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2021 Vol.38(3)

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2021, 38(3): 0-0.
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2021, (3): 1-4.
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Effects of exclosure on plant and soil nutrients in an alpine grassland
LI Runfu, NIU Haishan, KONG Qian, LIU Qiang
2021, 38(3): 399-409. doi: 10.11829/j.issn.1001-0629.2020-0368
[Abstract](4009) [FullText HTML] (1063) [PDF 940KB](33)
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Exclosure is among the most common measures applied to restore degraded alpine grasslands on the Qinghai-Tibetan Plateau. The study aimed to examine the effects of exclosure on soil physicochemical properties and plant nutrient contents and to evaluate the impact of exclosure on grassland restoration based on the relationship between soil properties and plant nutrient content. In this study, three pairs of grazed and fenced plots that had been enclosed for 6, 11, and 12 years were selected in Bange County, Nagchu City, Tibetan Autonomous Region, China. The results showed that 1) exclosure significantly increased aboveground biomass and vegetation coverage (P < 0.05) but significantly decreased the Shannon-Wiener diversity index and Margalef richness index (P < 0.05); 2) no significant differences existed between bulk density, total carbon (TC), and total nitrogen (TN) of soils at different depths within and outside of fences (P > 0.05); 3) the effects of exclosure on the relative importance of plants varied with species, and significant differences in TC, TN, and nitrogen-use efficiency (NUE) existed among species (P < 0.05); and 4) the correlation between vegetation and the primary nutrient content of topsoil only existed between some species and some nutrients. The results indicated that exclosure could significantly change vegetation productivity and community composition but had relatively little effect on soil properties and plant nutrient utilization. Therefore, the restorative effects of exclosure on degraded alpine grassland ecosystems on the Qinghai-Tibetan Plateau require further and more comprehensive investigation.
Effects of different sand-cover thicknesses on crops in bare saline-alkali land in the Songnen Plain
HU Juan, ZHOU Daowei, WANG Xiaoyu, ZHANG Dan, GUAN Shengchao
2021, 38(3): 410-418. doi: 10.11829/j.issn.1001-0629.2020-0379
[Abstract](3111) [FullText HTML] (991) [PDF 936KB](11)
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The salinization of the Songnen Plain seriously restricts the sustainable development of farming and animal husbandry. Sand-covering and planting crops on the sand layer are effective methods to utilize salinized land. To study the effects of different sand-cover thicknesses on different crops, maize, sunflower, barley, and alfalfa were planted on bare saline-alkaline land with sand-cover thicknesses of 10, 20, 30, and 40 cm in the Songneng Plain. All four crops grew normally in the first year after sand-covering but grew weakly at the settlement stage. In the second year, all four crops grew powerfully. Sand-cover of over 20 cm significantly promoted maize growth. Maize yield was 4 298 kg·ha−1 with sand-cover of 40 cm, which was 2.5 times higher than that with sand-cover of 10 cm (P < 0.05). The hay yield and total root biomass of alfalfa were the highest with sand-cover of 30 cm, and reached 8 597 and 3 367 kg·ha−1, respectively; these were 3.36 and 1.28 times higher than those with sand-cover of 10 cm (both P < 0.05). The yields of sunflower and barley were highest with sand-cover of 40 cm; these were 33.4% and 269.5% higher than those with sand-cover of 10 cm, respectively. However, there were no significant differences among sand-cover thicknesses of 20 cm, 30 cm, and 40 cm. Therefore, maize should be planted with sand-cover of more than 20 cm, alfalfa with sand-cover of 30 cm, and sunflower and barley with sand-cover of 40 cm. The results show that these crops can be grown successfully by sand-covering in saline-alkali land.
