The Empty Forest
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MAY 2002 NUMBER 25 Porcupine! Newsletter of the Department of Ecology & Biodiversity, The University of Hong Kong The empty forest In Hong Kong’s climate, forest is the natural vegetation everywhere. It can be suppressed by regular cutting or burning, but the harvesting of biomass for fuel ended decades ago and fires, although still common, are less often started and more rapidly controlled near urban areas than next to rural villages. An increase in the area of forest is therefore an inevitable, if paradoxical, consequence of the increasing urbanisation of the New Territories. Hong Kong Island, where the last grassland is disappearing under a tidal wave of shrubs and trees, illustrates the future for the whole territory. Within fifty years, forest will cover most of Hong Kong. Good news for native biodiversity, surely? Well…yes… partly. It is true that many of our most diverse inland sites are in forest, but these are areas that have had continuous tree cover for centuries, as a result of inaccessibility or the protection of feng shui. The much larger areas of young secondary forest are a lot less diverse. Even at the best sites, the diversity is in the plants and invertebrates – organisms that can persist in the tiniest of forest patches. Vertebrates do not survive in such situations so Hong Kong has lost most species that require forest. The new forests are therefore empty in comparison with the larger, older forest areas in Guangdong, and even more so if compared with what must have been here a thousand years ago. There are no reliable records for Hong Kong from before the nineteenth century, when the vertebrate fauna was already impoverished. To get an idea of what has been lost, we must therefore extrapolate from recent and historical records for the South China region. These records suggest the local extinction, by the nineteenth century, of at least the following families of forest vertebrates: monkeys, gibbons, elephants, rhinoceroses, squirrels, flying squirrels, bamboo rats, pheasants, woodpeckers and trogons (Corlett, 2002). A species list would be much longer, since several major vertebrate groups, such as the babblers, cats, mustelids and rodents, are represented by just a few survivors of the original diversity. But Hong Kong today does have squirrels and monkeys, and babbler list increases year by year. Doesn’t this suggest that forest vertebrate diversity will recover of its own accord? Unfortunately, the presence of these species is as much bad news as good. Almost all the increase in diversity over the past century was the result of the deliberate release of captive animals: the first monkeys in 1913, the squirrels around 1970, and most babblers within the last 20 years. Motivations have varied but few, if any, of the releasers have been concerned with the ecological consequences of their actions. The released species have been a random selection from those imported into Hong Kong, usually for sale as pets. Our monkeys are a hybrid mix, our squirrels are from Thailand and Shanghai, and while some of our new babblers were probably present in the region before deforestation, others are from Southwest China (Carey et al., 2001). A few bird species have made it to Hong Kong of their own accord, but the non-forest areas north of the border are an impenetrable barrier to most forest specialists. Neither letting the new forests remain empty, nor filling them with exotic species released by kind-hearted Buddhists, makes any ecological sense. Only a program of planned reintroductions of species that used to be here in the past can restore a diverse, functioning forest ecosystem (see p.16). Such a program would have multiple benefits: it would restore ecological processes, such as seed dispersal, that have been truncated by local extinctions; it would enhance public awareness and support for conservation; and it would increase the security of the species concerned, by providing additional wild populations. Reintroduction of ecologically appropriate species would also reduce the risk that invasive exotics will fill the many vacant niches in our empty forests. Richard T. Corlett (For bibliography see back page.) 2 Porcupine! News from DEB NUMBER 25 It is always good to start on a positive note. Accordingly, May 2002 as promised in my last Porcupine! missive, I am going to report some good news from the Department of Ecology & Biodiversity. Firstly, recruitment of ‘new blood’. DEB Newsletter of the Department of Ecology & has added not one, but two new members of staff to the ranks this year. Both have been appointed as Research Biodiversity, The University of Hong Kong Assistant Professors (more or less equivalent to a junior lecturer), and will have some teaching duties in addition INSIDE THIS ISSUE: to the responsibility (as the title suggests) of undertaking lots of research. Dr Kenny Leung joined us in January from Royal Holloway College in London; a