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is liable for the fast distribution of the Russian wheat pest. failed to isolate the Russian wheat aphid in limited locales. provides data about foreign species imported by regulated routes. is responsible for introducing harmful plants onto federal lands.
Human factors affect its rates more than its long-term amount. Natural expansions of species account for their slow contractions. Natural environments created by humans facilitate species movement. Long-range species movement relies on the ranges of man’’s mobility.
earth fertility. import restrictions. natural obstacles. fire disasters.
die away leave off die out leave out
whether the species is considered to be a pest. whether the species enters by a closely-checked route. the rate at which the species extends geographically. the magnitude of the average number of the species.
die away die out die down die off
To explain the difficulties in tracing the pathways for long-established species. To describe the events leading to the detection of non-indigenous species. To identify the problems in assessing the weight of entry tracks for foreign species. To discuss the role of time lags and geographic expansion in species detection.
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