為什么樹會(huì)讓附近的樹樁存活?

為什么樹會(huì)讓附近的樹樁存活?

A tree stump without leaves shouldn't be able to survive on its own. In a New Zealand forest, however, two researchers recently found a leafless stump defying death.

一個(gè)沒有葉子的樹樁是不可能獨(dú)立生存的。然而，在新西蘭的一個(gè)森林里，兩位研究人員最近發(fā)現(xiàn)了一個(gè)沒有葉子的樹樁。

The stump had callus tissue growing over its wounds, and it was also producing resin, a sign of living tissue. While this might leave a casual observer feeling ... stumped, Bader and Leuzinger are ecologists, and they quickly figured out what was going on.

樹樁的傷口上長(zhǎng)著愈傷組織，它還在分泌樹脂，這是活組織的跡象。雖然這可能會(huì)讓一個(gè)不經(jīng)意的觀察者覺得……貝德和魯澤格是生態(tài)學(xué)家，他們被難住了，但很快就弄明白了發(fā)生了什么。

This stump wasn't surviving on its own; it was surviving with help from nearby trees.

這個(gè)樹樁不是靠自己存活的;它是在附近樹木的幫助下存活下來的。

This image shows the Kauri tree stump from the new study. (Photo: Sebastian Leuzinger/iScience)

Trees in a forest are often connected by vast underground networks of symbiotic soil fungi, whose subterranean internet helps the trees exchange nutrients and information. Trees of the same species also sometimes physically graft their roots together, blurring the line between individual trees to the point that an entire forest could be considered a "superorganism," sort of like an ant colony.

森林中的樹木通常由龐大的地下共生土壤真菌網(wǎng)絡(luò)連接，其地下互聯(lián)網(wǎng)幫助樹木交換營(yíng)養(yǎng)和信息。同一物種的樹木有時(shí)也會(huì)把它們的根嫁接在一起，模糊了單個(gè)樹木之間的界限，以至于整片森林都可以被視為“超有機(jī)體”，有點(diǎn)像蟻群。

Linking with neighbors lets trees expand their root systems, providing more stability when growing on a slope — which could be a significant perk for a species known to grow more than 50 meters (164 feet) tall. The stump may be a shadow of its former self aboveground, but it presumably still has a substantial root system underground, and can thus offer some additional stability to its neighbors.

與鄰居的聯(lián)系可以讓樹木擴(kuò)展它們的根系，在斜坡上生長(zhǎng)時(shí)提供更多的穩(wěn)定性——這對(duì)于一個(gè)已知能長(zhǎng)到50米(164英尺)高的物種來說可能是一個(gè)顯著的優(yōu)勢(shì)。樹樁可能是它以前在地面上的影子，但它可能仍然有一個(gè)堅(jiān)實(shí)的地下根系，因此可以為它的鄰居提供一些額外的穩(wěn)定性。

Kauri trees tower above the ground in Waipoua Forest on New Zealand's North Island. (Photo: riekephotos/Shutterstock)

Plus, because a combined root network lets trees exchange water as well as nutrients, a tree with poor access to water could boost its chances of survival in a drought by withdrawing water from the community's shared roots. Yet there could also be drawbacks to that, the researchers point out, since it might enable the spread of diseases like kauri dieback, a mounting problem for this species in New Zealand.

此外，由于一個(gè)聯(lián)合的根系網(wǎng)絡(luò)可以讓樹木交換水和營(yíng)養(yǎng)物質(zhì)，一棵無法獲得水的樹可以通過從社區(qū)共享的根系抽離水來提高其在干旱中生存的機(jī)會(huì)。然而，研究人員指出，這種方法也可能存在缺陷，因?yàn)樗赡軙?huì)導(dǎo)致kauri dieback等疾病的傳播，kauri dieback在新西蘭是一個(gè)日益嚴(yán)重的問題。

Leuzinger plans to look for more kauri stumps in this kind of situation, hoping to reveal new details about the roles they play. "This has far-reaching consequences for our perception of trees," he says. "Possibly we are not really dealing with trees as individuals, but with the forest as a superorganism."

Leuzinger計(jì)劃在這種情況下尋找更多的kauri樹樁，希望揭示它們所扮演角色的新細(xì)節(jié)。“這對(duì)我們對(duì)樹木的感知有著深遠(yuǎn)的影響，”他說。“也許我們并不是把樹木當(dāng)作個(gè)體來對(duì)待，而是把森林當(dāng)作一個(gè)超有機(jī)體來對(duì)待。”

Ferns grow on the forest floor beneath kauri trees in New Zealand. (Photo: Bildagentur Zoonar/Shutterstock)

"This is a call for more research in this area, particularly in a changing climate and a risk of more frequent and more severe droughts," he adds. "This changes the way we look at the survival of trees and the ecology of forests."

他補(bǔ)充說:“這是對(duì)這一領(lǐng)域進(jìn)行更多研究的呼吁，特別是在氣候變化和更頻繁、更嚴(yán)重干旱的風(fēng)險(xiǎn)下。這改變了我們看待樹木生存和森林生態(tài)的方式。”