Michael Fenner

Bio: Michael Fenner is an academic researcher from University of Southampton. The author has contributed to research in topics: Seedling & Germination. The author has an hindex of 33, co-authored 58 publications receiving 7810 citations.

Seeds: the ecology of regeneration in plant communities.

Abstract: Reproductive allocation and reproductive effort in plants, F.A. Bazzaz and D.D. Ackerly maternal effects on seeds during development, Y. Gutterman the ecology of seed dispersal, M.F. Wilson animals as seed dispersers, E.W. Stiles fruits and frugivory, P. Jordano seed predators and plant population dynamics, M.J. Crawley longevity, viability and dormancy, A.J. Murdoch and R.H. Ellis the functional ecology of seed banks, K. Thompson seed responses to light, T.L. Pons the role of temperature in germination ecophysiology, R.J. Probert effect of chemical environment on seed germination, C.M. Karssen and H.W.M. Hilhorst the contribution of seedling regeneration to the structure and dynamics of plant communities and larger units of landscape, J.P. Grime and S.H. Hillier.

The ecology of seeds

Abstract: What determines the number and size of the seeds produced by a plant? How often should it reproduce them? How often should a plant produce them? Why and how are seeds dispersed, and what are the implications for the diversity and composition of vegetation? These are just some of the questions tackled in this wide-ranging review of the role of seeds in the ecology of plants. The authors bring together information on the ecological aspects of seed biology, starting with a consideration of reproductive strategies in seed plants and progressing through the life cycle, covering seed maturation, dispersal, storage in the soil, dormancy, germination, seedling establishment, and regeneration in the field. The text encompasses a wide range of concepts of general relevance to plant ecology, reflecting the central role that the study of seed ecology has played in elucidating many fundamental aspects of plant community function.

The effects of the parent environment on seed germinability

Abstract: The growing conditions of a parent plant may affect the degree of dormancy of its seeds. This has been demonstrated in numerous species, both wild and cultivated. The evidence comes from field observations and controlled experiments. A survey of the literature shows that some well defined patterns emerge, with certain environmental factors tending to have similar effects over a wide range of species. Lower dormancy (i.e., increased germinability) is generally associated with the following environmental conditions during seed development: high temperatures, short days, red light, drought and high nitrogen levels. The effects are probably the result of changes in the quantity, mobility or activity of growth substances such as abscisic acid. The ecological implications of the phenomenon are briefly discussed.

The Theory of Island Biogeography

Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

The dilemma of plants: To grow or defend.

Abstract: Physiological and ecological constraints play key roles in the evolution of plant growth patterns, especially in relation to defenses against herbivores. Phenotypic and life history theories are unified within the growth-differentiation balance (GDB) framework, forming an integrated system of theories explaining and predicting patterns of plant defense and competitive interactions in ecological and evolutionary time. Plant activity at the cellular level can be classified as growth (cell division and enlargement) of differentiation (chemical and morphological changes leading to cell maturation and specialization). The GDB hypothesis of plant defense is premised upon a physiological trade-off between growth and differentiation processes. The trade-off between growth and defense exists because secondary metabolism and structural reinforcement are physiologically constrained in dividing and enlarging cells, and because they divert resources from the production of new leaf area. Hence the dilemma of plants: Th...

Plant Ecological Strategies: Some Leading Dimensions of Variation Between Species

Abstract: An important aim of plant ecology is to identify leading dimensions of ecological variation among species and to understand the basis for them. Dimensions that can readily be measured would be especially useful, because they might offer a path towards improved worldwide synthesis across the thousands of field experiments and ecophysiological studies that use just a few species each. Four dimensions are reviewed here. The leaf mass per area-leaf lifespan (LMA-LL) dimension expresses slow turnover of plant parts (at high LMA and long LL), long nutrient residence times, and slow response to favorable growth conditions. The seed mass-seed output (SM-SO) dimension is an important predictor of dispersal to establishment opportunities (seed output) and of establishment success in the face of hazards (seed mass). The LMA-LL and SM-SO dimensions are each underpinned by a single, comprehensible tradeoff, and their consequences are fairly well understood. The leaf size-twig size (LS-TS) spectrum has obvious consequences for the texture of canopies, but the costs and benefits of large versus small leaf and twig size are poorly understood. The height dimension has universally been seen as ecologically important and included in ecological strategy schemes. Nevertheless, height includes several tradeoffs and adaptive elements, which ideally should be treated separately. Each of these four dimensions varies at the scales of climate zones and of site types within landscapes. This variation can be interpreted as adaptation to the physical environment. Each dimension also varies widely among coexisting species. Most likely this within-site variation arises because the ecological opportunities for each species depend strongly on which other species are present, in other words, because the set of species at a site is a stable mixture of strategies.

Seed dormancy and the control of germination

Abstract: Seed dormancy is an innate seed property that defines the environmental conditions in which the seed is able to germinate. It is determined by genetics with a substantial environmental influence which is mediated, at least in part, by the plant hormones abscisic acid and gibberellins. Not only is the dormancy status influenced by the seed maturation environment, it is also continuously changing with time following shedding in a manner determined by the ambient environment. As dormancy is present throughout the higher plants in all major climatic regions, adaptation has resulted in divergent responses to the environment. Through this adaptation, germination is timed to avoid unfavourable weather for subsequent plant establishment and reproductive growth. In this review, we present an integrated view of the evolution, molecular genetics, physiology, biochemistry, ecology and modelling of seed dormancy mechanisms and their control of germination. We argue that adaptation has taken place on a theme rather than via fundamentally different paths and identify similarities underlying the extensive diversity in the dormancy response to the environment that controls germination.

Benefits of plant diversity to ecosystems: immediate, filter and founder effects

Abstract: 1 It is useful to distinguish between the immediate effects of species richness on ecosystems and those which become apparent on a longer time scale, described here as filter and founder effects. 2 Relationships between plant diversity and ecosystem properties can be explored by classifying component species into three categories – dominants, subordinates and transients. Dominants recur in particular vegetation types, are relatively large, exhibit coarse-grained foraging for resources and, as individual species, make a substantial contribution to the plant biomass. Subordinates also show high fidelity of association with particular vegetation types but they are smaller in stature, forage on a more restricted scale and tend to occupy microhabitats delimited by the architecture and phenology of their associated dominants. Transients comprise a heterogeneous assortment of species of low abundance and persistence; a high proportion are juveniles of species that occur as dominants or subordinates in neighbouring ecosystems. 3 A ‘mass ratio’ theory proposes that immediate controls are in proportion to inputs to primary production, are determined to an overwhelming extent by the traits and functional diversity of the dominant plants and are relatively insensitive to the richness of subordinates and transients. Recent experiments support the mass ratio hypothesis and the conclusion of Huston (1997) that claims of immediate benefits of high species richness to ecosystem functions arise from misinterpretation of data. 4 Attribution of immediate control to dominants does not exclude subordinates and transients from involvement in the determination of ecosystem function and sustainability. Both are suspected to play a crucial, if intermittent, role by influencing the recruitment of dominants. Some subordinates may act as a filter influencing regeneration by dominants following major perturbations. 5 Transients originate from the seed rain and seed banks and provide an index of the pool of potential dominants and subordinates at specific sites. Where the landscape carousel operates against a background of declining diversity in the reservoir of colonizing transients, we may predict that a progressive loss of ecosystem functions will arise from the decline in the precision with which dominants can engage in the re-assembly and relocation of ecosystems.