The multiple correlation coefficient (R²), root-mean-square error (RMSE), population deviation, and the average prediction accuracy were 0.6025, 0.1479 g/cm³, 14.39%, and 85.61%, respectively. The soil bulk density in the river valley was higher than in the high altitude region. The highest soil bulk density was found in temperate desert type grassland (about 1.3340 g/cm³), and the lowest was found in alpine meadow grassland which is distributed on the northern slopes of the Southern Tianshan mountains (about 0.7310 g/cm³). The results indicated that the spatial distribution of soil bulk density was consistent with the distribution of different soil types and grassland in Yili. The information collected has potential for use in the evaluation of grassland degradation.

Community structure characteristics of culturable cellulose-decomposing fungi in soils from different ecosystems in the Sanjiangyuan Regions

LU Guang-Xin, LI Zong-Ren, LI Xi-Lai, WANG Jun-Bang, WU Chu, LI Xin, ZHANG Geng-Xiong, SUN Qian, LI Feng-Ke, ZHENG Hui-Mei

2016, 25(1):  76-87.  DOI: 10.11686/cyxb2015085

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In order to understand the community structure characteristics of culturable cellulose-decomposing fungi in soils from different ecosystem in the Sanjiangyuan Regions, the fungi in soil from four typical grassland types were isolated by dilution plate method using a sodium carboxymethyl cellulose plate medium. The population dominance index, Shannon-Wiener index, evenness, niche breadth and community similarity were employed to analyze the community structure of the isolated fungi. The results showed that the amount and species distribution of culturable cellulose-decomposing fungi varied strongly by ecosystem. Species number decreased in the following order: shrub grassland>alpine meadow>Kobresia tibetica grassland>grass pasture. In total 17 genera were isolated from the four grassland types. The population dominance index, species diversity index and evenness index of fungi from grass pasture were highest, whereas the population dominance and species diversity indices from alpine meadow were lowest. Analysis of community similarity between the different ecosystems showed that fungi in shrub grassland and Kobresia meadow soils had the highest similarity. The similarity coefficient for fungi in grass pasture and Kobresia tibetica grassland soils was the lowest. The results of niche breadth analysis indicated that the species of Mucor, Fusarium, Mortierella and Penicillium had wider niche breadth and adaptability, while the species of Didymella, Thielavia and Humicola had narrower niche breadth and adaptability. The study thus shows that the diversity and community structure of soil cellulose-decomposing fungi are closely related to ecosystem types.

Influence of yak grazing on plant niche characteristics in alpine meadow communities at the northeastern edge of the Qinghai-Tibetan Plateau

MIAO Fu-Hong, XUE Ran, GUO Zheng-Gang, SHEN Yu-Ying

2016, 25(1):  88-97.  DOI: 10.11686/cyxb2015033

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The grazing intensity changes the plant composition of alpine meadow. A field survey was carried out to determine the effect of grazing intensities on plant niche characteristics of alpine meadow communities in the Qinghai-Tibet Plateau. This study showed that the number of plant species appearing in plots reduced as the grazing intensity increased, and Anaphalis tibetica, Stipa purpurea and Allium sikkimense disappeared when grazing intensity exceeded 1.25 yak/ha. The numbers of unpalatable plants increased when the grazing intensity in plots was over 1.00 yak/ha. With increasing grazing intensity, the importance value of Kobresia capillifolia, a dominant species, initially increased and then decreased, peaking at 1.00 yak/ha grazing intensity, and the importance value of Polygonum viviparum, another dominant species peaked at 0.75 yak/ha grazing intensity. The niche breadth of K. capillifolia and P. viviparum was greater than that of other species in alpine meadow communities differing in grazing intensity and increased as the grazing intensity increased. The plants with the biggest niche overlap with K. capillifolia and P. viviparum were different. P. viviparum was one of two populations which had a bigger coefficient of niche overlap at 0 and 0.75 yak/ha grazing intensity, however, P. viviparum did not appear in the populations which had the biggest coefficient of niche overlap when the grazing intensity was over 0.75 yak/ha. K. capillifolia was one of two populations which had the biggest coefficient of niche overlap at 1.25 yak/ha grazing intensity. These results suggest that the grazing intensity changed the plant composition, species importance values, niche breadth and niche overlap of alpine meadow communities, and that a grazing intensity of 1.00 yak/ha was advantageous to the dominant species, P. viviparum and K. capillifolia, in alpine meadow at the northeastern edge of the Qinghai-Tibetan Plateau.

