Loss of top predators and fragmentation lead to the decline of dominant plants in forests: A balance needed for conservation and management on overabundant large herbivore species

2021 ◽  
Author(s):  
Lin CAO ◽  
Zhibin ZHANG
2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Annika M. Felton ◽  
Emma Holmström ◽  
Jonas Malmsten ◽  
Adam Felton ◽  
Joris P. G. M. Cromsigt ◽  
...  

AbstractDiet quality is an important determinant of animal survival and reproduction, and can be described as the combination of different food items ingested, and their nutritional composition. For large herbivores, human landscape modifications to vegetation can limit such diet-mixing opportunities. Here we use southern Sweden’s modified landscapes to assess winter diet mixtures (as an indicator of quality) and food availability as drivers of body mass (BM) variation in wild moose (Alces alces). We identify plant species found in the rumen of 323 moose harvested in Oct-Feb, and link variation in average calf BM among populations to diets and food availability. Our results show that variation in calf BM correlates with variation in diet composition, diversity, and food availability. A varied diet relatively rich in broadleaves was associated with higher calf BM than a less variable diet dominated by conifers. A diet high in shrubs and sugar/starch rich agricultural crops was associated with intermediate BM. The proportion of young production forest (0–15 yrs) in the landscape, an indicator of food availability, significantly accounted for variation in calf BM. Our findings emphasize the importance of not only diet composition and forage quantity, but also variability in the diets of large free-ranging herbivores.


2019 ◽  
Author(s):  
Joseph O. Ogutu ◽  
Patricia D Moehlman ◽  
Hans-Peter Piepho ◽  
Victor A Runyoro ◽  
Michael B Coughenour ◽  
...  

The Ngorongoro Crater is an intact caldera with an area of approximately 310 km2. Long term records on herbivore populations, vegetation and rainfall made it possible to analyze historic and project future herbivore population dynamics. In 1974 there was a perturbation in that resident Maasai and their livestock were removed from the Crater. Vegetation structure changed in 1967 from predominately short grassland to mid and tall grasses dominating in 1995. Even with a change in grassland structure, total herbivore biomass remained relatively stable from 1963 to 2012, implying that the crater has a stable multi-herbivore community. However, in 1974, Maasai pastoralists were removed from the Ngorongoro Crater and there were significant changes in population trends for some herbivore species. Buffalo, elephant and ostrich numbers increased significantly during 1974-2012. The zebra population was stable from 1963 to 2012 whereas numbers of other eight species declined substantially between 1974 and 2012 relative to their peak numbers during 1974-1976. Numbers of Grant’s and Thomson’s gazelles, eland, kongoni, waterbuck (wet season only) declined significantly in the Crater in both seasons after 1974. Wildebeest numbers decreased in the Crater between 1974 and 2012 but this decrease was not statistically significant. In addition, some herbivore species were consistently more abundant inside the Crater during the wet than the dry season. This pattern was most evident for the large herbivore species requiring bulk forage, comprising buffalo, eland, and elephant. Analyses of rainfall indicated that there was a persistent annual cycle of 4.83 years. Herbivore population size was correlated with rainfall in both the wet and dry seasons. The relationships established between the time series of historic animal counts in the wet and dry seasons and lagged wet and dry season rainfall series were used to forecast the likely future trajectories of the wet and dry season population size for each species under three alternative climate change scenarios.


2017 ◽  
Vol 88 (1) ◽  
pp. 129-151 ◽  
Author(s):  
Guillermo Rodríguez-Gómez ◽  
Jesús Rodríguez ◽  
Jesús A. Martín-González ◽  
Ana Mateos

AbstractFossil remains and the technological complexes recorded in archaeological sites suggest that the human presence in Europe late in the early and middle Pleistocene was discontinuous. Moreover, competition for meat with other secondary consumers could have delayed the human dispersal through Europe. However, evaluation of the extent competition intensity among secondary consumers suggests this influenced the discontinuity of the human settlement of Europe between 1.1 and 0.2 Ma. Using a mathematical model, we estimate the amount of biomass available in a community for secondary consumers. The amount of available biomass is subsequently distributed among the guild of secondary consumers according to their requirements and prey preferences. Indexes that quantify the competition intensity among secondary consumers to compare the conditions in different paleoecosystems show that the competition intensity late in the early Pleistocene, early in the middle Pleistocene, and late in the middle Pleistocene does not support the view that an increase in competition intensity constrained the expansion of human populations early in the middle Pleistocene. Somewhat paradoxically, the lowest competition intensity is estimated to have occurred early in the middle Pleistocene, most likely because of an increase in the number of large herbivore species and a decrease in the number of secondary consumers. The early Pleistocene paleoecosystems supported higher competition intensity than the middle Pleistocene ecosystems, likely because of the different configuration in the food webs of these two periods (the early and middle Pleistocene).


Diversity ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 359
Author(s):  
Emilio Virgós ◽  
Noemí Baniandrés ◽  
Tamara Burgos ◽  
Mariano R. Recio

Top predators shape the communities of sympatric predators by killing and displacing smaller predators. Predation risk pushes smaller predators to select enemy-free spaces irrespective of food availability, which results in changes in their behaviour, space use, distribution, and abundance. Although the landscape of fear dynamics are known for top predators such as the eagle owl and its impact on smaller raptors, the effect of the presence and abundance of the eagle owl on the space use of mesopredator carnivores remains poorly understood. Here, we studied this effect on the space use of the stone marten in a Mediterranean ecosystem where it shares rabbits as main prey with the eagle owl. We also accounted for the presence of another sympatric carnivore, the red fox. Using a multi-model inference, we found stone martens avoided areas with a higher abundance of eagle owls and rabbits, which suggested a hyperpredation process and a cognitive association by stone martens between rabbit hotspots and owl presence. We found a positive relationship between the space use of the red fox and the stone marten, which suggested foxes behaved as competitors and not predators of martens. Understanding intraguild predation can assist the conservation and management of predators and their prey.


