Pub Date : 2022-07-21DOI: 10.2989/10220119.2022.2073611
Nangamso Mlaza, S. Tefera, A. Hassen
In this study, we examined forage, soil and cattle serum mineral status, and their relationships in severely (SD) and less severely (LSD) degraded rangelands, South Africa. Such evidence is essential to inform rangeland policies and interventions. In each rangeland, three villages were identified, and sites near, at intermediate and far distance from homesteads were selected. Soil from LSD had generally greater macro and microelement levels than soil from SD rangelands. Soil elements (i.e. N, P, Mg and Cu) displayed variations at local scale (between villages or distance points from homestead) depending on degradation condition. Degradation level significantly influenced the local distribution of grasses between the distance points from the homestead (Themeda triandra Forssk., Aristida congesta Roem. & Schult.) and between villages [Digitaria eriantha Steud., Eragrostis curvula (Schrad.) Nees, T. triandra]. Forage biomass was low (range: 45–223 kg ha−1) in both degraded conditions. During the dry periods, cattle grazing SD rangelands had most serum minerals below a critical level, but pastures showed Cu and N deficiencies only. We conclude that the low forage yield may limit animal mineral intake. On the other hand, the great abundance of grasses with high forage values (60–76%) indicates that degraded areas may be regenerated. In SD rangelands, complete mineral supplementation is recommended during the dry period.
在这项研究中，我们研究了南非严重(SD)和轻度(LSD)退化牧场的牧草、土壤和牛血清矿物质状况及其相互关系。这些证据对于牧场政策和干预措施至关重要。在每个牧场中，确定三个村庄，并选择离牧场近、中、远的地点。与SD牧场相比，LSD牧场土壤的宏量元素和微量元素含量普遍较高。土壤元素(即N、P、Mg和Cu)在局部尺度上(村庄之间或与宅基地的距离点之间)根据退化情况表现出差异。退化程度显著影响了草地在离草地距离点之间的分布。阿里斯提达。)和村庄之间[Digitaria eriantha Steud]。，《曲形虫》(Schrad.)Nees, T. triandra]。在两种退化条件下，牧草生物量都很低(范围:45-223 kg ha - 1)。在干旱期，SD牧场放牧的牛血清矿物质含量大部分低于临界水平，而牧场只出现Cu和N缺乏。我们认为，低饲料产量可能限制了动物的矿物质摄入量。另一方面，高饲用价值禾草的丰度(60-76%)表明退化区可能得到更新。在SD牧场，建议在干旱期补充完全的矿物质。
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Pub Date : 2022-05-13DOI: 10.2989/10220119.2022.2066177
M. Stalmans
African Journal of Range & Forage Science is co-published by NISC (Pty) Ltd and Informa UK Limited (trading as Taylor & Francis Group) This publication is promoted by the publisher as part of a series exploring the cutting edge of science and technology – ‘these are books for popular science readers who like to go a little deeper’. Indeed, it is a very accessible, easy read that strikes an upbeat tone despite the parlous state of affairs that rewilding is attempting to address. Already coined in the mid-1990’s, the concept of ‘rewilding’ shot to prominence in 2005–2006. It popularly conjures up an image of charismatic megaherbivores or large carnivores being brought back in an area from which they have been lost. Or, in the words of the authors, ‘the creation of large wilderness complexes and supporting populations of top predators (notably wolves in Yellowstone National Park) and the creation of a Serengeti-like landscape through the re-assembly of a guild of large herbivores in The Netherlands’. These large animals are, however, more often a means to an end. The emphasis of ‘rewilding’ is on restoring lost interactions at the landscape scale (page 5). In the second chapter of the book, the authors go back to the Pleistocene era to understand the potential of rewilding and to make the argument for multiple biodiversity baselines. They describe a past that up until 30 000 to 10 000 years ago was characterised by an abundance of megafauna that co-evolved alongside grasses and shrubs. As megafauna disappeared from