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Biological invasions pose a major threat to biodiversity conservation in protected areas, with roads, tracks, and trails being the main pathways for the spread of non-native species. This study aimed to assess the distribution patterns of non-native and native plant species in relation to elevational gradient, public use intensity, and disturbance by roads and trails in a protected tropical mountain forest in southeastern Brazil. Specifically, we recorded plant species along this gradient and tested whether the richness of native and non-native species differed with elevation. Additionally, we investigated whether the high-altitude non-native species community was a subset of lower-elevation communities and whether non-native species richness was linked to anthropogenic disturbances and public use intensity. Our findings revealed that native and non-native species richness varied along the elevational gradient. Native species exhibited a hump-shaped pattern, with richness peaking at mid-elevations. In contrast, non-native species did not show a clear trend along the altitudinal gradient. Notably, higher non-native species richness was observed in roadside and trailside plots. The non-native species communities at higher altitudes were not simply subsets of those found at lower elevations. Thus, while the richness and composition of native species appeared to be driven by environmental factors along the elevational gradient, the presence of non-native species was more closely associated with anthropogenic disturbances. In summary, our results indicate that non-native plants, although widespread along trails and roads, establish primarily in the most disturbed areas. Therefore, roads, trails, and human and vehicular traffic are key determinants of biological invasions in this mountainous protected area.
Several authors suggest that greater vegetation complexity provides more shelters, supporting higher parasitoid diversity. Additionally, it serves as visual cue in host searching. This study evaluates how visual stimuli and herbivore-induced vegetation changes affect parasitoid strategies and guilds in low deciduous forest [Yabucu], and Medium Semi-Evergreen forest [Noh-Bec]. We calculated the relative abundance of idiobiont and koinobiont life strategies for each vegetation type and constructed the range-abundance curves of these communities. Also, the relationship of guilds with the different types of damage from herbivory and leaf characteristics were described. The koinobiont:idiobiont (K:I) ratio was 6:1 (86.65% koinobionts and 13.35% idiobionts) in Yabucú and 1:2 (32.78% koinobionts and 67.22% idiobionts) in Noh-Bec. Some guilds were associated with vegetation: a negative correlation between fluctuating asymmetry seedlings (FAS) and parasitoids attacking larvae into the fruiting bodies of fungi was founded; the FAS is an indirect indicator of herbivory, nonetheless, the parasitoids found do not target phytophagous hosts, which makes an inverse relationship plausible and could potentially reduce intra-guild competition. Hyperparasitoids were positively associated with holes in adult plants (HA); with an association with herbivore parasitoids, which could be contributing to the recorded evidence of holes.
In West Africa, vast areas are being deforested; the remnant forest patches provide a wealth of ecosystem services and biodiversity conservation potential, yet they are threatened by human activity. Forest patches <100 ha have not been widely catalogued before; we mapped forest loss of small forest patches outside of protected areas in the Guinean savannah and humid Guineo-Congolian bioclimatic regions of Togo, Benin, Nigeria and Cameroon between 2000 and 2022. Focusing on the dynamics of small patches, without considering the splitting process of larger patches, we quantified changes in their number and area and the rate and trend of forest loss. Small forest patches are widespread, yet their area and number have decreased, while the forest loss rate is increasing. Primary forest patches lost almost half of their area annually – twice as much as secondary forests, and this loss was especially pronounced across small patches (0.5 – 10 ha), suggesting deforestation preferentially occurs in the smallest patches of primary forest. If forest loss continues at the current rate, 14% of the total forest area mapped in this study will have disappeared by 2032, jeopardizing their potential to provide ecosystem services and emphasizing the need for measures to counter their deforestation.
Carbon stocks in root biomass and soil organic carbon (SOC) were analysed in tropical mountain cloud forest (TMCF) of Mexico. Additionally, the hypothesis that the concentration of roots in the forest is not homogeneous but that they are concentrated near the trunks of the trees was evaluated. Root biomass was 707.68 ± 150.41 g·m−2, which stores ∼353.85 ± 75.21 g·C·m−2. Coarse roots contributed 36.8%, fine roots 35.5%, and very fine roots 27.7% of the total biomass. The results did not support the hypothesis that fine roots are concentrated near the trunks of the trees. On average, SOC was 108.23 ± 33.21 Mg·C·ha−1. Mean C stored in the soil (C in roots + SOC) was 111.77 ± 32.97 Mg·C·ha−1. The TMCF is an ecosystem with a high potential for soil carbon storage, with similar C values reported to those in other tropical forests.
