只见树木不见森林
NDSU教授 投入事业 引入 北方平原的木本植物
让戴尔·赫尔曼挑选他最喜欢的树, 他看起来像是被要求选择一个最喜欢的孩子.
不可否认, it's no easy question for a plant scientist who has dedicated his life to the study of trees.
但在紧张地咧着嘴笑，清了清嗓子之后, 赫尔曼选定了一个宠物品种:赫尔曼草原政治家, 一棵好到可以刻上他名字的树.
瑞士石松是在阿布萨拉卡附近的一个试验场种植的, 它在哪里长成了高大的, 优雅标本，密实, emerald-hued针. The pine won't be available to the tree-buying public until at least 2007. Some of Herman's connections in the wholesale nursery trade wanted him to cut down the tree so thousands of propagation samples could be collected to start a whole new fleet of baby Statesmen. But Herman and his colleagues couldn't stand the thought of sacrificing such a remarkable tree. And so they decided to cut far fewer propagation samples from the elder Statesman, 在这个过程中保存它. The pine remains, standing like a stately aristocrat among the other trees in the research arboretum.
有时候，你只需要等待一件好事.
Nobody understands this better than Herman, a professor in plant sciences. 他花了33年的时间挑选, 种植, evaluating and introducing new varieties of trees and shrubs in the Northern Plains.
It's a job that might have stopped Johnny Appleseed in his bare-footed tracks. 该地区多变的气候, drought concerns and diverse soil and pH conditions do not a forest make.
因此, the state's native species of large trees -- such as cottonwood, 绿灰和木灰——两只手就能数出来.
Yet any plant scientist worth his microscope knows diversification is as important to nature as it is to farming or stock portfolios.
Herman's fear is in developing a "monoculture," a high population of just a few different species. 如果害虫或疾病来袭，这种同质性会带来灾难.
为了说明这一点，赫尔曼指出了荷兰榆树病. At one time, 75 percent of the trees planted on many cities' boulevards were elms. 当疾病来袭时，它很容易从一棵树传播到另一棵树. As a result, many city officials remain wary of 种植 replacement elms.
He is optimistic -- in the cautious way that scientists are optimistic -- about one of his proposed introductions: an American elm that shows promising disease resistance. But then again, he's excited about all 30 of the introductions he's trademarked since 1986. 就像他希望有一天能够繁殖的杂交橡树一样, or the maples that would add some highly coveted reds and oranges to the region's fall palette. It could take years for Herman to fully study and foster these varieties, 但他希望当他的职业生涯结束时, 他的学生将拿起铁锹.
如果他的事业结束了. 你会觉得赫尔曼, 匀称而有力, is as enthused about his work today as he was as a farm boy growing up on the treeless Plains.
北达科他州中北部的情况与当时不同, before the heavier precipitation of recent years filled lakes and caused trees to sprout on the prairies.
In the '30s, '40s and '50s, the rolling terrain around tiny Brinsmade, N.D.那里干燥、多沙、光秃秃的. 但是戴尔的父母, 乔治和埃尔西·赫尔曼, 需要喂养它们正在成长的幼崽, 所以他们把一整英亩的土地用作菜园.
他们也有自己的办法. Tomatoes fattened on the vine; cucumbers thrived; pea pods grew plump and sweet. 有几年，埃尔西罐装了多达一千夸脱的农产品.
在大萧条最艰难的岁月里, 乔治靠种植土豆来增加家庭收入, 甜瓜, 干涸湖底的西瓜和南瓜, 然后挨家挨户地推销他的产品.
只有一种植物违背了最绿色的赫尔曼拇指. 戴尔, 九个孩子中最小的, watched for years as his family and their neighbors planted saplings in the area's light, 砾石土. 脆弱的树木一次又一次地死去.
小戴尔下定了决心. Someday, he decided, he would find varieties of trees that could survive throughout the state.
“这是一个挑战，”赫尔曼说. “你想证明自然是错的." Fortunately, the state's land-grant university offered a robust horticulture program. 1960年从NDSU获得学士学位后, 赫尔曼被普渡大学录取了, where he earned his master's and doctoral degrees in horticulture.