Response of vegetation cover to drought in the Qilian Mountains Region from 2001 to 2016
LIU Jiaru, ZHAO Jun, WANG Jianbang
2021, 38(3): 419-431. doi: 10.11829/j.issn.1001-0629.2020-0318
[Abstract](3511) [FullText HTML] (652) [PDF 3054KB](30)
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The Qilian Mountains are located in the arid and semi-arid areas of Northwest China, where the climate is dry with little precipitation; thus, the internal ecological environment is fragile. Global warming and economic development have an important impact on the regional ecological environment. The study of the temporal and spatial distribution characteristics and trends of fractional vegetation cover (FVC) and the response of FVC to drought can provide a basis for the improvement of the ecological environment and mitigation of drought impacts. Based on MOD13Q1 remote sensing and meteorological data, the spatial and temporal distribution characteristics and dynamic trends of FVC and standardized precipitation evapotranspiration index (SPEI), and the correlation between them, in the Qilian Mountains Region from 2001 to 2016 were calculated using the dimidiate pixel model, Thornthwaite method, trend analysis method, Hurst exponent, and correlation analysis method. From 2001 to 2016, the overall FVC in the Qilian Mountains showed an increasing trend. FVC was the lowest in 2001 and highest in 2011. Moreover, there were seasonal changes, and coverage was the highest in summer. From a spatial perspective, FVC in the Qilian Mountains was generally high in the southeast and low in the northwest, with an average annual value of 0.4522. Thus, there were regional differences, although FVC in most regions showed an increasing trend. During the past 16 years, 77.13% of the vegetation area in the Qilian Mountains improved and 22.87% degenerated. In the future, this change will likely tend to be negative rather than positive, although 28.1% of the vegetation area in the Qilian Mountains may continuously improve. However, the future trend of 49.23% of this area is uncertain at the maximum; therefore, these areas need more focus and protection. Most areas in the Qilian Mountains were in a humid state, and some areas in the middle and eastern sections were in a mild drought. The SPEIs on the 1-, 3-, 6-, and 12-month scales showed a trend of increasing aridity. Overall, the degree of drought in the Qilian Mountains showed a decreasing trend between 2001 and 2016, and the climate was developing in a better direction. On an annual scale, SPEI and FVCwere positively correlated. On a seasonal scale, summer FVC had the highest response to SPEI drought, followed by spring and fall, which indicates that the higher the significance between FVC and SPEI, the greater the response.
Comparison of vegetation coverage models based on comprehensive segmentation advantages
BIAN Huiqin, WANG Xuemei
2021, 38(3): 432-442. doi: 10.11829/j.issn.1001-0629.2020-0438
[Abstract](5260) [FullText HTML] (527) [PDF 1089KB](12)
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On the basis of Landsat 8 OLI remote sensing images, nine vegetation indices were selected to analyze the correlation between vegetation indices and field-measured vegetation coverage. A sensitive vegetation index was selected based on the segmentation method, and regression and FCD (forest canopy density mapping model) models were used to invert the vegetation coverage in the Weigan-Kuqa River delta oasis. The following results were obtained. 1) Using the measurement data, the change proportion of different vegetation indices in different vegetation coverage ranges was calculated, and 0.3 and 0.7 were determined as the segmentation points of vegetation coverage in the study area. 2) The modeling accuracy of the segmented regression and FCD segmentation models was approximately 79%; however, the R2 (0.832) and RMSE (0.154) values of the FCD segmentation model were higher and smaller, respectively, than those of the segmented regression model. Thus, the FCD segmentation model was established as providing better validation results (PRECISION of 82.018%). The FCD segmentation model is therefore considered more suitable for inversion of the total vegetation coverage in the study area, and will contribute to the quantitative monitoring of vegetation coverage and evaluation of the ecological environment in arid areas.
Characteristics of the soil seed bank under different disturbance intensities in an arid mining area
FENG Changdong, GUO Xiaoping, LUO Chao, YE Jinpeng, ZHANG Xin, MA Yuan
2021, 38(3): 443-452. doi: 10.11829/j.issn.1001-0629.2020-0400
[Abstract](2563) [FullText HTML] (673) [PDF 857KB](28)
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Soil seed banks are an important factor that can affect vegetation restoration in mining areas, and their characteristics reflect the vegetation restoration potential of the region to a certain extent. In this study, the relationship between the soil seed bank and its surface vegetation under three different disturbance conditions in the Wuhai Xinxing coal mine area was analyzed using sample site investigation and indoor germination techniques. The results show that 1) Species are scarce in the study area. There are a total of 18 plant species belonging to 7 families and 16 genera. The species life forms are mainly perennial herbs. 2) The average soil seed bank reserve in the Xinxing mining area is relatively small (226.51~739.17 seed·m−2) and shows a decreasing trend as the soil depth increases. More than 90% of the seeds are stored in the surface soil (0 − 10 cm). 3) The plants in the soil seed bank across the study area have few species in common with above-ground vegetation in the same area and the plant community similarity between the soil seed bank and the above-ground vegetation is low. 4) When the disturbance intensity increased, the vegetation restoration potential of the seed bank rose at first and then decreased. The natural vegetation area around the road with moderate disturbance developed in a favorable direction, while the natural vegetation area around the mining area with severe interference was strongly negatively affected, its diversity and similarity with other district communities were small, and the seed density significantly decreased (P < 0.05).
