Table of Content

20 August 2021, Volume 30 Issue 8

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Effects of different stocking rates on interspecific relationships among dominant species and their spatial distribution characteristics in the Stipa breviflora desert steppe

Feng ZHANG, Jia-wei SUN, Yu SUN, Jia-hua ZHENG, Ji-rong QIAO, Meng-li ZHAO

2021, 30(8):  1-11.  DOI: 10.11686/cyxb2021027

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The aim of this study was to explore the effects of different stocking rates on the relationships among dominant plant species and their spatial distribution in the Stipa breviflora desert steppe. A field study was conducted from July to September 2020 in the Siziwang Banner， Inner Mongolia. The constructive species S. breviflora and the dominant species Cleistogenes songorica and Artemisia frigida were selected as the research objects. Different stocking rates corresponding to the control， light grazing， moderate grazing， and heavy grazing （0， 4， 8， and 12 sheep grazing， respectively） were established. We analyzed the frequency， abundance， strength of interspecific relationships， and spatial distribution characteristics of the constructive and dominant species combining conventional methods and geostatistical methods. The results show that： 1） The frequency of A. frigida was significantly decreased （by 50.55%） in the light grazing treatment as compared with the control （P<0.05） in July， while moderate and severe grazing significantly reduced its frequency from July to September （P<0.05）. The average decreases in the frequency of A. frigida from July to September were 77.76% （moderate grazing） and 97.53% （heavy grazing）. The frequency of S. breviflora and C. songorica did not differ significantly among different stocking rates and among different months （P>0.05）. 2） Compared with the control， the light， moderate， and heavy grazing treatments resulted in increased abundance of S. breviflora （by 37.34%， 75.72%， and 99.32%， respectively）， and decreased abundance of A. frigida （by 61.26%， 66.32%， and 99.31%， respectively） from July to September （P<0.05）. The species abundance of C. songorica increased significantly from July to September in all treatments， except for the light grazing treatment in September （P<0.05）. 3） S. breviflora and C. songorica mainly showed an affinity relationship， but showed a competitive relationship in the heavy grazing treatment in September. S. breviflora and A. frigida mainly showed a competitive relationship， and grazing did not change this interspecific relationship. 4） S. breviflora and C. songorica had stronger effects on A. frigida， while A. frigida had weaker effects on S. breviflora and C. songorica. 5） Finally， a simulation of the spatial distribution among dominant species in September revealed that the abundance of S. breviflora increased with increasing abundance of C. songorica in the control， and decreased with increasing abundance of A. frigida. In the heavy grazing treatment， the abundance of A. frigida was not affected by the abundance of S. breviflora and C. songorica. As the abundance of C. songorica increased， the abundance of S. breviflora tended to decrease， indicating that the relationship between S. breviflora and C. songorica changed from an affinity relationship in the control to a competitive relationship under heavy grazing. In summary， these results show that grazing can change intra-specific abundance and inter-specific relationships among dominant plant species.

Soil and vegetation successional responses in natural restoration of mixed Potentilla parvifolia-Salix cupularis shrubland in the Eastern Qilian Mountains

Xiang HE, Mei-mei BAI, Chang-lin XU, Mei-juan SONG, Peng-bin WANG, Xiao-jun YU

2021, 30(8):  12-24.  DOI: 10.11686/cyxb2020280

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This research aimed to scientifically evaluate the characteristics of natural succession and provide a theoretical basis for planning ecological restoration and sustainable utilization of shrub meadow. Differences in carbon storage and soil nutrient status were measured for a ‘time series’ of sites at different successional stages in mixed Potentilla parvifolia-Salix cupularis shrub meadow in the Eastern Qilian Mountains. For a prolonged natural restorative succession of about 20 years， it was found that the carbon storage of shrub communities increased by 1.1 to 3.8 times and the respiration rate of soil between shrubs increased by 1.1 to 2.0 times， while soil respiration under shrubs remained unchanged. The soil water content of the 0-30 cm soil layer under shrubs of shrub decreased by up to one third and the soil bulk density under shrubs increased in the 0-30 cm soil depth. Soil organic matter levels in the 0-30 cm soil layer displayed a single-peak curve with an initial increase of 2.0% to 48.7% and then a decrease of 4.4% to 32.0% in soil organic matter， available nitrogen and available phosphorus， while levels of total phosphorus and total potassium increased by 3.0% to 76.0%. No consistent pattern over time was detected for levels of other soil nutrients. To summarize， the carbon storage increased， but the physical and chemical properties of soil were negatively affected over the course of restorative succession of shrub meadow vegetation. Therefore， it is suggested that for sustainable and balanced development of grassland ecosystems there will be a need for proactive exploration of ways to achieve efficiency， so that the shrubs and herbs can develop positive plant community interaction and grow harmoniously. In this way the goal of stabilizing and balancing the ecosystem could be achieved and the production capacity of grass and the economic income of farmers and herdsmen increased.

