caa a22 4500 469097698 CHVBK 20180323133036.0 cr unu---uuuuu 170328e19920901xx s 000 0 eng 10.1007/BF00317633 doi (NATIONALLICENCE)springer-10.1007/BF00317633 Detection of density dependence from annual censuses of bracken-feeding insects [Elektronische Daten] [M. Holyoak, J. Lawton] Summary: A variety of techniques were used to test for density dependence in 32 time series from bracken-feeding insects. Seventeen taxa (primarily species, but including some pooled data from two or more closely related species whose larvae could not be distinguished in frond surveys) occurred on an open site; a woodland site held 15 taxa. For series of 12 years, collected on the open habitat, direct density dependence was detected by one or more of the techniques in 10 (58.8%) of 17 taxa, compared to only 5 (33.3%) of 15 taxa with time series of 8 years in length from the woodland habitat. Delayed density dependence was detected in 6 cases for the open site and in no cases at the woodland site. Either direct or delayed density dependence was found in 13 (76.5%) of 17 taxa for the open site and 13 (86.7%) of the 15 taxa which occurred on both sites. Although these results suggest a high frequency of density dependence in the species making up the bracken insect community, results from individual tests were extremely variable. Density dependence was detected least often by Vickery and Nudds' (1984) test, and most frequently by Varley and Gradwell's (1960) test, although the latter is prone to high rates of detecting spurious density dependence. Direct density dependence was detected most frequently in taxa that were univoltine and did not have delayed diapause, i.e. in those taxa whose life-histories conform most closely to the assumptions of the models underlying the analyses. Delayed density dependence occurred more frequently in species with more complex life-histories at the open site (taxa that were either bivoltine or multivoltine, or had delayed diapause). The results are consistent with the view that that the bracken herbivore assemblage consists of populations which are independently regulated by density dependent processes, although the present analyses suggest that we cannot rely on these tests to firmly show whether density dependence is present or not in an individual time series of the lengths considered here. Springer-Verlag, 1992 Bracken nationallicence Insect populations nationallicence Density dependence nationallicence Delayed density dependence nationallicence Time series nationallicence Holyoak M. Department of Biology, Imperial College at Silwood Park, SL5 7PY, Ascot, Berks, UK aut Lawton J. Department of Biology, Imperial College at Silwood Park, SL5 7PY, Ascot, Berks, UK aut Oecologia Springer-Verlag 91/3(1992-09-01), 425-430 0029-8549 91:3<425 1992 91 442 https://doi.org/10.1007/BF00317633 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00317633 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Holyoak M. Department of Biology, Imperial College at Silwood Park, SL5 7PY, Ascot, Berks, UK aut NATIONALLICENCE 700 1- Lawton J. Department of Biology, Imperial College at Silwood Park, SL5 7PY, Ascot, Berks, UK aut NATIONALLICENCE 773 0- Oecologia Springer-Verlag 91/3(1992-09-01), 425-430 0029-8549 91:3<425 1992 91 442 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer