Summary
The many evolutionary modifications to seed biology in response to seed predation do not necessarily imply that seed predators have an important impact on population recruitment. This is because competition between individual plants for rare safe sites can cause an ‘oversupply’ of seeds so far as a population is concerned. The importance of seed losses to population recruitment at any point in time is related to the abundance of safe sites (Fig. 1): it is zero when safe sites are absent, negligible when safe sites are rare, and greatest when safe sites are numerous enough for recruitment to be limited by seed supply. Here I interpret the impact of severe seed losses on population recruitment in four species of long-lived perennials (Eucalyptus baxteri, Leptospermum juniperinum, Casuarina pusilla and L. myrsinoides) by considering these losses in terms of the overall seed dynamics of the populations. I focus on seed supply and seedling survival, as a measure of the current abundance of safe sites, and the maintenance of seed banks, as a measure of the ability of populations to exploit any future changes in safe site abundance. Insect seed predators destroyed about 95% of total seeds in each case. However, these losses do not necessarily have an important impact on population recruitment, because: (i) in most years recruitment appears to be limited by a rarity of safe sites, and not by seed supply (which was as high as 43 germinable seeds/m2/yr); and (ii) the losses did not prevent the establishment of large seed banks (ranging from >30 to >1000 viable seeds/m2) potentially capable of exploiting temporary conditions favourable for recruitment. In contrast to the situation with many annual plants, patterns of recruitment in stable populations of long-lived perennials are often extremely complex, and the significance of seed losses therefore difficult to determine.
References
Andersen AN (1986) Diversity, seasonality and community organization of ants at adjacent heath and woodland sites in southeastern Australia. Aust J Zool 43:53–64
Andersen AN (1987) Effects of seed predation by ants on seedling densities at a woodland site in southeastern Australia. Oikos 48:171–174
Andersen AN (1988a) Insect seed predators may cause far greater losses than they appear to. Oikos 53:337–340
Andersen AN (1988b) Immediate and longer-term effects of fire on seed predation by ants in sclerophyllous vegetation in southeastern Australia. Aust J Ecol 13:285–293
Andersen AN (1989a) Predispersal seed losses to insects in species of Leptospermum (Myrtaceae). Aust J Ecol 14:13–18
Andersen AN (1989b) Impact of insect predation on ovule survivorship in Eucalyptus baxteri. J Ecol 77:62–69
Andersen AN, Ashton DH (1985) Rates of seed removal by ants at heath and woodland sites in southeastern Australia. Aust J Ecol 10:381–390
Andersen AN, New TR (1987) Insect inhabitants of fruits of Eucalyptus, Leptospermum and Casuarina in southeastern Australia. Aust J Zool 35:327–336
Ashton DH (1976) The development of even-aged stands of Eucalyptus regnans F. Muell. in Central Victoria. Aust J Bot 24:397–414
Ashton DH (1979) Seed harvesting by ants in forests of Eucalyptus regnans F. Muell. in central Victoria. Aust J Ecol 4:265–277
Auld TD (1986) Population dynamics of the shrub Acacia suaveolens (Sm.) Willd.: Fire and the transition to seedlings. Aust J Ecol 11:373–385
Boland DJ, Brooker MIH, Turnbull JW (1980) Eucalyptus Seed. CSIRO, Australia
Borchert MI, Jain SK (1978) The effect of rodent seed predation on four species of Californian annual grasses. Oecologia 33:101–113
Borchert MI, Davis FW, Michaelsen J, Oyler LD (1989) Interactions of factors affecting seedling recruitment of blue oak (Quercus douglasii) in California. Ecology 70:389–404
Briese DT (1982) Relationship between the seed-harvesting ants and the plant community in a semi-arid enviroment. In: Buckley R (ed) Ant-Plant Interactions in Austrilia. Junk, The Hague, pp 11–24
Brokaw NVL (1985) Gap-phase regeneration in a tropical forest. Ecology 66:682–687
Brown JH, Reichman OJ, Davidson DW (1979) Granivory in desert ecosystems. Annu Rev Ecol Syst 10:201–227
