Knowledge Resource Center for Ecological Environment in Arid Area
| Ecological resilience at semi-arid and temperate boundaries of the Mediterranean-type Fynbos Biome, South Africa, during the Holocene | |
| Macpherson;Allan J | |
| 出版年 | 2017 |
| 学位授予单位 | University of Cape Town, Faculty of Science, Department of Biological Sciences |
| 英文摘要 | Mediterranean-type ecosystems are amongst the most vulnerable to global change. Threats from desertification are projected due to rapid expansion of adjacent semiarid systems. Changes in fire frequency and intensity can alter ecosystem composition and structure, and potentially facilitate transitions between alternative stable states. Given the outstanding biodiversity of the Mediterranean-type fynbos biome in the Greater Cape Floristic Region (GCFR) of South Africa, understanding of the longterm impacts of global change are particularly important. In this study, palaeoecological data are used to assess the effects of changes in climate, fire and land use on vegetation at the semi-arid and temperate margins of the fynbos biome. Previous palaeoecological studies have shown stable fynbos during the recent geologic past, which restricts interpretation of the long-term ecological processes that determine biome resilience. This study sourced sediment cores directly from presentday fynbos-succulent karoo (semi-arid) and fynbos-afrotemperate forest biome boundaries to emphasise ecological dynamics. Fossil pollen, spores and charcoal were extracted from radiocarbon dated sediment cores to provide proxies for vegetation, hydrology, large herbivore abundance and fire. Constrained hierarchical clustering (CONISS), optimal sequence splitting by least-squares, and Non-metric Multidimensional Scaling (NMDS) was applied to the fossil data to identify distinct assemblages in the record, and to further elucidate ecosystem trajectories through time. At the semi-arid boundary at Groenkloof (5,500 cal yrs BP - near present), decreased moisture and fire from 4,000-735 cal yrs BP allowed colonisation of fynbos by a possible 'no-analogue' community dominated by Asteraceae and Poaceae. From 735 cal yrs BP however, climatic amelioration allowed fynbos to re-establish. The system can therefore be viewed as resilient through a capacity for 'recovery' and persistence through turnover in internal composition of fynbos taxa. This sensitive response to climatic forcing reflects the dominant influence of physiological stress at the semiarid limits of Mediterranean-type ecosystems, as well as a Gleasonian type community composition with loose species associations. In contrast, ecosystem |
| 英文关键词 | Palaeoecology |
| 语种 | 英语 |
| URL | http://hdl.handle.net/11427/25357 |
| 来源机构 | University of Cape Town |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/250878 |
| 推荐引用方式 GB/T 7714 | Macpherson;Allan J. Ecological resilience at semi-arid and temperate boundaries of the Mediterranean-type Fynbos Biome, South Africa, during the Holocene[D]. University of Cape Town, Faculty of Science, Department of Biological Sciences,2017. |
| 条目包含的文件 | 条目无相关文件。 | |||||
| 个性服务 |
| 推荐该条目 |
| 保存到收藏夹 |
| 导出为Endnote文件 |
| 谷歌学术 |
| 谷歌学术中相似的文章 |
| [Macpherson;Allan J]的文章 |
| 百度学术 |
| 百度学术中相似的文章 |
| [Macpherson;Allan J]的文章 |
| 必应学术 |
| 必应学术中相似的文章 |
| [Macpherson;Allan J]的文章 |
| 相关权益政策 |
| 暂无数据 |
| 收藏/分享 |
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。