Author(s):  
Tammy L. Silva ◽  
David N. Wiley ◽  
Michael A. Thompson ◽  
Peter Hong ◽  
Les Kaufman ◽  
...  

2020 ◽  
Vol 62 (1) ◽  
pp. 64-79 ◽  
Author(s):  
Christine Saint‐Andrieux ◽  
Clément Calenge ◽  
Christophe Bonenfant

2015 ◽  
Vol 1 (4) ◽  
pp. e1400103 ◽  
Author(s):  
William J. Ripple ◽  
Thomas M. Newsome ◽  
Christopher Wolf ◽  
Rodolfo Dirzo ◽  
Kristoffer T. Everatt ◽  
...  

Large wild herbivores are crucial to ecosystems and human societies. We highlight the 74 largest terrestrial herbivore species on Earth (body mass ≥100 kg), the threats they face, their important and often overlooked ecosystem effects, and the conservation efforts needed to save them and their predators from extinction. Large herbivores are generally facing dramatic population declines and range contractions, such that ~60% are threatened with extinction. Nearly all threatened species are in developing countries, where major threats include hunting, land-use change, and resource depression by livestock. Loss of large herbivores can have cascading effects on other species including large carnivores, scavengers, mesoherbivores, small mammals, and ecological processes involving vegetation, hydrology, nutrient cycling, and fire regimes. The rate of large herbivore decline suggests that ever-larger swaths of the world will soon lack many of the vital ecological services these animals provide, resulting in enormous ecological and social costs.


Koedoe ◽  
1999 ◽  
Vol 42 (2) ◽  
Author(s):  
I. Thrash ◽  
J.F. Derry

Gradients in utilisation pressure tend to develop around watering points because water dependent herbivores are forced to congregate within a maximum distance of about 10-15 km from water in the dry season. Artificial watering points cause previously migratory or nomadic indigenous large herbivores to become sedentary, so that natural grazing patterns are disrupted. Under this altered grazing pattern, piosphere patterns tend to develop in herbaceous species composition, range condition, grass production, plant biomass, understory cover, standing crop and basal cover. In areas with large populations of elephants the density and canopy cover of trees is directly proportional to distance from watering points. In the absence of elephants an increase in woody plant density and canopy cover tends to occur in a zone just beyond a sacrifice area. Soil erosion, compaction and capping tend to occur at watering points on soils containing clay and silt. Artificial watering points are advantageous to the non-mobile water dependent large herbivore species and disadvantageous to the water independent large herbivore species. The processes underlying piosphere development and maintenance are numerous and diverse. While being parsimonious treatments of a complex system, conceptual models do provide a reasonable basis upon which to design an improved understanding. The logistic curve has been proposed as a convenient tool for estimating piosphere dimensions, but ignoring the 'best-fit' regression model for a piosphere data set may be an inaccurate practice. A large number of gradient models have been developed, each an attempt to shed some light on the behavioural response underlying what appears to be a complex grazing pattern. Several system models that take piosphere effects into account have been constructed. Some of these produce good simulations of herbaceous materi- al dynamics and especially good simulations of bush dynamics.


2009 ◽  
Vol 25 (5) ◽  
pp. 483-492 ◽  
Author(s):  
Nicole Hagenah ◽  
Herbert H.T. Prins ◽  
Han Olff

Abstract:Our study presents experimentally based results on how large herbivore species affect savanna vegetation and thus murid rodents in the Hluhluwe-iMfolozi Park in KwaZulu-Natal, South Africa. We permanently excluded groups of large herbivore guilds of various body sizes (ranging from white rhino to hares) from sixteen 40 × 40-m plots of vegetation by using different fence types. We determined grass species composition and vegetation height and collected capture–mark–recapture data on murid rodents. Nutrient concentrations of the dominant grass species and rodent diet compositions were analysed. We found that herbivore species of different body sizes had different effects on murid rodents. The exclusion of medium-sized herbivores, such as warthog, impala and nyala increased the abundance of high-quality grass species, especiallyPanicum maximum. However, the dominant rodent speciesLemniscomys rosaliapreferred the most abundant grass species, rather than high-quality grasses. The absence of large bulk feeders, such as zebra, buffalo and white rhino led to an increase in vegetation height. In response, tall vegetation promoted both rodent abundance and species diversity and altered rodent species composition. Ultimately, our results indicate that the greatest effect on murid rodents came from the reduction of vegetation cover by large bulk feeders, which likely increased rodent predation risk.


2019 ◽  
Vol 28 (14) ◽  
pp. 3891-3914 ◽  
Author(s):  
Arie Trouwborst

Abstract Large wild herbivore species are important to ecosystems and human societies, but many of them are threatened and in decline. International wildlife treaties have a role to play in arresting and reversing these declines. This paper provides a global overview and analysis of relevant legal instruments and their roles regarding the conservation of the 73 largest terrestrial herbivores, i.e., those with a body mass of ≥ 100 kg. Outcomes reveal both significant positive contributions and shortcomings of the Ramsar Wetlands Convention, the World Heritage Convention, the Convention on International Trade in Endangered Species, the Convention on Migratory Species and its subsidiary instruments, the Convention on Biological Diversity, and a range of regional and bilateral treaties. Maximizing the potential of these treaties, and attaining their objectives regarding the conservation and restoration of large herbivores, requires substantial increases in funding and political will. Even before such game-changing increases occur, however, it remains worthwhile to seek and use the many opportunities that exist within the current international legal framework for enhancing the conservation of the world’s largest herbivores.


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