Effects of tourism disturbance and altitudinal gradient on leaf and soil ecological stoichiometry of a mountain meadow in Altai Mountains, China
HAO Shuai, ZHENG Wei, ZHU Yaqiong, WANG Rui, QIAO Zimei, LIU Yuehan, Ailifeire
2021, 38(3): 453-467. doi: 10.11829/j.issn.1001-0629.2020-0426
[Abstract](2251) [FullText HTML] (554) [PDF 909KB](25)
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Exploring the variation laws and coupling relationships of carbon (C), nitrogen (N), and phosphorus (P) content and their ratios in plant leaves and soil along altitudinal gradients can provide insight into grassland ecosystem stability and maintenance mechanisms under tourism disturbance. To identify spatial heterogeneity and compare tourism disturbance intensity, we set four group plots (1 300 m, 1 500 m, 1 700 m, and 1 900 m group, each group including tourism disturbance plot and no tourism disturbance plot, totaling 8 plots) from 2015 to 2017 in the Kanas Scenic Area, Xinjiang, China. We investigated the C, N, and P content in leaves and their ratios in the dominant species and main companion species and soil ecological stoichiometry characteristics of the 0 − 20 cm layer, and analyzed the correlation between leaf and soil ecological stoichiometry. The results were as follows: 1) Leaf C, N, and P content decreased, and C/N, C/P, and N/P increased under tourism disturbance. Soil C, N, and P content and their ratios all decreased under tourism disturbance in the 0 − 20 cm layer. However, the decreased ranges of soil N and P content and N/P were not significantly different from those of the no-disturbance plots; 2) Leaf C, N, and P content increased and C/N, C/P, and N/P decreased with increasing altitudinal gradient in the no-disturbance plots. Tourism disturbance altered the changing trends of leaf stoichiometry characteristics. In all plots, soil C content and C/N decreased, soil N content and N/P increased, and soil P content and C/P did not change. However, tourism disturbance barely altered the changing trends of soil stoichiometry characteristics; 3) In all plots, leaf N content was positively correlated with soil C content and C/N. Leaf P content was positively correlated with soil C/P. Leaf C/P was negatively correlated with soil C/P. Leaf C content was not significantly correlated with soil ecological stoichiometry. In high-altitude plots, leaf N/P was negatively correlated with soil C content, C/N, and C/P. With regard to spatial variations of leaf and soil ecological stoichiometry, leaf and soil ecological stoichiometry were correlated along the altitudinal gradient. Tourism disturbance altered the spatial heterogeneity of leaf stoichiometry characteristics along the altitudinal gradient, and the influence on the soil stoichiometry characteristics was negligible. These findings improve our understanding of the influence of tourism disturbance on leaf and soil ecological stoichiometry, stability, as well as the maintenance mechanism of the mountain meadow ecosystem.
Study on soil pH and nutrients in a roadside green belt in a central urban area of Lanzhou
CHENG Xiaoyue, XU Honggang, ZHU Yaling, ZHANG Jianqi
2021, 38(3): 468-479. doi: 10.11829/j.issn.1001-0629.2020-0245
[Abstract](4041) [FullText HTML] (895) [PDF 1021KB](14)
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To determine the pH and nutrient status in roadside greenbelt soil in a central urban area of Lanzhou, uncover the main limiting factors, and propose solutions, the soil around street trees, which was divided into 0 − 30 cm and 30 − 60 cm layers, were sampled. Depending on whether the soil was covered by vegetation, the samples were further divided into bare and vegetation-covered groups. The relationship between soil pH and soil nutrients was analyzed using the group regression method. The soil pH ranged from 7.91 to 9.39, with an average value of 8.49, and was generally high, with 33.42% and 0.47% of the soil being strongly and extremely alkaline, respectively. Soil organic matter content ranged from 5.30 to 47.80 g·kg−1, with an average value of 18.29 g·kg−1, and 37.64% and 21.77% of the soil were relatively and seriously deficient, respectively. Soil alkali-hydrolyzable nitrogen content ranged from 5.24 to 167.55 mg·kg−1, with an average value of 48.54 mg·kg−1, and 35.68% and 5.95% of the soil were relatively and seriously deficient, respectively. Soil available phosphorus content ranged from 4.68 to 184.46 mg·kg−1, with an average value of 45.66 mg·kg−1, and 19.58% and 1.67% of the soil were relatively and seriously deficient, respectively. Soil available potassium content ranged from 72.35 to 449.64 mg·kg−1, with an average value of 177.60 mg·kg−1, and was not deficient. Organic matter, available nitrogen, available phosphorus, and available potassium contents in the 0 − 30 cm layer of bare soil were significantly higher than those in the 30 − 60 cm soil layer. Additionally, available nitrogen and available potassium contents in the 0 − 30 cm soil layer covered by vegetation were significantly higher than those in the 30 − 60 cm soil layer. The results of correlation analysis showed that organic matter, alkali-hydrolyzable nitrogen, and available phosphorus contents were negatively correlated with soil pH, and that high pH was an important factor that limited the exertion of soil nutrients in the Lanzhou road greenbelt. Vegetation coverage significantly decreased soil pH and significantly increased the contents of organic matter, alkali-hydrolyzable nitrogen, and available phosphorus. Therefore, vegetation coverage on a bare surface can effectively improve the main problems that exist in roadside green belt soil.