much of the Earth towards the end of the Holocene ca. 10 000 years ago, many terrestrial ecosystems transitioned from grassland to more woody habitats. Whereas livestock herding maintained simplified, yet biodiverse ecosystems, these went into decline as a result of intensive livestock farming, land abandonment and rural depopulation. The latter obviously applying more to the north with African savannas and their megafauna in the south remaining more intact. This means that overall, the world’s terrestrial ecosystems have moved to both extremes of the wood-pasture gradient: less productive and abandoned land has become more wooded whereas land with more productive soils has become intensively managed pasture or agricultural fields (page 12). Rewilding is in part about recovering these more open habitats and the ecological richness they produce. Key to the rewilding is getting those animals that disappeared back into the system. In Chapter 4, the practical origins of rewilding are described including the examples of the Oostvaardersplassen in The Netherlands where the emphasis was on the introduction of primitive breeds of horse and cattle, and that of Yellowstone in the United States where the emphasis was on the re-establishment of wolves. At its core, rewilding is ecological restoration. The differences between rewilding and the discipline of restoration ecology in terms of ethos and focus are discussed in Chapter 5. Rather than attempt
《非洲牧场与饲料科学杂志》由NISC (Pty)有限公司和Informa英国有限公司(以Taylor & Francis集团的名称进行交易)联合出版。该出版物由出版商作为探索科学和技术前沿系列的一部分进行推广——“这些书是为喜欢深入研究的科普读者准备的”。的确，这是一本非常通俗易懂的书，尽管野生化正试图解决危险的事态，但它却带有一种乐观的基调。“野化”这个概念早在上世纪90年代中期就已经出现，在2005年至2006年期间开始崭露头角。它通常会让人联想到一幅有魅力的巨型食草动物或大型食肉动物被带回它们失去的地方的画面。或者，用作者的话来说，“创造了大型荒野综合体和支持顶级食肉动物的种群(特别是黄石国家公园的狼)，并通过荷兰大型食草动物公会的重新组装创造了塞伦盖蒂般的景观。”然而，这些大型动物更多的是达到目的的手段。“重新野生化”的重点是在景观尺度上恢复失去的相互作用(第5页)。在书的第二章中，作者回到更新世时代，以了解重新野生化的潜力，并提出了多种生物多样性基线的论点。他们描述了一个直到3万到1万年前的过去，其特征是大量的巨型动物与草和灌木共同进化。随着巨型动物在大约1万年前全新世末期从地球的大部分地区消失，许多陆地生态系统从草原过渡到更多的木本栖息地。虽然畜牧业维持了简化但生物多样性的生态系统，但由于集约化畜牧业、土地遗弃和农村人口减少，这些生态系统正在衰退。后者显然更多地应用于北方，非洲稀树草原和南方的巨型动物则更完整。这意味着，总体而言，世界陆地生态系统已经走向了木牧场梯度的两个极端:生产力较低和被遗弃的土地变得树木繁茂，而土壤生产力较高的土地变成了集约化管理的牧场或农田(第12页)。野化在一定程度上是为了恢复这些更开放的栖息地和它们产生的生态丰富性。野化的关键是让那些消失的动物回归生态系统。在第四章中，描述了野生化的实际起源，包括荷兰的Oostvaardersplassen的例子，重点是引入原始品种的马和牛，以及美国黄石公园的例子，重点是重新建立狼。野化的核心是生态恢复。第五章讨论了野化与恢复生态学在精神和重点方面的差异。野生化的重点是恢复群落和生物及其物理环境之间的相互作用网络，而不是试图将时钟拨回到任意的过去基线。这一章描述了“恐惧的景观”。虽然这总是回到黄石公园的教科书例子，但最近在莫桑比克的戈龙戈萨国家公园(Gorongosa National Park)描述了这一概念，该公园在旷日持久的内战期间遭受了食草动物和食肉动物数量的大幅下降，目前正在进行修复。随着公园里的豹子和非洲野狗的灭绝，生活在森林里的灌木(Tragelaphus sylvaticus)扩展到没有树木的洪泛平原，在那里它们吃新的食物，抑制了一种常见的食物植物(水草，Bergia mossambicensis)。通过实验模拟捕食风险，证明了这种行为是可逆的。因此，尽管人为的捕食者灭绝通过使猎物行为快速分化而破坏了营养级联，但食肉动物的恢复可能同样迅速地重建这一级联(Atkins et al. 2019)。同样，戈龙戈萨河漫滩上正在恢复的食草动物种群开始自上而下地控制一种入侵的外来植物——含水草。1972年至2015年间，含羞草的数量有所增加，这一时期大型食草动物几乎灭绝。从2015年到2019年，含羞草丰度随着有蹄类生物量的恢复而下降。DNA元条形码显示，反刍食草动物以含水草为食，实验证实了哺乳动物的食草性在抑制灌木入侵中的因果作用。这些结果提供了机制证据，表明营养性野化已经迅速恢复了生物对臭名昭著的木质入侵者的抵抗力(Guyton et al. 2020)。在第七章中，伦理和政治的重新回归占据了中心位置。事实上，野生化这个话题在环保界引发了激烈的争论。这一点没有比《书评》更明显的了
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Pub Date : 2022-05-13DOI: 10.2989/10220119.2022.2059702
J. Compton
That humans originated in Africa is well-known. However, this is widely regarded as a chance outcome, dependent simply on where our common ancestor shared the land with where the great apes lived. This volume builds on from the ‘Out of Africa’ theory, and takes the view that it is only in Africa that the evolutionary transitions from a forest-inhabiting frugivore to savanna-dwelling meat-eater could have occurred. This book argues that the ecological circumstances that shaped these transitions are exclusive to Africa. It describes distinctive features of the ecology of Africa, with emphasis on savanna grasslands, and relates them to the evolutionary transitions linking early ape-men to modern humans. It shows how physical features of the continent, especially those derived from plate tectonics, set the foundations. This volume adequately conveys that we are here because of the distinctive features of the ecology of Africa.