Changes of relationships between dominant species and their relative biomass along elevational gradients in Xinjiang grasslands

Jing-jing MA, Yun-hua LIU, Jian-dong SHENG, Ning LI, Hong-qi WU, Hong-tao JIA, Zong-jiu SUN, Jun-hui CHENG

2021, 30(8):  25-35.  DOI: 10.11686/cyxb2020277

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In grassland， dominant species make a major contribution to aboveground biomass. A large number of studies have shown that biomass of dominant species is regulated both by environmental factors and by interspecific relationships among coexisting species. However， our current understanding about relationships between biomass of dominant species and environmental factors remains incomplete for many species and environmental conditions. To address this knowledge gap， this study investigated relative biomass （RB） of dominant species among 9 grassland types across 397 sites in Xinjiang grassland during 2011-2013. Firstly， we evaluated community composition for each grassland type and identified dominant species. Secondly， we explored relationships between RB of dominant species and elevation as well as linkage of RB among coexising dominant species using a general linear model. Our results showed that： 1） A total of 169 dominant species， which belong to 120 genera and 31 families， were identified in Xinjiang grasslands， with 19.53% of dominant species belonging to the Poaceae. In particular， Stipa capillata was the most important dominant species for alpine steppe， temperate meadow steppe， temperate steppe desert， temperate steppe and temperate desert steppe， while Polygonum viviparum， Achillea millefolium， and Ceratocarpus arenarius were the most important dominant species for alpine meadow， mountain meadow and temperate desert， respectively. 2） Relationships between RB of dominant species and elevation could be classified into the following five groups： no significant relationship， a U pattern （decreased initially and then increased with increasing elevation）， a significant positive relationship， a significant negative relationship and an arch-shaped pattern （increased initially and then decreased）. These five behavioral groups comprised， respectively， 50 （64.9%）， 9 （11.7%）， 8 （10.4%）， 6 （7.8%） and 4 （5.2%） of dominant species. 3） A total of 19 significant paired relationships were found involving 24 dominant species coexisting with another species. Most coexisting dominant species pairs were negatively correlated with each other in terms of their RB. These findings demonstrated that previous results indicating a varied relationship between biomass of dominant species and elevation were not conflicting. Rather different patterns concurrently exist in Xinjiang grassland driven by variation between sites in species behavior. Our findings highlight the importance of dominant species and interspecific relationships among coexisting dominant species in biomass conservation and management in Xinjiang grasslands.

Effects of nitrogen application and mowing on yield and quality of forage in degraded grassland in northwest Liaoning Province

Jing-dong ZHAO, Yan-tao SONG, Xin-lei XU, Wuyunna

2021, 30(8):  36-48.  DOI: 10.11686/cyxb2020292

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Nitrogen application and mowing treatment are effective management methods for natural grassland. In order to explore the efficient use of degraded grassland， the degraded grassland in the pastoral transitional zone of northwestern Liaoning Province was taken as the research object， and nitrogen fertilizer addition （0， 10 g N·m^-2·yr^-1） and mowing treatment （stubble height at 3， 6， 12 cm and no mowing） experiment were set up， by measuring forage yield and 22 forage quality indicators for two consecutive years， to analyze the effects of nitrogen application and mowing on the yield and quality of degraded grasslands in northwestern Liaoning Province. The results showed that： 1） Nitrogen application significantly increased the forage yield， crude protein in 2018 and 2019， and the forage net energy for lactation， net energy for maintenance， net energy for gain， total digestible nutrients， MT （kg milk·t^-1 DM） in 2019， nitrogen application significantly reduced the acid detergent fiber in 2019， and promoted the increase of forage yield， net energy and nutrient content in degraded grassland. 2） Mowing treatment significantly affected the forage neutral detergent fiber， calcium content， phosphorus content， in vitro dry-matter digestibility and relative feeding value in 2018 and 2019， and the forage crude ash and magnesium content in 2018， and the forage non-fibrous carbohydrate， net energy for maintenance， net energy for gain， total digestible nutrients and relative forage quality in 2019， while the degraded grassland was properly utilized， the quality of forage grass also improved greatly. 3） The interaction of nitrogen application and mowing treatment had a significant impact on the crude protein， crude ash， net energy for lactation and MT of degraded grassland. 4） The forage crude ash， acid detergent fiber， neutral detergent fiber， digestible neutral detergent fiber， neutral detergent fiber digestibility， magnesium content， net energy for lactation， net energy for maintenance， net energy for gain， MT， total digestible nutrients as well as the relative feeding value， a total of 12 nutritional quality index were significant correlated with crude protein. The results showed that nitrogen application and mowing treatment as effective management and utilization way of degraded grassland， both the independent or interactive effects had different degrees of positive feedback on the improvement of forage yield and quality， the yield and quality of forage grass were the highest under the treatment of nitrogen application combined with mowing of stubble height at 3 cm， which could provide a theoretical reference for the rational use and sustainable development of degraded grassland.