Effects of cold-season snow on late warm-season vegetation on the Tibetan Plateau
WANG Yuanxiang
2021, 38(3): 480-488. doi: 10.11829/j.issn.1001-0629.2020-0200
[Abstract](1988) [FullText HTML] (603) [PDF 1685KB](29)
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Studying the effects of cold-season snow on warm-season vegetation and understanding the underlying mechanisms may help conserving ecosystems and implementing effective steps to counteract climate change on the Tibetan Plateau (TP). Using regression, correlation, and composition analysis as well as data on fractional snow cover (FSC), normalized difference vegetation index (NDVI), National centers for Environmental Prediction (NCEP) and climate Prediction Center Merged Analysis of Precipitation (CMAP), the relationships between cold-season snow and warm-season vegetation on the TP were investigated. The results showed that when cold-season snow increased, warm-season vegetation also increased on the TP, and vice versa. This relationship is supported by background atmospheric circulation. When the amount of snow in the cold season is untypically large, the eastern Asia summer monsoon weakens, and the Pacific subtropical high increases, moves westward and affects the eastern TP during the warm season. Such an atypical high during the warm season results in higher surface temperatures, snow melting, increased soil moisture, increased solar radiation, and decreased precipitation, the first four phenomenona of which favor vegetation growth. Especially, melting snow provides considerable amounts of water to the soil, which favors vegetation rejuvenation and early growth. Precipitation is the main source of soil water, and it is typically abundant and meets the requirements of vegetation growth during warm season; however, NDVI is highest during the warm season, and excessive precipitation may result in reduced vegetation growth, thus a slight decrease in precipitation may promote vegetation growth.
A primary survey of the diversity of arbuscular mycorrhizal fungi on Xinglong Mountain, Gansu Province
DONG Wanqing, YAN Zhichen, DENG Jie, LI Yingde, DING Tingting, DUAN Tingyu
2021, 38(3): 489-500. doi: 10.11829/j.issn.1001-0629.2020-0374
[Abstract](2306) [FullText HTML] (573) [PDF 869KB](22)
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In this study, Illumina HiSeq molecular sequencing technology was used to examine the diversity of arbuscular mycorrhizal fungi and their distribution characteristics at different altitudes in the Xinglong Mountain Nature Reserve (East Mountain), Gansu Province. A total of 52 species of arbuscular mycorrhizal fungi belonging to four orders, eight families, and 13 genera were obtained from soil samples. Among these, species of Glomus and Archaeospora were predominant, being represented by 20 and 9 species, respectively, and accounting for 55.77% of the total species. Results obtained for the distribution of arbuscular mycorrhizal fungi at different altitudes revealed that the dominant genera Glomus and Paraglomus were regularly distributed with changes in altitude, whereas the remaining genera were uniformly distributed at different altitudes. Gigaspora margarita, Acaulospora mellea, Glomus albidum, Glomus sp. 1, Glomus sp. 4, and Sclerocystis sinuosa appeared only at certain elevation levels, and are assumed to be restricted to different elevations. Analysis of arbuscular mycorrhizal fungal species richness indicated that from low altitude to high altitudes, the ACE and Chao1 indices generally had a “single peak” change curve, and showed significant differences at certain altitudes (P < 0.05). Spearman correlation analysis indicated that the distribution of arbuscular mycorrhizal fungi in this region is less affected by the altitude factor, and that there were no significant correlations between altitudes. In summary, arbuscular mycorrhizal fungi resources on the East Xinglong Mountain are rich and have considerable application potential.