He returned to his alma mater in 1971 after spending five years on the faculty at South Dakota State University. Almost immediately, he committed himself to the greening of the Plains.
Or, 因为他毕生的作品更正式的名字是, “选择, Evaluation and Introduction of Hardy Superior Woody Plants for the Northern Plains." 经过15年的努力, Herman introduced his first woody plant: the Meadowlark Forsythia, a sturdy ornamental shrub that produces a flurry of bright yellow flowers. 从那时起, he has introduced new woody plants at a dependable rate of one or two new varieties a year.
Much has changed since Herman's earliest years in horticulture. The inventory of plant varieties has exploded, partly because scientists now covet plant diversity. “他们, 包括护工, used to go down the rows and rogue out anything that looked odd or different,赫尔曼说. "Now, if they find a plant that is different from the norm, they guard it." 人们对园林绿化植物的兴趣也在激增. The nursery trade views the shift from practical to aesthetic gardening as evidence of a maturing society.
半个世纪前, Americans tended gardens for the same reason the Hermans did: They needed the food. "Landscaping was a lilac bush and maybe a box-elder tree,赫尔曼说.
Today, homeowners tend to view gardening as the meringue on the pie. 他们看HGTV, know about the latest perennials and spend thousands of dollars on elaborately staged landscaping.
Northern Plains dwellers are just as interested in aesthetic plants, but they also want durability. The ideal plant must have thick, glossy leaves that also resist pests. It should produce fruits and flowers that are exuberant, but not messy. And it needs to possess both vibrant fall foliage and a tolerance for extreme weather conditions.
As more people become urban dwellers, they also need to downsize their plants. A mighty oak may be magnificent, but it doesn't leave much room for the kids' swing set.
So Herman also introduces compact trees and shrubs that tuck neatly into small backyards.
Verona Prairie Radiance exemplifies all he has worked to achieve. The rugged winterberry tree produces fall foliage that changes according to its soil - red leaves in sandy loam, 强烈的粉红色在沉重, 红河谷的黑色粘土. In late September, its display of delicate pink capsules split to expose bright red seeds.
其他受欢迎的介绍包括赫尔曼的桦树三重奏, which provide the white-as-sugar bark that homeowners covet for landscape appeal. Before Herman's work, few birches naturally fit the area's climate and soil.
现在是Varen Prairie Dream, a paper birch with a snow-white bark that peels away in artful layers year-round, creating extra visual interest; Ver戴尔 Prairie Vision, an Asian white birch with white bark and blackish markings; and Fargo Dakota Pinnacle, 一种树皮呈奶油状的亚洲桦树.
The birches aren't just showy; they're tough. Bronze birch borers threaten to do to white birches what Dutch elm disease did to elms. The borers' larvae tunnel beneath the bark, causing the trunk to girdle and the tree to die. But after 25 years of study, Varen and Ver戴尔 have both defied the pest.
The original wood samples for Herman's trees come from sources near and far. His Prairie Expedition American elm was a lone survivor found among diseased elms along the Wild Rice River. Varen sprouted up from a seed source in the Killdeer Mountains, the Fargo cultivar from a multi-species birch seedling population, 和Ver戴尔来自原产于中国西部的亚洲白桦树.
In fact, some of Herman's most successful newcomers have Eastern origins. "Only one area on Earth has similar climatic conditions to the Northern Plains, 这就是亚洲,赫尔曼说. “这个地区包括西伯利亚南部, 中国北方和俄罗斯, 蒙古, Manchuria - that region is very akin to climatic conditions here."
The beauty of Herman's varieties is they survive cold, as well as drought and heat. Their resistance to extremes makes them ideal for marketing in the "intermountain region,包括蒙大拿州, 犹他州, 怀俄明, 内华达州和科罗拉多州. So Herman promotes his trees at events like the Pro-Green Expo in Denver, where - following a three-year drought - wholesalers are clamoring for stress-resistant landscaping plants.
