A Carbon-balance Model of Stand Growth: a Derivation Employing Pipe-model Theory and the Self-thinning Rule

A carbon-balance model of the growth of an even-aged, self-thinning,mono-specific stand of trees is derived using a structural frameworkbased on pipe-model theory. Within the pipe-model framework,dry matter arising from extension of roots and shoots is separablefrom that arising from the cross-sectional expansion of stems.This permits the derivation of models describing the growthof average stem length, total basal area, and total volume ofthe stand. Variations of these models are described for twosituations: (1) where the annual rates of substrate productionand feeder-root turnover can be assumed constant over time;and (2) where these rates are expected to change over time,such as in polluted environments. The model describing the growthof stand volume for the first situation fits published yieldtables. Growth-rate models applicable to individual trees arealso described. Carbon-balance model, dry-matter partitioning, pipe-model theory, stand growth, self-thinning     

Ten polymorphic microsatellite loci for the endangered Buena Vista Lake shrew (Sorex ornatus relictus)

The ornate shrew (Sorex ornatus) is restricted to the vanishing wetlands of California, USA and Baja California, Mexico. Several subspecies of ornate shrews are considered ‘mammal species of special concern’ in California by the Department of Fish and Game, and one (Sorex ornatus relictus) has recently been listed as endangered. Populations of shrews around Buena Vista Lake have been diminished or extirpated due to habitat deterioration and human development. In order to study the patterns of genetic variation in isolated populations of Buena Vista Lake shrews, we developed 10 polymorphic microsatellite loci. There were 6–27 alleles per locus, and the loci had heterozygosity values that ranged from 20 to 80%. In addition, we screened 20 different populations of S. ornatus, eight species within two subfamilies of shrews (Soricinae and Crocidurinae), as well as in a mole (Talpidae, Neurotrichus gibbsii), to determine if these loci could be informative in other species as well.     

Activity following arousal in winter in North American vespertilionid bats

• 1 Many bat species hibernate to conserve energy during winter and like all hibernators they commonly arouse. During these arousals, some bats may undertake activities away from the hibernation site. Systematic ecological studies of the frequency and purpose of winter activity in temperate zone bats of North America are rare and much of the literature involves observations of single individuals or unmarked populations.
• 2 We review the available literature on winter activity among North American vespertilionid bats to highlight the paucity of data on this subject and to stimulate future research. Due to the lack of repeated, systematic studies on most North American species, the conclusions drawn are general or pertain only to parts of the geographical range of any species.
• 3 We suggest that winter activity is ubiquitous among temperate zone bats, but the degree and purpose of activity varies greatly between and within species. In general, cave‐dwelling bats tend to be relatively inactive compared with tree and foliage roosting bats during winter.
• 4 Cave‐dwelling and tree cavity‐dwelling species do not appear to feed, but they do drink and occasionally copulate during the hibernation period. Species that hibernate in foliage or leaf litter are the most active species during winter and may feed and drink throughout winter, although they probably do not copulate because of their solitary nature.
• 5 We encourage researchers to conduct studies on all aspects of winter activity for North American vespertilionids across wide latitudinal and altitudinal gradients. We suggest studies in the near future be focused on estimating the energetic costs and benefits of winter activity through determination of the frequency and intensity of winter feeding activity and more thorough examinations of movements within and among caves. Studies on common, wide‐ranging species have the potential to illuminate large‐scale patterns and differences and should be favoured over studies on rarer species.