Flagship species are those chosen to raise support for broader conservation marketing campaigns and can be used as symbols of the ecosystem services and evolutionary history of particular areas. Thus, flagship species can be employed for the protection of endangered species and threatened ecosystems. Northeastern Michoacán, Mexico, is an important region for amphibian diversity but approximately 40% of its mature forest has been removed. Among northeastern Michoacán amphibians, the use of Ambystoma ordinarium as a flagship species is supported by its co-occurrence with other threatened amphibians along riparian zones. To support this proposal, however, it is important to assess the functional traits and evolutionary history of amphibian species sharing their habitat with A. ordinarium. To evaluate the potential of A. ordinarium as a flagship species, we estimated the functional and phylogenetic diversity of amphibian assemblages in 60 riparian zones. The results showed that amphibian assemblages sharing habitat with A. ordinarium presented higher functional and phylogenetic diversity than those in which this species was absent. These results highlight the potential of A. ordinarium as a flagship species for the protection of associated amphibian species, their functions, and evolutionary history.
The extensive clearing and modification of forests by anthropogenic activities is a major driver of biodiversity loss. Declines of common species are especially concerning because of the potentially large cascading effects they might have on ecosystems. Regrowth of secondary forests may help reverse population declines by restoring habitats to similar conditions prior to land conversion but the value of these secondary forests to fauna is not well understood. We compared the abundance of a direct-developing terrestrial frog, Craugastor stejnegerianus, in riparian and upland habitats of pasture, secondary forest, and mature forest sites. Mean abundance per transect was lower in upland pasture compared to mature forest. Secondary forest had similar abundance to mature forest regardless of age. We show that conversion of forest habitat to pasture represents a conservation threat to this species. However, riparian buffers help mitigate the negative effect of conversion of forest to pasture, and regrowth of secondary forest is an effective management strategy for restoring the abundance of this common leaf-litter species.
Coconut farming contributes to the livelihoods of millions of people in tropical countries but is less frequently considered as a threat to biodiversity compared to other palm commodities such as oil palm. The expansion of coconut farming alongside other smallholder agriculture in Sulawesi, Indonesia, is of potential concern as the region is a centre of species endemism. We studied bird diversity and community structure in forests, coconut palm plantations and mixed farmland in Gorontalo Province, northern Sulawesi. Forest and non-forest sites supported similar numbers of species overall, but compared to agricultural areas, forest sites had communities that were more diverse and more even (i.e. different species were present at similar abundances). We found far fewer endemic species in agricultural areas compared to forests, and the communities in palm plantations and mixed farmland sites were dominated by generalist birds, with few indicator taxa. Nevertheless, there was a higher number of endemic species in coconut palm plantations than in mixed farmland sites. These findings mirror patterns of biotic homogenization documented elsewhere in the Wallacea centre of endemism, and imply that coconut palm plantations have comparable biodiversity value to other farmland systems. Increased protection of lowland forests and improved management of coconut farms could be important for supporting the conservation of the endemic birds of Sulawesi in the long term, but this warrants further study.
One of the biggest issues in plant ecology is determining the interaction outcome between seeds and scatter-hoarding rodents because the latter has a dual role as dispersers and predators of seeds. Density-dependence contexts involving resource abundance largely influence the outcome of this interaction. Here, we investigated how the variation in the density of a large-seeded tropical tree (Joannesia princeps Vell) affects its probability of seed removal, consumption, dispersal, and burial by a neotropical rodent (Dasyprocta azarae Lichtenstein). We tested whether the elevated resource availability in high tree density areas would cause scatter hoarder’s satiation by decreasing seed removal and consumption (predator satiation hypothesis) or increasing seed dispersal and burial (predator dispersal hypothesis). We tracked the fate of 461 seeds in 14 plots with distinct J. princeps abundances inside a large Atlantic Forest fragment. We used spool-and-line tracking and camera trappings to determine seed fate and identify interacting animals. Agouti was the only species removing J. princeps seeds. Tree density benefitted J. princeps by increasing seed dispersal through buried seed but not affecting seed removal and consumption. This result shows how density-dependent contexts, such as tree density, may alter seed fate in seed–rodent interactions supporting future studies aiming to reestablishing seed dispersal functions in Atlantic Forest fragments.
