Rodent-limited establishment of bush lupine: field experiments on the cumulative effect of granivory

Citation
Jl. Maron et El. Simms, Rodent-limited establishment of bush lupine: field experiments on the cumulative effect of granivory, J ECOLOGY, 89(4), 2001, pp. 578-588
Citations number
53
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
JOURNAL OF ECOLOGY
ISSN journal
0022-0477 → ACNP
Volume
89
Issue
4
Year of publication
2001
Pages
578 - 588
Database
ISI
SICI code
0022-0477(200108)89:4<578:REOBLF>2.0.ZU;2-T
Abstract
1 Plants often suffer substantial loss of seeds to consumers. However, beca use the seed-to-seedling transition is frequently ignored, quantitative est imates of the effects of seed consumers on plant population dynamics are ra re. 2 We examined how post-dispersal seed predation by rodents affected seedlin g emergence and subsequent adult plant abundance of bush lupine (Lupinus ar boreus), a large N-fixing shrub common to coastal dunes in California. We m onitored patterns of seedling emergence and survival over 3 years for seeds sown into exclosed and control plots. 3 We sowed additional cohorts of seeds in the second and third years and co mpared interannual variation in emergence patterns. 4 Rodent exclusion substantially reduced seedling emergence, with an averag e of 109 seedlings emerging over 3 years from 476 seeds sown in rodent excl usion plots vs. 26 from control plots. The intensity of granivory, however, varied between years, with rodent exclusion increasing emergence from seed s sown in year one, but not in year two. 5 Winter seedling mortality, due to cutworm herbivory, was similarly high i n rodent-free and control plots, and its net impact was to reduce the diffe rence in seedling abundance. Thus. by mid-summer in each of the three years , there were only marginally more seedlings in rodent-excluded vs. control plots. 6 The cumulative effect of protecting seeds, was, however, large. After 3 y ears, an average of four adult lupines were established in rodent-free plot s, whereas only 0.5 were found in control plots and lupine biomass was more than 5-fold higher in exclusion plots. 7 Taken together, the results indicate that rodents play a critical role by limiting the abundance and biomass of a large N-fixing shrub in dunes.