Effects of mixed sowing of rye and common vetch on forage yield and nutrient quality in alpine pastoral areas

Qiang XU, Xin-hui TIAN, Wen-hua DU

2021, 30(8):  49-59.  DOI: 10.11686/cyxb2020310

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This research investigated the optimum mixed seeding planting ratio of common vetch and rye in an alpine pastoral area of Gansu. In this study the yields and nutritional quality of three varieties of common vetch （Green Arrow No. 1， Green Arrow No. 2 and Green Arrow No. 431） sown with rye strain C33 at different mixed ratios （0∶100， 20∶80， 30∶70， 40∶60， 50∶50， 60∶40， 70∶30， 80∶20， 100∶0） were evaluated. Results showed that the average total hay yield （7.16 t·ha^-1） and multivariate performance score （0.860） of C33×Green Arrow No. 1 were highest among the tested treatments. For the planting ratio of 60∶40， the average total hay yield （8.01 t·ha^-1） and the comprehensive evaluation value （0.691） were the highest. For the interaction between the species combination and the mixture rate， the best performing treatment was C33×Green Arrow No. 1 planted at a ratio 60∶40， with a total hay yield of 9.03 t·ha^-1 and a multivariate performance score of 0.711.

Effects of planting method on seed yield and its components in Medicago ruthenica in an arid area of Longzhong

Yu-xia WANG, Jin-long CHAI, Yang-yang ZHOU, Chang-lin XU, Lin WANG, Xiao-jun YU

2021, 30(8):  60-72.  DOI: 10.11686/cyxb2020273

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This research evaluated alternative cultivation methods for Medicago ruthenica seed production in arid regions， and the results provide a theoretical basis and practical guidance for seed production practice in the study region. We set up experiments in Dingxi， Gansu Province， from 2017 to 2019 to study seed yield and its components in M. ruthenica. The experiment comprised 6 planting configurations， all in 30 cm rows： i） planted on flat ground without mulch （F0， Control）， ii） planted on flat ground with a white 0.008 mm thick plastic film mulch （FP）， iii） planted on flat ground with 4500 kg·hm^-2 straw mulch （FS）； iv） planted in furrows between 10 cm-high rain harvesting ridges （R0）， v） as for （iv） but with a plastic film mulch （RP） and vi） as for （iv） but with straw mulch （RS）. It was found that the absolute height， branch number， taproot length， photosynthetic characteristics， pod number， seed number， harvested seed yield and seed yield of M. ruthenica over the 3 years ranked as follows： RP>FP>FS>RS>R0>Control. For RP and FP treatments in 2017， the absolute height， branch number， photosynthetic characteristics and harvested seed yield of plants were significantly higher than those of other treatments. Differences between the treatments RP and FP were not significant in 2018-2019， and the treatments FS and RS did not differ in absolute plant height， branch number and harvested seed yield of plants in 2018-2019. Over the 3 years， the harvested seed yield of treatment RP was highest， with increases of 110.4%， 38.6% and 20.4%， respectively compared with the Control. After RP， the second highest performance was obtained in FP and FS treatments， with the FP treatment producing， respectively 94.6%， 38.4% and 15.5% more harvested seed than the Control in 2018-2019， and the FS treatment producing， respectively 48.0%， 37.1%， 13.3% more than the Control in the three years. Considering a range of factors including yield， plastic film cost， soil pollution and the convenience of cultivation， it was concluded that the FS treatment should be recommended for M. ruthenica seed production in the Longzhong area.

Nitrogen utilization and interspecific feedback characteristics of intercropped alfalfa/oat with different root barriers

Xue WANG, Xiao-jing LIU, Ya-jiao ZHAO, Jing WANG

2021, 30(8):  73-85.  DOI: 10.11686/cyxb2021037

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In this study， we explored the effects of root barriers on interspecific nitrogen competition and mutual feeding in an alfalfa/oat intercropping system using a bucket soil culture method. The nitrogen metabolism characteristics and root characteristics of alfalfa and oat plants， as well as the nodulation characteristics of alfalfa plants， were investigated at different growth stages， under two different nitrogen levels， and with different root barriers. The root barrier treatments could be ranked， from highest to lowest values of nitrogen metabolism characteristics and root characteristics of oat， nodulation of alfalfa at different growth stages， and nitrogen levels， as follows： No barrier>nylon mesh barrier>plastic barrier≥monoculture， and the differences among these treatments were significant. The activities of nitrogen metabolism enzymes， the nitrogen concentration， and nitrogen accumulation in alfalfa in the budding stage and initial blooming stage were significantly higher in the monoculture treatment than in the no barrier and nylon mesh barrier treatments （P<0.05）. The root barrier treatments could be ranked， from largest to smallest root average diameter and root volume across all growth stages and nitrogen levels， as follows： Monoculture>plastic barrier>nylon mesh barrier>no barrier. The root average diameter and root volume were significantly higher in the monoculture treatment than in the no barrier treatment. The activities of nitrogen metabolism enzymes， dry weight， nitrogen concentration， nitrogen accumulation， root surface area， root average diameter， root volume， and root activity of alfalfa and oat at different growth stages were higher in the N₂₁₀ （nitrogen application） treatment than in the N₂₁ treatment （no added nitrogen）. The total nodule weight， total nodule number， effective nodule number， and effective/nodule number of alfalfa were lower in the N₂₁₀ treatment than in the N₂₁ treatment. Therefore， in the alfalfa/oat intercropping system， closer interspecific root interactions are conducive to oat root growth and root activity， nitrogen assimilation by oat， nodulation and nitrogen fixation by alfalfa， and transfer of nitrogen from alfalfa to oat. Such conditions can enhance the complementary utilization of nitrogen by both species， and improve the feedback of interspecific nitrogen nutrition in the alfalfa/oat intercropping system. These results show that closer interspecific root interactions can effectively improve nitrogen-use efficiency in this intercropping system. These findings also show that the addition of nitrogen at an appropriate dose to promote growth at the early period can strengthen the interspecific root interaction and the complementary utilization of nitrogen， thereby improving nitrogen-use efficiency in this intercropping system.

