scholarly journals Hunting pressure modulates the composition and size structure of terrestrial and arboreal vertebrates in Amazonian forests

2021 ◽  
Author(s):  
Andressa B. Scabin ◽  
Carlos A. Peres
Keyword(s):  
Community Structure ◽  
Tropical Forests ◽  
Forest Canopy ◽  
Linear Models ◽  
Size Structure ◽  
Management Policy ◽  
Primary Forest ◽  
Population Declines ◽  
Hunting Pressure ◽  
Cascading Effects

AbstractOverhunting is a leading contemporary driver of tropical forest wildlife loss. The absence or extremely low densities of large-bodied vertebrates disrupts plant-animal mutualisms and consequently degrades key ecosystem services. Understanding patterns of defaunation is therefore crucial given that most tropical forests worldwide are now “half-empty”. Here we investigate changes in vertebrate community composition and size structure along a gradient of marked anthropogenic hunting pressure in the Médio Juruá region of western Brazilian Amazonia. Using a novel camera trapping grid design deployed both in the understorey and the forest canopy, we estimated the aggregate biomass of several functional groups of terrestrial and arboreal species at 28 sites along the hunting gradient. Generalized linear models (GLMs) identified hunting pressure as the most important driver of aggregate biomass for game, terrestrial, and arboreal species, as well as nocturnal rodents, frugivores, and granivores. Local hunting pressure affected vertebrate community structure as shown by both GLM and ordination analyses. The size structure of vertebrate fauna changed in heavily hunted areas due to population declines in large-bodied species and apparent compensatory increases in nocturnal rodents. Our study shows markedly altered vertebrate community structure even in remote but heavily settled areas of continuous primary forest. Depletion of frugivore and granivore populations, and concomitant density-compensation by seed predators, likely affect forest regeneration in persistently overhunted tropical forests. These findings contribute to a better understanding of how cascading effects induced by historical defaunation operate, informing wildlife management policy in tropical peri-urban, rural and wilderness areas.

scholarly journals Top carnivore decline has cascading effects on scavengers and carrion persistence

2018 ◽  
Vol 285 (1892) ◽  
pp. 20181582 ◽  
Author(s):  
Calum X. Cunningham ◽  
Christopher N. Johnson ◽  
Leon A. Barmuta ◽  
Tracey Hollings ◽  
Eric J. Woehler ◽  
...  
Keyword(s):  
Severe Disease ◽  
Tasmanian Devil ◽  
Population Declines ◽  
Mesopredator Release ◽  
Landscape Of Fear ◽  
Feral Cat ◽  
Cascading Effects ◽  
Remote Cameras

Top carnivores have suffered widespread global declines, with well-documented effects on mesopredators and herbivores. We know less about how carnivores affect ecosystems through scavenging. Tasmania's top carnivore, the Tasmanian devil (Sarcophilus harrisii) , has suffered severe disease-induced population declines, providing a natural experiment on the role of scavenging in structuring communities. Using remote cameras and experimentally placed carcasses, we show that mesopredators consume more carrion in areas where devils have declined. Carcass consumption by the two native mesopredators was best predicted by competition for carrion, whereas consumption by the invasive mesopredator, the feral cat ( Felis catus ), was better predicted by the landscape-level abundance of devils, suggesting a relaxed landscape of fear where devils are suppressed. Reduced discovery of carcasses by devils was balanced by the increased discovery by mesopredators. Nonetheless, carcasses persisted approximately 2.6-fold longer where devils have declined, highlighting their importance for rapid carrion removal. The major beneficiary of increased carrion availability was the forest raven ( Corvus tasmanicus ). Population trends of ravens increased 2.2-fold from 1998 to 2017, the period of devil decline, but this increase occurred Tasmania-wide, making the cause unclear. This case study provides a little-studied potential mechanism for mesopredator release, with broad relevance to the vast areas of the world that have suffered carnivore declines.

scholarly journals Haiti’s biodiversity threatened by nearly complete loss of primary forest

