One of the consequences of a warming world is that high mountain habitats, which used to be too chilly for trees, are heating up. "There is now newly available real estate above what we call tree line—the sort of literal line in the sand above which trees can’t grow because it’s too cold. But now it’s not."

　　全球变暖的其中一个后果是，对树木来说曾经过于寒冷的高山环境正在逐渐升温。“现在，在我们称为“林木线”的上方出现了新的可用生长空间——这种线类似于分界线，由于过于寒冷，树木在该线之上无法生长。但是，现在情况已经改变。”

　　Brian Smithers is an ecologist at U.C. Davis. He compares this slow-moving migration to land-grabs back in pioneer times. "You know, they fired the guns and all the settlers made a mad dash to claim their stake. It’s that, but if everybody were crawling on their bellies or something like that instead."

　　布莱恩史密瑟斯是加州大学戴维斯分校的生态学家。他将这种缓慢迁移与开拓时期的土地掠夺进行了比较。“你知道，他们开了火，当时所有开拓者都在疯狂地占领地盘。事实就是这样，但是如果所有人都匍匐前进，或是替换成会爬的东西会怎么样?”

　　Smithers is studying this upslope race among bristlecone pines. These trees can live for more than 5,000 years—making them the oldest individual organisms on Earth. Many of them eke out a living in dry, rocky soils, on windblown ridgelines around 11,000 feet, in eastern California and Nevada. "They look like the worst bonsai tree imaginable. They just look gnarled and twisted, something that looks like it’s taken a beating for 5,000 years and still living."

　　史密瑟斯正在研究狐尾松之间的上升竞赛。这些树的寿命可超过5000年，这使它们成为地球上最古老的生物个体。在加州东部和内华达州干燥的石质土以及约1.1万英尺高的风蚀山脊线上，许多狐尾松在勉强度日。“它们看起来像是你能想得到的最糟糕的盆景树。这些树有很多节瘤，而且形状扭曲，看上去像过去5000年一直在挨打，但依然存活着。”

　　So, as tree line rises, these giant bonsais are following. But Smithers says the ancient trees now have a competitor—a species called limber pines. The limbers are passing the bristlecones at tree line, sprouting seedlings in that fresh real estate upslope more quickly. ‘Quickly’ being a relative term. "It’s the tortoise and the slightly faster tortoise." Smithers documents the race in the journal Global Change Biology.

　　因此，随着林木线的上升，这些巨型盆景也开始不断长高。但是史密瑟斯说这些古树现在有了一个竞争者，那是一种名为柔枝松的树种。柔枝松正在林木线上超越狐尾松，以更快的速度将幼苗蔓延至上升的新空间。而这种“快”是一种相对的说法。“那就像乌龟与稍快些的乌龟进行的比赛。”史密瑟斯记录了这种比赛，并将记录发表在《全球变化生态学》期刊上。

　　The leapfrogging limber pines could put bristlecones in a bind, hemmed in by competing seedlings upslope, and hotter temperatures downslope. And that, Smithers says, would have long-lasting consequences. "You know, we talk about the effects of climate change happening on scales of 100 years. What’s going to happen by 2100. But in 5,000 years someone will be able to go to this stand and say, oh it looks like this because people made climate change happen 5,000 years ago. It just changes the scale, when we talk about the effects of climate change." Assuming, that is, we stick around long enough to notice.

　　赶超的柔枝松可能让狐尾松陷入困境，上方有竞争者的幼苗，而下方是升高的温度。史密瑟斯认为，这种情况会带来持久的影响。“我们在说的是以百年为尺度的气候变化影响。即2100年时会出现的影响。但在5000年内，可能有人能走进这片林木并说：哦，因为5000年前人类造成的气候变化，这些林木现在成了这个样子。在我们谈论气候变化的影响时，只是尺度改变了。”也就是说，假设我们逗留的时间足够长，我们就能注意到这个问题。