Research progress on the effects of root niche differences on ecosystems
LI Hui, HE Yixuan, Sirimuji, WANG Baojie, LIU Kesi
2021, 38(3): 501-513. doi: 10.11829/j.issn.1001-0629.2020-0422
[Abstract](2561) [FullText HTML] (627) [PDF 794KB](22)
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Root systems play an important role in plants, communities, and ecosystems, and plants are also influenced by the external environment. For communities with high plant diversity, root niche differences have different impacts on the biomass, root distribution, soil structure, and nutrient resource allocation of the entire community, which in turn determine species coexistence and community ecological stability. In this study, after summarizing domestic and foreign literature relating to root systems, we drew the following three conclusions. 1) Communities characterized by higher species diversity have higher productivity, and with an increase in species richness, an increase in community biomass is closely related to an increase in the root biomass of deep-rooted plants. 2) In communities characterized by different species richness, there will be vertical distribution of the root niche. Consequently, root exudates and root traits will affect the structural characteristics of soil aggregates and nutrient utilization, thereby improving soil nutrition. Furthermore, the co-occurrence of shallow- and deep-rooted species is conducive to species coexistence and a more effective use of soil resources. 3) Both root complementation and selection effects will have an effect on the ecosystem, and with an increase in species diversity, the complementation effect will increase and the selection effect will decrease. This complementary effect is considered to be a key factor with respect to increasing resource utilization. In this study, we examined the impact of the interactions between specific species and competition in the community, and briefly summarized the effects of root systems on terrestrial ecosystems. On the basis of our findings, we propose further research on root systems, with a particular focus on the following two areas of root ecology research. 1) The influence of the community on variations in the vertical distribution of underground root characters needs to be further verified and clarified. 2) Given the difficulties associated with sampling roots, future research should be combined with modern molecular and imaging technologies to gain a better understanding of the characteristic of belowground roots.
Effects of nitrogen levels on the photosynthetic physiology and forage quality of bermudagrass
WANG Hongli, ZHANG Yinkun, ZHAO Chuncheng, ZHANG Ting, FU Jinmin, XU Xiao
2021, 38(3): 514-522. doi: 10.11829/j.issn.1001-0629.2020-0346
[Abstract](2246) [FullText HTML] (531) [PDF 1179KB](15)
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Nitrogen is an important component of proteins, nucleic acids, chlorophyll in plants. It is thus an essential nutrient element for plant growth, and different plants are known to have different nitrogen requirements. In this study, Cynodon dactylon ‘Wrangler’ was used as the experimental material to examine the effects of different nitrogen levels (N1, N2, and N3) on photosynthetic physiology and forage quality based on nutrient solution hydroponics. The purpose of the study was to determine the optimal levels of nitrogen with respect to growth, photosynthesis, and forage quality. The results revealed that compared with the N1 conditions, plant growth was better and plant height increased significantly (P < 0.05) under the N2 and N3 conditions. Moreover, there were significant increases in chlorophyll content, the chlorophyll fluorescence kinetic curve, Fv / Fm value, and other photosynthetic indices (P < 0.05). In addition, forage quality indices, including the crude fiber content, were significantly higher, whereas there was a significant reduction in the content of ash (P < 0.05). Overall, the best photosynthetic characteristics (PICS) of bermudagrass were detected in plants subjected to the N3 treatment, and these plants had significantly higher contents of nitrogen and crude protein than those receiving the N2 and N1 levels of nitrogen (P < 0.05). The findings of this study therefore indicate that the 10 mmol·L–1 level would be the optimal level of nitrogen application for ‘Wrangler’ bermudagrass. This information will accordingly provide theoretical guidance for the practical application of nitrogen for this crop.
Cloning and expression of the AcDREB2 transcription-factor gene in Atriplex canescens
GOU Yanli, GAO Lili, WU Xinxin, GUO Huan, BAO Aike
2021, 38(3): 523-530. doi: 10.11829/j.issn.1001-0629.2020-0559
[Abstract](2399) [FullText HTML] (480) [PDF 2188KB](20)
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Dehydration-responsive element-binding proteins (DREB) play an important role in plant responses to salt and drought stress. To investigate the function of DREB in Atriplex canescens and their application prospects, a pair of degenerate primers was designed, and the DREB transcription-factor coding-gene AcDREB2 was cloned via PCR (polymerase chain reaction) amplification and the RACE (Remote Analysis Computation for gene Expression data) method. The full-length cDNA of AcDREB2 was 867 bp, encoding 242 amino acids. The BLAST and homology matrix results showed that AcDREB2 was highly homologous with the DREBs of other plants. The expression patterns of AcDREB2 were analyzed via RT-PCR. AcDREB2 was highly expressed in the leaves of A. canescens, and its expression was rapidly induced by NaCl and osmotic stress, indicating that AcDREB is involved in the A. canescens stress response.
