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1
Milchunas, D. G. "Plant community dynamics in shortgrass steppe with grazing relaxation and imposition by large and small herbivores." Israel Journal of Ecology and Evolution 57, no. 1-2 (May 6, 2011): 23–41. http://dx.doi.org/10.1560/ijee.57.1-2.23.
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Semiarid rangelands often respond slowly to rest/relaxation of grazing pressure by large herbivores, and the effects of grazing are most often inferred from this direction of study because the imposition of grazing onto previous ungrazed/lightly grazed areas occurred prior to the age of scientific studies. These rangelands host a diversity of small and large herbivores, but grazing studies most often concern effects of the large generalists. Here, the effects of herbivore body size on plant species richness and dominant species, and imposition and relaxation of grazing by large herbivores were studied by opening half of exclosures established in 1939 and building new exclosures to large herbivores, and to small-plus-large herbivores. Plant richness using sensitive species-area sampling was studied in a dry and a wet year, about 62 years after initiating the long-term experiment and about 6-10 years after initiating the altered designs. Convergence of the newly opened to large herbivore grazing treatment to the long-term grazed treatment occurred within 10 years, but convergence of the newly excluded to large herbivore treatment to the long-term excluded treatment had only partly occurred. This indicated that recovery from grazing is slow relative to imposition of grazing by large herbivores, but effects of the additional exclusion of small-plus-large herbivores occurred relatively rapidly. These results were mirrored by trajectories of convergence of the dominant species, and this is discussed with respect to implications for state-and-transition models. Short-term exclusion of small-plus-large herbivores resulted in greater richness than even long-term exclusion of only large herbivores, even though quantities consumed by small herbivores are much less than by large. Grazing effects on plant richness were large in the wet year, but the very dry year suppressed richness on all treatments. When sampling effort and area are the same, the numbers and attributes of species unique to a treatment are indicators of rareness of the richness and traits selected for by the treatment. More unique species were sampled in the small-plus-large herbivore exclosures when comparing body size, and the long-term large herbivore exclosures when comparing time of exclosure. Unique species encountered during sampling the ungrazed treatments were generally forbs, exotic and/or weedy invasive species, and often tall, annual species.
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Potter, Arjun B., Muhammad Ali Imron, Satyawan Pudyatmoko, and Matthew C. Hutchinson. "Short-term plant-community responses to large mammalian herbivore exclusion in a rewilded Javan savanna." PLOS ONE 16, no. 7 (July 22, 2021): e0255056. http://dx.doi.org/10.1371/journal.pone.0255056.
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Grassy biomes such as savannas are maintained by an interacting suite of ecosystem processes from herbivory to rainfall to fire. Many studies have examined the impacts of large mammalian herbivores on herbaceous plant communities, but few of these studies have been conducted in humid, fertile savannas. We present the findings of a short-term experiment that investigated the effects of herbivory in a fertile, humid, and semi-managed savanna. We erected large-herbivore exclosures in Alas Purwo National Park, Java, Indonesia where rainfall is high and fire is suppressed to test how herbivores impact plant community development across the growing season. Where large mammalian herbivores were excluded, herbaceous plant communities contained more non-grasses and were less similar; diverging in their composition as the growing season progressed. Effects of herbivore exclusion on plant species richness, evenness, and biomass per quadrat were generally weak. Notably, however, two weedy plant species (one native, Imperata cylindrica and one introduced, Senna cf. tora) appeared to benefit most from herbivore release. Our results suggest that heavy grazing pressure by native large mammalian herbivores controlled the composition of the herbaceous plant community. Moreover, exclusion of large mammalian herbivores led to divergence in the plant species composition of exclosures; compositional dissimilarity between herbivore-exclusion plots was higher than between plots exposed to large mammalian herbivores. Our findings suggest that, at this high-rainfall site, large mammalian herbivores constrained the developmental trajectory of plant communities across the growing season.
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Faast, Renate, and José M. Facelli. "Grazing orchids: impact of florivory on two species of Caladenia (Orchidaceae)." Australian Journal of Botany 57, no. 4 (2009): 361. http://dx.doi.org/10.1071/bt08140.
