Diversity in tropical rain forests and coral reefs   总被引：18，自引：0，他引：18  

Connell JH 《Science (New York, N.Y.)》1978,199(4335):1302-1310

The commonly observed high diversity of trees in tropical rain forests and corals on tropical reefs is a nonequilibrium state which, if not disturbed further, will progress toward a low-diversity equilibrium community. This may not happen if gradual changes in climate favor different species. If equilibrium is reached, a lesser degree of diversity may be sustained by niche diversification or by a compensatory mortality that favors inferior competitors. However, tropical forests and reefs are subject to severe disturbances often enough that equilibrium may never be attained.  相似文献   

Successful small intestinal resection and anastomosis in a late term broodmare with colic via a standing left flank laparotomy          下载免费PDF全文

D. A. Howes  T. A. Kerr  R. McQuillan  R. T. Kerr  J. S. Connell 《Equine Veterinary Education》2018,30(10):531-535

A late term broodmare presented with low‐grade intestinal colic. Clinical findings were consistent with a small intestinal lesion requiring surgical intervention. The risks of general anaesthesia to the fetus, combined with clinical findings in an otherwise quiet natured horse influenced the decision to choose an alternative standing left flank approach first. A small intestinal resection and anastomosis was performed successfully and the mare delivered a healthy foal without complications a month later. Standing colic surgery might be a preferred alternative to general anaesthesia in certain circumstances as discussed in this case report.  相似文献   

The spore coat of the bean anthracnose fungus Colletotrichum lindemuthianum is required for adhesion, appressorium development and pathogenicity     

Sarah L. Rawlings  Richard J. O&#x;Connell  Jonathan R. Green 《Physiological and Molecular Plant Pathology》2007,70(4-6):110-119

The spores (conidia) of the bean anthracnose fungal pathogen, Colletotrichum lindemuthianum, adhere to the aerial parts of plants to initiate the infection process. In previous studies we have shown that the Colletotrichum spores are surrounded by a fibrillar spore coat, comprising several major glycoproteins. Previous evidence showed that a monoclonal antibody (UB20) that recognised these glycoproteins was able to inhibit adhesion of spores to a hydrophobic surface. In this paper we have further studied the role of the spore coat in adhesion, germination and fungal development by studying the effects of UB20 and protease treatment of spores. The latter treatment has previously been shown to remove the spore coat. Spores germinate on glass, polystyrene and water agar, however, appressoria only develop on glass or polystyrene, showing a requirement for a hard surface. Removal of the spore coat with protease inhibits adhesion at 30 min, before the secretion of ECM glycoproteins. Protease treatment also inhibits the development of appressoria and reduces pathogenicity on leaves. Incubation of spores with the MAb UB20 inhibits adhesion at 30 min, but does not affect appressorium formation or pathogenicity. The results suggest that an intact spore coat has two functions; it is required for adhesion to a hydrophobic surface and for the detection of a hard surface necessary for appressorium formation. We suggest that contact with a hard surface, rather than adhesion, is the key event leading to appressorium formation.  相似文献   

Effects of water availability and fertilization on nitrogen cycling in a stand of Pinus radiata     

R. J. Raison  P. K. Khanna  M. J. Connell  R. A. Falkiner 《Forest Ecology and Management》1990,30(1-4):31-43

Nitrogen cycling was studied for four years (1983–1987) in an N-deficient 10-year-old stand of Pinus radiata growing on a yellow podzolic soil which had a low water-holding capacity. Trees were subjected to combinations of irrigation of N-fertilization resulting in a wide range of N uptake and tree growth. Net mineralization, plant uptake and leaching of soil N was monitored using a sequential coring and in-situ incubation technique. Nitrogen concentrations were measuredd monthly in live needles and litterfall. Average rates of weight loss and release of N from decomposing litter were estimated over a 3-year period using a budgeting approach.

