Fay Philip A, Gherardi Laureano A, Yahdjian Laura, Adler Peter B, Bakker Jonathan D, Bharath Siddharth, Borer Elizabeth T, Harpole W Stanley, Hersch-Green Erika, Huxman Travis E, MacDougall Andrew S, Risch Anita C, Seabloom Eric W, Bagchi Sumanta, Barrio Isabel C, Biederman Lori, Buckley Yvonne M, Bugalho Miguel N, Caldeira Maria C, Catford Jane A, Chen QingQing, Cleland Elsa E, Collins Scott L, Daleo Pedro, Dickman Christopher R, Donohue Ian, DuPre Mary E, Eisenhauer Nico, Eskelinen Anu, Hagenah Nicole, Hautier Yann, Heckman Robert W, Jónsdóttir Ingibjörg S, Knops Johannes M H, Laungani Ramesh, Martina Jason P, McCulley Rebecca L, Morgan John W, Olde Venterink Harry, Peri Pablo L, Power Sally A, Raynaud Xavier, Ren Zhengwei, Roscher Christiane, Smith Melinda D, Spohn Marie, Stevens Carly J, Tedder Michelle J, Virtanen Risto, Wardle Glenda M, Wheeler George R
United States Department of Agriculture, Agricultural Research Service, Grassland, Soil, and Water Lab, Temple, TX 76502.
Department of Environmental Sciences, Policy, and Management, University of California, Berkeley, CA 94720.
Proc Natl Acad Sci U S A. 2025 Apr 15;122(15):e2410748122. doi: 10.1073/pnas.2410748122. Epub 2025 Apr 11.
Ecosystems are experiencing changing global patterns of mean annual precipitation (MAP) and enrichment with multiple nutrients that potentially colimit plant biomass production. In grasslands, mean aboveground plant biomass is closely related to MAP, but how this relationship changes after enrichment with multiple nutrients remains unclear. We hypothesized the global biomass-MAP relationship becomes steeper with an increasing number of added nutrients, with increases in steepness corresponding to the form of interaction among added nutrients and with increased mediation by changes in plant community diversity. We measured aboveground plant biomass production and species diversity in 71 grasslands on six continents representing the global span of grassland MAP, diversity, management, and soils. We fertilized all sites with nitrogen, phosphorus, and potassium with micronutrients in all combinations to identify which nutrients limited biomass at each site. As hypothesized, fertilizing with one, two, or three nutrients progressively steepened the global biomass-MAP relationship. The magnitude of the increase in steepness corresponded to whether sites were not limited by nitrogen or phosphorus, were limited by either one, or were colimited by both in additive, or synergistic forms. Unexpectedly, we found only weak evidence for mediation of biomass-MAP relationships by plant community diversity because relationships of species richness, evenness, and beta diversity to MAP and to biomass were weak or opposing. Site-level properties including baseline biomass production, soils, and management explained little variation in biomass-MAP relationships. These findings reveal multiple nutrient colimitation as a defining feature of the global grassland biomass-MAP relationship.
生态系统正经历着年平均降水量（MAP）全球格局的变化以及多种养分的富集，这些养分可能共同限制植物生物量的生产。在草原地区，地上植物平均生物量与MAP密切相关，但在多种养分富集后这种关系如何变化仍不清楚。我们假设随着添加养分数量的增加，全球生物量与MAP的关系会变得更加陡峭，陡峭程度的增加与添加养分之间的相互作用形式相对应，并且植物群落多样性的变化起到更大的调节作用。我们在代表全球草原MAP、多样性、管理方式和土壤范围的六大洲的71个草原上测量了地上植物生物量生产和物种多样性。我们以各种组合向所有地点施加氮、磷、钾以及微量营养素，以确定每个地点限制生物量的养分。正如我们所假设的，施加一种、两种或三种养分逐渐使全球生物量与MAP的关系变得更加陡峭。陡峭程度增加的幅度对应于各个地点是否不受氮或磷的限制、是否仅受其中一种限制，或者是否同时受到两者以相加或协同形式的共同限制。出乎意料的是，我们仅发现了微弱的证据表明植物群落多样性对生物量与MAP关系起到调节作用，因为物种丰富度、均匀度和β多样性与MAP以及生物量之间的关系微弱或相反。包括基线生物量生产、土壤和管理方式在内的地点水平属性对生物量与MAP关系的解释能力很弱。这些发现揭示了多种养分共同限制是全球草原生物量与MAP关系的一个决定性特征。
