Kemp William P, Dennis Brian
Rangeland Insect Laboratory, USDA Agricultural Research Service, 59717-0366, Bozeman, MT, USA.
College of Forestry, Wildlife, and Range Sciences, University of Idaho, 83844, Moscow, ID, USA.
Oecologia. 1993 Oct;96(1):1-8. doi: 10.1007/BF00318023.
We tested for the existence of density dependence in annual adult rangeland grasshopper (Orthoptera: Acrididae) data from Montana, USA (1951-1991). Statistical density dependence was, in the sense of a stochastic equilibrium or return tendency, detected in all of the grasshopper mean density time-series from the three major physiographic regions of the state, Northern Glaciated Plains, Southern Unglaciated Plains, and Western Mountains. Parameters were estimated for a model that described the stochastic equilibrium characteristics of regional mean densities. The analyses showed that rangeland grasshopper regional densities fluctuate according to gamma distribution with a mean of 6.1-6.3 grasshoppers per m. Further, when regions exhibit outbreaks, the resulting infestation period (duration of outbreak) is short, spanning only a few generations.
我们在美国蒙大拿州（1951 - 1991年）成年草原蝗虫（直翅目：蝗科）年度数据中测试了密度依赖性的存在。从该州三个主要地貌区域，即北部冰川平原、南部非冰川平原和西部山区的所有蝗虫平均密度时间序列中，在随机平衡或回归趋势的意义上检测到了统计密度依赖性。对一个描述区域平均密度随机平衡特征的模型进行了参数估计。分析表明，草原蝗虫区域密度按照伽马分布波动，平均每平方米有6.1 - 6.3只蝗虫。此外，当区域出现蝗灾时，由此产生的侵染期（蝗灾持续时间）很短，仅跨越几代。
