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Seedling recruitment patterns over 4 years in an Australian perennial grassland community with different fire histories

Seedling recruitment patterns over 4 years in an Australian perennial grassland community with... Summary 1 Seedling recruitment was followed from 1993 to 1996 in four remnant Themeda triandra grassland sites in south‐eastern Australia subjected to different long‐term fire histories (1‐, 2‐, 4‐year fire intervals, unburnt > 10 years). Multivariate analyses were used to separate the effects of site and year on recruitment and community dynamics. 2 Exotic species (mostly annual monocots such as Aira spp., Briza minor and Juncus capitatus) dominated the seedling flora at all sites in all years. Seedlings of most native species were absent or rare in all years, despite their abundance in the standing flora. 3 Seedling recruitment (richness and density) in the long unburnt grassland was significantly less than in burnt sites in all years. Hence, the seedling floristic composition of this site was substantially different from all other sites on PCA axis 1, which did not differ in all years. 4 Amongst burnt sites, some differences in the annual seedling cohort were evident on PCA axes 2 and 3, but these were due to small differences in the relative abundance rather than the composition of recruiting species. Seedling recruitment was not cued or promoted by fire but rather, seedling density was influenced by, and interacted with, yearly (presumably rainfall) variation. 5 Amongst the native species seen as seedlings, yearly emergence occurred in some cases (14 of 24 species) but always at low densities (< 10 seedlings/0.25 m2). Seedling survival amongst native species varied from nil (0%) to high (> 60%), with most mortality occurring in early summer. 6 The temporal and spatial variation observed in seedling regeneration suggests that long‐term native species coexistence may be promoted by differences in the ‘regeneration niche’. Seedling regeneration, however, has minimal impact on the short‐term dynamic of this community, whose conservation requires maintenance of the existing ‘bud‐ and tuber‐bank’ of native species. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Ecology Wiley

Seedling recruitment patterns over 4 years in an Australian perennial grassland community with different fire histories

Journal of Ecology , Volume 89 (6) – Dec 1, 2001

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References (49)

Publisher
Wiley
Copyright
Copyright © 2001 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0022-0477
eISSN
1365-2745
DOI
10.1111/j.1365-2745.2001.00617.x
Publisher site
See Article on Publisher Site

Abstract

Summary 1 Seedling recruitment was followed from 1993 to 1996 in four remnant Themeda triandra grassland sites in south‐eastern Australia subjected to different long‐term fire histories (1‐, 2‐, 4‐year fire intervals, unburnt > 10 years). Multivariate analyses were used to separate the effects of site and year on recruitment and community dynamics. 2 Exotic species (mostly annual monocots such as Aira spp., Briza minor and Juncus capitatus) dominated the seedling flora at all sites in all years. Seedlings of most native species were absent or rare in all years, despite their abundance in the standing flora. 3 Seedling recruitment (richness and density) in the long unburnt grassland was significantly less than in burnt sites in all years. Hence, the seedling floristic composition of this site was substantially different from all other sites on PCA axis 1, which did not differ in all years. 4 Amongst burnt sites, some differences in the annual seedling cohort were evident on PCA axes 2 and 3, but these were due to small differences in the relative abundance rather than the composition of recruiting species. Seedling recruitment was not cued or promoted by fire but rather, seedling density was influenced by, and interacted with, yearly (presumably rainfall) variation. 5 Amongst the native species seen as seedlings, yearly emergence occurred in some cases (14 of 24 species) but always at low densities (< 10 seedlings/0.25 m2). Seedling survival amongst native species varied from nil (0%) to high (> 60%), with most mortality occurring in early summer. 6 The temporal and spatial variation observed in seedling regeneration suggests that long‐term native species coexistence may be promoted by differences in the ‘regeneration niche’. Seedling regeneration, however, has minimal impact on the short‐term dynamic of this community, whose conservation requires maintenance of the existing ‘bud‐ and tuber‐bank’ of native species.

Journal

Journal of EcologyWiley

Published: Dec 1, 2001

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