{"title":"南非半干旱稀树草原木本植物清除梯度沿线的土壤种子库：对恢复的影响","authors":"Mthunzi Mndela , Mziwanda Mangwane , Nothando Ngcobo , Nchaupa Johannes Rasekgokga , Piet Monegi","doi":"10.1016/j.actao.2023.103891","DOIUrl":null,"url":null,"abstract":"<div><p>Woody plant encroachment threatens ecosystem services and functions, thereby reducing herbaceous plant population persistence and community stability. Consequently, woody plant control projects are implemented in South Africa to restore herbaceous vegetation. Because persistent seeds drive passive restoration and vegetation trajectories, management following woody plant control entails examining soil seed bank (SSB) size and composition. However, a knowledge gap exists regarding how SSB characteristics respond along a woody plant removal gradient. This study was conducted at Roodeplaat in Gauteng Province of South Africa to assess the impact of woody density reduction [hereafter woody plant removal intensity (WPRI)] on SSB density, composition, diversity and richness. Woody plant vegetation composed of a mixture of species, mainly <em>Vachellia robusta</em>, <em>Ziziphus mucronata</em>, <em>Euclea</em> species and <em>Pappea capensis</em>. Selective tree removal was applied to downscale woody density (4065 ± 109 plants ha<sup>−1</sup>) of the control (0% WPRI) to 10, 20, 50, 75 and 100% WPRIs in four blocks, resulting in four replicates per WPRI. A total of 120 soil samples (<em>n</em> = 20 per WPRI) were collected at 5 cm depth after 3 years of tree removal. Germination method was used to assess the SSB. Fifty-one species, mainly forbs (<em>n</em> = 26) and grasses (<em>n</em> = 16) were recorded from 32 237 seeds. The SSB densities of grasses increased from 649 to 6000 seeds m<sup>−2</sup> from 0 to 100% WPRI whilst sedges and forbs exhibited differential declining trends along WPRI gradient. <em>Cyperus rotundus</em> accounted for more than one-third of the SSB densities at 0 and 10% WPRIs, whereas <em>Panicum maximum</em> contributed nearly half (46%) to the SSB density at 100% WPRI. Woody plant removal increased SSB diversity (H<em>′</em>) and richness, but diversity peaked at 20% WPRI (H<em>'</em> = 1.78); thereafter it declined. Overall, our results signified that complete woody plant clearing has a potential for restoration of woody-encroached rangelands through increasing SSB size and species richness.</p></div>","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":null,"pages":null},"PeriodicalIF":16.4000,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":"{\"title\":\"Soil seed banks along a woody plant removal gradient in a semi-arid savanna of South Africa: Implications for restoration\",\"authors\":\"Mthunzi Mndela , Mziwanda Mangwane , Nothando Ngcobo , Nchaupa Johannes Rasekgokga , Piet Monegi\",\"doi\":\"10.1016/j.actao.2023.103891\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Woody plant encroachment threatens ecosystem services and functions, thereby reducing herbaceous plant population persistence and community stability. Consequently, woody plant control projects are implemented in South Africa to restore herbaceous vegetation. Because persistent seeds drive passive restoration and vegetation trajectories, management following woody plant control entails examining soil seed bank (SSB) size and composition. However, a knowledge gap exists regarding how SSB characteristics respond along a woody plant removal gradient. This study was conducted at Roodeplaat in Gauteng Province of South Africa to assess the impact of woody density reduction [hereafter woody plant removal intensity (WPRI)] on SSB density, composition, diversity and richness. Woody plant vegetation composed of a mixture of species, mainly <em>Vachellia robusta</em>, <em>Ziziphus mucronata</em>, <em>Euclea</em> species and <em>Pappea capensis</em>. Selective tree removal was applied to downscale woody density (4065 ± 109 plants ha<sup>−1</sup>) of the control (0% WPRI) to 10, 20, 50, 75 and 100% WPRIs in four blocks, resulting in four replicates per WPRI. A total of 120 soil samples (<em>n</em> = 20 per WPRI) were collected at 5 cm depth after 3 years of tree removal. Germination method was used to assess the SSB. Fifty-one species, mainly forbs (<em>n</em> = 26) and grasses (<em>n</em> = 16) were recorded from 32 237 seeds. The SSB densities of grasses increased from 649 to 6000 seeds m<sup>−2</sup> from 0 to 100% WPRI whilst sedges and forbs exhibited differential declining trends along WPRI gradient. <em>Cyperus rotundus</em> accounted for more than one-third of the SSB densities at 0 and 10% WPRIs, whereas <em>Panicum maximum</em> contributed nearly half (46%) to the SSB density at 100% WPRI. Woody plant removal increased SSB diversity (H<em>′</em>) and richness, but diversity peaked at 20% WPRI (H<em>'</em> = 1.78); thereafter it declined. Overall, our results signified that complete woody plant clearing has a potential for restoration of woody-encroached rangelands through increasing SSB size and species richness.</p></div>\",\"PeriodicalId\":1,\"journal\":{\"name\":\"Accounts of Chemical Research\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":16.4000,\"publicationDate\":\"2023-05-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"1\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Accounts of Chemical Research\",\"FirstCategoryId\":\"93\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S1146609X23000036\",\"RegionNum\":1,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Accounts of Chemical Research","FirstCategoryId":"93","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1146609X23000036","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
Soil seed banks along a woody plant removal gradient in a semi-arid savanna of South Africa: Implications for restoration
Woody plant encroachment threatens ecosystem services and functions, thereby reducing herbaceous plant population persistence and community stability. Consequently, woody plant control projects are implemented in South Africa to restore herbaceous vegetation. Because persistent seeds drive passive restoration and vegetation trajectories, management following woody plant control entails examining soil seed bank (SSB) size and composition. However, a knowledge gap exists regarding how SSB characteristics respond along a woody plant removal gradient. This study was conducted at Roodeplaat in Gauteng Province of South Africa to assess the impact of woody density reduction [hereafter woody plant removal intensity (WPRI)] on SSB density, composition, diversity and richness. Woody plant vegetation composed of a mixture of species, mainly Vachellia robusta, Ziziphus mucronata, Euclea species and Pappea capensis. Selective tree removal was applied to downscale woody density (4065 ± 109 plants ha−1) of the control (0% WPRI) to 10, 20, 50, 75 and 100% WPRIs in four blocks, resulting in four replicates per WPRI. A total of 120 soil samples (n = 20 per WPRI) were collected at 5 cm depth after 3 years of tree removal. Germination method was used to assess the SSB. Fifty-one species, mainly forbs (n = 26) and grasses (n = 16) were recorded from 32 237 seeds. The SSB densities of grasses increased from 649 to 6000 seeds m−2 from 0 to 100% WPRI whilst sedges and forbs exhibited differential declining trends along WPRI gradient. Cyperus rotundus accounted for more than one-third of the SSB densities at 0 and 10% WPRIs, whereas Panicum maximum contributed nearly half (46%) to the SSB density at 100% WPRI. Woody plant removal increased SSB diversity (H′) and richness, but diversity peaked at 20% WPRI (H' = 1.78); thereafter it declined. Overall, our results signified that complete woody plant clearing has a potential for restoration of woody-encroached rangelands through increasing SSB size and species richness.
期刊介绍：
Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance.
Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.
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