An assessment of heavy metal absorption patterns in herbaceous plants and pollution risks in manganese mining areas in Guizhou Province

Jun REN, Yao SHI, Fang LIU, Rong TIAN, Xing LIU

2021, 30(8):  86-97.  DOI: 10.11686/cyxb2020570

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This research explored the occurrence of heavy metal pollution in manganese mining areas， and quantified the heavy metal absorption characteristics of dominant herbaceous plants in typical manganese mining areas in Tongren County， Guizhou Province， China. Samples of 18 commonly occurring herbaceous plant species belonging to 11 families and 18 genera， together with soil samples were collected. Asteraceae and Poaceae were the dominant families. We determined and analyzed the content of 7 elements （Cr， Ni， Cu， Zn， Cd， Pb， Mn） in plants and their soils or growth substrates. It was found that heavy metal pollution was widespread in manganese mine waste areas， Mn pollution was the most serious， followed by Cd， and it belonged to the compound pollution of Mn and Cd. The enrichment and transport coefficients of 7 heavy metal elements in herbaceous plants were calculated， and cluster analysis was performed on the 18 herbaceous plant species sampled. Alopecurus aequalis has a strong enrichment ability for Cd， with a bioaccumulation factor of 22.49； Phytolacca acinosa and Miscanthus floridulus have strong enrichment and transport capacities for Cr and Ni； Saussurea japonica and Prunella vulgaris showed strong enrichment and transfer ability for various heavy metals. To summarize， Mn and Cd were found to be the main pollutants in manganese mining areas， and the native dominant herbaceous plants have suitable uptake characterisitcs for use in ecological restoration in the manganese mining areas.

Effects of fertilizer application rate on vegetation and soil restoration of coal mine spoils in an alpine mining area

Xin-guang YANG, Xi-lai LI, Pan-pan MA, Jing ZHANG, Wei ZHOU

2021, 30(8):  98-108.  DOI: 10.11686/cyxb2020274

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Spoils accumulated in the process of coal mining are usually deficient in plant nutrients. Fertilization is an effective means to improve the soil physical and chemical conditions and promote the revegetation of coal mine spoils. This research studied the establishment of artificial grassland on coal mine spoils in Jiangcang alpine mining area， and explored the appropriate fertilization level for ecosystem restoration in this locality. Treatments imposed included light， medium， and heavy fertilizer application， no fertilization within the first year （CK）， and no fertilization within 5 years， and the grassland community structure， plant growth and soil properties were characterized under the different fertilizer regimes. Correlations between plant and soil parameters were evaluated. The main results were as follows： There were no significant differences in species composition among the different fertilizer application levels， but the community diversity and evenness indexes decreased significantly （P<0.05） under heavy fertilization， and the community richness and diversity index decreased significantly （P<0.05） compared with CK after 5 years without fertilization. Both excessive fertilization and a period of some years without fertilization were detrimental to the stability of the grassland community. Compared with CK， light fertilization， moderate fertilization and heavy fertilization increased the vegetation cover， plant density， height and above-ground biomass of the established artificial grassland to varying degrees， and the results under moderate fertilization were superior to those of other treatments. Compared with CK， heavy fertilization significantly increased soil available nitrogen， total phosphorus and available phosphorus content （P<0.05）. Moderate fertilization was more conducive to the accumulation of soil organic matter compared with other treatments. With the exception of soil pH value， plant growth parameters were positively correlated with soil properties. In particular， there was a significant positive correlation between plant growth parameters and soil total potassium and soil organic matter content （P<0.01）. In summary， an appropriate level of fertilization improved vegetation growth and soil properties of artificial grassland established on coal mine spoils. However， both too much fertilizer application and no fertilizer application were detrimental to the stability of the artificial grassland ecosystem in Jiangcang mining region.

