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SPORADIC SEED PRODUCTION IN MAST SEEDING TREES – WASTED RESOURCES OR SUCCESSFUL STRATEGY?

Project Leader
Gratzer Georg, Project Leader
Duration:
01.08.2017-30.06.2022
Programme:
Einzelprojekte
Type of Research
Basic Research
Project partners
Cary Institute of Ecosystem Studies, 2801 Sharon Turnpike; P.O. Box AB , NY 12545 Millbrook, United States (USA).
Contact person: Dr. Charles Canham;
Function of the Project Partner: Partner
Federal Forest Office (BFW), Seckendorff-Gudent-Weg 8, 1131 Wien, Austria.
Contact person: Dr. Heino Konrad;
Function of the Project Partner: Partner
Jagellonian University, 31-007 Krakow, Poland.
Contact person: Univ.Prof. Dr. Jerzy Szwagrzyk;
Function of the Project Partner: Partner
Staff
Nopp-Mayr Ursula, Sub Projectleader
Sachser Frederik, Project Staff (bis 14.11.2022)
BOKU Research Units
Institute of Forest Ecology
Institute of Wildlife Biology and Game Management
Funded by
Fonds zur Förderung der wissenschaftlichen Forschung (FWF) , Sensengasse 1, 1090 Wien, Austria
Abstract
Seed production, germination and establishment are critical processes determining structure of plant populations and composition of terrestrial ecosystems. In many perennial plants, seed production shows strong inter-annual variation with a gradient ranging from years without seed production to years with heavy seed crops (“masting”). In a number of plant populations, this intermittent production of very large seed crops is synchronized over large areas and sometimes across species. Mast seeding events are common in boreal, temperate and tropical forest ecosystems and have spurred considerable scientific interest. As the number of long-term studies of the phenomenon grows, a new picture of temporal variation in tree seed production is emerging. In particular, many studies have documented both the irregular length of intervals between very large seed crops, and the more frequent production of small or moderate seed crops between the years of peak seed production. To date, there has been little examination of the consequences of these “inter-mast” seeding events for the long-term population dynamics of tree species. The general goal of the proposed research is to understand and predict the consequences of spatial and temporal variation in tree seed rain for long-term population dynamics of tree species. We hypothesize that inter-mast seed production is a bet-hedging strategy for capturing windows of opportunity for successful regeneration after stochastic disturbances for species and sites with longer masting cycles, and that the long-term average abundance of species is increased as a result of inter-mast seed production. We further hypothesize that, for species with palatable seeds, inter-mast seed production is particularly successful when seed predators are driven into hunger cycles by mast years, and subsequent crashes in seed predator populations result in lower than average population sizes during inter-mast years. The hypotheses will be tested using a combination of empirical research, e.g. on seed fate, combined with the parameterization of a spatially explicit individual based tree population model (SORTIE-ND). Detailed age distributions of seedlings and saplings will be characterized in old growth forests of known seed production. Seed fate will be documented by tracking of marked seeds.
Keywords
Forest ecology;
Masting; Seed predation; Seed production; Old growth forest; Forest dynamics;
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