Vegetation responses to season of fire in an aseasonal, fire-prone fynbos shrubland
Date
2017-08-10
Journal Title
Journal ISSN
Volume Title
Publisher
PeerJ
Abstract
Season of fire has marked effects on floristic composition in fire-prone Mediterranean-
climate shrublands. In these winter-rainfall systems, summer-autumn fires lead to
optimal recruitment of overstorey proteoid shrubs (non-sprouting, slow-maturing,
serotinous Proteaceae) which are important to the conservation of floral diversity.
We explored whether fire season has similar effects on early establishment of five
proteoid species in the eastern coastal part of the Cape Floral Kingdom (South Africa)
where rainfall occurs year-round and where weather conducive to fire and the actual
incidence of fire are largely aseasonal. We surveyed recruitment success (ratio of
post-fire recruits to pre-fire parents) of proteoids after fires in different seasons. We
also planted proteoid seeds into exclosures, designed to prevent predation by small
mammals and birds, in cleared (intended to simulate fire) fynbos shrublands at different
sites in each of four seasons and monitored their germination and survival to one
year post-planting (hereafter termed `recruitment'). Factors (in decreasing order of
importance) affecting recruitment success in the post-fire surveys were species, pre-fire
parent density, post-fire age of the vegetation at the time of assessment, and fire season,
whereas rainfall (for six months post-fire) and fire return interval (>7 years) had little
effect. In the seed-planting experiment, germination occurred during the cooler months
and mostly within two months of planting, except for summer-plantings, which took
2 3 months longer to germinate. Although recruitment success differed significantly
among planting seasons, sites and species, significant interactions occurred among
the experimental factors. In both the post-fire surveys and seed planting experiment,
recruitment success in relation to fire- or planting season varied greatly within and
among species and sites. Results of these two datasets were furthermore inconsistent,
suggesting that proteoid recruitment responses are not related to the season of fire.
Germination appeared less rainfall-dependent than in winter-rainfall shrublands,
suggesting that summer drought-avoiding dormancy is limited and has less influence
on variation in recruitment success among fire seasons. The varied response of proteoid
recruitment to fire season (or its simulation) implies that burning does not have to be
restricted to particular seasons in eastern coastal fynbos, affording more flexibility for
fire management than in shrublands associated with winter rainfall.
Description
CITATION: Kraaij, T., et al. 2017. Vegetation responses to season of fire in an aseasonal, fire-prone fynbos shrubland. PeerJ, 5:e3591, doi:10.7717/peerj.3591.
The original publication is available at https://peerj.com
The original publication is available at https://peerj.com
Keywords
Fire season, Post-fire recruitment, Cape Floral Kingdom -- South Africa, Germination
Citation
Kraaij, T., et al. 2017. Vegetation responses to season of fire in an aseasonal, fire-prone fynbos shrubland. PeerJ, 5:e3591, doi:10.7717/peerj.3591