The impact of an invasive ambrosia beetle on the riparian habitats of the Tijuana River Valley, California.

摘要: The Tijuana River Valley is the first natural habitat in California to be substantially invaded by Kuroshio Shot Hole Borer (KSHB, Euwallacea sp.), an ambrosia beetle native Southeast Asia. This paper documents distribution of KSHB riparian vegetation valley and assesses damage done as early 2016, approximately six months after was observed valley. I divided habitats into 29 survey units so that within each unit relatively homogenous terms plant species composition, age density. From a random point unit, examined 60 individuals dominant for evidence infestation major such limb breakage. In 22 forested units,I arroyo black willows (Salix lasiolepis Benth. S. gooddingii C.R. Ball), seven scrub units, mule fat (Baccharis salicifolia (Ruiz & Pav.) Pers.). Evidence found 25 units. forest rates ranged from 0 100% were high (>60%) 16 33%. Infestation significantly correlated with wetness unit; wetter had higher rates. physical 24 dense stands reduced broken trunks several areas. Overall, estimated more than 280,000 (70%) infested, 140,000 suffered damage. addition, recorded other common valley; 23 examined, 14 showed attack. four highest trees Salicaceae family. three considered worst invasive plants valley, Ricinus communis L., Tamarix ramosissima Ledeb. Arundo donax low infestation. Several findings this study have significance resource managers: (1) attack caused extensive mortality soon being discovered so, if managers are control spread beetle, they will need develop effective detection rapid response program; (2) wet, trying detect areas should thoroughly search near water, particularly nutrient-enriched water; (3) appears novel form disturbance, affected forests may special management actions order recover; (4) has altered structure canopy, likely promote growth inconspicuous prior but now attention.