The home-field advantage (HFA) hypothesis establishes that plant litter decomposes faster at ‘home’ sites than in ‘away’ sites due to more specialized decomposers acting at home sites. This hypothesis has predominantly been tested through ‘yes or no’ transplanting experiments, where the litter decomposition of a focal species is quantified near and away from their conspecifics. Herein, we evaluated the occurrence and magnitude of home-field effects on the leaf litter decomposition of Myrcia ramuliflora (O.Berg) N. Silveira (Myrtaceae) along a natural gradient of conspecific litterfall input and also if home-field effects are affected by litter and soil traits. Litter decomposition of M. ramuliflora was assessed through litterbags placed in 39 plots in a tropical heath vegetation over a period of 12 months. We also characterized abiotic factors, litter layer traits, and litter diversity. Our results indicated the occurrence of positive (i.e. Home-field advantage) and negative (i.e. Home-field disadvantage) effects in more than half of the plots. Positive and negative effects occurred in a similar frequency and magnitude. Among all predictors tested, only the community weighted mean C/N ratio of the litterfall input was associated with home-field effects. Our results reinforce the lack of generality for home-field effects found in the literature and thus challenge the understanding of litter-decomposer interaction in tropical ecosystems.
Pedro Rojas's 1961 excavation of numerous stone vessels at the Huayurco site has led scholars to suspect that the Jaén region of the northeastern Peruvian Andes was an important center of early ceremonial stone bowl production. This discovery not only provided clear evidence of an independent craft technology within the ceja de selva, or eastern Andean tropical montane forest, but the similarity of these stone vessels to examples found at coastal and highland Andean sites also suggested that the Jaén region produced these vessels as a means of participating within early interregional exchange networks. Because empirical evidence of tropical forest exchange items within coastal and highland sites is difficult to obtain because of these items’ suspected perishable nature, the stone vessels represented an alternative means for understanding early Andean–Amazonian relations. Despite the importance of this discovery, little follow-up investigation has been conducted. In this article, I define the Jaén stone vessel tradition on the basis of form, design, and technology. I then review the archaeological literature on early Andean stone vessels to show how these vessels help articulate Jaén's participation within Andean interaction spheres between 2500 and 800 BC.
Seed predation by rodents can strongly influence plant recruitment and establishment. The extent to which predation risk indirectly alters plant survival in tropical forests via impacts on granivory is unclear, making it difficult to assess the cascading impacts of widespread predator loss on tree recruitment and species composition. Experimental field studies that manipulate predation risk can help address these knowledge gaps and reveal whether antipredator responses among small mammals influence plant survival. We used camera traps and seed predation experiments to test the effects of perceived predation risk (via predator urine gel) on foraging behaviour of and seed removal by murid rodents in an unlogged and unhunted rainforest in Malaysian Borneo. We also explored the influence of seed traits (e.g., seed size) on removal by granivores and assessed whether granivore preferences for particular species were affected by predator urine. Murid visits to seed plots were positively related to overall seed removal, but were not affected by predator scent. Granivory was the lowest for the largest-seeded (>6 g) plant in our study, but was not influenced by predation risk. Predator urine significantly affected removal of one seed taxon (Dimoocarpus, ∼0.8 g), suggesting that removal by granivores may be affected by predation risk for some seed species but not others. This could have implications for plant species composition but may not affect the overall level of granivory.
Preserving wildlife and their environment from anthropogenic activities requires identification and establishment of protected areas, and monitoring of their long-term effects on wildlife and habitat. Tropical forests are one of the most at-risk habitats and many tropical species have become extinct recently due to human activity. It is imperative to monitor habitat in protected areas and without in order to identify strategies and legislative policies that optimize conservation outcomes. To this end, I quantified habitat fragmentation for the great hornbill (Buceros bicornis) in Om Koi Wildlife Sanctuary, Thailand, pre- and post-establishment, within and outside the protected area, from 1973, 1985, and 1992, to assess the effectiveness of the protected area status, established in 1978, and a national logging ban, established in 1989, in preserving and restoring hornbill habitat. The results demonstrate that the establishment of Om Koi Wildlife Sanctuary did not decrease the rate of hornbill habitat fragmentation relative to areas outside the protected area. While the protected area had less fragmentation to begin with, protection status did not affect the rate of loss. Fragmentation increased significantly both inside and outside the protected area between the first and second time points (p < 0.05), after the protected area was first established. However, the national logging ban policy implemented in 1985 seems to have successfully halted the fragmentation of habitat within the protected area and surrounding unprotected areas, with all areas showing no significant change (p > 0.05). While not significant, the rate of fragmentation outside the protected area was greater. This suggests that the establishment of a protected area alone may not be sufficient to stop or reverse anthropogenic damage to endangered habitat and the species that utilize these environments. The incorporation of multiple strategies for management is likely needed to increase the ability of protected areas to preserve tropical forest species and habitats. The assessment of protected areas via satellite and ground-level data is an essential tool for evaluating the effectiveness of conservation strategies and improving outcomes.