2018 ◽  
Vol 115 (46) ◽  
pp. 11850-11855 ◽  
Author(s):  
S. Blair Hedges ◽  
Warren B. Cohen ◽  
Joel Timyan ◽  
Zhiqiang Yang
Keyword(s):  
Tropical Forests ◽  
National Parks ◽  
Mass Extinction ◽  
Forest Cover ◽  
Secondary Growth ◽  
Complete Loss ◽  
Primary Forest ◽  
The Difference ◽  
Primary Forests ◽  
Agricultural Organization

Tropical forests hold most of Earth’s biodiversity. Their continued loss through deforestation and agriculture is the main threat to species globally, more than disease, invasive species, and climate change. However, not all tropical forests have the same ability to sustain biodiversity. Those that have been disturbed by humans, including forests previously cleared and regrown (secondary growth), have lower levels of species richness compared with undisturbed (primary) forests. The difference is even greater considering extinctions that will later emanate from the disturbance (extinction debt). Here, we find that Haiti has less than 1% of its original primary forest and is therefore among the most deforested countries. Primary forest has declined over three decades inside national parks, and 42 of the 50 highest and largest mountains have lost all primary forest. Our surveys of vertebrate diversity (especially amphibians and reptiles) on mountaintops indicates that endemic species have been lost along with the loss of forest. At the current rate, Haiti will lose essentially all of its primary forest during the next two decades and is already undergoing a mass extinction of its biodiversity because of deforestation. These findings point to the need, in general, for better reporting of forest cover data of relevance to biodiversity, instead of “total forest” as defined by the United Nation’s Food and Agricultural Organization. Expanded detection and monitoring of primary forest globally will improve the efficiency of conservation measures, inside and outside of protected areas.

scholarly journals The effect of Broussonetia papyrifera invasion on the regeneration of selected native timber species in a tropical moist forest in Uganda

2021 ◽  
Author(s):  
Davis Mark Ssemanda ◽  
Enock Ssekuubwa
Keyword(s):  
Tropical Forests ◽  
Linear Models ◽  
Block Design ◽  
Basal Area ◽  
Timber Production ◽  
Timber Species ◽  
Production Potential ◽  
Broussonetia Papyrifera ◽  
Randomized Block Design ◽  
Moist Forest

Abstract Broussonetia papyrifera has been identified as one of the top invasive species in some African tropical forests with potentially devastating impacts on the conservation and timber production potential of the forests. This study determined the effect of B. papyrifera on the regeneration of selected native timber species in Mabira Forest Reserve, Uganda. The abundance, basal area and population structure of the timber species were compared between areas invaded and uninvaded by B. papyrifera. Employing a complete randomized block design, a total of forty plots (30 x 30 m each), and equally distributed between invaded and uninvaded areas with similar habitat conditions were surveyed. Counts of seedlings were recorded and diameter of saplings and trees measured. Generalized linear models were used to analyze the abundance, tree basal area and size class distributions of the selected species. The study revealed that the effects of B. papyrifera invasion vary depending on the growth stage and species studied. Overall, B. papyrifera invasion significantly reduced tree abundance and basal area, and suppressed the regeneration of some but not all the selected species. Our results demonstrate that if the spread of B. papyrifera is not abated, it will lower the conservation and timber production potential of tropical forests. Therefore, we call for interventions to control the spread of B. papyrifera to the uninvaded parts of the forests and halt its multiplication in invaded areas so as to enhance the regeneration and growth of timber species.

scholarly journals Amblyomma tapirellum  (Acari: Ixodidae) collected from tropical forest canopy

F1000Research ◽  
2014 ◽  
Vol 2 ◽  
pp. 194
Author(s):  
Jose R Loaiza ◽  
Matthew J Miller ◽  
Eldredge Bermingham ◽  
Oris I Sanjur ◽  
Patrick A Jansen ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Forest Canopy ◽  
Ground Level ◽  
Barro Colorado Island ◽  
Light Traps ◽  
Ecological Relationship ◽  
Questing Ticks ◽  
Free Ranging ◽  
Central Panama ◽  
Tropical Forest Canopy

