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The moss Campylopus introflexus is a Southern Hemisphere species in the process of expanding its distributional range. It was first found in Europe in 1941. Some of the potential impacts of the invasion of C. introflexus into moorland habitats are investigated. In particular, the effects that the moss carpets may have on germination and subsequent growth of Calluna vulgaris are assessed. A glasshouse experiment contrasted both the amount of germination of Calluna seeds and the performance of the seedlings on moss carpets and on bare ground. The effect of moisture availability was analysed, comparing normal daily watering with continuous water supply at the base of the pots. A significant depressive effect (60% reduction) of the moss carpet on the amount of germination was observed, irrespective of the form of water supply (...)

SUMMARY (1) Analysis of published studies generally indicates that ecological succession can be considered as a non-random process. (2) Two examples are discussed in detail, termite succession on baitwood blocks in Ghana (Usher 1975) and predator-prey dynamics of mites in a complex universe of oranges (Huffaker 1958), and both indicate that succession is a non-stationary Markovian process. (3) The discussion considers that complex non-random or Markovian processes are likely to characterize ecological successions, the transition probability matrix elements not being constant but being functions either of the abundance, or of the rate of change of abundance, of a recipient class. (4) Tests of various hypotheses, using x2 criteria, are given.

SUMMARY The species-area relation, S = cAz, is shown to fit the data for the occurrence of higher plant species on nature reserves in Yorkshire. The discussion concentrates on the dynamic nature of the coefficients c and z, demonstrating that both can change in time, and considers the implications of the relation in formulating a conservation policy.

(1) Conservation in the United Kingdom is divided (co-operatively and not antagonistically) between government organizations, of which the foremost is the Nature Conservancy Council, and non-government organizations, bodies that tend to attract large membership from the British population. (2) Four areas of achievement are described: (i) methods of site evaluation and the creation of an inventory of the British nature resource in 1977; (ii) creation of wildlife areas in man-made habitats, abandoned farmland, and urban areas; (iii) management of nature reserves, now being codified in technical manuals for the management of particular habitat types; and (iv) problems of invasive, alien species that can dramatically reduce or even replace natural communities. (3) Three areas for further research are discussed. As answers are still needed, these are posed as the questions 'What does ecological theory have to offer?', 'Is there a minimum size for a nature reserve?' and 'What is the role of monitoring?'. (4) It is seen that practical conservation in the U.K. will benefit from an integration of (i) the traditional survey approach, (ii) monitoring studies, (iii) an experimental programme and (iv) ecological theory. Modelling can use information from several of these approaches.