Effects of Experimental Defoliation on Growth, Reproduction and Survival of Astrocaryum Mexicanum

Mendoza, Ana; Piñero, Daniel; Sarukhán, José

doi:10.2307/2260433

Cited by 90 publications

(85 citation statements)

References 22 publications

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“…This idea is supported by observations that large domestic mammals (cows and horses) consume palm leaves when they occasionally intrude into the forest. Experimental evidence suggests that a single total defoliation event increases mortality of juvenile palms by 50% (43), but such damage is absent in the LTS (26). A vertebrate exclusion experiment between 1985 and 1991 (Methods) did not find significant differences in density of seedlings between enclosure and control (open to vertebrate activity) treatments (Fig.…”

Section: Resultsmentioning

confidence: 99%

Anthropogenic disturbances jeopardize biodiversity conservation within tropical rainforest reserves

Martı́nez-Ramos

Ortiz-Rodríguez

Piñero

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

120

102

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Anthropogenic disturbances affecting tropical forest reserves have been documented, but their ecological long-term cumulative effects are poorly understood. Habitat fragmentation and defaunation are two major anthropogenic threats to the integrity of tropical reserves. Based on a long-term (four decades) study, we document how these disturbances synergistically disrupt ecological processes and imperil biodiversity conservation and ecosystem functioning at Los Tuxtlas, the northernmost tropical rainforest reserve in the Americas. Deforestation around this reserve has reduced the reserve to a mediumsized fragment (640 ha), leading to an increased frequency of canopy-gap formation. In addition, hunting and habitat loss have caused the decline or local extinction of medium and large herbivores. Combining empirical, experimental, and modeling approaches, we support the hypothesis that such disturbances produced a demographic explosion of the long-lived (≈120 y old, maximum height of 7 m) understory palm Astrocaryum mexicanum, whose population has increased from 1,243-4,058 adult individuals per hectare in only 39 y (annual growth rate of ca. 3%). Faster gap formation increased understory light availability, enhancing seed production and the growth of immature palms, whereas release from mammalian herbivory and trampling increased survival of seedlings and juveniles. In turn, the palm's demographic explosion was followed by a reduction of tree species diversity, changing forest composition, altering the relative contribution of trees to forest biomass, and disrupting litterfall dynamics. We highlight how indirect anthropogenic disturbances (e.g., palm proliferation) on otherwise protected areas threaten tropical conservation, a phenomenon that is currently eroding the planet's richest repositories of biodiversity.H uman activities operate as dominant drivers of biodiversity change and disruption of ecosystem processes in tropical forest ecosystems (1). Forest fragmentation modifies the structure, diversity, dynamics, and species composition of arboreal communities through habitat reduction and edge effects on tree mortality and recruitment rates (2, 3), liana proliferation (4), and invasive species (5). In addition, fragmentation reduces area of habitat necessary for many vertebrates (herbivores, seed predators, or seed dispersers) to maintain viable populations (6, 7). Fragmentation also facilitates poaching of game animals (7,8), which, in turn, disrupts trophic interactions that are critical for the maintenance of species diversity (9, 10). More specifically, fragmentation reduces population sizes of some shadetolerant tree species while fostering the presence of generalist and pioneer plant species (5, 11). Additionally, defaunation is differential, leading to the disappearance or decline of medium and large herbivores (12), and favors the proliferation of large-seeded, shadetolerant tree species (13). All these changes reduce tree diversity in forest fragments (14,15). Studies documenting the effects of forest fr...

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Section: Resultsmentioning

confidence: 99%

Anthropogenic disturbances jeopardize biodiversity conservation within tropical rainforest reserves

Martı́nez-Ramos

Ortiz-Rodríguez

Piñero

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

120

102

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“…Hexopetion mexicanum (as Astrocaryum mexicanum) has been a model species in tropical forest population ecology (Piñero et al, 1977(Piñero et al, , 1984(Piñero et al, , 1986Piñero and Sarukhan, 1982;Burquez et al, 1987;Mendoza et al, 1987;Martinez-Ramos et al, 1988;Eguiarte et al, 1992Eguiarte et al, , 1993.…”

Section: Ecologymentioning

confidence: 99%

The genus Hexopetion Burret (Arecaceae)

Pintaud

Millán

Kahn³

2008

Rev peru biol

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“…Recovery of reproductive and vegatative palms was followed by increased production of leaves. Mendoza, et al (1987) reported that defoliation of mature leaves of Astrocaryum mexicanum palm increased leaf production by 30.0 per cent. Defoliation greater than 33-0 per cent of total leaf production, nevertheless, resulted in lowered reproductive capacity of mature palms.…”

Section: St Basal Stemsmentioning

confidence: 99%

Effects of wildfire on a semidesert riparian woodland along the Turkwel river, Kenya, and management implications for turkana pastoralists

Oba¹

1990

Land Degrad Dev

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Regeneration following a wildfire in a semidesert riparian woodland near the Turkwel River, Kenya was monitored from 2nd June, 1987 to 6th July, 1988. The pre-fire tree density was 417 plants ha-' and the canopy cover was 36.5 per cent ha-'. Hyphaene cornpressa (a palm) accounted for 93 per cent of total density and Acacia tortilis 6.9 per cent. A . tortilis contributed a pre-fire aboveground fuel biomass of 64.92 t ha-', while H . compressa provided 23.35 t ha-'. The wildfire reduced tree canopy cover to about 7.0 per cent and resulted in a 100.0 per cent top-kill of A. tortilis and 24.0 per cent for H . compressa. Seed germination of A. tortilis and canopy density of H . compressa saplings were stimulated by the wildfire. The post-fire A. tortilis seedling density was 9 554 ha-' compared to the pre-fire density of 213 plants ha-'. Canopy cover of palms in the burnt area increased by 457.0 per cent, while crown heights increased by 100.0 per cent between the sampling dates. Where H . compressa palms were not top-killed, recovery following the post-burn period resulted in higher foliage yield compared to unburnt palms. In reproductive palms, burning delayed fruit production although the effect may not be long lasting.The impact of wildfire on this Turkwel riparian woodland has important management implications. Elimination of pod-bearing A . tortilis by fire creates acute shortage of a critical dry season forage for Turkana livestock, while loss of woody cover results in destruction of riparian habitats.

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Effects of Experimental Defoliation on Growth, Reproduction and Survival of Astrocaryum Mexicanum

Cited by 90 publications

References 22 publications

Anthropogenic disturbances jeopardize biodiversity conservation within tropical rainforest reserves

Anthropogenic disturbances jeopardize biodiversity conservation within tropical rainforest reserves

The genus Hexopetion Burret (Arecaceae)

Effects of wildfire on a semidesert riparian woodland along the Turkwel river, Kenya, and management implications for turkana pastoralists

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