Interactive effects of drought and UV-B radiation on physiological defences in Artemisia sphaerocephala

Xiao-xu HAN, Yuan-yuan ZHAO, Li-jing ZHANG, Ding GUO, Hua FU, Yong-shan LI, Cheng-xin YANG

2021, 30(8):  109-118.  DOI: 10.11686/cyxb2020290

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This research explored the physiological effects of drought （D）， UV-B radiation stress （U） and their interactions （D+U） on Artemisia sphaerocephala and its stress tolerance. The seedling growth， membrane lipid oxidation， flavonoid metabolism， fatty acid metabolism and FAD gene expression in A. sphaerocephala were studied under D， U， and D+U， and unstressed （CK） treatments. In D and UV treatments， leaf weight， stem weight， root weight， total biomass， plant height， leaf area and relative water content were decreased， compared to CK. For the D+UV treatment， biomass reductions were less than those observed in D or UV treatments applied alone. Compared to CK， relative electric conductivity increased significantly in both D and UV treatments， but decreased significantly in the D+UV treatment. Malondialdehyde （MDA） content and lipoxygenase （LOX） activity in the D treatment were， respectively， 1.65 and 3.69 times those in the control treatment （CK）， while MDA content and LOX activity in the UV treatment showed no significant change. MDA content and LOX activity in the D+UV treatment were， respectively， 66.69% and 44.00% of those in the D treatment. Flavonoid content in D and UV treatments was， respectively， 1.25 and 1.37 times that in CK. Flavonoid content in the D+UV treatment was 1.57 times that in the D treatment. An index of unsaturated fatty acid （IUFA） in the D treatment showed no significant change， while IUFA in the UV treatment were 91.96% of that in CK. IUFA in the D+UV treatment was 1.08 times of that in UV treatment. These results indicate： An important reason for the stress-induced biomass decline in A. sphaerocephala was that drought and UV-B radiation caused membrane damage； The combined stress of drought and UV-B radiation inhibited LOX activity by increasing flavonoid content and increased unsaturated fatty acids， which alleviated the membrane damage caused by drought and UV-B radiation in A. sphaerocephala.

Maternal grazing exposure altered the responses of Leymus chinensis cloned offspring to drought environment

Feng-hui GUO, Yong DING, Wen-jing MA, Xian-song LI, Xi-liang LI, Xiang-yang HOU

2021, 30(8):  119-126.  DOI: 10.11686/cyxb2020308

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Grazing disturbance on maternal plants can induce legacy effects on the progeny plants. Meanwhile， grazing disturbance also can exacerbate ecosystem drought by changing the evapotranspiration pattern and intensity. However， little is known about whether the grazing-induced legacy effects regulate the response of progeny plants to drought. In this study， we conducted a greenhouse experiment with Leymus chinensis offsprings collected from long-term no grazing plots （which have been fenced for about 40 years） and seriously grazed plots to explore whether grazing could enhance the adaptation of the plant to drought. Results showed that： 1） Relative to NG （cloned offspring collected from no grazing plots）， individual height and biomass of GZ （cloned offspring collected from grazed areas） are more resistant to drought， and the interaction between material source and drought treatment is significant. In contrast， the response of GZ to drought in terms of ramet number is more sensitive than that of NG. 2） NG and GZ exhibit similar responses to drought in terms of aboveground and total biomass. 3） NG is more sensitive to drought than GZ in terms of total rhizome length and internode number. Under control treatment， the total rhizome length and internode number of NG are significantly greater than GZ， while there are no significant differences under drought treatment. 4） Rhizome and aboveground biomass allocation of NG under drought treatment are higher than that under control treatment， while the root biomass allocation increases under drought treatment. However， for GZ， rhizome biomass allocation decreases and aboveground biomass allocation increases under drought treatment， while there is no significant change in terms of root biomass allocation. This study showed that the grazing-induced legacy effects altered the response pattern of L. chinensis to drought treatment. This information provides a new perspective for understanding grazing ecosystem processes.

Studies on drought tolerance of wild Elymus sibiricus at the seedling stage

Chuan-qi WANG, Wen-hui LIU, Yong-chao ZHANG, Qing-ping ZHOU

2021, 30(8):  127-136.  DOI: 10.11686/cyxb2020542

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In this study， we evaluated the drought tolerance of Elymus sibiricus， a plant native to the Northwest Sichuan Plateau， in a pot experiment. Changes in the morphological and physiological characteristics of E. sibiricus under drought stress at the seedling stage were analyzed. The main results were as follows： as the period of drought stress extended， the rate of increase in plant height， leaf area， and aboveground biomass of E. sibiricus became slower， the root system dry weight and relative conductivity gradually increased， and the survival percentage and chlorophyll content gradually decreased. Drought stress caused different degrees of damage to E. sibiricus at the seedling stage， as indicated by growth inhibition and decreased survival. To absorb more water under drought conditions， E. sibiricus tended to distribute more biomass to the roots， and reduced biomass allocation to plant height and leaf area. These adaptations promoted effective water transport and prevented excessive evaporation of water. According to a subordinate degree analysis， eight wild E. sibiricus materials were ranked from most to least drought tolerant as follows： 14-001>14-165>14-235>14-065>14-251>14-115>14-189>14-021. These findings provide an important theoretical basis for the breeding of drought-resistant E. sibiricus， and have practical significance for effectively controlling ecological disasters such as degradation and desertification of alpine grassland on the Northwest Sichuan Plateau.

