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.
Večina gozda se nahaja v senci velikanov, ki imajo največje krošnje. To so najstarejša drevesa s stotinami otrok in tisoči vnukov. Pazijo na svoje sosede, si delijo hrano, potrebščine in modrost, ki so jo razvila skozi svoja dolga življenja.
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.
Vse to počnejo zakoreninjena, brez besed, dotikov in premikanja. Skrivnost njihovega uspeha leži pod gozdnimi tlemi, kjer ogromni sistemi korenin podpirajo debla nad njimi. S koreninami sodelujejo simbiotične glive, imenovame mikorize.
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.
Te glive imajo nešteto razvejanih, vlaknom podobnih hif, ki skupaj sestavljajo micelij. Micelij je razvejan po večjem območju kot sistem drevesnih korenin in med sabo povezuje korenine več dreves. Te povezave oblikujejo mikorizno mrežo. Preko teh mrež glive med drevesi prenašajo vire in signalne molekule.
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.
Vemo, da imajo najstarejša drevesa največje mikorizne mreže z največ povezavami do drugih dreves, a tem povezavam je neverjetno težko slediti. To pa zato, ker obstaja okoli sto vrst mikoriznih gliv, vsako drevo ima lahko na sebi na ducate različnih organizmov gliv, od katerih je vsak povezan z drugo skupino dreves, kar pomeni, da ima vsak svojo skupino povezav preko gliv. Da bi dobili občutek, kako snovi tečejo po tej mreži, si oglejmo sladkorje, ki potujejo od zrelega drevesa k sosednji sadiki.
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.
Pot sladkorja se začne visoko nad tlemi v listih najvišjih dreves nad krošnjo. Listi s pomočjo veliko sončne svetlobe s fotosintezo ustvarijo sladkorje. To gorivo potem potuje po drevesu do podnožja debla kot gost sok.
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.
Od tam steče v korenine. Mikorizne glive najdejo konce korenin in jih obkrožijo ali vstopijo v zunanje celice korenin, odvisno od vrste gliv. Glive ne proizvajajo sladkorjev, čeprav jih tudi one potrebujejo kot gorivo. Lahko pa iz prsti bolj učinkovito kot drevesa pobirajo hranila in jih prenašajo v korenine dreves. Na splošno snovi tečejo od tam, kjer jih je več, tja, kjer jih je manj, oziroma od izvira k potrebam. To pomeni, da sladkorji tečejo iz drevesnih korenin v hife gliv. Ko sladkor vstopi v glivo, potuje po hifih skozi pore med celicami ali skozi posebne votle transportne hife. Gliva vsrka nekaj sladkorja, ostali del potuje naprej do korenin sosednjega drevesa, do sadike, ki raste v senci in ima manj priložnosti za fotosintezo sladkorjev.
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.
Ampak zakaj gliva prenaša vire med drevesi? To je ena od skrivnosti mikoriznih mrež. Smiselno je, da gliva z drevesom izmenja sladkorje in hranila iz prsti, oba imata koristi od tega. Gliva ima verjetno koristi od tega, da je del mreže med drevesi, a ne vemo točno, kako. Morda glivam koristijo povezave s čimveč različnimi drevesi, zato te povezave krepijo s prenašanjem molekul med drevesi. Morda pa rastline zmanjšajo svoj prispevek glivam, če te ne pomagajo pri izmenjavi med drevesi.
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.
Kakorkoli že, glive prenašajo neverjetno veliko informacij med drevesi. Skozi mikorize drevesa vedo, ali hranila oziroma signalne molekule prihajajo od drevesa iste vrste ali ne. Vedo celo, kdaj informacija prihaja od bližnjega sorodnika, recimo brata, sestre ali starša. Drevesa delijo tudi informacije o dogodkih, kot je suša, ali napad insektov, vse to skozi mreže gliv. S tem njihovi sosedje povečajo proizvodnjo zaščitnih encimov, da so pripravljeni na grožnje.
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.
Zdravje gozdov je odvisno od teh zapletenih izmenjav. Ker je vse tako zelo povezano med seboj, tisto, kar vpliva na eno vrsto, vpliva tudi na druge.