Effects of different crops and straw mulching on soil aggregate and carbon sequestration potential in the dryland, triple cropping systems of Southwest China

ZHANG Sai, WANG Long-Chang, DU Juan, ZHAO Lin-Lu, CHEN Jiao, SHI Chao, HUANG Zhao-Cun, XIONG Ying, JIA Hui-Juan

2016, 25(1):  98-107.  DOI: 10.11686/cyxb2015272

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A study has been undertaken in experimental field sat Southwest University in Beibei, Chongqing, in order to explore changes in soil aggregate distribution and organic carbon content, and to estimate soil carbon sequestration potential, in southwest China farmland that uses the triple cropping system (wheat/corn/soybean). There were two treatments: traditional tillage (T) and T plus straw mulching (TS). There was a significantly negative correlation between >2 mm and 2-0.25 mm aggregate contents (r=0.985, P<0.05) during the planting periods of the three crops. The responses of soil aggregates to the different crops varied. In the wheat and soybean belts, the content of water-stable aggregates (>0.25 mm) was as high as 90% of total soil, while it was approximately 80% in the corn belt, indicating that corn performance was beneficial to the formation of soil water-stable micro-aggregates. Straw mulching significantly increased soil organic carbon content and particle size at the 0-5 cm and 5-10 cm soil layers. Increases in organic carbon content at the 5-10 cm soil layer were especially notable. Soil carbon sequestration potential was greater in the corn than in the wheat and soybean belts. The study shows that the distribution of soil aggregates and of organic carbon content in soil particles with different sizes were influenced by both tillage measures and crops. In conclusion, the selection of crops and straw mulching will play important roles in promoting soil carbon sequestration in the dryland, triple cropping systems of southwest China.

Effects of fire on above-ground vegetation and offspring recruitment in a semiarid steppe on the Loess Plateau

ZHAO Ling-Ping, BAI Xin, WANG Zhan-Bin, CHENG Ji-Min, TAN Shi-Tu, WANG Qing-Yi

2016, 25(1):  108-116.  DOI: 10.11686/cyxb2015087

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There is an increased understanding of the role of fire in population dynamics, plant community structure and succession. However, few studies have examined the mechanism of the effect of fire on plant community structure and offspring recruitment. This study explored the short term responses of perennial grassland vegetation and offspring recruitment following fire on the Loess Plateau. The results showed that fire significantly reduced total cover, species diversity, litter thickness and litter biomass, and significantly increased community density; however it did not alter species richness. Fire exerted important effects on plant community structure and species composition in the short-term. Fire significantly increased asexual recruitment by clonal ramification, but had no effect on sexual recruitment through increased seedling numbers. Burnt grassland had a significantly higher density in tiller and rhizome offspring recruitment number than the unburnt grassland, however, recruitment from root suckers, branches and stolons did not differ significantly between the treatments. Our results indicate that asexual recruitment contributed more to vegetation regeneration of the perennial-steppe community than seedling recruitment. Lack of sexual recruitment is not related to fire management but to species composition.

Effect of change to simulated precipitation patterns on seedling growth of Nitraria tangutorum

ZHANG Rong, SHAN Li-Shan, LI Yi, DUAN Gui-Fang, DUAN Ya-Nan, ZHANG Zheng-Zhong, Жигунов Анатолий Васильевич

2016, 25(1):  117-125.  DOI: 10.11686/cyxb2015076

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Nitraria tangutorum is an important, dominant species in arid desert. Our objective was to explore the responses of N. tangutorum seedlings to various precipitation patterns. This approach will provide basic theoretical data to predict seedling survival in degraded N. tangutorum scrub vegetation, and accelerate desert region recovery. In this article, we report an experiment using simulated rainfall to examine the effect of precipitation (increased by 30%, reduced by 30%, unchanged) and precipitation interval (increased, unchanged) on N. tangutorum seedlings. Differences in root length, leaf biomass, above ground biomass, total biomass and root-shoot ratio under the various simulated precipitation regimes are reported. The total precipitation and precipitation interval both strongly affected N. tangutorum growth, but had no significant interaction. Plant crown, basal diameter and biomass were increased by extended precipitation interval, with the same total precipitation. As a result, the leaf biomass was increased by 81%, so that the above ground biomass accumulation was far greater than for below ground biomass, and the root-shoot ratio was decreased. With unchanged precipitation interval, reduced precipitation had no significant effect on stem and below ground biomass, but root length was increased by 86%; while leaf biomass, above ground biomass and total biomass were reduced by 67%, 48%, and 27%, respectively, and the root-shoot ratio was increased by 74%. The treatment in which precipitation was increased by 30% had no significant effect on biomass. Therefore, appropriate increase of precipitation and precipitation interval promote growth of N. tangutorum seedlings, and vegetation restoration where this shrub is present.