Diversity characteristics of dung beetle of Seirphidium semidesert and its secondary distribution of seeds in the feces

Jia-min CAO, Ya-ya GUO, Na-na LI, Hai-rong SUN, Zhao-bi CHE, Wei-hua LU

2021, 30(8):  137-145.  DOI: 10.11686/cyxb2020296

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Seriphidium semidesert grassland provides important spring and autumn pasture for sheep grazing in Xinjiang Province in China. The activities of dung beetles provide a mechanism of seed dispersal， which is of great significance for the restoration of grassland vegetation. The objectives of this study were to explore the horizontal and vertical displacement distances of seeds of different sizes in dung， resulting from the activities of dung beetles and to determine the seasonal changes in species diversity characteristics of dung beetles in the Seriphidium semidesert grassland. A total of 14797 dung-eating insects were captured， belonging to 17 species and 3 families， among which there were 9 species from the family Aphodiidae， 7 species of the family Scarabaeidae， 1 species of the family Geotrupidae. Diversity analysis demonstrated that the species richness index was highest in June at which time the dominant species is Aphodius impunctatus， whilethe largest number of individuals occurred in October at which time the dominant species is A. rectus. Observation of dung beetle behavior in June and October showed that in June the number of dung beetles reached a peak 8 hours after dung placement and in October 4 hours after dung placement. Over time after dung placement， the number of feces-eating insects entering the dung， and the degree of dung decomposition progressively increased. The distribution of seeds in dung by dung beetles depends on the size of the seeds. Three sizes of beads， small （1.3 mm）， medium （3.6 mm）， and large （5.8 mm）， were used as artificial seeds to evaluate seed movement by dung beetles. It was found that about 80% of the artificial seeds were buried within a horizontal distance of 20 cm and to a soil depth in the range of 0-10 cm. Conversely， 20% of the seed simulants were moved beyond a horizontal range of 20 cm or buried below 10 cm by dung beetles. With larger-sized artificial seeds， the proportion that were buried decreased. The results of the study showed that the secondary dispersal by dung beetles of seeds in feces contributes to the ecological restoration of the Seriphidium semidesert grassland.

Effects of substituting dietary alfalfa meal with kudzu vine （Pueraria lobata） meal on serum biochemical indexes， apparent nutrient digestibility and growth performance in Boer crossbred goats

Jun-nian LI, Shao-hua KANG, Dong-mei YANG, Qian HE, Shuang LI, Shuang-lun TAO

2021, 30(8):  146-153.  DOI: 10.11686/cyxb2020584

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This study aimed to measure the effects of substituting dietary alfalfa meal with kudzu vine （Pueraria Lobata） meal on serum biochemical parameters， apparent nutrient digestibility， and growth performance in Boer crossbred goats. Seventy-five Boer×Matou castrated male goats with similar body weight ［（18.20±1.65） kg］ were selected and randomly assigned to five groups with 15 animals as replicates in each group. A Control group was fed a base diet， and those in the other four experimental groups were fed experimental diets in which 25%， 50%，75% or 100% of alfalfa meal in the base diet were substituted by kudzu vine meal. After a feeding trial was carried out for 55 days， a 7-day digestibility trial was conducted. The results showed that the apparent digestibility of dry matter， crude protein and neutral detergent fiber （NDF） was significantly increased （P<0.05） by the substitution of alfalfa with kudzu vine meal. However， the apparent digestibilities of crude fiber， acid detergent fiber， calcium and total phosphorus did not differ among treatments （P>0.05）. With increased substitution level of kudzu meal， malondialdehyde （MDA） levels in serum of the 25%， 50%， 75% and 100% treatment groups decreased by 11.3%， 19.8%， 25.4% and 26.3%， respectively， compared with the control group. However， with increased substitution level of kudzu vine meal， superoxide dismutase （SOD）， catalase （CAT） and glutathione peroxidase （GSH-Px） activities， and total antioxidant capacity （T-AOC） in serum in Boer crossbred goats were significantly increased （P<0.05）. When 100% of alfalfa in the control diet was substituted with alfalfa powder， SOD， T-AOC， CAT and GSH-Px were increased （P<0.05） by 8.8%， 20.7%， 49.4% and 34.4%， respectively. Compared with control diet， serum IgA of 25%， 50%， 75% and 100% treatment groups was increased by 15.8%， 21.0%， 26.3% and 21.0%， respectively； serum IgG of 25%， 50%， 75% and 100% treatment groups was increased （P<0.05） by 6.8%， 9.5%， 12.2% and 10.8%， respectively； and serum IgM of 25%， 50%， 75% and 100% treatment groups was increased （P<0.05） by 9.1%， 12.1%， 15.2% and 12.1%， respectively. As judged from the average daily gain， feed intake and ratio of gain： feed， the 75% substitution treatment was optimal. The daily body weight gain of the 75% substitution treatment group was increased by 23.2%， and the ratio of gain： feed was increased by 15.49% （P<0.05） in comparison with control group. In conclusion， inclusion of kudzu vine meal in the diet of Boer crossbred goats improved the bodyweight gain and immune function of the goats. Kudzu vine meal can be used as a high quality feed for goats in place of alfalfa meal.

