Gibson David J, Freeman Craig C, Hulbert Lloyd C
Division of Biology, Kansas State University, 66506, Manhattan, KS, USA.
Oecologia. 1990 Sep;84(2):169-175. doi: 10.1007/BF00318268.
A factorial field experiment was designed to test the effects of small mammals and above- and below-ground invertebrates on plant species richness and composition in native tallgrass prairie at Konza Prairie Research Natural Area, northeast Kansas. Over a 4-year period, Microtus ochrogaster densities were maintained by live-trapping in fenced plots, and invertebrate levels were reduced using the pesticides carbaryl for above-ground invertebrates and an organophosphate (isofenphos) for belowground invertebrates. ANOVA according to a split-plot design of plant species biomass data harvested in 1984 and 1986 revealed few significant effects of either small mammal densities or pesticide application. Of 54 species harvested from both sample dates, only 10 were significantly affected by either treatment. Analysis of species richness according to 8 life-form classes provided a clearer pattern of response than did biomass either by species or life-form class. For example, numbers of C4 grasses were reduced by increasing small mammal densities, whereas numbers of C4 annual forbs were lowest when above-ground herbivory was reduced. While consumers have been shown to have strong effects on successional communities, the few significant results observed in this study suggests that the manipulated levels of small mammals and insects had few effects on a mature tallgrass prairie.
在堪萨斯州东北部的孔扎草原研究自然区，设计了一项析因田间试验，以测试小型哺乳动物以及地上和地下无脊椎动物对原生高草草原植物物种丰富度和组成的影响。在4年的时间里，通过在围栏地块中活体诱捕来维持奥氏田鼠的密度，并使用西维因杀虫剂减少地上无脊椎动物的数量，使用有机磷酸酯类（异柳磷）减少地下无脊椎动物的数量。根据1984年和1986年收获的植物物种生物量数据的裂区设计进行方差分析，结果显示小型哺乳动物密度或农药施用几乎没有显著影响。在两个采样日期收获的54个物种中，只有1０个物种受到任何一种处理的显著影响。根据8个生活型类别对物种丰富度进行分析，比按物种或生活型类别分析生物量提供了更清晰的响应模式。例如，C4禾本科植物的数量随着小型哺乳动物密度的增加而减少，而当减少地上食草动物数量时，C4一年生杂类草的数量最低。虽然消费者已被证明对演替群落有强烈影响，但本研究中观察到的少数显著结果表明，小型哺乳动物和昆虫的受控水平对成熟的高草草原影响很小。
