Department of Physical and Environmental Sciences and The Centre for Critical Development Studies, University of Toronto Scarborough, Scarborough, Canada.
Department of Biological Sciences, University of Toronto Scarborough, Scarborough, Canada.
PLoS One. 2019 Feb 6;14(2):e0209788. doi: 10.1371/journal.pone.0209788. eCollection 2019.
The Anthropocene epoch is partly defined by anthropogenic spread of crops beyond their centres of origin. At global scales, evidence indicates that species-level taxonomic diversity of crops being cultivated on large-scale agricultural lands has increased linearly over the past 50 years. Yet environmental and socio-economic differences support expectations that temporal changes in crop diversity vary across regions. Ecological theory also suggests that changes in crop taxonomic diversity may not necessarily reflect changes in the evolutionary diversity of crops. We used data from the Food and Agricultural Organization (FAO) of the United Nations to assess changes in crop taxonomic- and phylogenetic diversity across 22 subcontinental-scale regions from 1961-2014. We document certain broad consistencies across nearly all regions: i) little change in crop diversity from 1961 through to the late 1970s; followed by ii) a 10-year period of sharp diversification through the early 1980s; followed by iii) a "levelling-off" of crop diversification beginning in the early 1990s. However, the specific onset and duration of these distinct periods differs significantly across regions and are unrelated to agricultural expansion, indicating that unique policy or environmental conditions influence the crops being grown within a given region. Additionally, while the 1970s and 1980s are defined by region-scale increases in crop diversity this period marks the increasing dominance of a small number of crop species and lineages; a trend resulting in detectable increases in the similarity of crops being grown across regions. Broad similarities in the species-level taxonomic and phylogenetic diversity of crops being grown across regions, primarily at large industrial scales captured by FAO data, represent a unique feature of the Anthropocene epoch. Yet nuanced asymmetries in regional-scale trends suggest that environmental and socio-economic factors play a key role in shaping observed macro-ecological changes in the plant diversity on agricultural lands.
人类世部分由作物在起源地以外的人为传播来定义。在全球范围内，有证据表明，过去 50 年来，在大规模农业土地上种植的作物的种级分类多样性呈线性增长。然而，环境和社会经济差异表明，不同地区的作物多样性变化存在时间差异。生态理论还表明，作物分类多样性的变化不一定反映作物进化多样性的变化。我们利用联合国粮食及农业组织（FAO）的数据，评估了 1961 年至 2014 年 22 个次大陆尺度区域的作物分类和系统发育多样性的变化。我们记录了几乎所有地区都存在的某些广泛一致性：i）从 1961 年到 70 年代末，作物多样性变化不大；其次，ii）在 80 年代初的 10 年时间里，作物多样性急剧多样化；随后，iii）从 90 年代初开始，作物多样化开始“趋平”。然而，这些不同阶段的具体开始时间和持续时间在不同地区差异显著，与农业扩张无关，这表明独特的政策或环境条件影响了特定地区种植的作物。此外，尽管 70 年代和 80 年代以区域范围内作物多样性的增加为特征，但这一时期标志着少数作物物种和谱系的主导地位不断增强；这一趋势导致了跨地区种植作物的相似性增加。在 FAO 数据捕捉的大工业规模上，各地区种植作物的种级分类和系统发育多样性的广泛相似性代表了人类世的一个独特特征。然而，区域尺度趋势的细微差异表明，环境和社会经济因素在塑造农业土地上植物多样性的观测宏观生态变化方面发挥着关键作用。