Potassium release characteristics of microcrystalline potassium mineral and its effects on growth of grain amaranth

LV Le-Fu, DOU Xing-Xia, ZHANG Hong-Wei, XIE Xing-Yuan, GAI Guo-Sheng

2016, 25(1):  126-133.  DOI: 10.11686/cyxb2015072

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In order to improve potassium availability, potassium minerals were finely ground in a microcrystalline mill with an organic activator, and the physical properties studied, including kinetics of potassium release and fertilizer efficiency. The results showed that the physical and chemical characteristics of the microcrystalline potassium mineral were improved significantly. Compared to the untreated potassium mineral, the median particle size was decreased by 37.22%, the specific surface area was increased by 194.14% and the total dose of potassium in 60 days was improved by 492.44%. After application of the microcrystalline potassium mineral to soil as fertilizer, plant height, stem diameter and biomass were increased by 12.16%, 20.55% and 13.76%, respectively, compared to the unground potassium mineral treatment. Application of finely ground potassium minerals also raised the levels of soil rapidly available K, and slowly available K, and these differences were statistically significant, compared to application of unground potassium mineral. The stimulation to growth of grain amaranth from a treatment which applied increments of microcrystalline potassium feldspar mineral or a combined application of microcrystalline potassium mineral and potassium chloride was less than that obtained from a conventional potassium chloride fertilizer treatment, but not significantly so (P>0.05).

Seasonal variations of leaf cuticular wax in herbs widely distributed in Chongqing

GAO Jian-Hua, HE Yu-Ji, GUO Na, GUO Yan-Jun

2016, 25(1):  134-143.  DOI: 10.11686/cyxb2015198

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Cuticular wax covers the outmost leaf surface and plays an important role in protecting plants from biotic and abiotic stress. The composition and amount of cuticular wax varies with environmental conditions. In this study, nine widely distributed herbs in Chongqing have been seasonally analyzed for the amounts of total cuticular wax and for variations in its composition. Analysis has been undertaken of the distributions of n-alkanes, n-alkanoic acids and primary alcohols, and their average chain length (ACL) and carbon preference index (CPI). Five plant species were observed in four seasons: Solanum nigrum, Conyza canadensis, Oplismenus undulatifolius, Calystegia hederacea and Sonchus oleraceus. Four species were observed in three seasons: Kalimeris indica, Plantago asiatica, Humulus scandens and Chenopodium glaucum. The results showed that the amount of total cuticular wax and its composition varied by plant species, with the highest total cuticular wax in Sonchus oleraceus (18.42 μg/cm²) and the lowest in Kalimeris indica (0.83 μg/cm²). The leaf cuticular wax in Sonchus oleraceus, Humulus scandens and Chenopodium glaucum was dominated by n-alkanoic acids and primary alcohols, whereas that in the other species was dominated by n-alkanes. In most plant species, total cuticular wax reduced from spring to autumn and then increased in winter, with the lowest levels in summer. The predominant carbons of n-alkanes in most plant species were C₂₉, C₃₁ and C₃₃, except for Humulus scandens in winter and Chenopodium glaucum in spring, where C₂₇, C₂₉ and C₃₁ predominated. The CPI of n-alkanes in most plant species reduced from spring to autumn and then increased in winter, whereas the ACL of n-alkanoic acids and primary alcohols in most plant species was higher in summer than winter. Overall, seasonally distributed herbs might adapt to changing environments by adjusting wax deposition on leaves, altering the average chain length of the main cuticular wax compositions and the relative contents of even and odd numbered carbons.

Adaptive responses of eremophyte Pugionium cornutum seedlings to different concentrations of NaCl

YUE Li-Jun, YUN Kun, LI Hai-Wei, KANG Jian-Jun, WANG Suo-Min

2016, 25(1):  144-152.  DOI: 10.11686/cyxb2015115

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To investigate the adaptive mechanisms of Pugionium cornutum seedlings at different NaCl concentrations, 5-week-old seedlings were treated with a series of external NaCl concentrations (5, 25, 50, 100 and 200 mmol/L). The seedlings exhibited different adaptive mechanisms at different NaCl concentrations. At low salt concentrations (5 mmol/L NaCl), leaf dry weight and water content significantly increased by 25% and 35% respectively compared to the control (P<0.05). The adaptation of P. cornutum to low salt concentrations was mainly due to the rapid growth and increased water content of the plant, which could dilute the excessively absorbed Na⁺ to below toxic levels. At moderate salt concentrations (50 mmol/L NaCl), a strong controlled K⁺ and promoted Na⁺ transportation from root to leaf was observed, and leaf Na⁺ concentration was 8-fold higher than that in the control plants (P<0.05). This adaptation might be explained by the plant’s ability to compartmentalize excess Na⁺ into the vacuole in leaf cells, which could protect leaves from Na⁺ toxicity and produce a 75% decrease in leaf osmotic potential (P<0.05). Therefore, the ability of plants to resist the osmotic stress induced by NaCl was enhanced and normal plant growth could be maintained. The adaptation of P. cornutum to high concentrations of salt (200 mmol/L NaCl) was caused by a strong controlled Na⁺ and promoted K⁺ transportation from the outside into the plant and then from root to leaf. This resulted in a 55% increase in leaf K⁺ concentration under the high-concentration treatment compared to the 50 mmol/L treatment (P<0.05), with a corresponding increase from 10.28% to 12.51% in the contribution of K⁺ to osmotic potential. This mechanism could help to maintain a low Na⁺/K⁺ within the cytoplasm, reduce Na⁺ toxicity to cells, balance the osmotic pressure from vacuole and apoplast to cytoplasm, and reduce osmotic stress on cells due to the primary location of K⁺ mainly in the cytoplasm. However, leaf dry weight significantly decreased by 51% at 200 mmol/L NaCl grown for 7 d compared to control (P<0.05), indicating that P. cornutum seedling has limited salt tolerance.