Brum GD (1973) Ecology of Saguaro (Carnegiea gigantea): phenology and establishment in marginal populations. Madrono 22:195–204
Cavers PB, Harper JL (1967) Studies in the dynanics of plant populations. 1. The fate of seed and transplants introduced into various habitats. J Ecol 55:59–71
Connell JH, Tracey JG, Webb LJ (1984) Compensatory recruitment, growth and mortality as factors maintaining rainforest tree diversity. Ecol Monogr 54:141–164
Deevy ES (1947) Life tables for natural populations of animals. Quanrt Rev Biol 22:283–314
Duggan AE (1985) Pre-dispersal seed predation by Anthocaris cardamines (Pieridae) in the population dynamics of the perennial Cardamine pratensis (Brassicaceae). Oikos 44:99–106
Gill AM, Groves RH, Noble IR (1981) Fire and the Australian Biota. Australian Academy of Science, Canberra
Grice AC, Westoby M (1987) Aspects of the dynamics of the seedbanks and seedling populations of Acacia victoriae and Cassia ssp. in arid western New South Wales. Aust J Ecol 12:209–215
Grubb PJ (1977) The maintenance of species-richness in plant communities: the importance of the regeneration niche. Biol Rev 52:107–145
Harper JL (1977) Population Biology of Plants. Academic Press, New York
Harper JL, Lovell PH, Moore KG (1970) The shapes and sizes of seeds. Annu Rev Ecol Syst 1:327–356
Inouye RS, Byers GS, Brown JH (1980) Effects of predation and competition on survivorship, fecundity, and community structure of desert annuals. Ecology 61:1344–1351
Janzen DH (1969) Seed-eaters versus seed size, number, toxicity and dispersal. Evolution 23:1–27
Janzen DH (1971a) Seed predation by animals. Annu Rev Ecol Syst 2:465–492
Janzen DH (1971b) Escape of Cassia grandis L. beans from predators in time and space. Ecology 52:964–979
Janzen DH (1986) Seeds as products. Oikos 46:1–2
Jordan PW, Nobel PS (1979) Infrequent establishment of seedlings of Agave deserti (Agavaceae) in the northwestern Sonoran desert. Am J Bot 66:1079–1084
Lange R, Purdie R (1976) Western Myall (Acacia sowdenii), its survival prospects and management needs. Aust Rang J 1:64–69
Louda SM (1982a) Limitation of the recruitment of the shrub Haplopappus suarrosus (Asteraceae) by flower and seed-feeding insects. J Ecol 70:43–53
Louda SM (1982b) Distribution ecology: variation in plant recruitment over a gradient in relation to insect seed predation. Ecol Monogr 52:25–41
Mallik AU, Hobbs RJ, Legg CJ (1984) Seed dynamics in Calluna arctostaphylos heath in northeastern Scotland. J Ecol 72:855–871
Miles J (1972) Experimental establishment of seedlings on a southern English heath. J Ecol 60:225–234
Norton DA (1973) Population dynamics of subalpine Libocedrus bidwillii forests in the Cropp River Valley, Westland, New Zealand. NZ J Bot 21:127–134
O'Dowd DJ, Gill AM (1984) Predator satiation and site alteration: mass reproduction of alpine ash (Eucalyptus delegatensis) following fire in southeastern Australia. Ecology 65:1052–1066
Peart DR (1989) Species interactions in a successional grassland. I. Seed rain and seedling recruitment. J Ecol 77:236–251
Putwain PD, Machin D, Harper JL (1968) Studies in the dynamics of plant populations. II. Components and regulation of a natural population of Rumex acetosella L. J Ecol 56:421–431
Reichman OJ (1979) Desert granivore foraging and its impact on seed densities and distributions. Ecology 60:1085–1092
Risch SJ, Carroll CR (1986) Effects of seed predation by a tropical ant on competition among weeds. Ecology 67:1319–1327
Watkinson AR, Lonsdale WM, Andrew MH (1989) Modelling the population dynamics of an annual plant: Sorghum intrans in the wet-dry tropics. J Ecol 77:162–181
Wellington AB, Noble IR (1985) Seed dynamics and factors limiting recruitment of the mallee Eucalyptus incrassata Labill. in semi-arid, southeastern Australia. Aust J Ecol 73:657–666
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Andersen, A.N. How important is seed predation to recruitment in stable populations of long-lived perennials?. Oecologia 81, 310–315 (1989). https://doi.org/10.1007/BF00377076
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DOI: https://doi.org/10.1007/BF00377076