He educates expo audiences with a slide presentation and a three-page handout that outlines the characteristics of his introductions. 他生动的描述说明了他的科学倾向:“厚, 革质, 光滑的叶子,“乳白色的花圆锥花序”和“艳丽。, coppery-orange, 剥树皮." Herman's introductions spark a lot of interest outside of the state. 很少有人能像赫尔曼那样拥有如此严格的试验场. "If it's hardy in North Dakota, it's undoubtedly going to be hardy west of us," he says.
直到今天，赫尔曼农场仍然是一个绿色天堂.
尽管部分原因是降雨增加, 这也归功于赫尔曼的兄弟阿登的工作, a 1957 NDSU grad who majored in agronomy and minored in horticulture. 证明他也拥有家族的绿色基因, Ardon开了一个植物园, 戴尔在那里非正式地测试了他的一些品种.
“我们做了很多比较，”这位教授说.
The Brinsmade farm has even produced a tree that found its way onto Herman's list of introductions. The Prairie Reflection Laurel Willow stemmed from a super-hero of a specimen that never developed the telltale yellow leaves of iron deficiency despite growing for nearly 100 years in high-alkaline soil.
His brother's spread is just one testing ground in Herman's well-established network. 除了阿布萨拉卡附近的一个研究植物园, there are statewide trials at NDSU research extension centers in Minot, 迪金森, 卡灵顿和兰登. This allows Herman to test the same trees in a variety of soils and environments.
赫尔曼还与全州的城市森林管理员合作, 这是艾姆斯的一个区域性植物介绍站, 爱荷华州, 并全国批发生产苗圃, 哪些传播了他的新介绍.
Herman obtains most of his test specimens from asexual propagation, meaning he grows them from rooting cuttings or grafting shoots off the original tree. The result is "offspring" that are identical clones to the original.
Occasionally -- as in the case of oak trees -- propagation through traditional methods is too difficult, 或者太慢. 在这种情况下, 赫尔曼转向大卫·戴的实验室, 新大植物科学助理教授.
傣族可以种植数百种未来的木本植物, 并改变它们的基因以适应不同的需求, 通过组织培养和其他生物技术. A miniscule sliver of plant material is placed inside a baby food jar-sized container, 在无菌容器中悬浮的地方, 营养丰富的明胶. The jar is kept under grow lights and precisely monitored conditions, 创造了赫尔曼所说的“温室中的温室”."
可以以多种方式修改示例. 取决于添加的激素类型, the nub of vegetation will either sprout roots or Lilliputian stems and leaves. In some cases, the cells will grow willy-nilly into formless globs. 戴还可以附加一个新的基因-无论是侏儒, disease-resistance or some other desired trait - to the tiny plant.
When these test-tube trees grow large enough, they are transferred to artificial soil. 傣族可以用这种方式繁殖数百万种木本植物.
"There are only so many tissue-culture labs in the United States,赫尔曼说. "Dr. 戴在这类研究中处于领先地位." Such methods help expedite the introduction process, but only to a point. 整个过程需要充分的研究和耐心.
研究, because it can take years to evaluate how a new plant will fare against environmental factors like pests or salty soil.
And patience, because it isn't as easy to popularize new trees as one might think. The newest petunia can enjoy worldwide recognition a year after it's introduced, but people often hesitate to try out unfamiliar tree varieties. While annuals will bloom exuberantly just weeks after they're planted, trees take much longer to reap their benefits - energy conservation, 增加物业价值和长远的景观美感.
"How do you get the masses to know about it, so they demand and want to buy it?赫尔曼说. "The propagators can't produce something if they can't sell it. 你需要钱，需要全彩广告——你必须推销它. 我需要有人专职宣传我们的介绍." And, for the first time, he seems a bit frustrated by the magnitude of his task.
Then again, Herman has already accomplished a few amazing feats in his lifetime. 比如寻找能抵抗天敌的桦树. 或者在佛蒙特州推广看起来像九月的灌木丛. Or, most impressively, knowing how to make the Northern Plains a greener and brighter place.
--T. 斯威夫特
