Most of the forest lives in the shadow of the giants that make up the highest canopy. These are the oldest trees, with hundreds of children and thousands of grandchildren. They check in with their neighbors, sharing food, supplies, and wisdom gained over their long lives.
大部分森林生活在像巨人一样的 最高树冠形成的阴影下, 它们是最古老的树, 并拥有成百上千的子孙。 它们与邻居联系紧密, 与邻居分享食物、供给 和长久一生中所获得的智慧。
They do all this rooted in place, unable to speak, reach out, or move around. The secret to their success lies under the forest floor, where vast root systems support the towering trunks above. Partnering with these roots are symbiotic fungi called mycorrhizae.
它们扎根一处,完成了这一切, 不能讲话、伸出去或四处移动, 其成功的秘诀在于森林地面之下, 巨大的根系统支持上面高耸的树干。 与这些树根相配合的是共生真菌, 称为菌根。
These fungi have countless branching, thread-like hyphae that together make up the mycelium. The mycelium spreads across a much larger area than the tree root system and connect the roots of different trees together. These connections form mycorrhizal networks. Through mycorrhizal networks, fungi can pass resources and signaling molecules between trees.
这些真菌有无数的分岔的线状菌丝, 菌丝构成菌丝体。 菌丝体扩散的区域比树根系统更大, 并通过根把不同树连接在一起, 这些联结形成了菌根网络。 通过菌根网络, 真菌可以在树木之间 传递资源和信号分子。
We know the oldest trees have the largest mycorrhizal networks with the most connections to other trees, but these connections are incredibly complicated to trace. That’s because there are about a hundred species of mycorrhizal fungi– and an individual tree might be colonized by dozens of different fungal organisms, each of which connects to a unique set of other trees, which in turn each have their own unique set of fungal associations. To get a sense of how substances flow through this network, let’s zoom in on sugars, as they travel from a mature tree to a neighboring seedling.
我们知道最古老的树有 最大的菌根网络, 与其他树的联系最多, 但这些联系追踪起来非常的复杂。 因为大约有一百种菌根真菌—— 一棵树可被几十种 不同的真菌生物所占领, 每种真菌连接到特定的树种, 因此每种树拥有特定的真菌组织。 要了解物质如何在网络间流通, 我们来观察一下糖类 如何从成年的树传输到邻近幼苗。
Sugar’s journey starts high above the ground, in the leaves of the tallest trees above the canopy. The leaves use the ample sunlight up there to create sugars through photosynthesis. This essential fuel then travels through the tree to the base of the trunk in the thick sap.
糖类旅行开始远高于地面, 在树冠上方最高的树木的叶子。 叶子利用充足的阳光 通过光合作用产生糖分, 这种必要的养料通过树木 进入树干底部的浓树液中。
From there, sugar flows down to the roots. Mycorrhizal fungi encounter the tips of the roots and either surround or penetrate the outer root cells, depending on the type of fungi. Fungi cannot produce sugars, though they need them for fuel just like trees do. They can, however, collect nutrients from the soil much more efficiently than tree roots— and pass these nutrients into the tree roots. In general, substances flow from where they are more abundant to where they are less abundant, or from source to sink. That means that the sugars flow from the tree roots into the fungal hyphae. Once the sugars enter the fungus, they travel along the hyphae through pores between cells or through special hollow transporter hyphae. The fungus absorbs some of the sugars, but some travels on and enters the roots of a neighboring tree, a seedling that grows in the shade and has less opportunity to photosynthesize sugars.
从那里,糖流到根部。 菌根真菌遇到根尖, 然后,根据真菌的类型, 它们会围绕或穿透外根细胞。 真菌不能产生糖,尽管它们 像树一样需要糖作为养分。 然而, 它们可以比树根更高效的 吸收土壤中的营养—— 并将这些营养素传递进树根里。 通常, 物质会从更丰富的地方 流向缺乏的地方, 或者从源到库。 也就是说,糖从树根流到真菌菌丝。 一旦糖进入真菌, 它们沿着菌丝穿过细胞间的气孔, 或通过特殊的空心传送者菌丝。 真菌吸收一部分糖分, 但有些糖会继续进入相邻树的根, 一棵树荫下生长的小树, 它光合作用产生糖的机会少一些。
But why does fungus transport resources from tree to tree? This is one of the mysteries of the mycorrhizal networks. It makes sense for fungus to exchange soil nutrients and sugar with a tree— both parties benefit. The fungus likely benefits in less obvious ways from being part of a network between trees, but the exact ways aren’t totally clear. Maybe the fungus benefits from having connections with as many different trees as possible, and maximizes its connections by shuttling molecules between trees. Or maybe plants reduce their contributions to fungi if the fungi don’t facilitate exchanges between trees.
但为何真菌要在树间传送营养呢? 这是菌根网络的未解谜题之一。 真菌与树交换土壤养分和糖—— 实现共赢,是说得通的。 真菌可能以不明显的方式 从树间网络中获益, 但确切的方法并不完全清楚。 也许这种真菌得益于 与尽可能多的、不同的树建立联系, 并通过在树间来回运输分子 以实现其联系最大化。 如果真菌不促进树间的养分交流, 树可能会减少对真菌的供给。
Whatever the reasons, these fungi pass an incredible amount of information between trees. Through the mycorrhizae, trees can tell when nutrients or signaling molecules are coming from a member of their own species or not. They can even tell when information is coming from a close relative like a sibling or parent. Trees can also share information about events like drought or insect attacks through their fungal networks, causing their neighbors to increase production of protective enzymes in anticipation of threats.
无论何因, 这些真菌在树间传递了大量的信息。 通过菌根,树可以分辨出养分或信号分子 是否来自它们自己物种的成员。 它们甚至可以判断信息 是否来自近亲, 像手足或父母。 树还可以通过真菌网络分享信息, 如干旱或昆虫的袭击, 在威胁来临前, 引起邻近树木增加保护酶的产量。
The forest’s health relies on these intricate communications and exchanges. With everything so deeply interconnected, what impacts one species is bound to impact others.
森林的健康仰赖这些 复杂的沟通和交换。 由于万物紧密的相互联系, 影响一个物种的因素 必然会影响其他物种。