IV. Reading Comprehension: 15%1.       Exotic insect pests can produce both short and long-term effects on forestecosystem. Short-term effects include the disturbances directly associated with theaction of the pest, which may cause the defoliation, loss off vigor, or death. Long-termeffects are primarily mediated by changes in tree species composition and theconsequent alterations of forest structure, productivity, and nutrient uptake. Exoticpests are more efficient than most abiotic disturbances (e.g., fire or wind) at producinglong-term changes in species composition. Pests often target specific tree species and,if they become established, they usually remain as permanent components of theecosystem. Shifts in forest species composition ramify through the ecosystem in manyways because tree species have different, often unique properties.
【題組】41. Which of the following as effects if exotic pests on forest ecosystems is notmentioned in the passage?
(A)decreased vitality in trees
(B) defoliation of trees
(C) changes in forest structure
(D)transport of nutrients