{"title":"Only in Africa: The Ecology of Human Evolution","authors":"J. Compton","doi":"10.2989/10220119.2022.2059702","DOIUrl":"https://doi.org/10.2989/10220119.2022.2059702","url":null,"abstract":"That humans originated in Africa is well-known. However, this is widely regarded as a chance outcome, dependent simply on where our common ancestor shared the land with where the great apes lived. This volume builds on from the ‘Out of Africa’ theory, and takes the view that it is only in Africa that the evolutionary transitions from a forest-inhabiting frugivore to savanna-dwelling meat-eater could have occurred. This book argues that the ecological circumstances that shaped these transitions are exclusive to Africa. It describes distinctive features of the ecology of Africa, with emphasis on savanna grasslands, and relates them to the evolutionary transitions linking early ape-men to modern humans. It shows how physical features of the continent, especially those derived from plate tectonics, set the foundations. This volume adequately conveys that we are here because of the distinctive features of the ecology of Africa.","PeriodicalId":50841,"journal":{"name":"African Journal of Range & Forage Science","volume":"28 1","pages":"351 - 352"},"PeriodicalIF":1.4,"publicationDate":"2022-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91198334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-13DOI: 10.2989/10220119.2022.2070278
D. McGranahan
{"title":"The Pyrocene: How We Created an Age of Fire, and What Happens Next","authors":"D. McGranahan","doi":"10.2989/10220119.2022.2070278","DOIUrl":"https://doi.org/10.2989/10220119.2022.2070278","url":null,"abstract":"","PeriodicalId":50841,"journal":{"name":"African Journal of Range & Forage Science","volume":"22 1","pages":"240 - 241"},"PeriodicalIF":1.4,"publicationDate":"2022-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84591931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-10DOI: 10.2989/10220119.2022.2048418
Abuye Tulu, Mekonnen Diribsa, W. Temesgen
A 3 × 2 factorial study was conducted in 2015, 2016 and 2017, to assess the impact of dry season cutting management on fodder yield and quality of Napier grass. Three harvesting times (November, January and March) and two stubble- cutting heights (20 and 30 cm) were used in the study. The results revealed that the dry matter (DM) yield and leaf:stem ratio records in 2015 and 2016 were much higher than in 2017. Tilling performance was lower in 2017 than in 2015 and 2016. The highest DM yields were recorded during harvesting time in March. In the November harvest, however, the leaf:stem ratio was greater. In addition, tilling performance was better in March and November than it was in January. Overall, cutting at a height of 30 cm resulted in better DM yield and tiller numbers than cutting at a height of 20 cm. Experimental years and cutting height did not affect crude protein (CP), neutral detergent fibre (NDF) or acid detergent fibre (ADF). Harvesting times did, however, affect CP, NDF and ADF. As CP was greater in November than in March and both NDF and ADF levels were higher in March, cutting in November at 30 cm is advised.