Response of major species to grazing mode in an alpine grassland
FENG Bin, YANG Xiaoxia, DONG Quanmin, ZHANG Chunping, LIU Wenting, YU Yang, ZHANG Xiaofang, SUN Caicai, SHI Guang, YANG Zengzeng, ZHANG Yanfen
2021, 38(3): 531-543. doi: 10.11829/j.issn.1001-0629.2020-0321
[Abstract](2223) [FullText HTML] (638) [PDF 954KB](42)
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To explore the response of major alpine grassland species to grazing mode, the prevalence and individual characteristics of species belonging to four functional groups were measured through a manipulated grazing experiment in an alpine grassland in the Qinghai Lake Basin. The manipulated grazing experiment included yak and Tibetan sheep grazing along with mixed-species grazing (MG) featuring different ratios of yak to sheep (1 ꞉ 6, 1 ꞉ 4, and 1 ꞉ 2, abbreviated as MG 1 ꞉ 6,MG 1 ꞉ 4, and MG 1 ꞉ 2, respectively) and a control treatment. The results showed that 1) compared with the control treatment, the frequency of species with high palatability and large biomass decreased under all grazing modes, whereas the frequency of species with low palatability and low height increased, especially under MG 1 ꞉ 2. The height of all species decreased under all grazing modes; 2) the individual weights of graminoid, legume, and palatable forbs decreased under grazing, but that of low-tufted sedges and forbs increased; and 3) the mass-height ratio of each functional group was higher than that of the control treatment, except for Stipa purpurea and Koeleria macrantha. Thus, the response of alpine grassland plants to grazing was significant (P < 0.05) at the species level, and significant differences (P < 0.05) also existed between species; however, the response at the functional-group level was insignificant (P > 0.05). Compared to other grazing treatments, MG 1 ꞉ 2 had a significant impact on the frequency and individual characteristics of each functional group and species.
Remote sensing monitoring of grazing intensity in Zoige Plateau based on aboveground net primary productivity and aboveground biomass
ZHAI Xing, WANG Jiyan, YU Bing, SU Yong, YANG Yinghui
2021, 38(3): 544-553. doi: 10.11829/j.issn.1001-0629.2020-0410
[Abstract](1915) [FullText HTML] (502) [PDF 1485KB](20)
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As one of the three grassland pastoral areas in China, the Zoige Plateau is rich in forage resources; however, owing to grazing, the plateau has suffered wetland and grassland degradation and land desertification. The aim of this study was to accurately and quickly estimate the grazing situation in the Zoige Plateau on the regional scale and provide data and theoretical support for the rational organization of human activities and protection of the ecological environment in this area. MODIS-NDVI, ground measured, and meteorological data were used to simulate the aboveground biomass and aboveground net primary productivity (ANPP) and evaluate the grazing intensity in the Zoige Plateau from 2010 to 2019. The model that estimated grazing intensity had a good effect on simulation of actual grazing intensity, with an R2 value of 0.7813, and reached an extremely significant correlation level with measured data of grazing intensity (P < 0.05). Moreover, the root mean square error was small and the accuracy reached more than 70%; Thus, this model can distinguish regions with different grazing degrees. The average grazing intensity in the Zoige Plateau in 2019 was 1.87 AU·hm−2, which is a state of overgrazing, and the overall grazing intensity was higher in the southeast and lower in the northwest. Furthermore, the grazing intensity in the Zoige Plateau showed an overall increasing trend from 2010 to 2019, and increased first and then decreased during 2010−2014 and 2014−2019, respectively, and the distribution of ANPP and aboveground biomass was related to the grazing intensity to a certain extent.
Effect of desert steppe grazing on slaughtering performance and meat quality of Tan sheep
ZHAO Xingang, GUO Yanping, LIU Ming, ZHANG Can, LUO Hailing
2021, 38(3): 554-561. doi: 10.11829/j.issn.1001-0629.2020-0393
[Abstract](1576) [FullText HTML] (468) [PDF 677KB](21)
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To investigate the effect of desert steppe grazing on the Tan lamb, 39 Tan lambs were randomly divided into three groups: grazing (GZ), time-limited grazing with supplement (TG), the stall-fed (SF). Then, slaughtering performance and meat quality were measured. The final body weight, carcass weight, dressing percentage, pure meat percentage, and meat-bone ratio were significantly better in the SF group than in the TG group (P < 0.05). Moreover, the slaughtering performance was significantly better in the TG group than in the GZ group, except for the pure meat percentage and meat-bone ratio. There were no significant differences in meat color, pH, shear force, and drip loss, but SF group was lower in cooking loss (P < 0.05). The content of meat polyunsaturated fatty acids (C18 ꞉ 3n3, C20 ꞉ 5n3, C22 ꞉ 6n3, C18 ꞉ 2n6, C20 ꞉ 3n6, and C20 ꞉ 4n6) of Tan lambs in the GZ and TG groups was significantly higher than that in the SF group (P < 0.05); the GZ and TG groups had a significantly lower n-6/n-3 ratio in the muscles than the SF group (P < 0.05). These results suggest that grazing in the desert steppe can increase the content of unsaturated fatty acid in muscle, and have an adverse effect on cooking loss and the slaughtering performance of Tan sheep. Time-limited grazing with supplement feeding modes can improve the slaughtering performance, while preserving the fatty acid composition of Tan sheep.
