YOUNG, H. 1963. Age-specific mortality in the eggs and nestlings of blackbirds. Auk 80:145-155. ZIMMERMAN, J. L. 1984. Nest predation and its relationship to habitat and nest density in dickcissels.

No abstract

Coral ardisia (Ardisia crenata) has been present in Florida for more than 100 yr as an ornamental and has become invasive in hammocks of natural areas. This plant forms dense understory cover, often greater than 90%, which can suppress native plant recruitment and growth. Results from herbicide trials at two sites in Florida indicate that a single foliar treatment applied as a spot application of triclopyr amine, triclopyr ester, glyphosate, imazapic, dicamba, triclopyr amine + imazapic, or triclopyr ester + fluroxypyr reduced Ardisia crenata to less than 13% at 12 mo after treatment (MAT). A single treatment of imazapic (2.4 g ae L−1) or imazapic (2.4 g ae L−1) + triclopyr (10.8 g ae L−1) reduced cover of mature plants to less than 0.5% and seedlings to less than or equal to 4% at 12 MAT. Native plant cover was less than 5% prior to treatment indicating that dense infestations of Ardisia crenata may suppress native vegetation. In the dense infestations of Ardisia crenata observed in this study, nontarget damage was not a concern due to the rarity of native plants. However, applicators should use caution applying triclopyr and imazapic when small shrubs and trees are present in the treatment area. Additional follow-up treatments will be required for control of seedling and possible resprouts at 12 MAT.

Old World climbing fern (OWCF) spores had lower germination rates (P = 0.0072) after being frozen for ≥ 3 h compared to < 3 h, and were highly susceptible to freezing periods ≥ 6 h with a 5.8- to 13.3-fold reduction in spore germination compared to controls. Freezing temperature did not affect germination of Japanese climbing fern (JCF) spores compared to controls (P = 0.32). OWCF gametophytes had reduced survival at all exposures to freezing temperatures compared to controls (P < 0.0001), and had < 0.5% survival for exposure times ≥ 3 h. The gametophytes of JCF had reduced survival at exposures to freezing temperatures ≥ 1 h (P < 0.0001) compared to controls. JCF gametophyte survival was 52.5% at 3-h exposure time, but was reduced to ≤ 0.1% at exposure times ≥ 6 h. All OWCF sporophytes exhibited 100% necrosis for all exposure times 24 h postexposure, but new growth from resprouts was observed for exposure time ≤ 6 h at 6 mo postfreezing. OWCF sporophytes' dry weight biomass was greatly reduced for all exposure times compared to controls (P < 0.0001). Results with nonlinear regression (P < 0.0001, R2 = 0.92) indicated that a single freeze for 2.4 h at −2.2 C reduced OWCF dry weight biomass to 0.01 g, a 10-fold reduction, at 6 mo postfreezing. These results indicate that JCF spores and gametophytes are more tolerant of longer exposure periods to freezing temperatures than OWCF, but OWCF exhibited the potential to spread further into northern Florida.

Old World climbing fern (OWCF) is a highly invasive fern that disrupts natural communities in central and southern Florida. OCWF produces copious, wind-blown spores that have propelled its rapid invasion of Florida's natural areas over the last few decades. Current management of OWCF is limited to herbicides and natural resource managers in Florida have questioned if herbicides inhibit spore germination. This study compared spore germination rates of OWCF exposed to six herbicides and a surfactant from 1 to 24 h under laboratory conditions. Spores of OWCF were highly susceptible to metsulfuron, but exhibited tolerance to imazapyr, glyphosate, fluroxypyr, asulam, and triclopyr. Spore germination rates were 0.4% for spores exposed to 0.1 g ai L−1 of metsulfuron, but 0% for rates greater than or equal to 0.2 g ai L−1 at 30 d after treatment (DAT). Reduction in spore germination was observed with all other concentrations of herbicides tested, ranging from 10.4% with triclopyr (40 g ai L−1) to 42.6% with asulam (4.2 g ai L−1) compared to 47.9% germination for untreated checks 30 DAT. Spores were highly sensitive to metsulfuron with herbicide concentrations required for 50 and 95% inhibition of spore germination (I50 and I95) measuring 0.014 and 0.063 g ai L−1, respectively; spores were greater than 1,000-fold more sensitive to metsulfuron compared to I95 concentrations of any other herbicide tested. These results indicate that metsulfuron exhibits potential to control OWCF spore germination but spores are tolerant to the five other herbicides tested.