{"title":"Forage yield and quality response of Napier grass (Cenchrus purpureus) to different dry season harvesting management under the subhumid agroecology of western Ethiopia","authors":"Abuye Tulu, Mekonnen Diribsa, W. Temesgen","doi":"10.2989/10220119.2022.2048418","DOIUrl":"https://doi.org/10.2989/10220119.2022.2048418","url":null,"abstract":"A 3 × 2 factorial study was conducted in 2015, 2016 and 2017, to assess the impact of dry season cutting management on fodder yield and quality of Napier grass. Three harvesting times (November, January and March) and two stubble- cutting heights (20 and 30 cm) were used in the study. The results revealed that the dry matter (DM) yield and leaf:stem ratio records in 2015 and 2016 were much higher than in 2017. Tilling performance was lower in 2017 than in 2015 and 2016. The highest DM yields were recorded during harvesting time in March. In the November harvest, however, the leaf:stem ratio was greater. In addition, tilling performance was better in March and November than it was in January. Overall, cutting at a height of 30 cm resulted in better DM yield and tiller numbers than cutting at a height of 20 cm. Experimental years and cutting height did not affect crude protein (CP), neutral detergent fibre (NDF) or acid detergent fibre (ADF). Harvesting times did, however, affect CP, NDF and ADF. As CP was greater in November than in March and both NDF and ADF levels were higher in March, cutting in November at 30 cm is advised.","PeriodicalId":50841,"journal":{"name":"African Journal of Range & Forage Science","volume":"11 1","pages":"236 - 239"},"PeriodicalIF":1.4,"publicationDate":"2022-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79275242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-25DOI: 10.2989/10220119.2022.2052962
A Marquart, OB Sikwane, K Kellner
Evidently, bush encroachment caused by factors, such as overgrazing, results in a change in savanna ecosystems. This shift in vegetation structure can affect many factors, including insect fauna. E...
{"title":"The diversity of epigeal insects after the application of the brush packing restoration method following bush-encroachment control in South Africa","authors":"A Marquart, OB Sikwane, K Kellner","doi":"10.2989/10220119.2022.2052962","DOIUrl":"https://doi.org/10.2989/10220119.2022.2052962","url":null,"abstract":"Evidently, bush encroachment caused by factors, such as overgrazing, results in a change in savanna ecosystems. This shift in vegetation structure can affect many factors, including insect fauna. E...","PeriodicalId":50841,"journal":{"name":"African Journal of Range & Forage Science","volume":"38 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2022-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138513580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-27DOI: 10.2989/10220119.2022.2033834
Talita Roberta Firemand de Lira Menor, M. V. F. Santos, J. J. Coêlho, G. D. Gonçalves, A. Mello, M. V. Cunha, A. Santos, Ivany Ferraz, J. D. Júnior
This study evaluated the bromatological and histological features of native African grasses under grazing in Brazilian semi-arid rangelands. An experimental grid design was used in a randomised sampling method for four replicate samples of three African grasses. The grasses evaluated were: Cenchrus ciliaris L., Digitaria pentzii Stent. and Megathyrsus maximus (Jacq.). The bromatological and histological traits analysed included dry matter (DM), crude protein (CP), neutral detergent fibre corrected to ashes and protein (NDFap), lignin, mesophyll, vascular bundle, phloem, xylem, vascular sheath, sclerenchyma, bulliform cells, and the adaxial and abaxial epidermis. The type of grass and grazing cycle correlated with DM, NDF and lignin (p < 0.05), whereas CP was not affected by these factors (p > 0.05). Dry matter ranged between 128 and 304 g kg−1; CP ranged between 90 and 167 g kg−1; NDFap between 542 and 707 g kg−1, and lignin between 10 and 40 g kg−1. The proportion of xylem (8.4%), vascular sheath (30.5%) and total vascular bundles (38.1%) were greater in M. maximus (p < 0.05). The percentage of sclerenchyma did not differ between species (p > 0.05). Digitaria pentzii and C. ciliaris had a greater proportion of mesophyll than M. maximus (p < 0.05). Of the three grasses analysed. Digitaria pentzii exhibited the highest forage quality, because it had the lowest concentration of fibre and lignin, with lower proportions of lignified tissues.