Associative effects between whole crop maize silage and mixed silage made from raw potato crisp processing by-product and rice straw as determined using an in vitro gas production technique

Yuan-yuan WEN, Mei-qi ZHANG, Tao-tao LIU, Yi-zhao SHEN, Yan-xia GAO, Qiu-feng LI, Yu-feng CAO, Jian-guo LI

2021, 30(8):  154-163.  DOI: 10.11686/cyxb2020313

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The aim of this study was to evaluate the associative effects between whole crop maize silage （WCS） and mixed silage made from raw potato crisp processing by-product and rice straw （PRS）. The PRS （35% dry matter） was produced by mixing potato crisp processing by-product with rice straw at a ratio of 1∶2， adding silage additive， mixing with a blender， bundling and wrapping the silage substrate using a machine， and then fermenting for 60 days. The treatments consisted of seven combinations of PRS and WCS at different ratios： 0∶100 （T₀）， 20∶80 （T₂₀）， 40∶60 （T₄₀）， 50∶50 （T₅₀）， 60∶40 （T₆₀）， 80∶20 （T₈₀）， and 100∶0 （T₁₀₀） on a dry matter （DM） basis. Each combination had three replicates. Gas production （GP） was measured using an in vitro method. Dry matter digestibility （DMD）， pH， and the concentrations of ammonia nitrogen （NH₃-N）， microbial protein （MCP）， and volatile fatty acids （VFA） were determined at 48 h of incubation. The GP was recorded at 2， 4， 6， 8， 10， 12， 24， 36， and 48 h of incubation. The single factor associative effects index （SFAEI） and multiple factors associative effects index （MFAEI） of different combinations were calculated. The results show that： 1） GP and DMD decreased significantly or extremely significantly （P<0.05 or P<0.01） as the proportion of PRS increased. The SFAEIs of GP and DMD were the lowest in the T₅₀ and T₈₀ groups， respectively， and the highest values of those indexes were in the T₂₀ group. 2） The pH of different combinations ranged from 6.46 to 6.59. The pH of the T₈₀ group was the highest， and was significantly or extremely significantly higher than that in other groups， except for the T₁₀₀ group （P<0.05 or P<0.01）. The highest SFAEI of pH was in the T₈₀ group. 3） There was no significant difference in NH₃-N concentrations and MCP production among different combinations （P>0.05）， but the highest values were in the T₄₀ group. The SFAEIs of NH₃-N and MCP were highest in the T₄₀ and T₈₀ groups， respectively. 4） The concentrations of acetic acid， propionic acid， valeric acid， and total VFAs were highest in the T₀ group and lowest in the T₁₀₀ group， and the differences between the two groups were extremely significant （P<0.01）. The concentration of butyric acid was highest in the T₀ group and lowest in the T₈₀ group. The highest SFAEIs of acetic acid， propionic acid， and butyric acid were in the T₈₀， T₂₀， and T₆₀ groups， respectively. According to the MFAEI index evaluation， two combinations had positive associative effects； The combination in the T₄₀ group （40∶60） had the best effect， followed by that in the T₅₀ group （50∶50）.

Effects of tannic acid addition on the aerobic stability and mycotoxin content of kudzu vine silage

Dong-mei YANG, Jun-nian LI, Shuang-lun TAO

2021, 30(8):  164-170.  DOI: 10.11686/cyxb2021022

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This study investigated the potential benefits of tannic acid （TA） as an additive when making kudzu （Pueraria lobata） silage. The effects of 0 （control）， 1.0%， 1.5%， and 2.0% TA addition on the fermentation quality， aerobic stability， and mycotoxin content of kudzu silage were analyzed. It was found that after 70 days fermentation， the content of water-soluble carbohydrate levels in kuzdu silage with 2.0% tannic acid were 16% higher than in the control （P<0.05）. Propionic acid and butyric acids were not detected in kudzu vine silage treated with TA. The lactic acid content of kudzu vine silage decreased with increasing tannic acid addition （P<0.05）. Addition of TA also significantly reduced the levels of aflatoxin， vomitoxin， and zearalenone in kudzu vine silage （P<0.05）. After 70 days fermentation， the contents of aflatoxin， vomitoxin， and zearalenone in kudzu vine silage treated with 2.0% TA were reduced by 47.6%， 53.9%， and 37.4%， respectively， compared with those of the control. The kudzu vine silage with 2.0% TA acid had the lowest pH with a slight decrease in lactic acid， a slight increase in yeast count， and the best aerobic stability among the treatments. In summary， the addition of TA improved several quality indicators of kudzu vine silage.

