Exotic Plant Invasion Of Upland Plant Communities In Hong Kong China

This dissertation, "Exotic Plant Invasion of Upland Plant Communities in Hong Kong, China" by Pui-chi, Leung, 梁佩芝, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled EXOTIC PLANT INVASION OF UPLAND PLANT COMMUNITIES IN HONG KONG, CHINA Submitted by Leung Pui Chi For the degree of Master of Philosophy at The University of Hong Kong in October 2005 Plant communities in the continental tropics appear to have suffered less from exotic plant invasions than their oceanic island counterparts. Most attention has focused on near-pristine plant communities, while modern Hong Kong can provide a 'worst-case' test to examine the invasibility of a highly degraded tropical continental landscape. Exotic plant species in Hong Kong are most prominent in disturbed lowland habitats, while research on exotic plant species in upland plant communities is lacking. The major aim of this study was to investigate the general pattern and extent of exotic plant invasions in the plant communities of upland Hong Kong. Plant communities were surveyed in habitats exposed to different degrees of disturbance on Hong Kong's highest hill, Tai Mo Shan. Exotic plant species were most prominent along the roadside, with species richness but not percentage cover declining significantly with altitude. A small subset of the roadside exotics and a few additional species were found along a stream crossing the surveyed road. Invasion along streams was largely confined to exposed areas, while cattle disturbance might have facilitated invasion of shade-tolerant species in the shaded upstream areas. Most of the invaders were rare. A smaller subset of the roadside exotics was able to invade upland plant communities away from roads and streams, but only in unshaded areas recently disturbed by feral cattle. Seeds of exotic plants were found in cattle dung and two species germinated from dung in the study site, suggesting that feral cattle may act as dispersal agents. Eight of the nine hill streams surveyed in various parts of Hong Kong were invaded by exotic plant species. Invasions were largely confined to unshaded areas, but the bat-dispersed tropical Asian tree, Syzygium jambos, was found to invadeshaded streams without additional disturbance. Several commonly planted ornamental species invading the surveyed streams had roadside seed sources nearby. Surveys of both cattle-grazed and cattle-free open uplands away from roads and streams showed that exotic plant invasions were only found in the presence of feral cattle, and all were confined to unshaded and recently disturbed areas. No exotic plant species were found in closed vegetation or in open areas without cattle. The results suggest that the highly degraded tropical continental landscape of Hong Kong is resistant to invasions by exotic plants, which are still largely confined to chronically disturbed habitats. Feral cattle promote invasions where people are absent, but this problem still seems to be reversible. Only S. jambos appears to invade streams without human aid. Future control measures for invasive plants should focus on the control of feral cattle populations, eradication of existing invasions, and screening ornamental plants for potentially invasive species before planting in or near protected areas. DOI: 10.5353/th_b3663244 Subjects: Exotic plants - China - Hong Kong Invasive plants - China - Hong Kong

An updated edition of the only book dedicated to the terrestrial ecology of the East Asian tropics, authored by a world-renowned tropical ecologist

Invasive species have inspired concern for many reasons, including economic and environmental impacts in specific jurisdictions within particular countries. However, it is apparent that for some invasive plant species, political borders offer only weak barriers because these species have succeeded in invading many countries, emerging as threats at a global level. With this level of threat, a number of books on invasive plants and invasive species in general have been published in recent years, but none explicitly provides “global” coverage, perhaps because it is only recently that the full geographical, economic and environmental implications of widespread spread and adaptive nature of these particular invasive plants have been recognized. We plan to make this volume unique by profiling plant invasions in explicitly geographical contexts; on the world continents (Chapters 5-11), as well as islands (Chapter 12) and mountains (Chapter 13). This global approach is supported by an overview of invasion biology and recent advances (Chapter 1) and how different communities differ in invasibility (Chapter 2). Global factors influencing invasion are introduced in Chapter 3 (globalized trade) and Chapter 4 (climate change). Key species are profiled through geographic treatments, continent by continent (Chapters 5-11), and for islands (Chapter 12) and mountains (Chapter 13). The impact of invasive plants is highlighted in Chapter 14, both in biotic and economic terms, partly to counter the tendency for the young field of invasion biology to rely too much on anecdotal evidence. This chapters is also designed to bring home the message that these are serious problems that must be dealt with, as covered in the subsequent chapters. The book concludes with three chapters casting light on solutions to the many problems described in the rest of the volume. Chapter 15 features new, innovative technologies that are being developed to monitor and manage invasive plants, and Chapter 16 presents comprehensive strategies for public education and implementation of management on local and global scales. Chapter 17 describes different future scenarios depending on current trends in plant invasion and its management, just as climate change predictions employ various scenarios to project the future. The future is very much up to us, as humanity grapples with the question of how best to strategically meet the problems of global invasive plant problems that we ourselves have created that is further challenged by a changing climate. We are confident that this book will be of interest to invasion biologists, resource managers, and the legion of others who must deal with these invasive plants across the globe on a daily basis.

