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.
Depending on the materials used to produce a compost, it will contain lower or higher levels of nutrients and metals. If composts have been appropriately matured, nutrients are in plant-available forms for crop production, and the compost pH will be near neutral. After 25 years of research and development of regulations and advice for biosolids and compost utilization, pretreatment of industrial wastes allows biosolids composts, and composts prepared from biosolids mixed with municipal solid wastes or yard debris to contain levels of microelements needed for plant nutrition but not high levels that could cause phytotoxicity. Composts can supply N, P, K, Ca, Mg, Fe, Zn, Cu, Mn, B, Mo, and Se required by plants or animals. When used in potting media, supplemental N fertilization is usually required, depending on crop requirements. Use of compost can replace other forms of microelements used as fertilizers in media or fields. Detailed evaluation of potential food chain transfer of Cd, Pb, and other elements in composts clearly shows that consumption of 60% of garden foods produced on pH 5.5 soils with 1000 t compost/ha would not comprise risk over a lifetime of consumption, nor would ingesting the composts at 200 mg/day for 5 years. Potentially toxic organic compounds are either destroyed during composting, or bound very strongly by the compost so that plant uptake is trivial. Compost use can be a safe and wise choice for both home and commercial use to replace peat or uncomposted manures, etc. Many states have developed regulatory controls to assure that pathogenic organisms are killed during composting, and that product quality standards are attained that allow marketing for general use in the community.
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
) ( Fig. 1 ) mechanical harvester equipped with a picking head equivalent to the commercial Yung-Etgar evaluated in earlier field tests. Although there was a negligible amount of fruit on the ground, all fruit and debris on the ground alongside the harvest
., 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