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Herbivory is considered a major threat in many of the orchid-species recovery plans in Australia. Kangaroos and rabbits are the most commonly implicated herbivores; however, no studies have attempted to confirm their role. Regular monitoring of several populations of Caladenia rigida R.S.Rogers and C. tentaculata Schldl. during 3 years in the Mount Lofty Ranges, South Australia, revealed that up to 94% of flowers and 36% of seed capsules were browsed, whereas leaf herbivory was less prevalent. Furthermore, patterns of herbivory varied markedly among sites and across years. In two seasons, predation of C. rigida flowers inside a kangaroo- and rabbit-proof exclosure was equal to or higher than outside the exclosure. Florivory within populations was influenced by proximity to the habitat edge, although the direction of this response differed among sites. Various types of mesh cages were erected around plants to elucidate the size and type of herbivores. Plants protected from florivores were almost three times more likely to produce seed than were exposed plants; however, some cage types reduced pollination. Video surveillance confirmed the role of the white-winged chough, Corcorax melanorhamphos, as a florivore. The present study is the first one to identify a herbivore unequivocally, quantify the intensity and extent of floral herbivory across a range of populations, and assess the potential cost of florivory to the direct reproductive output of orchids.
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Bakker, E. S., H. Olff, and J. M. Gleichman. "Contrasting effects of large herbivore grazing on smaller herbivores." Basic and Applied Ecology 10, no. 2 (March 2009): 141–50. http://dx.doi.org/10.1016/j.baae.2007.10.009.
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Graham, Mark D., and Rolf D. Vinebrooke. "Trade-offs between herbivore resistance and competitiveness in periphyton of acidified lakes." Canadian Journal of Fisheries and Aquatic Sciences 55, no. 4 (April 1, 1998): 806–14. http://dx.doi.org/10.1139/f97-309.
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It was hypothesized that herbivores regulate periphyton succession in acidified lakes by suppressing loosely attached filamentous algae that otherwise persist and outcompete other growth forms for resources, such as dissolved inorganic carbon (DIC). This hypothesis was tested by conducting grazer-exclosure experiments over an ice-free season in acidified and circumneutral lakes that differed in DIC concentrations. In each lake, the two-factor experimental design had two herbivore (presence-absence) and five succession (early-late) treatments. Total periphyton biomass was greater and significantly suppressed by herbivores in the circumneutral lake. Here, acid-sensitive green frog (Rana clamitans) tadpoles suppressed loosely attached (i.e., zygnematacean taxa) while stimulating firmly attached (i.e., Coleochaete scutata) algae, causing succession towards a herbivore-resistant physiognomy. Conversely, a loosely attached and tall physiognomy persisted in the absence of significant grazing and greater resource limitation in the acid lake. Our findings suggest that trade-offs between competitiveness and herbivore resistance help predict changes in periphyton in recovering acidified lakes. During recovery, concomitant increases in herbivory and resources should favour a firmly attached and short periphyton physiognomy that is resistant to removal by herbivores, but that lacks the competitiveness of loosely attached and tall forms in DIC-limited acid lakes.
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Fröberg, Lars, Anette Baur, and Bruno Baur. "Field study on the regenerative capacity of three calcicolous lichen species damaged by snail grazing." Lichenologist 38, no. 5 (August 22, 2006): 491–93. http://dx.doi.org/10.1017/s0024282906005469.
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Lichen growth and regeneration depend on the net photosynthetic production, the lateral allocation of products, on abiotic factors, competition and herbivory, and may therefore vary both in space and time (Hill 1981). Herbivores cause different damage to lichens in response to different thallus structure (surface toughness) and growth form, presence/absence of secondary compounds, and due to herbivore-specific differences in feeding (Lawrey 1984; Fröberg et al. 1993; Baur et al. 1994; Hesbacher et al. 1995). Regeneration of artificially damaged lichen tissue has been investigated in detail, for example in Xanthoria parietina (L.) Th. Fr. (Honegger 1996; Honegger et al. 1996). However, quantitative assessments of the regenerative capacity of thalli damaged by herbivores are so far lacking. Damage to lichens by grazing gastropods is made by highly specialized radulae and can therefore not be imitated by any mechanical treatment (Baur et al. 2000). Herbivory by snails also involves the production of saliva and mucus, which both could affect lichen regeneration.
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Reķe, Agnese, Anita Zariņa, and Ivo Vinogradovs. "MANAGEMENT OF SEMI-WILD LARGE HERBIVORES’ GRAZING SITES IN LATVIA." ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference 1 (June 20, 2019): 241. http://dx.doi.org/10.17770/etr2019vol1.4082.
