Forest Ecology Notes

Can Trees Move?

  • Yes, but slowly, approximately 100 yards per year according to npr.org.

Migration Rates

  • Migration rates following the last ice age are estimated at a pace of around 100 yards per year.

Paleoecology

  • Paleoecology is the study of the distribution and abundance of ancient organisms and their relationship to the environment.
  • It involves the reconstruction of plant species during glaciation by examining the pollen in soil cores.

Pollen Analysis Process

  • Pollen Production: Pollen is produced by plants.
  • Transport: Pollen is transported via wind and other means.
  • Mixing: Pollen mixes with mud and accumulates in layers.
  • Preservation: Pollen is preserved in sediment layers.
  • Collection: Scientists collect core samples from sediment.
  • Preparation: Samples are prepared for analysis.
  • Identification and Counting: Pollen types are identified and counted.
  • Interpretation: Data is used to reconstruct past vegetation and climate.
  • Diagram: Diagrams are drawn to represent vegetation.
  • Reconstructed Vegetation: Vegetation is reconstructed based on pollen data.
  • Climate Data: Climate data are derived from other sources.
  • Landform: Landform also informs the analysis.

Pollen Record

  • Picea: Spruce
  • Juniperus/Thuja type: Juniper/Thuja type
  • Quercus: Oak
  • Tsuga: Hemlock
  • Castanea: Chestnut
  • Carya: Hickory
  • Juglans nigra: Black Walnut
  • Total Pinus: Total Pine
  • Poaceae: Grasses
  • Pteridium aquilinum: Bracken Fern
  • Ambrosia type: Ragweed
  • Iva: Marsh Elder
  • Helianthus type: Sunflower
  • Chenopodium type: Goosefoot
  • Plantago: Plantain
  • Rumex: Dock
  • CHAR cross-sectional area: Charcoal measurements indicate fire history, measured in mm^2 cyr^{-1}.

Laurentide Ice Sheet (LIS)

  • The map shows the maximum extent of the Laurentide Ice Sheet (LIS) during the last glacial period. The LIS covered a large portion of North America.

Anderson Pond, TN Profile

  • Pollen data from Anderson Pond, Tennessee, is used to reconstruct past vegetation.
  • Around 20,000 years ago, pine and spruce dominated the landscape.
  • Oak dominance began approximately 16,000 years ago as the glaciers retreated.

Spruce Distribution

  • Spruce distribution 21,000 years Before Present (BP).
  • Spruce distribution Modern.

Climate Change and Tree Migration

  • Trees may need to migrate at a rate 100 times faster than previously documented to keep pace with shifting climate.
  • Tree species are expected to experience lags in their response to changing climate.

Assisted Migration

  • Assisted migration: the human-aided relocation of species.
  • It involves moving species within or beyond their historical range to conserve species and facilitate adaptation to predicted climate change.

Tree Migration Mechanisms

  • Trees migrate in response to changing climate.
  • They disperse their seeds (sexual reproduction) or grow vegetatively (asexual reproduction).

Regeneration Ecology

  • The volumetric landscape ecosystem supports the plant life cycle with trees shown as repeating modular units.
  • Phases of Regeneration:
    • I: Seed bank in the forest floor.
    • II: Establishment and recruitment of seedlings into the understory.
    • III: Growth in height, mass, and number of modular units; vertical bars represent environmental constraints on growth; dashed line indicates the influence of the overstory on establishment and recruitment.
    • IV: Seed production and dispersal.

Life History

  • Life history: an organism’s lifetime pattern of growth, development, and reproduction.
    • Age of reproduction.
    • Size and age at maturity.
    • Life span.

Reproduction

  • Involves flowering, pollination, seed production, seed dispersal, seed germination, and seedling establishment.
  • Important for genetic diversity.

Plant Establishment and Recruitment

  • Plants establish and then either die or undergo a process of recruitment where certain individuals in the ground-layer reach the understory, and then even fewer are recruited into the canopy.

Factors Affecting Seedling Establishment

  • Seed production includes flower bud differentiation and flowering, pollen dispersal and pollination, seed formation, and abscission.
  • Seed dispersal involves primary dispersal (by wind, collisions with canopy, or ground) and secondary dispersal.
  • Seedling establishment involves germination and seedling growth.
  • Key factors include temperature, rainfall, wind, solar radiation, seed/seedling predation, seedling density, climate, forest management practices, canopy structure, and topography and ground vegetation.