13 May: Jørgen Jensen

A journey into the past ‒ the History of Botany at LIFE

Jørgen Jensen

dept. Agriculture and Ecology, Copenhagen University


Jørgen Jensen will review the important people and their contributions to plant science and education at LIFE. He will also discuss the organisational changes that have taken place during the long history of botanical study at this institution. This seminar will be held in Danish.

Baseret på et stort antal skriftlige kilder og egen erindring har Jørgen Jensen udarbejdet et antal lister, der belyser personale, lokalisering, økonomi, undervisning og forskning ved den botaniske enhed under Den kongelige Veterinær- og Landbohøjskole i perioden fra højskolens oprettelse i 1858 til dens ophør som selvstændig enhed i 2006. Baggrundsmaterialet er primært KVL’s årsberetninger, samt et stort materiale fra Rigsarkivet såsom undervisningsprotokoller, gamle byggesager og ikke mindst mødereferater fra den periode hvor universiteterne blev ledet af faglige og kollegiale råd og udvalg.

29 April: Jacob Weiner

Size and Reproduction within Plant Populations

Jacob Weiner

dept. Agriculture and Ecology, Copenhagen University


The quantitative relationship between size and reproductive output is a central aspect of a plant’s strategy: the conversion of growth into fitness. Since plant allocation changes with size, we take an allometric perspective and review existing data on the relationship between individual vegetative (V, x-axis) and reproductive (R, y-axis) biomass within plant populations, rather than analyzing biomass ratios such as reproductive effort (R/[R+V]).

The allometric relationship between R and V among individuals within a population is most informative when cumulative at senescence (‘total R–V relationship’), as this represents the potential reproductive output of individuals given their biomass. Earlier measurements may be misleading if plants are at different developmental stages and therefore have not achieved the full reproductive output their size permits. Much of the data that have been considered evidence for plasticity in reproductive allometry are actually evidence for plasticity in the rate of growth and development.

Although a positive x intercept implies a minimum size for reproducing, a plant can have a threshold size for reproducing without having a positive x-intercept.

Most of the available data are for annual and monocarpic species whereas data on long-lived iteroparous plants are scarce. We find three common total R–V patterns: short-lived, herbaceous plants and clonal plants usually show a simple, linear relationship, either (1) passing through the origin or (2) with a positive x intercept, whereas larger and longer-lived plants often exhibit (3) classical log-log allometric relationships with slope < 1. While the determinants of plant size are numerous and interact with one another, the potential reproductive output of an individual is primarily determined by its size and allometric program, although this potential is not always achieved.