Response and enrichment ability of perennial ryegrass under lead and cadmium stresses

FENG Peng, SUN Li, SHEN Xiao-Hui, JIANG Cheng, LI Ru-Lai, LI Zeng-Jie, ZHENG Hai-Yan, ZHANG Hua, GUO Wei, HAN Xu-Dong, HONG Ya-Nan

2016, 25(1):  153-162.  DOI: 10.11686/cyxb2015069

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The object of this study was to evaluate the effect of lead and cadmium stresses on growth and development of perennial ryegrass and to better understand the potential of perennial ryegrass for phytore mediation of Pb and Cd contaminated soils, and provide technical information for soil remediation planning. In a pot experiment, Pb was spiked at 0,300, 500, 1000, 1500 mg/kg, and Cd was spiked at,0,0.3, 3, 10, 50, 100 mg/kg. Further, Pb and Cd treatments were combined as follows: Pb₀Cd₀(CK), Pb₃₀₀Cd_0.3, Pb₅₀₀Cd_0.3, Pb₁₀₀₀Cd_0.3, Pb₁₅₀₀Cd_0.3, Pb₃₀₀Cd₁₀, Pb₅₀₀Cd₁₀, Pb₁₀₀₀Cd₁₀, Pb₁₅₀₀Cd₁₀. Measurements made included germination vigor, an establishment rate index, chlorophyll content, photosynthetic rate, transpiration, water use efficiencies of seedlings, as well as photosynthetically active radiation, and light use efficiency. The Pb and Cd contents of root, stem and leaf were determined in the seedlings. Compared to CK, there was no significant difference in germination at lower concentrations (300, 500 mg/kg) of Pb stress, but there was an adverse effect at higher concentrations (1000, and 1500 mg/kg). Lower concentrations of Cd stress promoted seed germination, but where Cd concentration was more than 10 mg/kg, there was inhibition of seed germination. With increase in Pb concentration, chlorophyll content also increased, but Cd stress the opposite tendency was noted. Photosynthetic rate decreased at lower concentrations and then increased at higher concentration under Pb or Cd single stress. Photosynthetic rate peaked when Pb concentration was 1000 mg/kg or Cd concentration was 10 mg/kg. The enrichment coefficient decreased with increase in concentration of the metals Pb or Cd. The Pb and Cd combinations showed stronger inhibitory effects on seed germination than single metal exposure stress. The enrichment ability of perennial ryegrass to Pb and/or Cd was root>stem>leaf. The enrichment coefficient of Cd was greater than that of Pb. Perennial ryegrass showed a better remediative effect on lightly polluted soils.

Cross adaptation under drought and low temperature stress in perennial ryegrass

LIANG Xiao-Hong, AI Fei-Fan, ZHONG Tian-Xiu, HAN Lie-Bao

2016, 25(1):  163-170.  DOI: 10.11686/cyxb2015230

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Turfgrass suffers from both drought and cold stress in winter which degrades turf quality in the following spring. In order to investigate the physiological mechanism of cross adaptation to drought and low temperature stress in perennial ryegrass “Accent” turf ryegrass was subjected to three watering regimes (30%, 60% and 100% of requirements) for 5 days and then exposed to 2℃ temperatures day and night for 15 days. The results showed that low temperature stress decreased the relative water content (RWC) and chlorophyll (Chl) content but increased electrolyte leakage (EL), proline, soluble sugar and antioxidant enzymes. Mild drought stress before exposure to cold stress produced a significantly lower reduction in RWC and Chl content but increased osmotic adjustment and antioxidant enzymes. It was concluded that moderate drought prior to exposure to low temperatures helped perennial ryegrass adapt to low winter temperatures but severe drought caused considerable damage to plants.