本研究评价了在巴西半干旱草原放牧条件下非洲原生禾本科植物的色谱和组织学特征。实验网格设计用于随机抽样方法，对三种非洲草的四个重复样本进行了研究。评价的禾草有:毛蕊草、五角马。和巨蟒(Jacq.)。对其干物质(DM)、粗蛋白质(CP)、中性洗涤纤维(NDFap)、木质素、叶肉、维管束、韧皮部、木质部、维管鞘、厚壁组织、球状细胞、近、背面表皮等性状进行了分析。牧草类型和放牧周期与DM、NDF和木质素相关(p < 0.05)，而CP不受这些因素的影响(p > 0.05)。干物质在128 ~ 304 g kg - 1之间;CP范围在90 ~ 167 g kg - 1之间;NDFap在542 ~ 707 g kg - 1之间，木质素在10 ~ 40 g kg - 1之间。木质部比例(8.4%)、维管鞘比例(30.5%)和总维管束比例(38.1%)均高于粗木质部(p < 0.05)。不同种属间厚壁组织百分率无显著差异(p > 0.05)。五子黄和毛缕黄牛的叶肉比例高于大黄(p < 0.05)。三种草的分析。五子柳的纤维和木质素含量最低，木质化组织比例较低，饲草质量最高。
{"title":"Bromatological and histological features of native African grasses under grazing in Brazilian semi-arid rangelands","authors":"Talita Roberta Firemand de Lira Menor, M. V. F. Santos, J. J. Coêlho, G. D. Gonçalves, A. Mello, M. V. Cunha, A. Santos, Ivany Ferraz, J. D. Júnior","doi":"10.2989/10220119.2022.2033834","DOIUrl":"https://doi.org/10.2989/10220119.2022.2033834","url":null,"abstract":"This study evaluated the bromatological and histological features of native African grasses under grazing in Brazilian semi-arid rangelands. An experimental grid design was used in a randomised sampling method for four replicate samples of three African grasses. The grasses evaluated were: Cenchrus ciliaris L., Digitaria pentzii Stent. and Megathyrsus maximus (Jacq.). The bromatological and histological traits analysed included dry matter (DM), crude protein (CP), neutral detergent fibre corrected to ashes and protein (NDFap), lignin, mesophyll, vascular bundle, phloem, xylem, vascular sheath, sclerenchyma, bulliform cells, and the adaxial and abaxial epidermis. The type of grass and grazing cycle correlated with DM, NDF and lignin (p < 0.05), whereas CP was not affected by these factors (p > 0.05). Dry matter ranged between 128 and 304 g kg−1; CP ranged between 90 and 167 g kg−1; NDFap between 542 and 707 g kg−1, and lignin between 10 and 40 g kg−1. The proportion of xylem (8.4%), vascular sheath (30.5%) and total vascular bundles (38.1%) were greater in M. maximus (p < 0.05). The percentage of sclerenchyma did not differ between species (p > 0.05). Digitaria pentzii and C. ciliaris had a greater proportion of mesophyll than M. maximus (p < 0.05). Of the three grasses analysed. Digitaria pentzii exhibited the highest forage quality, because it had the lowest concentration of fibre and lignin, with lower proportions of lignified tissues.","PeriodicalId":50841,"journal":{"name":"African Journal of Range & Forage Science","volume":"6 1","pages":"231 - 235"},"PeriodicalIF":1.4,"publicationDate":"2022-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75103756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-22DOI: 10.2989/10220119.2022.2033323
Shobie Arnoldi
{"title":"50 Grasses of the Limpopo Valley - Visual identification guide","authors":"Shobie Arnoldi","doi":"10.2989/10220119.2022.2033323","DOIUrl":"https://doi.org/10.2989/10220119.2022.2033323","url":null,"abstract":"","PeriodicalId":50841,"journal":{"name":"African Journal of Range & Forage Science","volume":"83 1","pages":"301 - 301"},"PeriodicalIF":1.4,"publicationDate":"2022-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83254422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-22DOI: 10.2989/10220119.2021.2014964
