Collaborative Research: Exploring the geography of sodium as a catalyst in terrestrial communities and ecosystems

地球生态系统提供的基本服务，如将碎屑分解为营养物质、将植物转化为肉类、形成肥沃土壤并使其通气，都是由数百万生物的共同作用产生的。每一种生物，从细菌到蝴蝶再到野牛，当它们摄入健康的饮食，包括获得矿物质，尤其是钠时，它们就能最好地为这些服务做出贡献。钠对于生态系统来说是一种至关重要的矿物质，因为植物的钠含量通常很低，但从真菌到蚱蜢等以植物为食的生物都需要钠来生长和繁殖。因此，每一个食草动物都必须寻找、收获和保持钠的数量，为了获得配额，他们会采取极端的做法，吃尸体、土壤和尿液。此外，钠在景观中的分布并不均匀。它像稀释的海水一样落在海岸附近，它附着在粘土上，但从沙质土壤中浸出，它以卡车为单位分布，以防止积雪的道路结冰。这个项目结合了这两个事实，钠可能是植物消费者健康的最重要驱动因素之一，钠在地理上是不完整的，以预测整个北美大陆植物消费者的丰度和服务。这项研究将有助于更好地预测一些不同的现象，比如为什么一个县的蝗虫比另一个县的农作物害虫更大；为什么碳能更好地储存在内陆土壤中而不是靠近海洋的土壤中；以及为什么白蚁损害索赔集中在美国墨西哥湾沿岸和大西洋中部各州。为了评估这个命题，该项目结合了两种方法。第一张地图描绘了钠在北美生态系统中的分布，重点关注了容易进入和广泛分布的草原、老田野和路边，以及生活在其中的无脊椎动物。第一年的目标是探索一个基本假设，即随着土壤钠供应的增加——由于海洋的沉积，高粘土含量，或者因为每年冬天都加盐——植物不会受到影响，但吃它们的动物（以及以植物为食的捕食者）会受到影响。因此，第一年将生成一张地图，显示地上和地下无脊椎动物的丰度和活动，以及两者追踪钠供应（和其他营养物质）的程度。然后，在第二年和第三年，这些相关性将在美国中部和东部的6个草原上进行实验测试。在每个草原上，50平方米的地块将被施用稀释钠浓度的肥料，模仿波多黎各岛的微咸降雨；较小的地块将接收模仿每只动物定期以尿液形式沉积的钠。通过仔细追踪钠的去向，以及它如何增加无脊椎动物的数量和活动，该项目将测试北美动物的健康和活力是如何受到钠供应的影响的。通过研究传粉媒介、食草动物和食腐动物的反应，该项目将测试钠是生态系统服务催化剂的变革理念。

Essential services performed by Earth's ecosystems, such as decomposing detritus into nutrients, transforming plants into meat, creating and aerating fertile soil, arise from the combined actions of millions of organisms. Each of these organisms, from bacteria to butterflies to bison, best contribute to these services when they consume a healthy diet, which includes access to minerals, especially sodium. Sodium is a critical mineral for ecosystems because plants are generally low in sodium but the things that eat them, from fungi to grasshoppers, require it to grow and reproduce. Thus every plant eater must search out, harvest, and hang onto quantities of sodium, and will go to extremes eating carcasses, soil, and urine, to get that quota. Moreover, sodium is not uniformly distributed on the landscape. It falls as dilute ocean water near the coasts, it clings to clay soils but is leached from sandy soils, and it is distributed by the truckload to keep snowy roads free from ice. This project combines these two facts, that sodium is potentially one of the most important drivers of the health of plant consumers, and that sodium is geographically patchy, to predict the abundance and services of plant consumers across the North American continent. This research should lead to better prediction of such disparate phenomena as why grasshoppers are bigger crop pests in one county than another; why carbon is better stored in inland soils than those near the ocean; and why termite damage claims are centered along the Gulf Coast of the U.S. and up into the Mid-Atlantic states.To evaluate this proposition, the project combines two methods. The first maps the distribution of sodium across and within North American ecosystems and focuses on the easily accessible and widespread grasslands, old fields, and roadsides, and the invertebrates that live in them. The goal in Year 1 is to explore the basic hypothesis that as soil supplies of sodium increase - due to deposition from the ocean, high clay content, or because they are salted every winter - plants will not be affected but the animals that eat them (and the predators that eat the plant consumers) will. Thus the first year will generate a map of the abundance and activity of invertebrates above and belowground, and the degree to which both track sodium supply (and other nutrients). Then, in Year 2 and 3, these correlations will be put to the test experimentally in 6 grasslands from the central and eastern U.S. At each grassland, 50 meter square plots will be fertilized with a dilute sodium concentrations mimicking the slightly salty rainfall of the island of Puerto Rico; smaller plots will receive sodium mimicking that deposited on a regular basis by every animal as urine. By carefully tracking where the sodium goes, and how it boosts the numbers and activity of invertebrates, the project will test how animal health and vigor across North America is influenced by sodium supply. By examining how pollinators, herbivores, and detritivores respond, the project will test the transformative idea that sodium is a catalyst for ecosystem services.