Lauchlan H. Fraser1, Cameron N. Carlyle2, Roy Turkington2, and Don Thompson3. (1) Thompson Rivers University, (2) University of British Columbia, (3) Federal Government of Canada
Recovery of grasslands from disturbance occurs on a decadal
scale; consequently, assessing their resilience is difficult. Cattle exclosures which have been constructed in dry grasslands in
the southern interior of British Columbia over the past 80 years provide an
opportunity to measure resilience. We
selected 50 exclosures. The sizes of the exclosures
varied but were no smaller than 400 m2. Some exclosures
date back to the 1920's, but most were built between the 1960's to 1990's. This study tested two hypotheses critical to
the management of grasslands: (1) The resilience of rangelands will increase
with primary productivity; (2) Dominant vegetation both influences the
resilience of grasslands and indicates recovery. Through the measurement of plant species
richness, diversity, community composition, primary productivity, soil
characteristics and seed banks in the 50 exclosures
of different ages we could determine the most probable factors influencing the
resilience of rangelands to disturbance caused by cattle grazing. Using
multivariate community analysis and regeneration indexes we compared grasslands
within exclosures to those which are unfenced. We
found that resilience was affected by elevation such that low-elevation, drier
grassland was less resilient to grazing disturbance than high-elevation
grassland of higher productivity.