Free-ranging ticks are widely known to be restricted to the ground level of vegetation. Here, we document the capture of the tick species Amblyomma tapirellum in light traps placed in the forest canopy of Barro Colorado Island, central Panama. A total of forty eight adults and three nymphs were removed from carbon dioxide–octenol baited CDC light traps suspended 20 meters above the ground during surveys for forest canopy mosquitoes. To our knowledge, this represents the first report of questing ticks from the canopy of tropical forests. Our finding suggests a novel ecological relationship between A. tapirellum and arboreal mammals, perhaps monkeys that come to the ground to drink or to feed on fallen fruits.

Climber Community Structure in Relation to Environmental and Tree Attributes in Lowland Tropical Forests of Eastern Himalaya, India

2021 ◽  
pp. 71-98
Author(s):  
Samiran Panday ◽  
Dinesh Singh Rawat ◽  
Vikas Kumar ◽  
Sudhansu Sekhar Dash ◽  
Bipin Kumar Sinha ◽  
...  
Keyword(s):  
Community Structure ◽  
Tropical Forests ◽  
Eastern Himalaya

scholarly journals Predator size-structure and species identity determine cascading effects in a coastal ecosystem

2018 ◽  
Vol 8 (24) ◽  
pp. 12435-12442 ◽  
Author(s):  
John N. Griffin ◽  
Brian R. Silliman
Keyword(s):  
Size Structure ◽  
Coastal Ecosystem ◽  
Species Identity ◽  
Cascading Effects ◽  
Predator Size

Contributions to the epidemiology of human sleeping sickness in Liberia: bionomics of the vector Glossina palpalis (R.-D.) in a forest habitat

1964 ◽  
Vol 54 (4) ◽  
pp. 727-744 ◽  
Author(s):  
R. Foster
Keyword(s):  
Forest Canopy ◽  
Activity Patterns ◽  
Effective Means ◽  
Climatic Conditions ◽  
Primary Forest ◽  
Wet Season ◽  
North West ◽  
Early Afternoon ◽  
Prolonged Contact ◽  
Glossina Palpalis

Glossina, palpalis (R.-D.) was studied in three localities near Voinjama, in a forest region in north-west Liberia, where human trypanosomiasis persists only as sporadic cases. Sites were chosen with different degrees of contact between man, fly and game, in transitional vegetation on the Zeliba River, and in primary forest on the Lofa and Lawa Rivers. The general features, fauna and climate of these areas are described. Catching by nets was found to be preferable to the use of traps. Trap catches averaged about one-quarter of the corresponding net catches. The theoretical basis of ‘animal’ traps is too uncertain for their use in quantitative studies, and under forest conditions there are practical difficulties in siting them in optimum positions; they failed to catch at all at very low fly densities. Heavy rain and the dry season were unfavourable to the fly, particularly outside the forest canopy. A wet-season resting site on horizontal twigs near to the ground is described. The percentage of females in the total catch differed significantly between different habitats, but apparently was not indicative of the degree of hunger in the population. There were no great differences between the sexes in activity patterns, and activity was greatest during the apparently unfavourable climatic conditions of early afternoon. The willingness of the fly to penetrate unfavourable surroundings suggests that the clearing of forest at potential places of transmission is unlikely to afford an effective means of protection. There is some evidence that breeding was curtailed during the rains. Very few engorged flies were found. Fly numbers and distribution were not affected by normal game movements. There is no evidence that the fly was ever dependent on man for food. Where game was driven away the fly tended to follow it. Occasional human foci did not affect the number or distribution of the fly, and fly activity was not correlated with human activity. Intimate and prolonged contact between man and fly did not occur.

scholarly journals Comparison of Modeling Algorithms for Forest Canopy Structures Based on UAV-LiDAR: A Case Study in Tropical China

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1324
Author(s):  
Xi Peng ◽  
Anjiu Zhao ◽  
Yongfu Chen ◽  
Qiao Chen ◽  
Haodong Liu ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Laser Scanning ◽  
Forest Canopy ◽  
Sustainable Forest Management ◽  
Mean Squared Error ◽  
Structural Parameters ◽  
Recursive Feature Elimination ◽  
Support Vector ◽  
Lidar Data ◽  
Area Index