Effects of different herbicides on weed control, grain yield and hull rate in naked oats

SONG Xu-Dong, ZHAO Gui-Qin, CHAI Ji-Kuan

2016, 25(1):  171-178.  DOI: 10.11686/cyxb2015105

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In order to select safe and effective herbicides and to determine optimal application rates for oat production, a field trial was conducted in central Gansu. Seven hormonal herbicides were trialed:72% 2, 4-D Butyl ester, 20% Fluroxypyr, 48% Dicamba, 50% Benazolin, 50% Quinclorac, 40% Bromoxynil octanoate plus MCPA-sodium (MCPA-sodium content by 20% plus Bromoxynil content by 20%) and 55% Tribenuron-methyl plus Carfentrazone plus MCPA-sodium (Tribenuron-methyl content by 2.6% plus MCPA-sodium content by 50% plus Carfentrazone content by 2.4%) and one non-hormonal herbicide 75% Tribenuron-methyl. The herbicides were tested at low, medium and high dosages with naked oats to determine their effects on weed control, grain yield and hull rate. The 72% 2, 4-D Butyl ester was harmful to oat production and caused significant increases in hull rates, indicating that it should not be used with this crop. The effectiveness of weed control increased with increases in herbicide dosage. Grain yield also fluctuated with dosage levels. Considering safety, weed control and grain yield, 40% Bromoxynil octanoate plus MCPA-sodium at 1350 mL/hm², 55% Tribenuron-methyl plus carfentrazone plus MCPA-sodium at 750 g/hm² were the best options, showing higher and longer weed control and improved grain yield (21.26% and 18.41% compared with the control, respectively).

A study of habitat selection by plateau zokor in paddocks with different grazing intensities in the eastern Qilian Mountain region

CHU Bin, HUA Li-Min, ZHOU Yan-Shan, LIU Li, LI Shuai

2016, 25(1):  179-186.  DOI: 10.11686/cyxb2015234

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The objective of this study was to analyze the habitat selection and habitat characteristics of plateau zokor (Eospalax baileyi) in paddocks with different grazing intensities in the eastern Qilian Mountain region, in order to provide scientific information for controlling plateau zokor and conserving biodiversity in alpine meadows. Four paddocks with different grazing intensities were selected to investigate the zokor population density and habitat characteristics, including soil compaction and bulk density (g/cm³), vegetation botanical composition, plant species richness, aboveground plant biomass, and palatable forage biomass. A multiple regression analysis was used to determine the relationship between the plateau zokor population density and habitat characters. The zokor population density was highest in paddocks with the highest grazing intensity, and lowest in ungrazed paddocks (P>0.05). The zokor population density had a significant negative correlation with soil compaction (P<0.05) and a non-significant negative correlation with soil bulk density and aboveground plant biomass (P>0.05). The multiple regression for the relation between plateau zokor density and soil compaction, forb biomass, grass biomass, plants richness indicated that soil compaction was the dominant factor that influenced the plateau zokor habitat selection.

Effects of shading during grain filling on nutritive value and in vitro digestibility of “Yangmai 15” wheat straw

LI Yuan-Fei, HE Xiang-Yu, CHENG Yan-Fen, ZHU Wei-Yun

2016, 25(1):  187-198.  DOI: 10.11686/cyxb2015065

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This study was conducted to investigate the effects of shading during the grain filling stage on the nutritive value and in vitro digestibility of “Yangmai 15” wheat straw. Three shading levels (0%, 50% and 66%) and three shade duration periods (2, 4 and 8 days) were compared. At harvest, the wheat straw was collected and stored for analysis of chemical composition and in vitro digestibility and fermentation characteristics. For in vitro fermentation, rumen fluid was collected from 4 Boer goats with permanent rumen fistulas. Bottles containing 10 mL rumen fluid and 50 mL media with 1 g wheat straw as substrate were incubated at 39℃ for 72 h. Gas production was measured throughout the fermentation and samples were collected for analysis of pH, in vitro digestibility and volatile fatty acids (VFA) at the end of fermentation. The results showed that shading level and period significantly affected the crude protein (CP) content, neutral detergent soluble (NDS) and neutral detergent fiber (NDF) (P<0.05) with no interaction between shade level and shade period. When the shade level increased from 0% to 66%, CP and NDS decreased significantly from 3.06% to 2.35%, and 23.97% to 20.46%, respectively (P<0.05), while NDF increased significantly from 76.03% to 79.54% (P<0.05). Increasing the shading period from 2 to 8 days decreased CP and NDS significantly; 3.11% to 2.51%, and 23.09% to 21.43%, respectively (P<0.05), while NDF increased significantly from 76.9% to 78.6% (P<0.05).Shade level and shade period significantly affected the neutral detergent fiber digestibility (NDFD) (P<0.05) but no interaction was observed. With increasing shade level dry matter digestibility (DMD), NDFD and acid detergent fiber digestibility (ADFD) decreased significantly from 40.33%, 40.82% and 36.56% to 35.20%, 36.03% and 33.36%, respectively (P<0.05). With increasing shade duration NDFD decreased significantly from 38.88% to 36.94% (P<0.05). Both shade level and shade duration significantly affected gas production (P<0.05) and an interaction between them was observed (P<0.05); gas production decreased significantly from 131.64 mL to 120.96 mL, and 130.46 mL to 121.22 mL with increasing shade level and duration, respectively (P<0.05). The concentration of VFA in the cultures showed that shade level significantly affected TVFA concentrations, butyrate and the acetate/propionate ratio (A/P) (P<0.05), but shade duration had no effect on these traits. With increasing shade level the concentrations of TVFA and butyrate decreased significantly from 57.04 mmol/L to 51.25 mmol/L and 5.18 mmol/L to 4.32 mmol/L, respectively (P<0.05), while the A/P ratio increased significantly from 2.47 to 2.60 (P<0.05). In conclusion, shade significantly increased the NDF, resulting in decreased CP, in vitro digestibility, gas production and VFA concentration. The impacts of shading increased increasing shade level and duration.

