Ants accelerate succession from mountain grassland towards spruce forest

Question: What is the role of mound‐building ants (Lasius flavus) in successional changes of a grassland ecosystem towards a spruce forest? Location: Slovenské Rudohorie Mountains, Slovakia; ca. 950 m a.s.l. near the Obrubovanec point (1020 m a.s.l.; 48°41′N, 19°39′E). Methods: Both chronosequence data along a successional gradient and temporal data from long‐term permanent plots were collected on ants, spruce establishment, and vegetation structure, together with additional data on spruce growth. Results: There are more spruce seedlings on ant mounds (4.72 m^?2) than in the surrounding vegetation (0.81 m^?2). Spruce seedlings grow faster on these mounds compared to surrounding areas. The first colonization wave of seedlings was rapid and probably occurred when grazing prevailed over mowing. Ant colony presence, mound volume, and plant species composition change along the successional gradient. Mounds become bigger when partly shaded but shrink in closed forest, when ant colonies disappear. Shade‐tolerant acidophylic species replace grassland plants both on the mounds and in surrounding areas. Conclusions: The massive occurrence of Lasius flavus anthills contributes to a runaway feedback process that accelerates succession towards forest. The effect of ants as ecosystem engineers is scale‐dependent: although they stabilize the system at the scale of an individual mound, they may destabilize the whole grassland system over a longer time scale if combined with changes in mowing regime.     

家白蚁的群飞及其在巢位判断中的地位

“群飞”是白蚁群体生活史中的一个重要环节。家白蚁(Coptotermes formosanus Shiraki)的群飞与气象因子有着密切关系。张祯祥(1956)、李始美(1958)、唐觉、李参(1959)、张寿东(1965)、大井达也(1965)、赵元(1981)和广东省昆虫研究所白蚁研究室(1982),都曾先后有过报道。笔者在前人工作的基础上,结合自己二十余年的工作实践,对家白蚁的群飞与巢位间所存在的内在联系、群飞这一生理现象在巢位判断中的作用等与巢位判断相关的问题,作了一些观察和研究。现整理如下。