Biodiversity trends within the Holocene

Abstract

There is a rapidly emerging interest in detecting and understanding biodiversity trends during the ‘Anthropocene’ in response to human stressors and climate change. Surprisingly few studies have, however, considered trends in biodiversity during the preceding Holocene. Here, we present general trends in terrestrial alpha- and beta-diversity and biomass for the four main ecological phases (protocratic, mesocratic, Homo sapiens, oligocratic) of the Holocene in north-west Europe based on palynological data at the meta-community scale. Alpha- and beta-diversity decreased in the protocratic, showed little change in the mesocratic, decreased in the oligocratic, and increased markedly in the Homo sapiens phase. Biomass was maximal in the mesocratic. Biodiversity changes in the last 200 years (‘Anthropocene’), as detected from palynological data, are small compared with the changes over the Holocene. There are minor decreases in α-diversity, spatial β-diversity and biomass and a slight increase in temporal β-diversity at sites on fertile soils. This analysis is designed to encourage ecologists and biogeographers interested in the ‘Anthropocene’ to extend the time-scale of their analyses and to consider whether ‘Anthropocene’ biodiversity trends are a simple continuation of trends in the late Holocene or whether recent ‘Anthropocene’ trends deviate from the long-term Holocene trends. Hopefully, it will also stimulate palaeoecologists to consider Holocene biodiversity trends in different geographical areas and different organism groups and ecological systems.