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Large herbivores were a common part of European nature in the pre-agrarian times. With the development of farming and over-hunting, the number of wild large herbivores rapidly decreased. Wild horses and cattle became extinct. In the 1920-30’s, scientists created two new herbivore breeds that resembled the extinct aurochs and tarpans - Heck cattle and Konik horses. Nowadays the introduction of Heck cattle, Konik horses and other similar large herbivore breeds is widely used in specially protected nature territories (SPNT) as a strategic answer to the question – what should we do with the agricultural lands that have lost their economical meaning. Since 1999, semi-wild large herbivores are introduced in various SPNT of Latvia as well, mainly in nature parks and nature reserves. Based on field visits, interviews and policy analysis, this paper discusses two main approaches to semi-wild grazing animal population management in Latvia: (1) introduced herbivores as a part of rewilding process and (2) introduced herbivores as instruments for habitat protection. The former represents the implementation of western wilderness values, while the latter is related to more specific protection of species and habitats according to particular place-based nature protection goals. This study contributes to the growing discussion on rewilding practises in Europe and the introduction ideas of semi-wild animals, as well as landscape management practices in the era of post-productivism.
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Tallowin, J. R. B., A. J. Rook, and S. M. Rutter. "Impact of grazing management on botanical diversity of grasslands." Proceedings of the British Society of Animal Science 2005 (2005): 244. http://dx.doi.org/10.1017/s1752756200011558.
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Grazing is a natural process affecting the composition and structure of plant communities and is widely considered to be an essential nature conservation tool. However, our understanding of the interrelations between grazing by large herbivores and biodiversity is relatively poor. Nature conservation imperatives, to control succession, for example, mean that practice has moved ahead of the science knowledge base on grazing. This gap now needs to be bridged. Improving our understanding of and ability to predict consequences of manipulating grazing pressure, duration, type and/or mix of large herbivore on biodiversity outcomes are particular issues that we are addressing.
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Kirkpatrick, J. B., and K. L. Bridle. "Comparative Effects of Stock and Wild Vertebrate Herbivore Grazing on Treeless Subalpine Vegetation, Eastern Central Plateau, Tasmania." Australian Journal of Botany 47, no. 6 (1999): 817. http://dx.doi.org/10.1071/bt98029.
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The existence of two 25-year-old grazing exclosures on Liawenee Moor, Eastern Central Plateau, Tasmania, created an opportunity to investigate the impacts of vertebrate herbivores on treeless subalpine vegetation. There were three treatments: sheep-, native herbivore- and rabbit-grazed; native herbivore- and rabbit-grazed; no grazing. The amount of bare ground was highest in the sheep-grazed plots, while vegetation cover was greatest in the ungrazed exclosure. The cover of all lifeform groups, except small herbs, was greater in the exclosures than in the sheep-grazed plots. The percentage frequency of tall herbs was significantly less in the sheep-grazed plots than either of the grazing exclosures. Tall herbs were more likely to be found under the canopy of other vegetation in the sheep-grazed plots while the same species were found to be growing in locations with no other vegetation cover in the ungrazed exclosure. Revegetation of bare ground averaged 1% per year over a 20-year period in the ungrazed exclosure. While percentage bare ground has also decreased in the native- and rabbit-grazed exclosure, it has increased in the sheep-grazed plots. Domestic stock grazing appears to have a much greater impact on vegetation cover, species composition and community structure than grazing by native herbivores and rabbits. No grazing allows for the fastest rehabilitation of the area. Our results are consistent with those from alpine and treeless subalpine areas of the Australian mainland.
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Eynaud, Yoan, Dylan E. McNamara, and Stuart A. Sandin. "Herbivore space use influences coral reef recovery." Royal Society Open Science 3, no. 6 (June 2016): 160262. http://dx.doi.org/10.1098/rsos.160262.
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Herbivores play an important role in marine communities. On coral reefs, the diversity and unique feeding behaviours found within this functional group can have a comparably diverse set of impacts in structuring the benthic community. Here, using a spatially explicit model of herbivore foraging, we explore how the spatial pattern of grazing behaviours impacts the recovery of a reef ecosystem, considering movements at two temporal scales—short term (e.g. daily foraging patterns) and longer term (e.g. monthly movements across the landscape). Model simulations suggest that more spatially constrained herbivores are more effective at conferring recovery capability by providing a favourable environment to coral recruitment and growth. Results also show that the composition of food available to the herbivore community is linked directly to the pattern of space use by herbivores. To date, most studies of variability among the impacts of herbivore species have considered the diversity of feeding modes and mouthparts. Our work provides a complementary view of spatial patterns of foraging, revealing that variation in movement behaviours alone can affect patterns of benthic change, and thus broadens our view of realized links between herbivore diversity and reef recovery.