Quality and lactic acid bacteria of mixed corn stalk and cabbage waste silage

REN Hai-Wei, ZHAO Tuo, LI Jin-Ping, LI Xue-Yan, XU Na, WANG Yong-Gang, WANG Xiao-Li, GAO Xiao-Hang

2016, 25(1):  197-206.  DOI: 10.11686/cyxb2015095

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Silage made with a mixture of corn stalk (CS) and cabbage waste (CW) were mixed and ensilaged at different ratios, 29∶19 (ME₁), 27∶21 (ME₂), 25∶23 (ME₃), 23∶25 (ME₄), 21∶27 (ME₅) and 19∶29 (ME₆), respectively. The chemical composition and fermentation traits were measured after 30 days (d) to identify the optimal ratio of corn stalk and cabbage waste and the diversity of lactic acid bacteria in each mixture. The pH and the ratio of ammonia nitrogen to total nitrogen (AN/TN) of the ME₅ silage was significantly lower than the other mixes (P<0.05). The lactic acid content (LA) of ME₅ was significantly higher than the other mixes (P<0.05) whereas the ammonia nitrogen/total nitrogen ratio (AN/TN) of ME₅ was significantly lower than other mixes. Analysis of lactic acid bacteria showed that a total of 10 lactic acid bacteria strains were isolated from the ME₅ group, belonging to three different genera; Lactobacillus, Enterococcus and Leuconostoc. Two strains of Lactobacillus brevis, one strain of Enterococcus faecium, five strains of Leuconostoc mesenteroides subsp. mesenteroides and two strains of Lactobacillus plantarum were identified. Among these isolates, Lactobacillus and Enterococcus were homofermentative lactic bacteria, which are able to produce more lactic acid than heterofermentative lactic bacteria. Lactobacillus and Enterococcus played a key role in the fermentation of these silages. In conclusion, mixed silages of CS and CW were found to be feasible with an optimum ratio of 21∶27 respectively.

Comparison of agronomical traits between the wild diploid and its autotetraploid in the Dactylis glomerata subsp. Himalayensis

HUANG Mei-Fen, XUE Shi-Ming, GAO Yue-E, LI Qiao-Xian, ZHANG Mei-Yan, YU Mei, ZHONG Sheng

2016, 25(1):  207-216.  DOI: 10.11686/cyxb2015221

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An experiment has been conducted using single and drill planting methods on the wild diploid Dactylis glomerata subsp. Himalayensis and its autotetraploid in order to compare the agronomic traits of different ploidy cocksfoot. The results showed that the vegetative growth stage of wild diploid cocksfoot was longer than the autotetraploid type and that it grew rapidly at later stages. The yields of leaf and single plants in each component of autotetraploid were significantly higher than wild diploid cocksfoot at the same stage (P<0.05). With the increase of ploidy, the number of tillers, reproductive branches and 1000 seed weights increased, while the percentage of reproductive branch, spike yield, number of seeds, germination potential and germination rate decreased. Autotetraploid fertility is thus not as strong as that of the wild diploid. In terms of dry matter, autotetraploid yields from each cutting and total annual output were 20.3%-72.8% and 18.3%-41.5% respectively, which were higher than those of the wild diploid, but yields of withered grass dropped 23.9%, which was lower than that of wild diploid. Based on equilibrium analysis, autotetraploid forage balance was better than the wild diploid. In terms of nutritive value, crude protein, crude fat, ash, contents of calcium, phosphorus and hemicelluloses for both the wild diploid and its autotetraploid decreased significantly with increased maturity, while neutral detergent fiber, acid detergent fiber and acid lignin increased. With increasing ploidy levels, the percentages of nutritional components fluctuated unevenly during the growth period, with only calcium contents increasing significantly after maturity.