Effects of tannic acid on food intake and micro-morphology of the small intestine in Lasiopodomys fuscus
ZHONG Liang, YU Yibo, ZHU Hongjuan, QU Jiapeng
2021, 38(3): 562-570. doi: 10.11829/j.issn.1001-0629.2020-0360
[Abstract](2493) [FullText HTML] (516) [PDF 580KB](14)
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This study aimed to evaluate the effects of tannic acid on food intake and micromorphology of the small intestine in mature Qinghai voles (Lasiopodomys fuscus). We examined changes in body weight, food intake, villus length, and crypt depth in 24 male Qinghai voles under diets containing 0%, 3%, and 6% tannic acid (TA). The results showed that under the action of TA, the body weight of Qinghai voles changed significantly, and the individual body weight of each group showed significant differences. On day 60 of the experiment, no significant differences were identified between the body weights of voles in the 6% TA and 3% TA groups, which were significantly higher than that of voles in the control group. Tannic acid also had a significant effect on vole food intake. At the beginning of the experiment, the food intake in the control group was significantly lower than that in the 3% TA group but significantly higher than that in the 6% TA group. On day 7, food intake in the 3% TA group was significantly lower than that in the control group. On days 28, 42, and 60, the food intake of voles in the 3% TA and 6% TA groups was significantly higher than that in the control group. Tannic acid had significant effects on villus length and crypt depth of the voles’ small intestines, which were significantly longer in the TA groups than in the control group. The results suggest that TA could inhibit the feeding of Qinghai voles, and the inhibitory effect decreased over time. After Qinghai voles were adapted to TA, TA could promote the feeding of Qinghai voles, but this promotion was not achieved by changing the structure of the small intestine.
Estimating the population density of desert rodents using a camera trap method
YUAN Shuai, LI Xin, HOU Shuaijun, YANG Suwen, YUE Xiuxian, ZHANG Zhuoran, FU Heping, WU Xiaodong
2021, 38(3): 571-579. doi: 10.11829/j.issn.1001-0629.2020-0446
[Abstract](2841) [FullText HTML] (734) [PDF 989KB](19)
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Rodents are important components of grassland ecosystems. Monitoring rodent population dynamics is of considerable significance with respect to the study of small mammal ecology and has applications in grassland pest control. Until recently, snap traps and live traps have been the main methods for monitoring rodent population; however, both methods are time-consuming and laborious. Although infrared camera technology can be used to overcome these shortcomings, few studies have estimated the population density of small desert rodents using this technology. In this study, infrared camera traps and capture–mark–recapture methods were used to investigate the population density of desert rodents, and the advantages and disadvantages of the respective methods were compared. Our aim was to select a suitable method for monitoring desert rodents populations using infrared camera technology. The results indicated that random encounter and capture rate models based on infrared camera technology performed well in evaluating the population density of two jerboa species (Allactaga sibirica and Dipus sagitta). However, the capture rate model was found to be the more effective of the two models in evaluating the population density of midday gerbils (Meriones meridianus). These results indicate that whereas both methods could be used for monitoring the population densities of jerboa in desert environments, the capture rate model would be more appropriate for multi-rodent species studies.