Trees responded only to N (not to P, and there was no N×P interaction), but there was a large positive interaction between N supply and water availability. Response to fertilizer averaged + 24% over a 4-year period, but was zero during a growing-season which contained a 4-month drought. Irrigation alone increased growth by 60%, but in combination with high N availability growth increased 2–3 fold. Annual uptake of N ranged from <10 (irrigated plots in years 2 and 3 after enhanced mineralization during the initial year) to 166 kg ha⁻¹ (during a wet growing season following heavy N fertilization). Although soil mineral-N concentrations were elevated for only about 1 year after fertilization, fertilization enhanced rates of N mineralization throughout the soil N mineralization may have resulted from re-mineralization of the large quantity (147 kg soil N mineralization may have resulted from re-mineralization of the large quantity (147 kg ha⁻¹) of fertilizer N immobilized by the soil during the initial 8 months after fertilization, or the N released from decomposition of fine roots having higher N content. Nitrification was negligible in unfertilized soils, but increased markedly 50–100 days after fertilization and resulted in the leaching of about 60 kg N ha⁻¹ during autumn and winter of the first year after fertilization. Fertilized soils have continued to nitrify readily. Irrigation increased rates of weight loss and N release from decomposing litter.

The rate of N uptake by trees markedly affected the concentrations of N in newly emerging and older needles, and the concentration of N in needlefall. The weighted mean concentration of N in annual needlefall ranged from 0.42% in the irrigated-only plot (most N-stressed) to 0.94% in the heavily fertilized plot during the first year after treatment. These weighted concentrations are a useful index of N uptake from the soil and of growth rate where water supply is not limiting. Except for the initial year after heavy N fertilization, annual uptake of N was equivalent to annual soil N mineralization, and N uptake was positively linearly correlated with annual basal-area increment of trees.  相似文献   

Stakeholder perspectives on the use of pig meat inspection as a health and welfare diagnostic tool in the Republic of Ireland and Northern Ireland; a SWOT analysis     

C. Devitt  L. Boyle  D. L. Teixeira  N. E. O’Connell  M. Hawe  A. Hanlon 《Irish veterinary journal》2015,69(1):17

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Multiple cutaneous leiomyomas in the perineum of a horse.     

Keith L Bailey  Michael J Kinsel  Kathy A Connell 《Journal of veterinary diagnostic investigation》2003,15(5):454-456

Multiple cutaneous masses developed in the perineum of a 14-year-old Saddlebred stallion over a period of approximately 5 years. Clinically, the masses ranged in size from 3- to 9-mm diameter and were not ulcerated, painful, or pruritic. Three of the masses were surgically excised and submitted for microscopic evaluation. The masses were dome shaped to nodular, located in the superficial dermis, and composed of haphazardly arranged bundles of plump spindle-shaped cells. The tumor cells immunoreacted with monoclonal antibodies directed against desmin, muscle-specific actin, and smooth muscle actin, confirming a smooth muscle origin. Multiple cutaneous leiomyomas have not been reported previously in horses.  相似文献   

Regulation of space in the contemporary postcolonial Pacific city: Port Moresby and Suva     

John Connell 《Asia Pacific viewpoint》2003,44(3):243-257

Abstract: National development problems in the weak states of Papua New Guinea and Fiji have resulted in external intervention. However neo‐liberal development strategies have not resolved development problems and may have further weakened state structures. In both capital cities rural‐urban migration, rising urban unemployment, and the expansion of squatter settlements and the informal sector have all continued in recent years. The numbers of beggars, street kids and prostitutes have increased, as has domestic violence and crime. Governments have opposed all these trends, by regulation and intolerance, violence, routine repression and eviction, rather than by pro‐poor policies. Settlers, prostitutes, beggars, street kids and market vendors have been evicted and moved on, on the ideological premise that that their true place is in rural areas, and that their urban presence challenges and threatens notions of urban order. Moral regulation, social exclusion and moral panic have divided ‘good citizens’ from marginal and possibly criminal others, intensifying social divisions within the cities. Sustainable urban development has proved difficult to achieve.  相似文献   

