种树可以预防犯罪吗？有可能哦。美国林务局研究员做的两项最新研究仔细调查了费城、巴尔的摩和俄亥俄州扬斯敦的市区绿化情况。研究人员发现，在这三个城市中，在治安糟糕的区域增加绿化面积可以有效减少犯罪率。

In 2000, Philadelphia launched a program to plant vegetation along roadways to help soak up rainwater. Researchers looked at 52 of these vegetation plots and compared them with control plots that didn't receive the greenery upgrade. After tracking 14 types of crime in nearby areas, researchers found that narcotics possession in those areas decreased by 18 to 27 percent, even as the rate for the rest of the city rose by 65 percent. 

2000年，费城启动了一个项目，在道路两旁种植绿化带吸收雨水。研究者们观察了52处绿化点，与没有进行绿化改造的对照区进行对比。在追踪了附近14种犯罪手段之后，研究者发现，这些区域的毒品持有量下降到27%，下降了18个百分点，尽管这一数字在城市的其它地区还上涨了65个百分点。

想要打击城市犯罪?多种树吧

Michelle Kondo, a social scientist and lead researcher with the forest service, speculated the increased presence of city trucks and vans in the landscaped areas—for planting and maintenance—was enough to deter illicit activity. 

林务局首席研究员、社会学家米歇尔·近藤推测，在这些区域负责绿化和养护的市政车辆增加，有效阻止了违法活动。

A similar effect was noted in Youngstown, Ohio—a depressed Midwestern town known for its high rates of crime and unemployment. From 2010 to 2014, city officials embarked on a project to reclaim some of the city's empty lots and derelict buildings by converting them into green space. In 2011, they added another initiative that gave local communities funding to plant green space in vacant lots in whatever method they chose—lawns, community gardens, playgrounds and more.

在俄亥俄州的扬斯敦也发现了类似的情况。这是一座经济萧条的中西部城市，以高犯罪率和失业率闻名。从2010年到2014年，政府开启了一项回收城市空地和无主建筑的计划，把这些区域改造成绿地。2011年，他们又启动了一项绿地基金计划，鼓励当地民众以各种形式绿化空地——无论是草坪、社区花园、运动场还是其它。

When Kondo and her team compared crime around these vegetation plots with undeveloped plots in nearby areas, they found the areas around new green spaces had lower crime rates than elsewhere in the city. Interestingly, the crime reduction was different depending upon the type of green space that was developed. For example, lots that were planted with grass and maintained by contractors saw a reduction in property crimes such as theft and burglary, whereas community-maintained plots saw a sharp reduction in violent crime. This suggests that different types of green space could be developed to deter certain types of crime.

近藤和她的团队对比了这些绿化区域和附近未绿化区域的犯罪情况，发现新绿化区域的犯罪率比城市其它地区的犯罪率低。有趣的是，开发的绿地类型不同，所减少的犯罪类型也不同。比如，种植了草坪并由承包商维护的绿地，周围盗窃和入室行窃之类的财产犯罪就减少了，而由社区维护的绿地附近，暴力犯罪大幅下降。这就表明可以通过开发不同类型的绿地来阻止特定类型的犯罪活动。

Kondo's study collaborates another forest service study conducted by researcher Morgan Grove on the link between lawn care and crime in downtown Baltimore. Grove's study looked at the level of lawn maintenance in 1,000 residential yards throughout Baltimore County. His team looked at everything from tree cover to litter to the presence of garden hoses. Not surprisingly, Grove found that well-maintained lawns were linked to lower crime rates than lawns that were given less care. 

与近藤的研究相合作的林务局另外一项研究中，研究员摩根·格鲁夫研究了巴尔的摩市中心犯罪率与草坪维护情况之间的关联。他调查了整个巴尔的摩郡1000户人家院子的草坪维护情况。他的团队查看了所有细节，包括林木植被、垃圾和花园的浇水管。果然，格鲁夫发现，维护良好的草坪周围的犯罪率比维护欠佳的草坪周围的犯罪率要低。

It's tempting to use income as the connection. After all, if you have the time and money to water your lawn, you probably live in a neighborhood that sees less crime. But Grove argued that the greenery itself helped to deter crime, by announcing to would-be criminals that there are "eyes on the street" that care for their neighborhood and would be more likely to report a crime.

当然你很容易把这个与收入联系起来。毕竟，如果你有时间和金钱为草坪浇水，那么你很有可能住在较为安全的社区。但是格鲁夫认为，是绿化本身减少了犯罪，绿地是一种宣示，警告潜在的罪犯“街上有眼睛”照看着社区，并且发生了犯罪会更有可能上报。

The takeaway from these two studies is that urban green space may help to deter crime and could be a useful tool in city-wide crime prevention policies. We already know greenery is beautiful to look at and can help improve mood and health while reducing pollution. Now we can add crime-fighting to the list of vegetation's many benefits. 

这两项研究的重要发现是，城市绿地有助于阻止犯罪，可以作为整个城市预防犯罪政策的有力工具。我们已经知道，绿色植物既养眼，又有助于改善情绪、提升健康状况、减少污染。现在我们又可以给植物的种种好处再加上一条“打击犯罪”。

Need a better reason to plant a tree? 

这难道还不是种树的最好理由吗？