Nutrient dilution and climate cycles underlie declines in a dominant insect herbivore
Nutrient dilution and climate cycles underlie declines in a dominant insect herbivore
复制标题
养分稀释和气候循环是占优势的食草昆虫数量下降的原因
DOI：
--
复制
发表时间：
2020
影响因子：
11.1
通讯作者：
M. Kaspari
中科院分区：
文献类型：
--
作者：
Ellen A. R. Welti;Karl A. Roeder;K. D. de Beurs;A. Joern;M. Kaspari
根据最近关于昆虫急剧减少的报告，分析昆虫丰度的长期模式的变化和分配机制是至关重要的。北美草原的蝗虫丰度在过去20年中表现出5年周期和2%/年的下降。大规模的气候振荡预测了蝗虫丰度的周期。此外，植物生物量在同一时期翻了一番--可能是由于气候变化和大气中二氧化碳的增加--稀释了植物组织中关键营养物质的浓度，这反过来又预测了一种主要草食动物的减少。营养物质的稀释，就像二氧化碳的增加一样，可能是一个全球现象，对地球上的食草动物种群构成了挑战。全球昆虫数量减少的证据越来越多，这增加了我们了解潜在机制的必要性。我们测试了营养稀释(ND)假说--随着植物生产力的增加，必需饮食矿物质的浓度不断下降--特别是针对昆虫食草动物。由于气候或二氧化碳浓度升高而导致的植物生物量增加，可能会导致养分稀释。此外，在考虑气候驱动的长期趋势时，必须考虑大范围振荡，包括厄尔尼诺南方涛动(ENSO)、北大西洋涛动(NAO)和太平洋年代际涛动(PDO)。我们结合蝗虫丰度、气候、植物生物量和季末叶元素含量的长期数据集，研究这种主要草食动物丰度循环和趋势的潜在驱动因素。从堪萨斯大草原的16年和22年的时间序列中，蝗虫的年丰度显示出5年的周期和2.1-2.7%/年的下降，春季ENSO、夏季NAO和冬季或春季PDO的气候周期指数解释了受天气和寄主植物影响的蝗虫丰度变化的40%-54%。与ND一致，草的生物量在同一时期翻了一番，叶片中N、P、K和Na的浓度--限制蝗虫丰度的养分--下降了。植物营养素的减少解释了过去20年蝗虫丰度变化的25%。因此，一个变暖、更潮湿、更富含二氧化碳的世界可能会耗尽本已缺乏营养的食草动物的营养，从而导致它们数量的减少。与昆虫减少的其他潜在驱动因素--栖息地丧失、光线和化学污染--不同，新城疫可能在剩余的自然地区普遍存在。
Significance Parsing variation in long-term patterns underlying insect abundances and assigning mechanisms are critical in light of recent reports of dramatic insect declines. Grasshopper abundances in a North American prairie exhibited both 5-y cycles and >2%/y declines over the past 20 y. Large-scale climate oscillations predicted the cycles in grasshopper abundances. Moreover, plant biomass doubled over the same period—likely due to changes in climate and increasing atmospheric CO2—diluting the concentrations in plant tissue of key nutrients which in turn predicted the declines of a dominant herbivore. Nutrient dilution, like CO2 enrichment, is likely a global phenomenon, posing a challenge to Earth’s herbivore populations. Evidence for global insect declines mounts, increasing our need to understand underlying mechanisms. We test the nutrient dilution (ND) hypothesis—the decreasing concentration of essential dietary minerals with increasing plant productivity—that particularly targets insect herbivores. Nutrient dilution can result from increased plant biomass due to climate or CO2 enrichment. Additionally, when considering long-term trends driven by climate, one must account for large-scale oscillations including El Niño Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO). We combine long-term datasets of grasshopper abundance, climate, plant biomass, and end-of-season foliar elemental content to examine potential drivers of abundance cycles and trends of this dominant herbivore. Annual grasshopper abundances in 16- and 22-y time series from a Kansas prairie revealed both 5-y cycles and declines of 2.1–2.7%/y. Climate cycle indices of spring ENSO, summer NAO, and winter or spring PDO accounted for 40–54% of the variation in grasshopper abundance, mediated by effects of weather and host plants. Consistent with ND, grass biomass doubled and foliar concentrations of N, P, K, and Na—nutrients which limit grasshopper abundance—declined over the same period. The decline in plant nutrients accounted for 25% of the variation in grasshopper abundance over two decades. Thus a warming, wetter, more CO2-enriched world will likely contribute to declines in insect herbivores by depleting nutrients from their already nutrient-poor diet. Unlike other potential drivers of insect declines—habitat loss, light and chemical pollution—ND may be widespread in remaining natural areas.
影响因子：
5.9
作者：
Harris, Jennifer E.;Rodenhouse, Nicholas L.;Holmes, Richard T.
通讯作者：
Holmes, Richard T.
影响因子：
56.9
作者：
Rosenberg, Kenneth V.;Dokter, Adriaan M.;Marra, Peter P.
通讯作者：
Marra, Peter P.