Analysis of the value of ecosystem services in the Dongting Lake area

XU Wei-Ping, KANG Wen-Xing, HE Jie-Nan

2016, 25(1):  217-229.  DOI: 10.11686/cyxb2015104

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The Dongting Lake area is the largest storage lake of the Yangtze River region and Asia’s largest inland wetland. It protects the ecological integrity of the Yangtze River basin region, and also influences the economic and social sustainable development of the region. It is important to assess the ecological service function in Dongting Lake Area to facilitate protection and restoration of Dongting Lake wetland ecosystems, and also to coordinate exchange of information between economic development and environmental protection agencies. In this article, the market value method, protection costs, opportunity costs, shadow engineering, consumer surplus and valuation methods were used to analyze 18 ecosystem service functions of the wetland ecosystem in Dongting Lake. The total value of wetland services was 1733634×10⁴ yuan in Dongting Lake in 2010, of which the social service value (895759×10⁴ yuan)>adjustment and support value (765662×10⁴ yuan)>supply function value (102213×10⁴ yuan). These values accounted for 51.67%,42.43% and 5.90%, respectively, of the total value of the ecosystem services. Whether these services can be captured by the market economy or not, the economic value of the direct services was assessed as 985863×10⁴ yuan, and the ecological value of indirect services was 747771×10⁴ yuan. Hence, the ratio of direct∶indirect value was 1∶0.76. The results of this study could provide data to guide the development of Dongting Lake Ecological Economic Zone.

Economic analysis of animal production in China

LI Lan, HOU Fu-Jiang

2016, 25(1):  230-239.  DOI: 10.11686/cyxb2015099

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Agriculture contributes significantly to GDP. Grassland agriculture, as an important part of modern agriculture, connects the grassland with livestock, and maximizes plant productivity and animal product yield while minimizing environmental disturbance. Grassland agro-ecosystems incorporate four production components, and the animal production component is one of these and also an important criterion in determining production efficiency. Based on data for 31 provinces and cities in China from 1992 to 2011, this issue was analyzed and conclusions drawn. Firstly, according to national and provincial data, animal production and the contribution of agriculture to GDP have increased. The data basically can be divided into three stages from 1992 to 2005, 2005 to 2006, and 2007 to 2011 which align with successive agricultural policies. Secondly, from the perspective of the emerging trends for animal production, the major agricultural provinces have a higher contribution to GDP from animal production. For other cities, due to either a small contribution of animal husbandry to economic development or low animal product returns, contribution of animal production to GDP is relatively small. Thirdly, the fastest-growing areas for animal production are also in most cases major agricultural provinces. This may be due production of stock feed required to develop animal production. Fourthly, animal production GDP and other economic indicators are positively correlated. Because of different endowment of resources and different policies, the situation differs in different provinces and cities. This suggests China’s grassland agriculture still has many problems. In order to support the development of agriculture, the government should consultatively review policy, and vigorously support the development of grassland agriculture.

The history of the introduction of alfalfa to China in the Han dynasty

SUN Qi-Zhong, LIU Qian, NA Ya, LI Feng, TAO Ya

2016, 25(1):  240-253.  DOI: 10.11686/cyxb2015090

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This paper applies the principles of textual analysis to a collection of historical literatures and a summary of modern research findings in order to investigate the various interpretations of who is responsible for introducing alfalfa to China during the Han dynasty. There are four characteristic views of alfalfa’s introduction from Western Regions in the historical, agricultural and pratacultural fields. Claims have been made that those responsible were envoys of the Han dynasty, or Zhang Qian, or the Ershi General Li Guangli, while others claim it remains uncertain. Our investigation shows that the first view is closest to the historical facts. The second view is popular and accepted by most scholars but it lacks the support of historical data. The third view has not been widely accepted at present. Thus the claims that alfalfa was introduced by either Zhang Qian or Li Guangli need further verification by exploring the available historical data.

Photosynthetic responses of Arundinella hirta populations to light intensity and CO₂ concentration

LIU Ying, BAI Long, LEI Jia-Jun

2016, 25(1):  254-261.  DOI: 10.11686/cyxb2015327

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Photosynthetic responses to light intensity and CO₂ concentration were determined in four Arundinella hirta Tanaka populations in Liaoning province in order to provide a basis for further studies of phenotypic variation in this species. Most of the characteristic parameters were significantly different among the four A. hirta populations, suggesting that there are genetic differences between them. The Benxi (P₁) and Beizhen (P₂) populations showed higher yield potentials as they had higher light saturation points (1782 and 1690 μmol/m²·s, respectively), apparent quantum yields (0.0553 and 0.0564, respectively), carboxylation efficiencies (0.0568 and 0.0783 μmol/m²·s, respectively) and lower CO₂ compensation points (14 and 12 μmol/mol), respectively. The Jianping (P₃) and Zhangwu (P₄) populations performed better with regard to drought tolerance, with lower stomata conductance (0.1227 and 0.1176 mol/m²·s, respectively) and transpiration rates (2.67 and 2.68 mmol/m²·s, respectively) and with higher water holding capacities.