Effects of Caragana intermedia on soil nematode communities in a steppe desert region
SONG Chengcheng, MEI Xufang, ZHANG Peng, WANG Yelin, WANG Dekai, XIE Li'na, MA Chengcang
2021, 38(3): 580-589. doi: 10.11829/j.issn.1001-0629.2020-0421
[Abstract](2654) [FullText HTML] (630) [PDF 1011KB](37)
Abstract:
This study examined the effect of shrubs on soil nematode communities. We took the dominant shrub species Caragana intermedia in the Inner Mongolia steppe desert area as the target plant and investigated the soil nematode communities composition and structure under C. intermedia shrub canopies and in open areas at different soil depths (0 − 10, 10 − 20, 30 − 40 cm) using the wet funnel method (Baermann method). The results showed that 1) The total number of soil nematodes in the top soil layer was higher under C. intermedia shrub canopies than in the open areas, but the species richness and Shannon-Wiener index were not significantly different between the canopy conditions (P > 0.05). The total number and Shannon-Wiener index of the soil nematodes decreased as the soil depth increased. 2) The number of bacterial-feeder and fungal-feeder nematodes in the top soil layer was higher under the shrub canopies than in open areas. Soil depth significantly affected the total number of bacterial-feeder, plant-parasitic, and omnivorous-predation nematodes, and their total numbers were highest at the soil surface and in the subsurface soil layer. 3) Shrubs had a significant effect on PPI/MI values (P < 0.05), which showed that the values were higher in open areas than under the shrub canopies. Soil depth had no significant effect on the PPI/MI values (P > 0.05). 4) As the soil depth increased, the community structure of the soil nematodes changed to the resident trophic groups (persister, cp3 – cp5) under the shrub canopies, and to the colonizer trophic groups (colonizer, cp1 or cp2) in open areas. The RDA analysis revealed that available P and available K are the primary environmental factors influencing soil nematode communities, and that nematodes communities belonging to different taxa and trophic groups respond to environmental conditions in different ways.
Effects of kudzu leaf meal on growth performance and the biochemical, antioxidant, and immune indexes for serum from broilers
GONG Jianping, LONG Wei, LYU Ya'ning, WU Dong, HUANG Yulin, CHEN Xiaolian
2021, 38(3): 590-597. doi: 10.11829/j.issn.1001-0629.2020-0420
[Abstract](2786) [FullText HTML] (516) [PDF 522KB](15)
Abstract:
A total of 384 21-day-old broilers with moderate body weights were randomly divided into four groups with six replicates per group and 16 birds per replicate. The broilers were fed a basal diet supplemented with 0 (control group), 1%, 2%, or 3% kudzu leaf meal. The experiment lasted 49 days. This study aimed to investigate the effects of kudzu leaf meal on growth performance, serum biochemical indexes, and the antioxidant and immune function of broilers. The results showed 1) The kudzu leaf meal had no significant effect on average daily gain, average daily feed intake, and the feed to gain ratio of broilers (P > 0.05); 2) Diets supplemented with 2% and 3% kudzu leaf meal significantly increased serum albumin and low density lipoprotein content, and showed reduced triglyceride content and glutamic transaminase activity (P < 0.05); the diet supplemented with 3% kudzu leaf meal significantly increased serum total protein and reduced the urea nitrogen, total cholesterol, high-density lipoprotein, and glutamine transaminase contents (P < 0.05); 3) Compared to the control group, the serum total antioxidant capacity and glutathione peroxidase activity of broilers in the kudzu leaf meal addition groups significantly increased and the malondialdehyde content of broilers in the 3% kudzu leaf meal group significantly decreased (P < 0.05). 4) Compared to the control group, the serum immunoglobulin M content of broilers in the 1% kudzu leaf meal group significantly increased, and the serum immunoglobulin M and Interleukin -1β contents significantly increased in the 2% kudzu leaf meal group. The serum immunoglobulin G and immunoglobulin M contents significantly increased, whereas the Interleukin -1β and Interleukin -2 contents decreased in the 3% kudzu leaf meal group (P < 0.05). In conclusion, diets supplemented with 1% to 3% kudzu leaf meal had no negative effects on growth performance, and increased the antioxidant and immune function and health of broilers to a certain extent. Kudzu leaf meal can be used in the diet of broilers and the addition of 3% kudzu leaf meal was the optimal dose.
The exploration and practice of R drawing guidance model for the promotion of programming teaching for the pratacultural science majors
LIU Wenxian
2021, 38(3): 598-604. doi: 10.11829/j.issn.1001-0629.2020-0006
[Abstract](4257) [FullText HTML] (1073) [PDF 4469KB](34)
Abstract:
Under the background of the biological big data era, it is of great practical significance to enhance the comprehensive quality and scientific research ability of students of pratacultural science majors to use programming language for big data processing and visual analysis. However, there are still many problems such as insufficient attention and poor teaching effect in the cultivation of the programming ability of non-computer majors in China. How to guide students to construct a programming knowledge system quickly is one of the main problems in the course reform of informatics in colleges and universities. The author based on years of experience in teaching and research practice, focus on the key problems, such as students' weak foundation in programming and learning interest, from the aspects of teaching guidance, learning content, teaching mode and in-depth learning mechanism, put forward a new programming teaching mode to help students of pratacultural science and other biology majors learning to program with R language-based drawing as guidance. Practice shows that this teaching model can effectively overcome students' fear of programming, stimulate students' potential and interest in programming learning, effectively improve the teaching quality and effect, and will lay a good foundation for students to independently study programming in the future.