新形势下《草地学》课程教学模式改革

《草地学》是草学专业专门为动物科学等专业开设的一门综合性强的,理论和实践紧密联系而又侧重于应用的主要课程之一,是该专业的限选课。该课程融合了多门课程内容,知识点庞杂,集知识抽象性与实践性于一体,对其进行教学模式改革与探讨具有重要的意义。因此本文基于教学目标和学情分析,梳理传统教学模式存在的弊端,探讨多媒体教学和雨课堂混合式信息化教学模式,并对未来课程的发展建设提出建议,以期为全国同类课程的完善提供参考。

《草地学》课程教学改革研究现状与建议

《草地学》是涉农高等院校草业科学及动物科学等多个本科专业开设的一门综合性专业课程,其内容体系具有多学科交叉、知识面广、知识点繁杂、抽象难懂、实践性强等特点,因而其教学改革一直是该领域关注的焦点。本文针对《草地学》课程教学改革研究现状及其存在问题,从推进课程思政教育、优化知识体系结构、强化综合实践教育和健全质量考评机制四个角度提出了新形势下的改革建议,以提高其课程教学的智育和德育效果,最终培育出符合新时代要求的一流专业人才。

《草地保护学》课程教学改革与思考

《草地保护学》是草业科学专业的核心骨干课程之一,是一门应用性和实践性很强的综合性应用学科。在对该课程性质及教学现状深入研究后,本文对该课程的教学模式、教学手段、教学及考核方法都根据现有的实际情况进行了探索和改革,分析了该课程在开设过程中取得的主要成果及存在的主要问题以及下一步计划,在教学各环节中注意采用多种教学手段和方法,理论联系实际,因人施教,提高学生的学习动力和兴趣,教学效果好,达到了预期的教学目标,以期为全国同类课程的发展与完善提供借鉴与参考。

Analysis for Soil Characteristics of Degraded Grassland on Alpine Meadow

[Objective]The aim of this study is to explore the effects of grassland degradation on soil physical and chemical properties.[Method]The ratio of plant root to soil and soil texture on Alpine Meadow were investigated in this study,and soil available N,P,K,Cu,Zn,organic matter and pH value were also analyzed by routine analysis of soil nutrients in different degraded grasslands.[Result]With the intensification of degraded gradient and the soil depth,the ratio of plant root to soil was decreased gradually.The highest ratio of plant root to soil was in 0-10 cm depth of soil in grassland with different degraded gradients,while its ratio of plant root to soil changed from 0.001 to 0.040 with soil type of loam.Soil chemical characteristic changed in different degraded gradients.The content of available N,P,K reduced significantly with the soil depth and the intensification of degraded gradients.The content of Cu and Zn was relatively lack in degraded grassland.[Conclusion]There is no significant correlation between nutrition content or pH value and the succession degree of degraded grassland.

Biological Characteristics of Carex brunnescens for Sand Fixation in the Source Region of the Yellow River

Carex brunnescens, a pioneer plant that has an excellent ability to fix sand in the source region of the Yellow River （Maqu）, plays an important role in maintaining the ecosystem stability of alpine grassland in Maqu. In this study, the biological characteristics （phonological characters, the growth process of overground and underground organs, and the morphological characters of underground organs） of C. brunnescens were studied by a field observation experiment. The results showed that C. brunnescens had the characteristics of turning green earlier than other plants, a long growth period, and two flowering and fruiting cycles. The leaf width, length and number of a single plant, and the density, coverage and leaf density of community increased significantly from the leaf extension period to the fruit mature period and then tended to be stable in the withering period, while the plant height and leaf area of a single plant and the leaf area of community rose significantly at first and then decreased. Underground stems （horizontal and vertical stems） and roots of C. brunnescens could survive in sand at a depth of 0-60 cm. The number of middle roots （0.2-0.5 mm in diameter） was the largest in all soil layers （0-20, 20-40 and 40-60 cm）, and the total length of fine roots （〈0.2 mm） were the maximum in the sand at a depth of 20-40 cm, while the total length of middle roots was the maximum in the sand layer at a depth of 0-20 cm. The length, fresh weight and dry weight of the main root, horizontal and vertical stems was the maximum in the sand layer at a depth of 10-30 cm and was the minimum in the sand layer at a depth of 40-50 cm. It is concluded that C. brunnescens can well adapt to the alpine sand habitat of Maqu, can be used as the constructive species for ecological restoration in the alpine desertified grassland of Maqu, and has good popularization and application prospects.

Chemotaxonomy of Two Satureja L. （Lamiaceae） Species from Different Localities of Turkey

In this study, two Satureja L. species from different localities of Turkey （Satureja hortensis L. and Satureja boissieri Hausskn. ex Boiss.） have been studied to determine their taxonomic classification based on chemical characters. For this purpose, aerial parts of the studied taxa were investigated by HS-SPME/GC-MS. 28, 30 and 29 compounds were identified in S. boissieri from Sanhurfa, BingS1 and Malatya accounting from 90.80%, 91.31% and 92.67% of the whole oil, respectively. 26, 30 and 28 compounds were identified in S. hortensis from Adlyaman, Diyarbaklr, Elazl~ accounting from 93.20%, 92.85% and 92.42% of the whole oil, respectively, y-terpinene （30.4%, 26.5% and 32.1%）, carvacrol （26.4%, 25.2% and 23.3%） and p-cymene （10.5%, 13.2% and 10.4%） were determined as main compounds of S. boissieri in Sanhurfa, Bing6l and Malatya species, respectively. Carvacrol （25.0%, 34.1% and 32.1%）, thymol （28.2%, 20.2% and 28.1%） and y-terpinene （10.1%, 11.3% and 9.4%） were found as main constituents of S. hortensis in Adlyaman, Diyarbaklr and Elazl~ samples, respectively. The chemical distributions of the essential oil compounds in the Satureja pattern were discussed in respect to their chemotaxonomy and natural products.

