The frequency of tropical cyclones is a major factor affecting the vegetation of the Mariana Islands, where these storms are called typhoons. An average of about one typhoon per year has passed within ≈100 km of Guam during the past 50 years. The physiognomy of Guam's natural and urban forests is largely determined by these typhoons. The impact of each typhoon is determined by a long list of interacting factors such as species characteristics; environmental and horticultural conditions preceding the typhoon; the intensity, direction, and duration of winds; the amount of rainfall associated with the typhoon; and the environmental and horticultural conditions following the disturbance. Many species survive typhoons by reducing aerodynamic drag of the canopy by abscising inexpensive leaves or breakage of small stems which results in an intact major structural framework. Speed of recovery for nonlethal damage following disturbance depends on nonlimiting conditions during recovery. Thus, the most destructive typhoons are those that occur in sequence with other environmental stresses. The most common of these may be heat and high-light stress, associated with subsequent high pressure systems, and severe drought conditions. For example, the 230–298 km·h–1 winds of Typhoon Paka in Dec. 1997 were followed by the driest year on record for Guam. Typhoon debris and drought generated 1400 forest and grassland fires from Jan. through May 1998. Sequential typhoons are also severely damaging. For example, Guam experienced three direct eye passages and two more typhoons within 113 km during the months Aug. to Nov. 1992. Damage susceptibility and recovery dynamics will be discussed in relation to these and other physical, chemical, biological, and human-induced factors.
An understanding of nitrogen (N) uptake and the partitioning of N during the season by the carrot crop (Daucus carota subsp. sativus [Hoffm.] Arkang.) is required to develop more efficient N fertilization practices. Experiments were conducted on both organic and mineral soils to track the accumulation of dry matter (DM) and N over the growing season and to develop an N budget of the crop. Treatments included two carrot cultivars (`Idaho' and `Fontana') and 5 N rates ranging from 0% to 200% of the provincial recommendations in Ontario. Foliage and root samples were collected biweekly from selected treatments during the growing season and assessed for total N concentration. Harvest samples were used to calculate N uptake, N in debris, and net N removal values. Accumulation of DM and N in the roots was low until 50 to 60 days after seeding (DAS) and then increased linearly until harvest for all 3 years regardless of the soil type, cultivar, and N rate. Foliage dry weight and N accumulation were more significant by 50 to 60 DAS, increased linearly between 50 and 100 DAS, and reached a maximum or declined slightly beyond 100 DAS in most cases. The N application rates required to maximize yield on mineral soil resulted in a net loss of N from the system, except when sufficient N was available from the soil to produce optimal yield. On organic soil, a net removal of N occurred at all N application rates in all years. Carrots could be used as an N catch crop to reduce N losses in a vegetable rotation in conditions of high soil residual N, thereby improving the N use efficiency (NUE) of the crop rotation.
Quantitative studies of plant roots are a consistent challenge. Extraction of roots from soil and debris of large samples for biomass quantification is time-consuming and tedious ( Calfee, 2003 ). This tends to limit research to small experiments
. 633 ) conducted a study in four greenhouses over a 28-week period in which they collected plant and growing medium debris and captured insects on yellow sticky cards attached to the inside of 32-gal containers. Western flower thrips, fungus gnats, and
sustainable and economical option for containerized plant production. Hummel et al. (p. 325) produced composts from biosolids and woody wastes, including construction debris, storm debris, and horse waste. They screened and blended the composts with bark to
from the Dec. 2000 storm was ≈50% and 35% in Jan. 2007. Damage in 2000 consisted of limb breakage and split limb crotches described earlier. In 2007, about one-half of the debris was from compensatory shoots 3 to 4 inches in diameter that were 15 to 20
collected from these nurseries included 1) diseased plants showing symptoms such as dieback, root rot, shoot blight, leaf lesions, defoliation ( Fig. 1A–E ); 2) soil, gravel, and leaf debris from underneath the pots from a symptomatic area ( Fig. 2A–D ); 3
berries per centimeter. The number of pieces of dehiscent floral debris retained in each cluster was also counted ( Hed et al., 2009 ). A subsample of frozen berries from each experimental unit (≈500 g) was thawed in a water bath at 60 °C, then ground in a
another bin for disposal was recorded. For the Paddock Vac, the time to pick up chestnuts and burs, sort them, move the equipment, and dump the burs and other debris was recorded. Nut numbers and their fresh weights were also recorded to calculate the time
., 2006 ; Sikora and Szmidt, 2001 ). Burkhard et al. (2009) found greater growth and yield in blueberry when using seafood- or manure-based composts. Larco et al. (2013) also reported better growth and yield in blueberry when using yard-debris compost