Great attention has been drawn to the impacts of habitat deforestation and fragmentation on wildlife species richness. In contrast, much less attention has been paid to assessing the impacts of chronic anthropogenic disturbance on wildlife species composition and behaviour. We focused on natural small rock pools (sartenejas), which concentrate vertebrate activity due to habitat’s water limitation, to assess the impact of chronic anthropogenic disturbance on the species richness, diversity, composition, and behaviour of medium and large-sized birds and mammals in the highly biodiverse forests of Calakmul, southern Mexico. Camera trapping records of fauna using sartenejas within and outside the Calakmul Biosphere Reserve (CBR) showed that there were no effects on species richness, but contrasts emerged when comparing species diversity, composition, and behaviour. These effects differed between birds and mammals and between species: (1) bird diversity was greater outside the CBR, but mammal diversity was greater within and (2) the daily activity patterns of birds differed slightly within and outside the CBR but strongly contrasted in mammals. Our study highlights that even in areas supporting extensive forest cover, small-scale chronic anthropogenic disturbances can have pervasive negative effects on wildlife and that these effects contrast between animal groups.
Many parasites spend part of their life cycle as infectious forms released from an infected host in the external environment, where they may encounter and infect new hosts. The emergence of infectious life stages often occurs once a day to minimize mortality in adverse environments. In bird hosts, intestinal parasites such as coccidia are generally released with feces in the late afternoon. This dynamic is adaptive since it allows avoiding desiccation and ultraviolet (UV) radiation, thus reducing mortality of oocysts in the environment until transmission to the next host. If this circadian rhythm is the result of natural selection to increase oocyst survival, we may hypothesize that oocysts will appear in feces at different times depending on the environment where hosts live. Particularly, in an environment where UV radiation and desiccation are very low, we may expect oocyst circadian release to disappear since the main selective pressure would be relaxed. We sampled different species of birds in tropical and temperate forests in spring and investigated coccidian oocyst output. A strong circadian variation in the prevalence of hosts shedding coccidian oocyst was detected for species caught in the temperate forest with an increase in prevalence in the late afternoon, whereas prevalence of birds shedding oocysts was constant over the course of the day for most species sampled in the tropical rain forest. These results are consistent with the hypothesis that oocysts’ circadian output is maintained by natural selection to increase oocyst survival. We discuss the adaptive significance of diurnal periodicity in parasite output.
The prevention of tropical forest deforestation is essential for mitigating climate change. We tested the machine learning algorithm Maxent to predict deforestation across the Peruvian Amazon. We used official annual 2001–2019 deforestation data to develop a predictive model and to test the model’s accuracy using near-real-time forest loss data for 2020. Distance from agricultural land and distance from roads were the predictor variables that contributed most to the final model, indicating that a narrower set of variables contribute nearly 80% of the information necessary for prediction at scale. The permutation importance indicating variable information not present in the other variables was also highest for distance from agricultural land and distance from roads, at 40.5% and 14.3%, respectively. The predictive model registered 73.2% of the 2020 early alerts in a high or very high risk category; less than 1% of forest cover in national protected areas were registered as very high risk, but buffer zones were far more vulnerable, with 15% of forest cover being in this category. To our knowledge, this is the first study to use 19 years of annual data for deforestation risk. The open-source machine learning method could be applied to other forest regions, at scale, to improve strategies for reducing future deforestation.
Among nectarivorous birds, the highest niche partitioning occurs between hummingbirds and plants. Although hummingbirds tend to visit morphologically well-matched resources, as ornithophilous species, they can also visit flowers with other traits. Here, we investigated whether the niche partitioning in hummingbird-plant interactions is also observed with ornithophilous species only. We also explored if hummingbird traits predicted resources use. We recorded a plant-ornithophilous species network in a semi-deciduous forest in Brazil. We quantified interaction partitioning through network connectance, complementary specialisation, and modularity. The influence of hummingbirds’ traits into their visits was investigated through methods of functional ecology and ecological networks. We recorded 948 interactions between nine hummingbirds and seven ornithophilous plants. We detected similar patterns of niche partitioning between hummingbirds and ornithophilous plants in comparison to networks considering the entire plant community. However, hummingbird species with the most specialised interactions are different from those when the whole system is evaluated. Therefore, we cannot downscale the patterns from one scale to the other. The pattern of interaction with ornithophilous plants was not related to hummingbirds’ traits. Therefore, the coexistence of species with shared traits might be occurring through facilitative and competitive processes, leading to trait mismatching and maintaining niche partitioning among ornithophilous plants.