The response of ecosystem carbon and nitrogen pools to experimental warming in grasslands: a meta-analysis

Carbon(C)and nitrogen(N)coupling processes in terrestrial ecosystems have the potential to modify the sensitivity of the global C cycle to climate change.But the degree to which C–N interactions contribute to the sequestration of terrestrial ecosystem C(C_(seq)),both now and in the future,remains uncertain.In this study,we used a meta-analysis to quantitatively synthesize C and N responses from feld experiments on grasslands subjected to simulated warming and assessed the relative importance of three properties(changes in ecosystem N amount,redistribution of N among soil,litter and vegetation,and modifcations in the C:N ratio)associated with grassland C_(seq) in response to warming.Warming increased soil,litter and vegetation C:N ratios and approximately 2%of N shifted from the soil to vegetation and litter.Warming-induced grassland C_(seq) was the result of the net balance between increases in vegetation and litter C(111.2 g·m^(−2))and decreases in soil C(30.0 g·m^(−2)).Warming-induced accumulation of C stocks in grassland ecosystems indicated that the three processes examined were the main contributors to C_(seq),with the changes in C:N ratios in soil,litter and vegetation as the major contributors,followed by N redistribution,whilst a decrease in total N had a negative effect on C_(seq).These results indicate that elevated temperatures have a signifcant infuence on grassland C and N stocks and their coupling processes,suggesting that ecological models need to include C–N interactions for more accurate predictions of future terrestrial C storage.

Response of Plant Community Carbon and Nitrogen Stoichiometry to Experimental Warming on the Qinghai-Tibet Plateau

Low temperature is an important limiting factor for alpine ecosystems on the Tibetan Plateau. This study is based on data from on-site experimental warming platforms(open top chambers, OTC) at three elevations(4300 m, 4500 m, 4700 m) on the Qinghai-Tibet Plateau. The carbon and nitrogen stoichiometry characteristics of plant communities, both above-ground and below-ground, were observed in three alpine meadow ecosystems in August and September of 2011 and August of 2012. Experimental warming significantly increased above-ground nitrogen content by 21.4% in September 2011 at 4500 m, and reduced above-ground carbon content by 3.9% in August 2012 at 4300 m. Experimental warming significantly increased below-ground carbon content by 5.5% in August 2011 at 4500 m, and the below-ground ratio of carbon to nitrogen by 28.0% in September 2011 at 4300 m, but reduced below-ground nitrogen content by 15.7% in September 2011 at 4700 m, below-ground carbon content by 34.3% in August 2012 at 4700 m, and the below-ground ratio of carbon to nitrogen by 37.9% in August 2012 at 4700 m. Experimental warming had no significant effect on the characteristics of community carbon and nitrogen stoichiometry under other conditions. Therefore, experimental warming had inconsistent effects on the carbon and nitrogen stoichiometry of plant communities at different elevations and during different months. Soil ammonium nitrogen and nitrate nitrogen content were the main factors affecting plant community carbon and nitrogen stoichiometry.

Geochemical characteristics and tectonic setting of the Middle Permian Tiaohu Formation mafic-ultramafic rocks of Santanghu area, Xinjiang, Northwest China

Santanghu area in northeastern Xinjiang region of Northwest China is an important component of the Central Asian Orogenic Belt(CAOB), in which the dynamic mechanism of Permian magmatism is controversial. In Santanghu area is exposed a thick succession of the Middle Permian basalts, including a small amount of picritic basalts and andesites, known as the Tiaohu Formation. The picritic basalts contain cumulate olivine, and have whole-rock Mg# up to 0.68–0.77; the basalts exhibit porphyritic or doleritic textures, and have relatively low Mg# of 0.41–0.54, typical of evolved magmas. The mafic-ultramafic rocks of the Tiaohu Formation are slightly enriched in Light Rare Earth Elements(LREEs), and exhibit negative Nb and Ti anomalies. They also have high Ti O2 content, and Nb/Y and Zr/Yb ratios greater than those of island arc volcanic rocks. Relatively low initial Sr isotopic ratios and high positive εNd(t) and εHf(t) values argue against contamination by ancient continental crust, and suggest formation of the Tiaohu Formation by partial melting of relatively refractory depleted lithospheric mantle that underwent metasomatism and extraction by fluid from the subducted slab. In addition, up to 38% olivine in picritic basalts indicates high-degree partial melting of lithospheric mantle, and the underlying Lucaogou Formation contains fragments of ultra-alkaline magmatic rocks that originated in the deep mantle. These observations imply wide-spread underplating in Santanghu area, which may have been associated with a mantle plume.