The response of geophytes to continuous human foraging on the Cape south coast, South Africa and its implications for early hunter-gatherer mobility patterns

M Susan Botha; Richard M Cowling; Jan C De Vynck; Karen J Esler; Alastair J Potts

doi:10.7717/peerj.13066

The response of geophytes to continuous human foraging on the Cape south coast, South Africa and its implications for early hunter-gatherer mobility patterns

PeerJ. 2022 May 3:10:e13066. doi: 10.7717/peerj.13066. eCollection 2022.

Authors

M Susan Botha¹, Richard M Cowling¹, Jan C De Vynck¹, Karen J Esler², Alastair J Potts³

Affiliations

¹ Botany Department, African Centre for Coastal Palaeoscience, Gqeberha, Eastern Cape, South Africa.
² Stellenbosch University, Conservation Ecology & Entomology, Stellenbosch, Western Cape, South Africa.
³ Botany Department, Nelson Mandela University, Gqeberha, Eastern Cape, South Africa.

Abstract

Current ecological understanding of plants with underground storage organs (USOs) suggests they have, in general, low rates of recruitment and thus as a resource it should be rapidly exhausted, which likely had implications for hunter-gatherer mobility patterns. We focus on the resilience (defined here as the ability of species to persist after being harvested) of USOs to human foraging. Human foragers harvested all visible USO material from 19 plots spread across six Cape south coast (South Africa) vegetation types for three consecutive years (2015-2017) during the period of peak USO apparency (September-October). We expected the plots to be depleted after the first year of harvesting since the entire storage organ of the USO is removed during foraging, i.e. immediate and substantial declines from the first to the second harvest. However, over 50% of the total weight harvested in 2015 was harvested in 2016 and 2017; only after two consecutive years of harvesting, was there evidence of significantly lower yield (p = 0.034) than the first (2015) harvest. Novel emergence of new species and new individuals in year two and three buffered the decline of harvested USOs. We use our findings to make predictions on hunter-gatherer mobility patterns in this region compared to the Hadza in East Africa and the Alyawara in North Australia.

Keywords: Bet-hedging; Geophyte ecology; Harvesting; Hunter-gatherer mobility patterns; Underground storage organs.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Africa, Eastern
Australia
Humans
Plants*
South Africa

Grants and funding

Susan Botha was funded by a South African National Research Foundation (NRF) Doctoral Scholarship. Alastair Potts is supported by the National Research Foundation Research Career Advancement Fellowship (Grant No: 91452). This research was also supported by the NRF of South Africa (Grant No: 93487, CPRR14072880885) and Curtis Marean. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.