Tropical East Asia is home to over one billion people and faces massive human impacts from its rising population and rapid economic growth. It has already lost more than half of its forest cover to agriculture and urbanization, and has the highest rates of deforestation and logging in the tropics. Habitat loss, coupled with hunting and the relentless trade in wildlife products, threatens all its large and many of its smaller vertebrates. Despite these problems, the region still supports an estimated 15-25% of global terrestrial biodiversity and a growing environmental awareness means that it is no longer assumed that economic development justifies environmental damage, and no longer accepted that this trade-off is inevitable. Effective conservation action now depends on integrating a clear understanding of the ecological patterns and processes in the region with the varied needs of its human population. This third edition continues to provide an overview of the terrestrial ecology of Tropical East Asia: from southern China to Indonesia, and from Bhutan and Bangladesh to the Ryukyu Islands of Japan. It retains the balance between compactness and comprehensiveness of the previous editions, and the even-handed geographical treatment of the whole region, but it updates both the contents and the perspective. Approximately one third of the text is new or greatly modified, reflecting the explosion of new research in the region in the last few years and the increasing use of new tools, particularly from genomics and remote sensing. The change in perspective largely reflects the growing realization that we are in a new epoch, the Anthropocene, in which human activities have at least as large an influence as natural processes, and that stopping or reversing ecological change is no longer an option. This does not mean that biodiversity conservation is no longer possible or worthwhile, but that the biodiverse future we strive for will inevitably be very different from the past. The Ecology of Tropical East Asia is an advanced textbook suitable for senior undergraduate and graduate level students taking courses on the terrestrial ecology of the East Asian tropics, as well as an authoritative regional reference for professional ecologists, conservationists, and interested amateurs worldwide.

Community-oriented conservation of natural resources and promotion and protection of trees in drylands are examples to deal with climatic adversities. This book provides knowledge on climatic, ecological, social and economic condition of dry areas and lay out approaches and strategies to restore degraded lands. There are 15 chapters and first five deals with physiography of Rajasthan, drylands ecology, problems of land degradation, its economic evaluation and the approaches and strategies of restoration and rehabilitation. Next two chapters describe the problems of sand drift, salinity, water logging and effluent inflicted areas and strategies to control them. Chapters 8-10 deal with seed production, quality planting materials, genetic improvement, propagation and planting techniques. Chapters 11-12 describe methods of rain water harvesting and irrigation, and resources conservation for seed sowing and favouring regeneration and successions. Effective management of pests/diseases in nurseries and plantation, growth and yield prediction equations and models, and people's perception and participation in managing forest resources have been described in last 3 chapters. Purpose of this publication is to strengthen the forest functionaries and readers with wide ranging knowledge on land degradation, desertification and eco-biology of drylands; and methods to restore and rehabilitate degrading forest (lands) to increase forest cover, enhance resilience and people livelihoods and improve environmental conditions. Academician, researchers, forest managers, non-government organizations, extension agents and environmentalists can use it in developing, conserving and managing drylands ecosystems for its long lasting beneficial effects. This book is also useful to policy makers in effective planning of restoring, protecting and conserving dryland's ecological and socioeconomic services.

Competitiveness describes a key ability important for plants to grow and survive abiotic and biotic stresses. Under optimal, but particularly under non-optimal conditions, plants compete for resources including nutrients, light, water, space, pollinators and other. Competition occurs above- and belowground. In resource-poor habitats, competition is generally considered to be more pronounced than in resource-rich habitats. Although competition occurs between different players within an ecosystem such as between plants and soil microorganisms, our topic focusses on plant-plant interactions and includes inter-specific competition between different species of similar and different life forms and intra-specific competition. Strategies for securing resources via spatial or temporal separation and different resource needs generally reduce competition. Increasingly important is the effect of invasive plants and subsequent decline in biodiversity and ecosystem function. Current knowledge and future climate predictions suggest that in some situations competition will be intensified with occurrence of increased abiotic (e.g. water and nutrient limitations) and biotic stresses (e.g. mass outbreak of insects), but competition might also decrease in situations where plant productivity and survival declines (e.g. habitats with degraded soils). Changing interactions, climate change and biological invasions place new challenges on ecosystems. Understanding processes and mechanisms that underlie the interactions between plants and environmental factors will aid predictions and intervention. There is much need to develop strategies to secure ecosystem services via primary productivity and to prevent the continued loss of biodiversity. This Research Topic provides an up-to-date account of knowledge on plant-plant interactions with a focus on identifying the mechanisms underpinning competitive ability. The Research Topic aims to showcase knowledge that links ecological relevance with physiological processes to better understanding plant and ecosystem function.