‘The Taste of Paradise’: Selling Fiji and FIJI Water     

John Connell 《Asia Pacific viewpoint》2006,47(3):342-350

Abstract: Effective global competitiveness is rare in the Pacific islands, yet FIJI Water has been a major success story since 1997, exporting bottled water to the USA and elsewhere. A bland commodity has been linked to an ‘exotic’ place, and sold to elite consumers, as a form of cultural capital. The company website and newspaper extol the virtues of a ‘pristine’ product, produced in a natural context, in an environmentally sensitive manner. Marketing these themes and product placement have enabled success in a highly competitive market. Place has been used as a means of marketing perceived taste, distinctiveness and quality.  相似文献   

Introduction: That most remarkable of outside men – Harold Brookfield's intellectual legacy     

John Connell  Eric Waddell 《Asia Pacific viewpoint》2005,46(2):129-133

Abstract: Harold Brookfield's academic career spans more than half a century, traversing small tropical and subtropical islands and mountainous uplands, focusing on people–environment relations and linking to a diversity of institutions and disciplines. His unwavering commitment to fieldwork at the local level and to comparative study is paralleled by a healthy scepticism with respect to academic trends and orthodoxy of any kind, whether intellectual or physical. It is the farmers of the developing world who are the source of much of his inspiration. His theoretical contributions are based essentially on his observations of their practices and his learning from their experiences. His academic insights into the processes of change in rural areas of Melanesia, East and South‐East Asia, Africa and South America, where small‐scale ecological studies are linked to global forces, are of lasting significance.  相似文献   

Legume cover cropping effects on early growth and soil nitrogen supply in eucalypt plantations in south-western India     

D.?S.?MendhamEmail author  S.?Kumaraswamy  M.?Balasundaran  K.?V.?Sankaran  M.?Corbeels  T.?S.?Grove  A.?M.?O’Connell  S.?J.?Rance 《Biology and Fertility of Soils》2004,39(5):375-382

Growth and soil N supply in young Eucalyptus tereticornis stands at two sites in Kerala, India, were examined in response to cover cropping with three legume species (Pueraria phaseoloides, Stylosanthes hamata, and Mucuna bracteata). The effects of legume residues on soil N supply were investigated in a long-term (392 day) laboratory incubation using leaching micro-lysimeters. Residues from the eucalypt and legume species had different rates of net N release during the laboratory incubation. Net N release was significantly related to residue N concentration (R² =0.94), the C:N ratio (R² =0.91), the lignin:N ratio (R² =0.83), and the (lignin + soluble polyphenol):N ratio (R² =0.95). Nitrogen release rates declined in the order Mucuna > Pueraria > Eucalyptus > Stylosanthes. There was no net N release from Stylosanthes residues during the 392-day laboratory incubation, whereas Mucuna and Pueraria released N throughout the incubation period. Net N release from mixtures of legume and eucalypt residues was not additive in the early phase of the incubation, probably because eucalypt residues initially immobilized a portion of the legume-derived N in addition to the soil-derived N. Legume establishment had no significant effect on tree growth at one site (Kayampoovam), but resulted in depressed tree growth at the lower rainfall site (Punnala) at 18 months. There were no significant treatment effects on growth at Punnala after that time. Cover cropping with legumes during the early phase of forest plantation growth may be a useful mechanism to enhance soil N supply and optimize the synchrony between N supply and tree N uptake. Although these effects did not translate into improved plantation growth in the 3 years of this study, improved soil organic matter and N fertility may help ensure sustainable productivity over several rotations in the future. This study showed that the effect of legumes on N dynamics varies markedly with legume species. This, together with other factors (e.g. competition with trees, N fixation capacity), will be important in selecting suitable species for cover cropping in forest plantations.  相似文献