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Tanentzap, Andrew J., Mark Vicari, and Dawn R. Bazely. "Ungulate saliva inhibits a grass–endophyte mutualism." Biology Letters 10, no. 7 (July 2014): 20140460. http://dx.doi.org/10.1098/rsbl.2014.0460.
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Fungal endophytes modify plant–herbivore interactions by producing toxic alkaloids that deter herbivory. However, studies have neglected the direct effects herbivores may have on endophytes. Antifungal properties and signalling effectors in herbivore saliva suggest that evolutionary pressures may select for animals that mitigate the effects of endophyte-produced alkaloids. Here, we tested whether saliva of moose ( Alces alces ) and European reindeer ( Rangifer tarandus ) reduced hyphal elongation and production of ergot alkaloids by the foliar endophyte Epichloë festucae associated with the globally distributed red fescue Festuca rubra . Both moose and reindeer saliva reduced the growth of isolated endophyte hyphae when compared with a treatment of distilled water. Induction of the highly toxic alkaloid ergovaline was also inhibited in plants from the core of F. rubra 's distribution when treated with moose saliva following simulated grazing. In genotypes from the southern limit of the species' distribution, ergovaline was constitutively expressed, as predicted where growth is environmentally limited. Our results now present the first evidence, to our knowledge, that ungulate saliva can combat plant defences produced by a grass–endophyte mutualism.
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Guignard, Maïté S., Michael J. Crawley, Dasha Kovalenko, Richard A. Nichols, Mark Trimmer, Andrew R. Leitch, and Ilia J. Leitch. "Interactions between plant genome size, nutrients and herbivory by rabbits, molluscs and insects on a temperate grassland." Proceedings of the Royal Society B: Biological Sciences 286, no. 1899 (March 20, 2019): 20182619. http://dx.doi.org/10.1098/rspb.2018.2619.
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Angiosperm genome sizes (GS) vary ca 2400-fold. Recent research has shown that GS influences plant abundance, and plant competition. There are also tantalizing reports that herbivores may select plants as food dependent on their GS. To test the hypothesis that GS plays a role in shaping plant communities under herbivore pressure, we exploit a grassland experiment that has experimentally excluded herbivores and applied nutrient over 8 years. Using phylogenetically informed statistical models and path analyses, we show that under rabbit grazing, plant species with small GS generated the most biomass. By contrast, on mollusc and insect-grazed plots, it was the plant species with larger GS that increased in biomass. GS was also shown to influence plant community properties (e.g. competitive strategy, total biomass) although the impact varied between different herbivore guilds (i.e. rabbits versus invertebrates) and nutrient inputs. Overall, we demonstrate that GS plays a role in influencing plant–herbivore interactions, and suggest potential reasons for this response, which include the impact of GS on a plant's response to different herbivore guilds, and on a plant's nutrient quality. The inclusion of GS in ecological models has the potential to expand our understanding of plant productivity and community ecology under nutrient and herbivore stress.
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Woolnough, Andrew P., and Christopher N. Johnson. "Assessment of the potential for competition between two sympatric herbivores - the northern hairy-nosed wombat, Lasiorhinus krefftii, and the eastern grey kangaroo, Macropus giganteus." Wildlife Research 27, no. 3 (2000): 301. http://dx.doi.org/10.1071/wr99053.
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The northern hairy-nosed wombat, Lasiorhinus krefftii, is a critically endangered grazing herbivore, restricted to a single population of just 65 individuals in the savanna of central Queensland. Lasiorhinus krefftii shares its habitat with another grazing herbivore of similar body size, the eastern grey kangaroo, Macropus giganteus. This study investigated the potential for M. giganteus to compete with L. krefftii for food. Analysis of faecal residues demonstrated that both herbivores consumed grass almost exclusively, with the exception of small quantities of sedges and dicotyledons. Dietary overlap between M. giganteus and L. krefftii was high, both in the consumption of plant species (90%) and plant parts (99%), suggesting that there is potential for dietary competition. Using the distribution of faecal deposits for both herbivores, analysis of habitat usage by multiple linear regression techniques indicated that M. giganteus exhibits clear associations with some habitat features but proved inconclusive for L. krefftii because of their use of defecation in social marking. However, an examination of the population dynamics of M. giganteus suggested that the densities reported in this study, although highly seasonal, are sufficiently low that competition with L. krefftii for food is currently negligible.