Index insurances for grasslands： A review and the Chinese scheme design

Hui-long LIN, Yan-fei PU, Dan-ni WANG, Hai-li MA

2021, 30(8):  171-185.  DOI: 10.11686/cyxb2020293

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Index insurances for grasslands （IIGs） are a new kind of agricultural insurance， whose claim trigger mechanism， including the index to be used when assessing claims and the threshold level for payment， is more scientific than that of traditional indemnity insurances. IIGs choose indices closely relevant to grassland production and study the relationships between yield， climate， NDVI and economic data to precisely calculate the claim trigger level of the selected index. Through this procedure， the local norm is identified and the claim trigger mechanism is used to decide whether the insured will receive a payout. We have explored the trigger mechanisms of 18 operational IIGs from 11 countries and grouped them into 3 types based on different categories of index selection. They are area-yield index insurance （AI）， weather index insurance （WI） and satellite/remote-sensing index insurance （SRI）. AI is based on the selected area’s average yield. When the actual average output of the area is lower than the specified level， all insured persons receive the same amount of compensation； WI choose climatic indicators （temperature， rainfall， etc.） as indices and measure the extent to which they limit grassland production； SRI is innovatively designed with satellites and remote-sensing， and NDVI is the most widely used index. However， even though China is a country with very large areas of grassland， China has little research into IIGs， and few products of this type under development or available to farmers. This situation is not conducive to the sustainable development of grassland. Considering the limited availability of relevant data in China and the vast area of grasslands， it is not advisable to simply adopt products from other countries. Therefore， there is an urgent need to develop a China-oriented scheme. This paper proposes a novel scheme based on the comprehensive and sequential classification system of grasslands （CSCS） using remote sensing data sources （providing macro data）， drone technology （providing supplementary meso data）， and economic data collected from grassland producers through household surveys of farmers and herdsmen（as micro data）. Through systematic analysis of relationships between yield， climate， NDVI and economic data over a number of years， a grassland category’s expected productivity can be determined. This will then make possible the establishment of indemnity whenever the productive capacity or income of the insured falls below the designated threshold relative to a normal year.

Research progress on the seed-shattering mechanism of Poaceae plants

Wen-gang XIE, Yi-yang WAN, Zong-yu ZHANG, Jun-chao ZHANG

2021, 30(8):  186-198.  DOI: 10.11686/cyxb2020579

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Seed shattering is an adaptive characteristic of wild plants for effective reproduction and population expansion， but it adversely affects seed production. The formation， development， and degradation of the abscission zone are the direct causes of seed shattering in plants. Plant hormones produce signals that promote or inhibit seed shattering. Cell wall hydrolases can cause the degradation of cells in the abscission zone. The occurrence of these processes is regulated by polygenes and the regulatory network is complex. Research on seed shattering has been carried out in rice， wheat， and other crops， but comparatively few studies have focused on forage grasses. In this paper， we review the latest advances in research on seed shattering in poaceous plants to provide a theoretical reference for in-depth exploration of seed-shattering mechanisms and species selection.

Effect of moisture content and additives on the fermentation quality of Neolamarckia cadamba leaf silage

Xiang GUO, De-kui CHEN, Na CHEN, Yun LI, Xiao-yang CHEN, Qing ZHANG

2021, 30(8):  199-205.  DOI: 10.11686/cyxb2020283

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In order to study the effects of moisture content and additives on the fermentation quality of Neolamarckia cadamba leaf silage， two batches of N. cadamba leaves with different water contents of 60% and 75% were chopped and ensiled without additive， or with one of three additive treatments： inoculant containing 6.00 log₁₀ cfu·g^-1Lactobacillus plantarum （LP）， 120 U·g^-1 cellulase （C）， or 6.00 log₁₀ cfu·g^-1 LP and 120 U·g^-1 cellulase （LP+C）. Six replicates of each treatment were weighed into plastic bags and stored at ambient temperature （about 30 ℃） for 60 days. Before ensiling the contents of crude protein and water-soluble carbohydrate in leaf dry matter were 12.48% and 4.49%， respectively. Compared to 60% water content， 75% water content caused a significant decrease in pH value， numbers of lactic acid bacteria and yeast cells， content of neutral detergent fiber， tannin content and ammonia nitrogen content of the silage （P<0.05）， while the contents of lactic acid and acetic acid increased significantly （P<0.05）. Treatments LP and LP+C significantly decreased the pH value， the number of lactic acid bacteria and the content of condensed tannins （P<0.05）， while increasing the content of lactic acid （P<0.05）. At the same time， C and LP+C significantly decreased the neutral and acid detergent fiber contents （P<0.05）， and increased crude protein content （P<0.05）. For the treatment with 75% water content and the additions of LP and LP+C， content of condensed tannins was were significantly reduced （P<0.05）. In conclusion， the 75% water content treatment had a positive effect on the fermentation quality of N. cadamba leaf silage. Silage quality was improved by additives， and the combined application of LP and C gave optimal results.