随着春季进入北美夏季，树木开花和鸟类迁移，自然似乎很丰富。然而，实际上，地球正在丢失动物，鸟类，爬行动物和其他生物，以至于某些科学家认为地球正在进入该地球第六次巨大灭绝in its history.
今年秋天，联合国将召集来自世界各地的政府in Kunming, China, to establish new goals for protecting Earth’s ecosystems and theirbiodiversity- 从基因到生态系统的各个层次的各种生活。
Some people, cultures, and nations believe biodiversity is worth conserving because ecosystems provide many services that support human prosperity, health, and well-being. Others assert that all living things have a right to exist, regardless of their usefulness to humans. Today, there’s also growing understanding that nature enriches our lives by providing opportunities for us to connect with each other and the places we care about.
作为一个conservation biologist，我一直是重视生物多样性多年的努力的一部分。这是该领域的思考如何发展的方式，以及为什么我相信有许多同样有效的保护自然的理由。
捍卫每个物种
保护生物学是一个具有使命的科学领域：protecting and restoring biodiversity around the world。随着人类对地球的影响越来越明显，它是在1980年代成年的。
在1985年的文章中迈克尔·塞雷（MichaelSoulé）, one of the field’s founders, described what he saw as thecore principles of conservation biology。Soulé认为，生物多样性本质上是良好的，应该保存，因为它具有内在的价值。他还建议保护生物学家应采取行动来拯救生物多样性，即使没有可靠的科学来为决策提供指导。
To critics, Soulé’s principles sounded比科学更喜欢环境行动主义。更重要的是，并非每个人都同意或现在，生物多样性本质上是好的。
毕竟，野生动物可以destroy crops and endanger human lives。与大自然接触可以导致疾病。And some conservation initiatives have使人们从他们的土地上流离失所or prevented development thatmight otherwise improve people’s lives。
Valuing nature’s services
Soule’s essay spurred many researchers to push for a more science-driven approach to conservation. They sought to directly quantify the生态系统的价值和其中扮演的角色物种。Some scholars focused on calculating the value of ecosystems to humans.
他们得出了一个初步的结论，即世界生态系统的总经济价值值得平均每年33万亿美元in 1997 dollars. At the time, this was nearly twice the global value of the entire world’s financial markets.
This estimate included such services as predators controlling pests that would otherwise ruin crops; pollinators helping to produce fruits and vegetables; wetlands, mangroves, and other natural systems buffering coasts against storms and flooding; oceans providing fish for food; and forests providing lumber and other building materials.
研究人员已经完善了他们的estimates of what these benefits are worth, but their central conclusion remains the same: Nature has shockingly high economic value that existing financial markets don’t account for.
第二组开始量化自然对人类健康，幸福和福祉的非货币价值。研究通常有人参加户外活动，例如漫步在绿色空间，在树林中远足或在湖上划独木舟。后来，他们measured the subjects’ physical or emotional health。
这项研究发现，在自然界中花费时间倾向于降低血压，与压力和焦虑相关的降低激素，减少抑郁症的可能性并改善认知功能和某些免疫功能。暴露于大自然的人比其他在非天然环境中参加类似活动的人（例如穿越城市，也可以参加类似活动）。
失去物种削弱了生态系统
A third line of research asked a different question: When ecosystems lose species,can they still function and provide services? This work was driven mainly by experiments where researchers directly manipulated the diversity of different types of organisms in settings, ranging from laboratory cultures to greenhouses, plots in fields, forests, and coastal areas.
到2010年，科学家已经发表了600多个实验，在淡水，海洋和土地生态系统中操纵了500多组生物。在2012年对这些实验的评论中，我和同事们发现，当生态系统失去生物多样性时，它们就会成为效率较低，生产力较低，稳定较低。而且他们无法提供人类福祉的许多服务。
例如，我们发现有力的证据表明，遗传多样性的丧失会降低农作物的产量，而树木多样性降低了森林产生的木材量。我们还发现证据表明，鱼类物种较少的海洋产生了较不可靠的捕获，并且植物多样性较低的生态系统更容易出现侵入性害虫和疾病。
我们还表明，有可能开发可靠的数学模型，这些模型可以很好地预测生物多样性损失如何影响生态系统中某些有价值的服务。
保护自然的许多动机
For years, I believed that this work had established the value of ecosystems and quantified how biodiversity provided ecosystem services. But I’ve come to realize that other arguments for protecting nature are just as valid, and often more convincing for many people.
我曾与许多捐赠金钱或土地支持保护的人合作。但是我从未听说有人说他们正在这样做是因为生物多样性的经济价值或其在维持生态系统服务中的作用。
Instead, they’ve shared stories about how they grew up fishing with their father, held family gatherings at a cabin, or canoed with someone who was important to them. They wanted to pass on those experiences to their children and grandchildren to preserve familial relationships. Researchers increasingly recognize that such关系价值—connections to communities and to specific places—are one of the most common reasons why people choose to conserve nature.
我也知道许多人拥有深厚的宗教信仰，很少受到科学论证的保护。但是，当教皇弗朗西斯出版了他的2015年百科全书Laudato SI’：照顾我们的普通房屋and said God’s followers had a moral responsibility to care for his creation, my religious relatives, friends, and colleagues suddenly wanted to know about biodiversity loss and what they might do about it.
Surveys show that 85% of the world’s population认同主要宗教。每个主要宗教的领导人都发表了与教皇方济各的百科全书类似的声明，呼吁他们的追随者成为better stewards of Earth。Undoubtedly, a large portion of humanity assigns moral value to nature.
研究清楚地表明，自然为人类具有巨大的价值。但是有些人只是认为其他物种有生存权，或者他们的宗教告诉他们成为地球的好管家。正如我所看到的，拥抱这些不同的观点是为了保护地球的生态系统和生物的利益而获得全球买入的最佳方法。
布拉德利·Cardinale是部门主管，生态系统科学与管理，宾夕法尼亚州。
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