Analysis and evaluation of the nutritional components of Stellera chamaejasme

JI Li-Ping, GUO Li-Zhu, LIU Xin, WANG Lin, ZHANG Shi-Feng, GUO Bin, FU Yan-Ping, HE Wei, WEI Ya-Hui

2016, 25(1):  262-267.  DOI: 10.11686/cyxb2015220

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This paper reports on an analysis and evaluation of the nutritional components of Stellera chamaejasme using standard methods. The results showed that dry matter, ash content, tannins, crude protein, ether extract, neutral detergent fiber, acid detergent fiber and lignin was (89.87±0.30)%, (5.59±0.62)%, (0.0508±0.0037)%, (15.00±1.46)%, (3.47±0.20)%, (39.11±0.77)%, (28.7±0.76)% and (6.87±0.26)% respectively. In addition, the types and amounts of amino acids and minerals were bountiful. These results show that the nutrition components of S. chamaejasme are almost equivalent to alfalfa. S. chamaejasme thus has great potential to be bred as forage if it can be detoxicated.

Effects of warming and grazing on growth and development of the grassland caterpillar (Gynaephora menyuanensis)

CAO Hui, ZHU Wen-Yan, ZHAO Xin-Quan

2016, 25(1):  268-272.  DOI: 10.11686/cyxb2015010

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The grassland caterpillar (Gynaephora menyuanensis) is an endemic pest in the northern Tibetan Plateau, which is a very susceptible region to global climate warming. Understanding how G. menyuanensis might respond to future warming under grazing conditions is critical to the sustainability of livestock husbandry in alpine meadows. We investigated the effects of diurnally asymmetrical warming (day/night 1.2/1.7℃) and grazing on the growth and development of G. menyuanensis in a Tibetan Plateau alpine meadow. Grazing significantly increased larval growth rate and pupal weight. The increase in female pupal weight was about two times greater than the increase in male pupal weight. Warming significantly accelerated larval pupation (female: 4.4 d; male: 7.0 d) and adult emergence (female: 3.6 d; male: 4.6 d). Male emergence under warming was significantly earlier (5.0 d) than female emergence. Combining the warming and grazing treatment, the larval growth rate and female pupal weight dramatically increased by 9% and 26%, respectively. The results of this study suggest that the fitness of G. menyuanensis may increase under future warming and moderate grazing conditions, posing a greater risk to the health of alpine meadows and livestock.

Nutrition effects on growth of Holstein bulls

LI Yan, LI Xiao-Meng, LI Qiu-Feng, DU Liu-Liu, CAO Yu-Feng, YU Chun-Qi, WANG Xiao-Ling, LI Jian-Guo, GAO Yan-Xia

2016, 25(1):  273-279.  DOI: 10.11686/cyxb2015113

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The objective of this trial was to evaluate the effects of different dietary energy and protein levels on linear-fattening performance of Holstein bulls. Thirty six Holstein bulls (mean live weight 121 kg) aged 4-5 months were allocated into two equal groups; group I (low nutrition diet) and groupⅡ(high nutrition diet). The experimental period continued for 440 days. The average daily gain (ADG) of group Ⅱ was 5.83% higher (P>0.05) than that of group I, but the feed/gain ratio of group Ⅱ was 3.11% lower than that of group Ⅰ(P>0.05). There was no difference between group Ⅰ and Ⅱ in the apparent digestibility of crude protein, ether extract, neutral detergent fiber, acid detergent fiber, calcium and phosphorus. Glutamic-oxalacetic transaminase, glutamic-pyruvic transaminase, growth hormone and tetraiodothyronine in the blood of group Ⅱbulls were increased by 8.27%, 13.85%, 6.70% and 1.26% (P<0.05) compared with group I bulls, respectively. The amount of blood urea nitrogen was significantly decreased 12.22% (P<0.01). Nutrition level had no effect on the dressing percentage, carcass weight and net meat percentage. Compared with group I, pH, drop loss, shear force and dehydration rate of group Ⅱ were decreased by 2.34%, 12.97%, 18.30% and 3.38% at 72 h, respectively. The amount of crude protein and ether extract were increased by 4.95% and 8.55%. The economic advantage of group Ⅱ bulls was 0.98 yuan/(head·day) compared to group Ⅰ. The total benefit from group Ⅱbulls was 431.20 yuan/head. Increasing energy and protein levels in diets of young Holstien bulls promoted growth and meat quality and the economic outcomes.