The consequences of tropical forest fragmentation on herbivory are poorly understood. The limited evidence suggests that forest fragmentation can have positive, negative or neutral effects on herbivory. Inconsistencies may be partly explained by plant interspecific variation and differential responses related to plant life history. In this study we examined the effects of forest fragmentation and plant regeneration mode (shade‐tolerant and light‐demanding species) on sapling herbivory using a large sample of the community (97 species, representing 25% of the woody flora of the study site), and a subset of species shared by forest fragments and continuous forest. For the latter, we also analyzed the effects of species identity on variation in herbivory. Also, for the shared species we used two techniques to measure herbivory: standing herbivory (i.e. instantaneous, actual damage) and cumulative herbivory (i.e. damage, accumulated over time, on initially intact leaves). Insect herbivory was the predominant type of damage in the two forest types, and standing herbivory at both the community and the shared species level was significantly higher in continuous forest than in fragments. Considering shared species, both standing and cumulative herbivory were significantly higher in light‐demanding than in shade‐tolerant species. Cumulative herbivory also showed a significant interaction between forest fragmentation and plant regeneration mode, whereby a significant decline in herbivory in fragments was driven by reduced herbivory in shade‐tolerant species, whereas for light‐demanding species herbivory did not change significantly, due to contrasting species‐specific responses. We conclude that tropical forest fragmentation reduces insect herbivory, but this depends on plant regeneration mode and species identity. These changes could have effects on plant regeneration and diversity in forest fragments via long‐term demographic consequences.
The consequences of habitat alteration on the role of understory insectivorous birds as predators of herbivorous insects in tropical forests are poorly understood. To examine whether fragmentation may affect the top-down controls of herbivory, we compared the number of species, individuals, and the community structure of insectivorous birds between fragments and continuous tropical moist forest in Mexico. We also registered insect herbivore abundances and conducted a larvae predation experiment to evaluate the potential role of insectivorous birds as predators of herbivorous insects. We recorded 63 bird species from 22 families, 43 percent of which were insectivorous birds. Species richness, abundance, and diversity of the avian community were higher in continuous forest compared with forest fragments. For insectivorous birds in particular, there was low similarity in avian insectivore communities between forest types, and forest fragments had more heavily dominated communities of avian insectivores. During the dry season, forest fragments presented significantly higher predation rates on artificial caterpillars, and lower abundance of herbivorous Lepidoptera larvae, compared with continuous forest. Furthermore, there was a significant negative correlation between artificial caterpillar predation rate and larval Lepidoptera abundance, with higher rates of predation in sample sites of low Lepidoptera abundance. Hence, the potentially greater light in the dry season combined with a more dominated avian insectivore community in forest fragments may facilitate increased predation by avian insectivores, resulting in a decline in abundance of larval Lepidoptera, with implications for the process of insect-driven herbivory in forest fragments.
Zuelania guidonia is a tree species of cultural importance in Totonac society. This tree is a central element of the Los Voladores (the "flying men") pre-Hispanic ritual ceremony. However, the populations of Z. guidonia have decreased due to anthropogenic activity. This study aimed to codesign an agroforestry model for the recovery of Z. guidonia populations by combining scientific and traditional agroforestry knowledge at the El Tajín archaeological site in Veracruz, Mexico. We assessed the abundance of Z. guidonia and analyzed plant species richness and diversity in forest fragments. Species were classified according to plant regeneration modes (light-demanding and shade-tolerant) and to the local uses of secondary forests and conserved forest fragments. In addition, we worked collaboratively in a project that consisted of workshops, focus groups, open interviews, drawings, and field walks with community members. We studied a small population of Z. guidonia and recorded 116 woody species. Our findings showed that conserved forests were more diverse than secondary forests. Seventy-four percent of the species are useful to people. The Totonac people chose traditional vanilla plantations as a guiding model to shape their agroforestry system for restoring native vegetation. The results of our collaborative work revealed the Totonac extensive Traditional Ecological Knowledge and the need for the Voladores' group to strengthen alliances with other government and nongovernment organizations. They designed a model of a diversified traditional agroforestry vanilla system enriched with multipurpose plants as the outset of local well-being and regional agrobiodiversity restoration. This study reveals a distinct heterogenous land management scheme that provides the necessary conditions for preserving plant diversity, which will be used by local people for different purposes. We argue for studies that build on the relationship between scientific knowledge and Traditional Ecological Knowledge in transformed landscapes as a step forward for the long-term conservation of biocultural diversity.
The abundance, species richness, similarity and dominance of braconid parasitoid wasps were estimated for 4 types of land use (secondary forest, rubber plantations, living fences and pastures), and remnants of preserved tropical rain forest in southern Mexico. We also analyzed whether specialist (koinobionts) taxa are more negatively affected by forest disturbance than generalists (idiobionts), and whether braconid abundance is correlated with adult host abundance. Braconids were sampled using 3 Malaise traps for each type of land use during March 2010 and May 2011. We collected 143 individuals belonging to 65 species and 15 subfamilies. Species richness and abundance were higher in preserved and secondary forests, than in other types of land use. Although abundance and richness were low in pastures, these sites potentially contain hosts for braconids. We detected no variation in abundance or species richness by land use, even when comparing idio-and koinobionts. The most dominant species belonged to the genera Apanteles (Microgastrinae) and Hetersopilus (Doryctinae) in all land use types, except pasture, where Bracon (Braconinae) dominated. We detected a positive relationship between braconids and adult host abundance. Altogether, the 4 types of land use and the preserved forest are able to host a diverse braconid community.
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