Ecological legacies of past fire and human activity in a Panamanian forest

Abstract

Tropical forests provide global ecosystem services and harbor much of Earth's terrestrial biodiversity, but the mechanisms driving the patterns of biodiversity remain uncertain. Palms are one of the most abundant and most widely used plant groups, particularly in the Neotropics. Our data highlight how both direct and indirect human influence that occurred decades to hundreds of years ago can affect the abundances of palm species in modern tropical forests. Our results highlight that biodiversity is dynamic, and changes through time, and that human activities can affect species composition for centuries in tropical forests. Summary• Human activities over the past decades and centuries, including fire, cultivation, and forest opening, may have left ecological legacies that persist in modern tropical forests, particularly among palms. We investigated whether past human activities affected modern palm abundances in a well-studied plot located in a tropical semievergreen forest of Panama.• We analyzed soil cores for charcoal to reconstruct past fire events and phytoliths to reconstruct past vegetation changes. We dated as many charcoal fragments as possible to place a temporal framework on past fire events.• Our analysis documented widespread fires that occurred 600-900 years ago across the plot. Oenocarpus mapora increased in abundance as a result of these fires, though other palms did not. A subsequent increase in O. mapora occurred later in the relative absence of fire and was likely due to game hunting during the construction of the Panama Canal.• Our results showed that the enrichment of O. mapora was determined by disturbance characteristics (e.g., timing, type, and intensity), but the persistence of increased abundances was likely determined by traits (life history characteristics). These data highlight the complexity of human-environment interactions and how they can persist for centuries in settings with long-lived trees such as tropical forests. These data highlight the importance of adding a historical context to further understand modern ecological patterns and processes.

Genomic footprints of (pre) colonialism: Population declines in urban and forest túngara frogs coincident with historical human activity

“…Surprisingly, the timing of these population declines predates recent anthropogenic disturbances, such as urbanisation and the spread of the pathogenic fungal disease chytridiomycosis (Hof et al., 2011; Rodríguez‐Brenes et al., 2016; Scheele et al., 2019). Instead, these declines coincide with significant human‐mediated disturbances, such as deforestation and landscape modification, during European colonialism (Rompré et al., 2008) and also extending back into the pre‐colonial period (McMichael et al., 2022). Below, we discuss some of the important considerations and implications for our findings.…”

“…400–800 ya) corresponds to a period of apparent reduced human activity in this area following a period of intense and recurrent fires linked with agriculture c . 700–1000 ya (McMichael et al., 2022).…”

Past human‐induced ecological legacies as a driver of modern Amazonian resilience

“…An example of pre‐European disturbances that resulted in increased fire and drought resistance and resilience comes from the lowland forests of Panamá. On the Gigante Peninsula (Panamá), widespread fire events that occurred around 600 years ago resulted in increased abundances of the palm Oenocarpus mapora that have survived to today (McMichael et al, 2022). This palm can resprout from its base, or expand clonally, allowing it to successfully recruit in high abundances following large tree mortality or fire events (De Steven, 1989).…”

“…Chazdon, 2003). The ecological legacies of human‐induced fire, deforestation, cultivation or plant enrichment or depletion that occurred over the last centuries to millennia can influence species composition and functional traits of modern Amazonian forests (Feldpausch et al, 2022; Iriarte et al, 2020; Maezumi, Alves, et al, 2018; McMichael et al, 2022). We hypothesize that these shifts in species composition and functional traits may also increase Amazonian forest resilience, which is a function of both resistance (the capacity to resist disturbance) and recovery (rate of return of ecosystem functions following disturbance) to drought and fire events in modern forests (sensu Hodgson et al, 2015).…”

“…Chazdon, 2003). The ecological legacies of human-induced fire, deforestation, cultivation or plant enrichment or depletion that occurred over the last centuries to millennia can influence species composition and functional traits of modern Amazonian forests (Feldpausch et al, 2022;Iriarte | 1417Iriarte | et al, 2020Maezumi, Alves, et al, 2018;McMichael et al, 2022).…”