宁夏荒漠草原针毛收获蚁对植物种子的觅食作用

Studies on the foraging function of Messor aciculants (F. Smith) on plant seeds in desert steppe ecosystem of Ningxia, China

针毛收获蚁 Messor aciculatus( F.Smith)是西北荒漠地区典型的食种子蚂蚁种类之一。以宁夏中卫县沙坡头自然保护区红卫固定沙丘地段为主要研究基地。由田间系统调查和室内饲养得出 :针毛收获蚁可取食的植物种子达 30余种以上。在红卫固定沙丘草地针毛收获蚁的自然种群收获的植物种子主要有 6种 :狗尾草 Setaria viridis、猪毛菜 Salsola collina、雾冰藜 Bassia dasyphylla、地锦 Euphobia humifuse、刺沙蓬 Salsola ruthenica、叉枝鸦葱 Scorzonera divaricata。被收获的种子大小主要在 1 .2 0～ 2 .5 0 mm之间 ,或有棱角、扁平、易于衔夹的种子。在蚁巢中种子以种类和形态的不同被分类、分层保存于不同深处的巢室 ,总贮量随工蚁和蚁后数量的增加而增加。在自然条件下 ,收获的种子种类及数量与穴巢附近环境中的植物种类及分布有关。蚂蚁对种子的收集贮藏在一定程度上可影响种子的萌发力 ,特别是对一些 1年生质量较轻的种子影响力较大。蚂蚁觅食对土壤中种子库种子密度的影响因植物种类的不同而异 ,其中对 1年生草本植物影响较大 。

Messor aciculatus (F. Smith) is a seed harvester dominant ant in the desert steppe ecosystem of northwest China. The investigation and experiment site lay in the fixed sand hill grassland of Hongwei at the Sha Po tou Protected Region in Zhongwei County in Ningxia. We dug 6 colonies of ants among which there were 600 ant workers fed on 30 kinds of plant seeds, among which 22 kinds were harvested and fed by the ant workers in the artificial raising experiment. Six dominant seeds were found in natural nest of Messor aciculatus, including Setaria viridis, Salsola collina, Bassia dasyphylla, Euphobia humifuse, Salsola ruthaeoides, Scorzonera divaricata. Setaria viridis and Salsola collina were dominant in number and weight in total preservation. The seed size is 1.20～2.50mm with edges and corners. They may be easy to be carried and foraged. The seed amount in nest was increased with the increasing of workers and queens' numbers. The amount of seeds in the nest was increased with the numbers of workers and greens. The number of storage seeds varied according to the depth of the nest. The germination rate of seeds could be reduced remarkably by the storage of Messor aciculatus , especially for some annual plant seeds with small quality. The deeper the storage depth, the lower the germination rate. Under the natural condition, the kinds and quantities of seeds are correlative with the varieties and distribution of seeds within the area of 8m surrounding the nest. The number of preferred seeds accounted for 50 percent of the total number of preferred seeds in the soil seed bank. The effect of the forage on the density of seeds in the soil seed bank was different with the different kinds of plants, especially, the distribution of preferred seeds, which further effected the composition and space distribution of plant community. The main effect is the farther distance from the nest, the higher the numbers of Setaria viridis, Salsola collina.