Tham khảo tài liệu 'gmat reading episode 1 part 5', ngoại ngữ, ngữ pháp tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Generated by Foxit PDF Creator Foxit Software http For evaluation only. D They contributed to the employment of many Irish construction workers. E They provided assistance for construction businesses owned by members of other ethnic groups. argument that spraying where the pollinators are sensi- 35 tive to the pesticide used decreases plant fecundity. The question of whether the decrease in plant fecundity caused by the spraying of pesticides actually causes a decline in the overall population of flowering plant species still remains unanswered. Plant species dependent 40 solely on seeds for survival or dispersal are obviously more vulnerable to any decrease in plant fecundity that occurs whatever its cause. If on the other hand vegetative growth and dispersal by means of shoots or runners are available as alternative reproductive strategies for a 45 species then decreases in plant fecundity may be of little consequence. The fecundity effects described here are likely to have the most profound impact on plant species with all four of the following characteristics a short life span a narrow geographic range an incapacity for vege- 10 various pesticides have been sprayed in the past 25 years 50 tative propagation and a dependence on a small number Passage 20 Species interdependence in nature confers many benefits on the species involved but it can also become a point of weakness when one species involved in the relationship is affected by a catastrophe. Thus flowering 5 plant species dependent on insect pollination as opposed to self-pollination or wind pollination could be endangered when the population of insect-pollinators is depleted by the use of pesticides. In the forests of New Brunswick for example of insect-pollinator species. Perhaps we should give special attention to the conservation of such plant species since they lack key factors in their defenses against the environmental disruption caused by pesticide use. 1. Which of the .
