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 Theory of Island Biogeography

1 The bryophyte and vascular flora were described for a range of forested and open peatlands in the mid-boreal Clay Belt region of Canada, and in the subarctic region of the Labrador Trough, Quebec. The floristic patterns and their relationships to methane (CH4) emission, hydrology and water chemistry were analysed with classification (TWINSPAN), detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA). 2 Despite differences in vegetation physiognomy, chemistry, and geology, water chemistry (pH, Ca, Mg, Kcorr) and hydrology explain most of the species distribution in both peatland regions. In the Clay Belt, bryophytes respond primarily to water table position, and secondarily to water chemistry; the reverse is true for the vascular flora. The bryophyte and vascular ordinations are more similar to each other in the Labrador Trough than in boreal sites. 3 Although CH4 emissions are lower in subarctic than in boreal sites, mean CH4 flux is strongly correlated with mean water table position (r2 = 0.73) in both regions, but is not correlated with water chemistry. The highest CH4 emissions (seasonal mean > 100mg m-2 day-') occur in raised bog and patterned poor fen pools where the peat mat is degrading. 4 The relationships among CH4 flux, mean water table position, and species distribution are similar in both boreal and subarctic regions. Bryophytes are generally better predictors of CH4 flux than vascular plants, except for certain species in flooded sites (e.g. Carex spp.). Bryophytes are also better indicators of the long-term average position of the water table, reflecting relative zones of methane production and oxidation over the season. In the vascular plant analyses, shrub cover indicates dry conditions and low CH4 flux in the sharply differentiated string-flark-pool topography of the subarctic fens, but is less predictive of CH4 emission in the drier hummockhollow microtopography at boreal sites where shrubs and trees are more pervasive. Overall herbaceous or sedge cover is not indicative of CH4 flux in either region.

The relationship of vegetation to methane emission and hydrochemical gradients in northern peatlands.

Bryophytes were a pivotal step in land plant evolution, and their significance in the regulation of ecosystems and the conservation of biodiversity is becoming increasingly acknowledged This introductory textbook assumes no prior knowledge of bryophyte biology, making it ideal for advanced undergraduate and graduate students, as well as amateur botanists The authors expertly summarise the diversity of bryophytes and outline recent advances in our understanding of their evolutionary history, their ecological roles and preferences, their distribution patterns and conservation needs The text is highly illustrated throughout, with boxed summaries of topics of current relevance in bryophyte biology, and a glossary of technical terms

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Introduction to Bryophytes

1 Hylocomium splendens is a perennial clonal moss with annual periodicity in the emergence of new modules. New growing points usually emerge in spring and develop into mature segments their second summer. Population increase is brought about by ramification (branching) of the youngest segment or by regeneration from older parts of the shoot system. 2 A technique for nondestructive re-identification of segments in permanent plots is devised. Precise demographic information on 9206 growing points and 7602 mature segments was obtained by following 119 local populations in seven Norwegian reference areas for monitoring during 3 years. The dry weight of each mature segment was estimated from morphological field measurements. 3 The potential of each mature segment for production of new growing points was strongly size-dependent; c. 40% of the variation in a segment's size was explained by the size of its mother segment. Integration within segment chains was largely restricted to neighbouring segments. The number offspring growing points (by ramification as well as regeneration) was positively size-dependent, while termination risk was negatively size-dependent. Mature segments produced by regeneration were smaller, while segments produced by ramification were larger than the average segment. Strong apical dominance was demonstrated. 4 Mortality and branching rates, averaged over populations, areas and years, are reported. Annual recruitment was 32.3%; 23.3% by regeneration, 7.5% by ramification, and 1.5% by accidentally introduced shoots. Annual mortality was 19.7%. 6.8% by loss, 1.9% by grazing, and 1 1.0% by termination for other reasons. 5 Demographic data for growing points and mature segments were analysed separately by stage-structured transition matrix models. The total population increased every year (average A = 1.10-1.11). Vital rates were strongly size-dependent. The contributions of ramification and regeneration to increase in i were equal as ramification occurred in large segments with high probability for survival. 6 Ramification is considered important for maintenance of size and risk-spreading among ramets under favourable conditions, while high regenerative ability facilitates resilience to, and recovery after, disturbance. The ecological significance of size is discussed. 7 Hylocomium splendens is closely similar to clonal forest vascular plants in major demographic traits, e.g. size-dependence of fitness and branching patterns.

