How do you get a tree that produces six or seven different fruits? Grafting, of course.
The process of getting a cutting of one plant to grow on the base of another, grafting is usually used in much more mundane contexts: it’s what lets farmers grow clones of an orange tree, say, with particularly succulent fruit, for decades after the original tree dies. The vast majority of the fruit we eat comes from such clones, since letting the tree mix its genes with another might produce a totally different fruit, much less marketable than the original.
But making a tree that fruits oranges, limes, and lemons all at the same time—now that’s a work of art. At Scientific American’s Brainwaves blog, Ferris Jabr explains how such fruit salad trees, also called fruit cocktail trees, work, and points readers in the direction of a purveyor of such wonders:
All clones are not alike.
What’s the News: Foresters have long noticed that trees with the exact same genes, when raised in separate nurseries, have very different responses to drought. While one shoots up through lean times, the other droops. Why the divergence?
Scientists have now found that twin trees raised separately are, just like human twins, expressing different genes. In other words, nurture is affecting nature.
The state of our forests is troubled, but maybe on the mend.
The United Nations, as part of its effort to brand 2011 the International Year of Forests, released an assessment this week about forest extent, and quality, all around the world. First, the good news: Forest destruction is slowing down, according to assistant director general Eduardo Rojas-Briales of the UN’s Food and Agriculture Organization.
The 4.032 billion hectares (9.9 billion acres) of forests in the world in 2010 is down from an estimated 4.085 billion in 2000, said the FAO. But the speed at which which trees are being cut down is slowing from 8.3 million hectares a year in 1990-2000 to 5.2 million in the past decade. “There are evident signs that we could arrive at a balance in a few years,” said Rojas-Briales, adding that the deforestation rate was 50 million hectares a year 30 years ago. [AFP]
Asian countries have achieved particularly impressive results, with many adding to their total of forested territory.
“China has increased its forest by three million hectares (30,000 sq km) per year – no country has ever done anything like this before, it’s an enormous contribution,” said … Rojas-Briales. “But we can also highlight the case of Vietnam, a small and densely populated country that’s implemented very smart and comprehensive forest reform – or India, which has not controlled its population as China has and where standards of living are even lower. Nevertheless India has achieved a modest growth of its forest area.” [BBC News]
But the world is not out of the woods, so to speak, in bringing back the forest health of old.
Here’s one that I didn’t touch on in DISCOVER’s creepy gallery of zombie animals controlled by mind-altering parasites: A parasitic fungus called Ophiocordyceps unilateralis that infects a plain old carpenter ant and takes over its brain, leading the ant to bite into the vein that runs down the center of a leaf on the underside. The ant dies shortly thereafter, but the fungus gains the nutrients it needs to grow this crazy stalk out of the ant’s body and release spores to create the next generation of ant-controlling fungi.
This cryptic cycle has been going on for at least 48 million years.
In a study forthcoming in Biology Letters, Harvard’s David Hughes argues that a fossilized leaf found in a fossil-rich part of Germany’s Rhine Rift Valley bears the scars of the ant’s trademark death bite. The ant bites down hard so the fungus will have a stable position when it grows a stalk out of the ant’s head. But even so, Hughes says, he doubted the mark would turn up in the fossil record—that is, until serendipity reared its random head:
The Sahara is the world largest desert, and getting larger. It threatens to creep ever further to the south and turn arable land in desert wasteland. The nations in its path have an idea, though: We’ll build a fence. Of trees.
The “Great Green Wall” would be a tree band that spans the breadth of northern Africa, 9 miles wide and nearly 5,000 miles long, from Senegal at the western edge near the Atlantic to Djibouti on the eastern edge near the pirate-infested Gulf of Aden. It may sound too dreamy or crazy to ever go forward, but this week at a meeting in Chad about desertification, the Global Environment Facility backed the belt idea with $119 million. Chad’s minister of environment, Hassan Térap, says it can be achieved:
When asked if the long-discussed but yet-to-be funded Green Wall initiative was too ambitious, Térap told IRIN: “We have to attack the problem, long ignored, through vision, ambition – and trees. What is wrong with ambition?” [IRIN Africa].
Now that many U.S. farmers have grown used to genetically modified (GM) soy and corn, the controversy surrounding GM crops may shift over to GM eucalyptus–a fast-growing Australian tree that, in its unmodified strains, dominates the tropical timber industry.
Two industry giants, International Paper Co. and MeadWestvaco Corp. have formed a biotech venture called ArborGen LLC that is looking to introduce this tree to the southeastern forests of the United States. The company is seeking greater governmental deregulation so it can roll out its plans of replacing native pines in southeastern plantation forests with the genetically engineered eucalyptus, which can survive freezing winter temperatures.
Unlike the pine trees used in Southern plantations — which have quietly helped displace tobacco in the region’s economy — eucalyptus can deploy a full canopy of leaves within a few years. It is greedy for carbon, and within 27 months can grow to 55 feet in height [The New York Times]. ArborGen points out that the high growth rate will allow the company to grow more wood on less land, which could provide a boost to the region’s timber exports. What’s more, the wood could potentially serve as a biofuel feedstock.
After 2,000 years of dozing in the dry heat of the Judean desert, the seed of a date palm has been coaxed back to life. The seed germinated, sprouted, and grew flourishing palm fronds. Now researchers are waiting for the young tree to mature and are hoping fervently that it’s a female, which could bear fruit that would allow botanists to propagate its line.
Back in the ancient era known as the 1960s, archaeologists discovered a handful of wizened seeds in the ruins of King Herod’s fortress in Masada, near the Dead Sea. The seeds were kept on a shelf for 40 years before the Israeli archaeobotanist Mordechai Kislev decided to see if some life remained in the brown husks.
In 2005, Kislev gave the seeds to botanists who soaked them in hot water and nutrients and planted three in enriched soil. Three months later, the dirt cracked and a single shoot appeared. The researchers nicknamed the tiny sapling “Methuselah” after the oldest person whose age is mentioned in the Old Testament [Science News]. (Methusaleh was a whopping 969 years old, per Genesis 5:27.)
Who knew that a white spruce in northern Canada, a red maple in Pennsylvania, and a mahogany tree in Puerto Rico have so much in common? Their environments are certainly very different, with icy winds buffeting the spruce tree’s needles and hot, humid air bathing the mahogany tree’s leaves. But despite these external variations, a new study shows that inside each tree leaf (or needle) it’s always just the right temperature for the delicate and vital process of photosynthesis, and the leaves are responsible for keeping that thermostat steady.
The findings, published in Nature [subscription required], show that trees all across North America favor the temperature of 70 degrees Fahrenheit for the photosynthesis process, which uses sunlight to convert carbon dioxide into oxygen and sugars. To keep in that comfort zone, they’ve come up with some clever adaptations. Trees release water, and during hot times, that botanical sweat cools them down. And trees that grow in cold places tend to cluster their leaves. These tight formations can affect the rate at which leaves lose heat on cold days, just as fingers pressed together in mittens stay warmer than fingers separated by space in gloves [Science News].