Knowledge of forest structure is vital for sustainable forest management decisions. Terrestrial laser scanning cannot describe the canopy trees in a large area, and it is unclear whether unmanned aerial vehicle-light detection and ranging (UAV-LiDAR) data have the ability to capture the forest canopy structural parameters in tropical forests. In this study, we estimated five forest canopy structures (stand density (N), basic area (G), above-ground biomass (AGB), Lorey’s mean height (HL), and under-crown height (hT)) with four modeling algorithms (linear regression (LR), bagged tree (BT), support vector regression (SVR), and random forest (RF)) based on UAV-LiDAR data and 60 sample plot data from tropical forests in Hainan and determined the optimal algorithms for the five canopy structures by comparing the performance of the four algorithms. First, we defined the canopy tree as a tree with a height ≥70% HL. Then, UAV-LiDAR metrics were calculated, and the LiDAR metrics were screened by recursive feature elimination (RFE). Finally, a prediction model of the five forest canopy structural parameters was established by the four algorithms, and the results were compared. The metrics’ screening results show that the most important LiDAR indexes for estimating HL, AGB, and hT are the leaf area index and some height metrics, while the most important indexes for estimating N and G are the kurtosis of heights and the coefficient of variation of height. The relative root mean squared error (rRMSE) of five structure parameters showed the following: when modeling HL, the rRMSEs (10.60%–12.05%) obtained by the four algorithms showed little difference; when N was modeled, BT, RF, and SVR had lower rRMSEs (26.76%–27.44%); when G was modeled, the rRMSEs of RF and SVR (15.37%–15.87%) were lower; when hT was modeled, BT, RF, and SVR had lower rRMSEs (10.24%–11.07%); when AGB was modeled, RF had the lowest rRMSE (26.75%). Our results will help facilitate choosing LiDAR indexes and modeling algorithms for tropical forest resource inventories.

Regeneration by sprouting in slash and burn rice cultivation, Taï rain forest, Côte d'Ivoire

1993 ◽  
Vol 9 (4) ◽  
pp. 387-408 ◽  
Author(s):  
Anneke de Rouw
Keyword(s):  
Seed Bank ◽  
Forest Canopy ◽  
Forest Type ◽  
Rice Cultivation ◽  
Permanent Plots ◽  
Primary Forest ◽  
Prolonged Cultivation ◽  
Rainfed Rice ◽  
Closed Forest ◽  
Plant Densities

ABSTRACTIn 14 forest plots (36 m2) all terrestrial plant species were recorded before slashing and burning of the vegetation. During subsequent cultivation with rainfed rice all resprouting plants were registered in permanent plots (72 m2). The fields studied (one per forest) covered all combinations of forest type and soil usually cultivated on local farms. Forest plots (total 409 species) and field plots (358 species) had 226 species in common. Most resprouting plants were woody. Though nine forests in the sample were secondary, 70% of resprouting plants belonged to primary forest species and with three exceptions, these species did not regenerate by seed.Experiments in one field inlcuded: different intensities of initial burning, weeding (none, once, twice) and length of the rice cultivation period (1, 2, 3 y). Resprouting plants were monitored in permanent plots (108 m2) during 3 y of cultivation and 2 y of fallow. More plants resprouted after a mild initial burning (5.8 plants m−2) than after a burn of normal intensity (1.4 plants m−2). Weeding and prolonged cultivation strongly reduced species diversity but plant densities were less affected because some climbers and trees were apparently stimulated and expanded.Fields abandoned after one rice harvest had, within six months, a closed forest canopy of pioneer trees emerging from the pre-existing seed bank and from the growth of resprouting trees. Prolonged cultivation (3 y) destroyed the pre-existing seed bank but affected sprouting plants less, these being the only component in the vegetation able to shade out weeds and forbs such as Chromolaena odorata.

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