当植物和虫子对资源存在竞争时，全世界的植物都可能形成“精灵圈”。这不是魔法。
翻译 韩宇
审校 卓思琪
位于巴西的土丘和 murundus。树只在土丘顶部生长。
图片来源：Edu Jung
精灵圈指的在达片植物生长的地方，由植物贫瘠的的圆圈状，它们通常被一圈茂盛生长的草所包围，直径在2-15米不等。它们看起来有点儿像麦田圈，又有点儿像土方艺术。在全世界，它们拥有很多名字：在非洲纳米布沙漠形成的叫“精灵圈（fairy circles）”；在巴西叫，它们被称作 “murundus”；在北美，它便是最为人所熟知的“美马冢（Mima mounds）”。
普林斯顿大学的生态学家 Corina E. Tarnita 及同事在 Nature 上发文，称之为“元素过分散（均布）景观（landscapes of overdispersed (evenly spaced) elements）”。这些区域的所有植物都长成了如此完美对称的大规模图案，这似乎有些不正常。
生态学家们热烈地讨论着这些图案的成因是否有相同点，其中，“植物协作”和“昆虫竞争”成为了最热门的假设。在水资源匮乏和不规律的地区，植物会运行“尺度依赖反馈”机制，它们在广阔的区域中聚集成一簇簇，而不是铺散开生长。
这样的机制使得植物成簇生长，植株的大小被限制，从而可以更好地利用水分。同时，该策略也保证了生殖成功。这大概也可解释精灵圈和美马冢的形成原因了。
但一些科学家反驳这一说法，他们认为是敌对的白蚁家族瓜分了这些区域的水资源。它们将水从干旱地区吸走，然后移至它们筑巢的土丘。另外，成功的蚁穴拥有大致相当的领土面积，这也许就能解释为什么那么多奇怪的区域同时存在土丘和干旱斑块。
研究者正在纳米布沙漠中检测一个精灵圈的结构。注意植物在空白圆圈周围成簇的生长为环形。
图片来源：Tyler Coverdale
Tarnita 和同事在文章中提出，植物和白蚁可能存在一种非比寻常的相互作用。它们都试图在干旱区域维持自身对水资源的获取。借助计算机模型对植物和昆虫生命周期的还原，研究者可以得到和精灵圈一模一样的图案。
Tarnita 在接受采访时惊讶地说道：“能够得到如此完整而美丽的几何图案，简直太神奇了。如此渺小的生物只是每天在自己的地盘上做它们该做的事情，最后竟然制造出了难以置信的大规模图案……大自然简直太神奇了。”
尽管我们还不确定是何种力量造成这些神秘而整齐的景观，但 Tarnita 及同事的模型帮助我们又向真相迈进了一步。
他研究者认为，我们正处于了解生态自组织的新时代，其中一部分原因是卫星图像为观察像精灵圈这样的图案特征提供了便利，但也仅仅是理解“生命群落是如何通过相互作用产生这种奇异分割环境”的开端。
科学家们呼吁道：“要集中理论和经验，努力找到多种机制跨尺度相互作用以构建生态系统的方法。”
大自然从不像看上去的那么简单。
文章来源
https://arstechnica.com/science/2017/01/all-over-the-globe-plants-are-growing-into-strange-circular-patterns/
查看更多分领域论文推荐，就到
www.keyanquan.net
也可提取下方二维码
论文信息
【题目】A theoretical foundation for multi-scaleregular vegetation patterns
【作者】Corina E. Tarnita, Juan A. Bonachela, EfratSheffer, Jennifer A. Guyton, TylerC. Coverdale, Ryan A.Long & Robert M. Pringle
【刊期】Nature 541, 398–401
【发表日期】18 January 2017
【DOI】10.1038/nature20801
【摘要】Self-organized regular vegetation patternsare widespread and thought to mediate ecosystem functions such as productivityand robustness, but the mechanisms underlying their origin and maintenanceremain disputed. Particularly controversial are landscapes of overdispersed(evenly spaced) elements, such as North American Mima mounds, Brazilian murundus,South African heuweltjies, and, famously, Namibian fairy circles. Two competinghypotheses are currently debated. On the one hand, models of scale-dependent feedbacks,whereby plants facilitate neighbours while competing with distant individuals,can reproduce various regular patterns identified in satellite imagery. Owingto deep theoretical roots and apparent generality, scale-dependent feedbacksare widely viewed as a unifying and near-universal principle of regular-patternformation despite scant empirical evidence. On the other hand, manyoverdispersed vegetation patterns worldwide have been attributed tosubterranean ecosystem engineers such as termites, ants, and rodents. Althoughpotentially consistent with territorial competition, this interpretation hasbeen challenged theoretically and empirically and (unlike scale-dependentfeedbacks) lacks a unifying dynamical theory, fuelling scepticism about its plausibilityand generality. Here we provide a general theoretical foundation forself-organization of social-insect colonies, validated using data from fourcontinents, which demonstrates that intraspecific competition betweenterritorial animals can generate the large-scale hexagonal regularity of thesepatterns. However, this mechanism is not mutually exclusive withscale-dependent feedbacks. Using Namib Desert fairy circles as a case study, wepresent field data showing that these landscapes exhibit multi-scalepatterning—previously undocumented in this system—that cannot be explained byeither mechanism in isolation. These multi-scale patterns and other emergentproperties, such as enhanced resistance to and recovery from drought, insteadarise from dynamic interactions in our theoretical framework, which couplesboth mechanisms. The potentially global extent of animal-induced regularity invegetation—which can modulate other patterning processes in functionallyimportant ways—emphasizes the need to integrate multiple mechanisms ofecological self-organization.
【原文链接】http://www.nature.com/nature/journal/v541/n7637/full/nature20801.html
阅读更多
内容合作请联系
[email protected]