Naledi Zama, A. Magadlela, N. Mkhize, M. Tedder, K. Kirkman
Nutrient enrichment influences grassland ecosystem structure, typically manifested by reduced species richness and increased productivity. Quantifying the long-term impacts of nutrient enrichment on grasslands contributes to understanding eutrophication effects on grassland, particularly for grasslands adapted to low soil nutrient status. Overextended time periods, nutrient enrichment may modify soil fertility. The Ukulinga Grassland Nutrient Experiment situated on a natural C4 grassland was set up in 1951 on the Ukulinga research farm, South Africa. Continuously applied treatments on plots measuring 2.7 × 9 m include combinations of nitrogen at 0, 7, 14 and 21 g m−2 per annum, phosphorus at 0 and 2.8 g m−2 per annum and lime at 0 and 225 g m−2 applied every five years. Nitrogen sources included ammonium sulphate (acidifying) and limestone ammonium nitrate (less acidifying). Grass species composition was influenced by both nitrogen forms. In contrast, forb species composition was more sensitive to LAN. We found evidence of nitrogen limitation on aboveground net-primary production. However, species richness (for grass and forbs) declined with increasing ammonium sulphate levels, owing to increased soil acidity and high aluminium concentrations. Aluminium toxicity can affect overall species composition by replacing Al-sensitive species with Al-tolerant species on site.
养分富集影响草地生态系统结构，典型表现为物种丰富度降低，生产力提高。量化养分富集对草地的长期影响有助于了解草地的富营养化效应，特别是对适应低土壤养分状况的草地。时间过长，养分的富集可能改变土壤肥力。1951年，南非乌库林加研究农场在天然C4草地上建立了乌库林加草地营养试验。在面积为2.7 × 9 m的地块上，连续施用的处理包括每年0、7、14和21 g m−2的氮肥，每年0和2.8 g m−2的磷，以及每五年施用0和225 g m−2的石灰。氮源包括硫酸铵(酸化)和石灰石硝酸铵(酸化程度较低)。禾草物种组成受两种氮素形态的影响。相比之下，牧草种类组成对LAN更为敏感。我们发现了氮素限制地上净初级产量的证据。然而，由于土壤酸度增加和铝浓度高，物种丰富度(牧草和牧草)随着硫酸铵水平的增加而下降。铝毒性可以通过在现场用耐铝物种取代铝敏感物种来影响整个物种的组成。
{"title":"Assessing long-term nutrient and lime enrichment effects on a subtropical South African grassland","authors":"Naledi Zama, A. Magadlela, N. Mkhize, M. Tedder, K. Kirkman","doi":"10.2989/10220119.2021.2014964","DOIUrl":"https://doi.org/10.2989/10220119.2021.2014964","url":null,"abstract":"Nutrient enrichment influences grassland ecosystem structure, typically manifested by reduced species richness and increased productivity. Quantifying the long-term impacts of nutrient enrichment on grasslands contributes to understanding eutrophication effects on grassland, particularly for grasslands adapted to low soil nutrient status. Overextended time periods, nutrient enrichment may modify soil fertility. The Ukulinga Grassland Nutrient Experiment situated on a natural C4 grassland was set up in 1951 on the Ukulinga research farm, South Africa. Continuously applied treatments on plots measuring 2.7 × 9 m include combinations of nitrogen at 