Population biology of the clonal moss Hylocomium splendens in Norwegian boreal spruce forests. I. Demography.

SUMMARY
1. The structure of bryophyte communities in streams in relation to habitat characteristics, especially disturbance, is described. Disturbance in rivers is quantified as movement of the stream bed, whereas in small streams water level fluctuation is used as an indicator of disturbance frequency.

2. Canonical correspondence analysis differentiated frequently disturbed sites from more stable ones. The existence of a disturbance gradient was confirmed in a subset of the study sites using long-term records of discharge variation. A parallel change was detected in the species composition of bryophyte communities with low-statured, potentially fast colonizers dominating the disturbed end and large perennial species the stable end of the gradient.

3. A consistent pattern of zonation of bryophyte species was found along the gradient from continually submersed to persistently dry conditions in small streams and lake outlets. An abrupt increase in species richness occurred at or just above the water line, where facultatively aquatic species tolerant of both conditions formed the bulk of the community.

4. The relationship between species richness and standing crop in stream bryophyte communities was consistent with the hump-backed model of Grime (1979), especially at the within-habitat scale. Quadrats of low and very high standing crop were characterized by low species richness, while peak richness was observed at intermediate standing crops.

5. A few perennial species (e.g. Fontinalis spp. and Rhynchostegium riparioides) capable of monopolizing space dominated the most stable habitats. Species composition in low biomass sites was more variable, yet only one basic growth-form (small-statured species with high allocation to spore production) seemed possible in these highly disturbed streams. In habitats of intermediate biomass, small-scale disturbances apparently allow the formation of a more varied bryophyte community.

6. A habitat templet for stream bryophyte life strategies and community structure is presented. Disturbance is proposed to be the factor filtering out traits unsuitable for a given environment. The potential of stream bryophytes for testing and developing general ecological theory is emphasized.

The stream as a habitat templet for bryophytes: species' distributions along gradients in disturbance and substratum heterogeneity

Bryophytes and ecological niche theory.

Rare and endangered bryophytes in New York State and Eastern United States: Current status and preservation strategies

Private Writings: Always, Rachel. The Letters of Rachel Carson and Dorothy Freeman, 1952-1964. Martha Freeman, Ed. Beacon, Boston, 1995. xxxii, 569 pp., illus., + plates. $35.

The lives and thoughts ofAmerican women field naturalists as researched and presented by Marcia Myers Bonta make a readable and thought-provoking book. The book includes 18th-century \"pioneers,\" early \"naturalists\" such as Mary Treat, an experimenter with carnivorous plants and a correspondent of Darwin's, and botanists, entomologists, ornithologists, and ecologists up to Rachel Carson in the 20th century. Women archeologists and geologists are not included. Some women about whom little is known or whose archives are not open, notably E. Lucy Braun, are briefly mentioned at the beginning of each section. Twenty-five women receive short biographies of 5 to 10 pages. Some of these women, particularly those of the 19th and early 20th centuries, led fascinating independent lives. They explored and collected far from home, often alone, in pursuit of plants and birds and, in many cases, of real science-all this in spite of society's expectations regarding roles for women and the scarcity of professional positions open to them. Several of the women, both single and married, traveled extensively on their own. Three California women botanists, Kate Brandegee, Alice Eastwood, and the amazing Ynes Mexia, made extensive solo collecting trips. Brandegee often collected alone in the high Sierra. At age 64 in 1908, she wrote to her husband at home, \"...may be gone two weeks. I have had considerable hardship in botanizing [but] I am unusually strong and well.\" Brandegee, born in 1844, was widowed early and subsequently earned a medical degree at Berkeley. Patients were few. Her medical botany and further study led in 1883 to a paid position as curator of botany at the California Academy of Sciences. Unlike some of the field naturalists portrayed in this book, she and also her successor as curator, Alice Eastwood, wrote many papers and made important contributions to systematic botany. Eastwood served as botanical guide to both Alfred Russel Wallace and John Muir. She almost single-

Nancy G. Slack

Papers

Bryophytes and ecological niche theory.

Rare and endangered bryophytes in New York State and Eastern United States: Current status and preservation strategies

Private Writings: Always, Rachel. The Letters of Rachel Carson and Dorothy Freeman, 1952-1964. Martha Freeman, Ed. Beacon, Boston, 1995. xxxii, 569 pp., illus., + plates. $35.

Scientific Adventuresses: Women in the Field . America's Pioneering Women Naturalists. Marcia Myers Bonta. Texas AM paper, $13.95.