Ocko Samuel A, King Hunter, Andreen David, Bardunias Paul, Turner J Scott, Soar Rupert, Mahadevan L
Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
J Exp Biol. 2017 Sep 15;220(Pt 18):3260-3269. doi: 10.1242/jeb.160895.
How termite mounds function to facilitate climate control is still only partially understood. Recent experimental evidence in the mounds of a single species, the south Asian termite , suggests that the daily oscillations of radiant heating associated with diurnal insolation patterns drive convective flow within them. How general this mechanism is remains unknown. To probe this, we consider the mounds of the African termite , which thrives in a very different environment. By directly measuring air velocities and temperatures within the mound, we see that the overall mechanisms and patterns involved are similar to that in the south Asian species. However, there are also some notable differences between the physiology of these mounds associated with the temporal variations in radiant heating patterns and CO dynamics. Because of the difference between direct radiant heating driven by the position of the sun in African conditions, and the more shaded south Asian environments, we see changes in the convective flows in the two types of mounds. Furthermore, we also see that the south Asian mounds show a significant overturning of stratified gases, once a day, while the African mounds have a relatively uniform concentration of CO Overall, our observations show that despite these differences, termite architectures can harness periodic solar heating to drive ventilation inside them in very different environments, functioning as an external lung, with clear implications for human engineering.
白蚁丘如何发挥作用以促进气候调节仍仅得到部分理解。最近在单一物种——南亚白蚁的蚁丘中的实验证据表明，与昼夜日照模式相关的辐射加热的每日振荡驱动了蚁丘内部的对流。这种机制的普遍性仍然未知。为了探究这一点，我们研究了非洲白蚁的蚁丘，它们在非常不同的环境中繁衍生息。通过直接测量蚁丘内的空气流速和温度，我们发现其中涉及的总体机制和模式与南亚物种相似。然而，这些蚁丘的生理学在与辐射加热模式和二氧化碳动态的时间变化相关方面也存在一些显著差异。由于非洲环境中由太阳位置驱动的直接辐射加热与南亚环境中更多阴影的差异，我们看到了两种类型蚁丘中对流的变化。此外，我们还发现南亚蚁丘每天有一次分层气体的显著翻转，而非洲蚁丘中二氧化碳浓度相对均匀。总体而言，我们的观察表明，尽管存在这些差异，白蚁建筑结构可以利用周期性的太阳能加热在非常不同的环境中驱动其内部通风，起到外部肺的作用，这对人类工程有明确的启示。
