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- Title
The effect of grassland gap size on establishment, growth and flowering of the endangered <em>Rutidosis leptorrhynchoides</em> (Asteraceae).
- Authors
Morgan, J. W.
- Abstract
1. To determine the effect of grassland gap size on patterns of' seedling recruitment and juvenile establishment of the endangered composite Rutidusis teptorrhynchoides seed and transplant were introduced into artificially created canopy gaps in both a 'short' and 'tall' temperate Themeda triandra tussock grassland in southern Victoria, Australia. Square gaps of 0 cm (undisturbed control), 15cm, 30cm, 50cm and 100cm width were created by removing the dominant grass, and the emergence. survival and growth of R. leptorrhynchoides were followed for 1 year. Survival and performance were compared with light quantity at ground level and soil moisture differences between the gaps. 2. Emergence or seedlings was greatest in large gaps (30cm, 50cm and 100cm but survival was restricted primarily to the 100 cm gaps in both grasslands. 3. Survival of transplants to 1 year occurred in 30-cm. 50-cm and 100-cm gaps. suggesting that juvenile plank tolerate competition for resources better than germinating seedlings do. Survival, rate of growth and total number of inflorescences produced however, was significantly greater in 100-cm gaps. 4. There were few differences in the seasonal pattern of soil moisture between gaps in both grasslands. The amount of light at ground level was significantly greater in the short-grassland and in large gaps (30 cm, 50cm and 100cm) at most times during the ear. Differences between gaps in total soil moisture and light levels, however, only partly explain the patterns of transplant survival and growth observed. Soil moisture variability is suggested to have been an important factor influencing transplant survival over summer. 5. These results confirm that T. leptorrhynchoides is a gap-sensitive species with recruitment and survival unlikely to occur in canopy gaps less than 30 50cm in diameter. Management of remnant populations needs to ensure that large canopy gaps are regularly maintained to maximize successful seedIing recruitment and maintain the standing population. This may he achieved by burning the grassland at 3-year interval. In the absence of the frequent burning of productive grasslands, localized extinction is likely 6. Reintroduction of the species into secure grassland reserves is likely to be problematic given the paucity of large Themeda-free gaps in these grasslands. Alternative stategies for conserving the species include its introduction into grassy woodlands where gap closure rates are likely to he slower.
- Subjects
ASTERACEAE; FLOWERING of plants; GRASSLANDS; SOIL moisture; THEMEDA; SEEDLINGS
- Publication
Journal of Applied Ecology, 1997, Vol 34, Issue 3, p566
- ISSN
0021-8901
- Publication type
Article
- DOI
10.2307/2404907