This chapter profiles contemporary examples of ecosystem collapse and recovery. Case studies presented include coral reefs, marine fisheries, freshwater ecosystems (streams, rivers and lakes), forests (including tropical, temperate and boreal), savanna, and temperate agroecosystems. In each case, the available empirical evidence is reviewed in relation to the ecological mechanisms underlying both ecosystem collapse and recovery. At the end of the chapter, the theoretical propositions identified in Chapter 2 and refined in Chapter 3 are then evaluated in the light of the evidence available from these contemporary case studies.
Climate change threatens tropical forests, ecosystem services, and indigenous peoples. The effects of climate change will force the San Blas Island communities of the indigenous Guna people to relocate to one of the most extensive, intact forests in Panama. In this paper, we argue that the impacts of climate change, and the proposed resettlement, will synergistically affect the jaguar. As apex predators, jaguars are sensitive to landscape change and require intact forests with ample prey to survive. Proactively planning for the intrinsically related issues of climate change, human displacement, and jaguar conservation is a complex but essential management task.
Technical summary
Tropical rainforest, coastal, and island communities are on the front line of increasing temperatures and sea-level rise associated with climate change. Future impacts on the interconnectedness of biological and cultural diversity (biocultural heritage) remain unknown. We review the interplay between the impacts of climate change and the displacement of the indigenous Guna people from the San Blas Islands, the relocation back to their mainland territory, and the implications for jaguar persistence. We highlight one of the most significant challenges to using resettlement as an adaptive strategy to climate change, securing a location where the Guna livelihoods, traditions, and culture may continue without significant change while protecting ecosystem services (e.g. biodiversity, carbon sequestration, and water). We posit that developing management plans that strive to meet social needs without sacrificing environmental principles will meet these objectives.
Social media summary
A biocultural approach increases adaptive capacity for ecological and human social systems threatened by climate change.
Understorey wildfires harm tropical forests by affecting natural regeneration, but the trajectories of fire-disturbed forests after disturbance are poorly understood. To fill this gap, we conducted experimental burns in a transitional forest between the Amazon forests and the Brazilian Savanna (Cerrado) and investigated their effects on plant community diversity of regeneration. The experiment consisted of three 50-ha plots that between 2004 and 2010 were burned either annually (six times), every three years (thrice) or not at all (Control). To evaluate early post-fire recovery, we recorded grass occurrence and regenerating stems (≤1 cm in diameter at breast height). We noted that high fire-frequency plots had a reduction of species richness (62%) and abundance (84%) and were associated with floristic and structural changes, dominance of few species and increase of grass colonization when compared with low fire-frequency. We observed that resprouts were the main pathway for forest restoration in both burned regimes, particularly in low fire-frequency. However, the forest can recover from fires by means of resprouting, until a threshold in fire frequency is reached, when resprouts and seedlings declined for most of the species, with a few fire-tolerant species becoming dominant.
Conversion of forest land into different land use types is the primary cause of degradation of land resources, which in turn alters nutrient and carbon cycles, land productivity and diversity of species. There is scarcity of information about land-use changes (LUC) and their effect on relationship of soil quality and species diversity at landscape level in the Vindhyan dry tropical region. We evaluated the impact of land-use changes on soil physicochemical quality and the influence of these qualities on species diversity and organic matter accumulation. We also established the relationship between soil quality indicators and species diversity parameters. To examine impact of LUC, we did a detailed field survey and analysed selected soil quality indicators by standard methods. We examined species diversity parameters and established the relationship between soil quality and species diversity. We found that there is a marked decline in soil porosity, water-holding capacity and soil moisture due to LUC. Conversion from forest land (FL) to savanna land (SL) resulted in soil organic carbon decreasing by ∼40–50%. The decrease was more pronounced in cultivated land (CL) and degraded land (DL) (65–70% and 83–85%, respectively). In the case of total N, maximum decrease in total N of 83–87% was noted in DL as compared with FL. The poor soil quality indicators in degraded and agricultural land can be explained by the interaction between the soil organic carbon and nitrogen loss with diversity loss. This study recommends that for management/restoration of land resources, planning strategies should consider the current landscape structure, with land-use planning.