0, 7, 14 and 21 g m−2 per annum, phosphorus at 0 and 2.8 g m−2 per annum and lime at 0 and 225 g m−2 applied every five years. Nitrogen sources included ammonium sulphate (acidifying) and limestone ammonium nitrate (less acidifying). Grass species composition was influenced by both nitrogen forms. In contrast, forb species composition was more sensitive to LAN. We found evidence of nitrogen limitation on aboveground net-primary production. However, species richness (for grass and forbs) declined with increasing ammonium sulphate levels, owing to increased soil acidity and high aluminium concentrations. Aluminium toxicity can affect overall species composition by replacing Al-sensitive species with Al-tolerant species on site.","PeriodicalId":50841,"journal":{"name":"African Journal of Range & Forage Science","volume":"104 1","pages":"206 - 218"},"PeriodicalIF":1.4,"publicationDate":"2022-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80576527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-17DOI: 10.2989/10220119.2021.2016967
Marcondes de Sá Souza, G. D. N. A. Júnior, L. S. B. de Souza, Alexandre Maniçoba da Rosa Ferraz Jardim, Gabriel Italo Novaes da Silva, G. D. de Araújo, F. Campos, M. L. D. M. V. Leite, J. N. Tabosa, T. G. F. Silva
This study aimed to quantify forage yield, economic performance, biological efficiency and competitive ability in cactus intercropped with millet, compared with their monocrops, both with and without mulch, under irrigation. The experiment was conducted over two years in semi-arid of Brazil. The experimental design was of randomised blocks with four replications and six treatments: monocropped cactus without mulch; monocropped cactus with mulch; monocropped millet without mulch; monocropped millet with mulch and cactus intercropped with millet, with and without mulch. The individual yields of fresh (270 t ha−1) and dry (23 t ha−1) matter in the cactus were not affected by the mulch or by intercropping. Mulching improved the individual yields of fresh (69.7 t ha−1) and dry (23.4 t ha−1) matter in the monocropped millet. Total dry matter was greater in the intercropping systems, both with (32.8 t ha−1) and without (31.4 t ha−1) mulching, being the average monetary advantage index equal to 8 404 BRL ha−1. The cactus-millet configuration, irrespective of the use of mulch, but irrigated in dry environments or during dry periods of the year, is more advantageous than the monocrops, because it promotes gains in production and food diversity for meeting the demand of the herd.
本研究旨在量化灌溉条件下仙人掌间作谷子与单作相比的饲料产量、经济效益、生物效率和竞争能力。该实验在巴西半干旱地区进行了两年多。试验设计为随机分组，有4个重复和6个处理:不加地膜的单一作物仙人掌;有覆盖物的单作仙人掌;无地膜的单作谷子;有地膜的单作谷子和间作谷子的仙人掌，不论有无地膜。覆盖和间作对仙人掌鲜物质(270 t ha−1)和干物质(23 t ha−1)单产没有影响。覆盖提高了单作谷子的鲜物质单产(69.7 t ha - 1)和干物质单产(23.4 t ha - 1)。间作系统的干物质总量大于间作系统，覆盖(32.8 t ha - 1)和未覆盖(31.4 t ha - 1)，平均经济效益指数为8404 BRL ha - 1。仙人掌-谷子的结构，不管使用地膜，但在干旱环境或一年中的干旱时期进行灌溉，比单一作物更有利，因为它促进了产量的增加和食物的多样性，以满足牛群的需求。
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