profile is included elsewhere in this issue (p. 5). Dr Benny Chan was formerly a postdoctoral fellow in DEB and, for the The empty forest 1 tenure of his RAP post, will be based at SWIMS. An DEB news 2 account of his ongoing activities will appear in the next Editorial 2 issue of Porcupine! Feedback 3 What else is new? Version 3.0 of the Biodiversity Survey Introducing Kenneth Mei-yee Leung 5 database has been completed, and was passed to Invertebrates 6 Government in February. Those of you with long memories may recall that the Survey was underwritten by Vertebrates 8 the Environment and Conservation Fund of Government, Flora 14 and that much of the fieldwork was undertaken in 1996 Miscellany 16 and 1997. Version 1.0 of the database was made available in 1999. Version 3.0 is more comprehensive and includes Book Review 24 over 5,000 species and around 100,000 records. The Wild Corner 24 biodiversity data have been complied and can be analysed Recent publications 27 using Geographic Information System software so that 2001 Postgraduate degrees from DEB 32 spatial patterns in the occurrence of plants and animals across Hong Kong can be examined. In short, the database shows what species occur where, and thus it can Editorial be interrogated and used as a starting point for finding out whether or not planned developments and designated As we move from child- to adulthood, one thing we learn is that projects are likely to have an impact on biodiversity. That the world is often not as it might seem, or, indeed, as it should be. information can then be taken into account when a In the area of conservation and resource management, this is thorough environmental impact assessment is undertaken particularly apparent when the perspectives or objectives of the and decisions about compensation, mitigation or public, government and/or big business are at odds, which they avoidance of impacts need to be taken. often are. It is therefore important to recognize the effects that such differences can have on legislation, and on the ways in Of less import to Hong Kong, but of concern to DEB, is a which our interests or concerns are actually being addressed. third matter. The University of Hong Kong is to undergo Examples emerge from among this issue's articles of Porcupine! a Teaching and Learning Quality Process Review in June that illustrate how alert we need to be. Reintroductions might that will be undertaken by a panel of overseas experts appear to be good in general but it is the types of reintroductions appointed by the University Grants Committee. The and the way(s) they are conducted that are critically important focus of the review is quality assurance mechanisms and (p.1). As biologists, we might reasonably expect that fishes and processes, and the results will “inform funding decisions” marine invertebrates are considered part of the animal kingdom in the long term. Given the size of HKU, it isn’t possible and therefore receive protection under the Wild Animals to review all teaching departments so a handful have been Protection Ordinance; surprisingly they are not and hence do not selected for special attention and site visits from the panel. receive protection (p.13). We might predict that the high DEB is one of the departments chosen to represent the economic value of our natural resources is factored into long-term University: whether that is an honour or a curse will development plans (p.17) but in reality short-term business become clearer as June nears. We shall see. interests generally override such potential benefits. Clearly we need to be aware about what 'is', rather than what 'appears to be' in the latest sound-bite or public relations hyperbole. Thanks to David Dudgeon many of our contributors for opening our eyes. YS 3 fisheries resources conservation and management strategies. Feedback Fisheries management proposals supported by the working group include a territorial-wide fishing licence system, the Dear Feedback, establishment of Fisheries Protection Areas (FPAs) at Tolo Channel and Port Shelter waters, the deployment of ARs and I refer to the front-page article in the last issue of Porcupine! restocking of fish fry. (issue 24), entitled, “Irresponsible Fishery” by Dr. Yvonne Sadovy. Yvonne states, “the principle (sic) recommendation ARs are one of the cheapest anti-trawl enforcement measures from top fishery experts of the University of British Colombia available and undoubtedly represent one of the simplest and (UBC) to address overfishing in Hong Kong was a substantial most pragmatic ways of protecting important spawning and reduction in fishing effort.” Yvonne goes on to criticise nursery areas subjected to heavy bottom trawling pressure. Agriculture, Fisheries and Conservation Department (AFCD) Our experience with AR to date demonstrates they are very for not heeding this advice and instead implementing costly effective at preventing bottom trawling and have been heavily artificial reef (AR) and restocking programmes.