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Mosley, Jeffrey C., Rachel A. Frost, Brent L. Roeder, Tracy K. Mosley, and Gerald Marks. "Combined Herbivory by Targeted Sheep Grazing and Biological Control Insects to Suppress Spotted Knapweed (Centaurea stoebe)." Invasive Plant Science and Management 9, no. 1 (March 2016): 22–32. http://dx.doi.org/10.1614/ipsm-d-15-00034.1.
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AbstractThe use of biological control insects is a promising option for suppressing spotted knapweed, a nonindigenous perennial forb that infests more than 3 million hectares of North American rangeland. Efficacy increases when spotted knapweed is attacked by more than one phytophagous insect; however, combined herbivory by biological control insects has not achieved widespread suppression of spotted knapweed in North America. Here we expand the concept of combined herbivory beyond two or more species of biological control insects to include a vertebrate herbivore, specifically targeted grazing by domestic sheep. Our experiment on foothill rangeland in northwestern Montana evaluated spotted knapweed response to three treatments: (1) biological control insects only, (2) biological control insects + targeted sheep grazing applied in late July (spotted knapweed in late bud–early flower stage), and (3) biological control insects + targeted sheep grazing applied in mid-August (spotted knapweed in full-flower stage). We combined targeted sheep grazing with herbivory by three species of biological control insects: knapweed flower weevil, knapweed root weevil, and sulfur knapweed root moth. Treatments were applied during four consecutive years (2009 to 2012). Spotted knapweed fitness was suppressed more where targeted sheep grazing and biological control insects were combined vs. areas treated with biological control insects alone. Combined herbivory was effective when targeted sheep grazing was applied during either late July or mid-August, but July grazing was more effective. Spotted knapweed produced 96 to 99% fewer viable seeds in sheep-grazed areas. After 4 yr of treatment, total spotted knapweed plant density (seedlings, juvenile, and adult plants) was 86% less in July-grazed areas and 61% less in August-grazed areas than in areas treated with biological control insects alone. Combined herbivory by targeted sheep grazing and biological control insects reduced adult plant density and prevented compensatory recruitment of spotted knapweed, but treatment with biological control insects alone did not.
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Arsenault, Randal, and Norman Owen-Smith. "Facilitation versus competition in grazing herbivore assemblages." Oikos 97, no. 3 (June 2002): 313–18. http://dx.doi.org/10.1034/j.1600-0706.2002.970301.x.
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Smith, David L. "A test of the herbivore optimization hypothesis using muskoxen and a graminoid meadow plant community." Rangifer 16, no. 2 (January 1, 1996): 69. http://dx.doi.org/10.7557/2.16.2.1199.
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A prediction from the herbivore optimization hypothesis is that grazing by herbivores at moderate intensities will increase net above-ground primary productivity more than at lower or higher intensities. I tested this hypothesis in an area of high muskox {Ovibos moschatus) density on north-central Banks Island, Northwest Territories, Canada (73°50'N, 119°53'W). Plots (1 m2) in graminoid meadows dominated by cottongrass (Eriophorum triste) were either clipped, exposed to muskoxen, protected for part of one growing season, or permanently protected. This resulted in the removal of 22-44%, 10-39%, 0-39% or 0%, respectively, of shoot tissue during each growing season. Contrary to the predictions of the herbivore optimization hypothesis, productivity did not increase across this range of tissue removal. Productivity of plants clipped at 1.5 cm above ground once or twice per growing season, declined by 60+/-5% in 64% of the tests. The productivity of plants grazed by muskoxen declined by 56+/-7% in 25% of the tests. No significant change in productivity was observed in 36% and 75% of the tests in clipped and grazed treatments, respecrively. Clipping and grazing reduced below-ground standing crop except where removals were small. Grazing and clipping did not stimulate productivity of north-central Banks Island graminoid meadows.
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Gedge, Kevin E., and M. A. Maun. "Effects of simulated herbivory on growth and reproduction of two beach annuals, Cakile edentula and Corispermum hyssopifolium." Canadian Journal of Botany 70, no. 12 (December 1, 1992): 2467–75. http://dx.doi.org/10.1139/b92-305.
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Cakile edentula var. lucustris (sea rocket) and Corispermum hyssopifolium (bugseed) are two annual flowering plants that grow on the sandy shores of the Great Lakes. This habitat is extremely unpredictable and plants are subject to grazing by a number of insect herbivores as well as browsing by white-tailed deer. The objectives of these studies were to estimate the extent of herbivore damage under natural conditions, to determine the most vulnerable stage of damage, and to examine the compensatory ability of each species to tolerate herbivory. Greenhouse experiments showed that both species were able to compensate for low to moderate levels of artificial defoliation. However, high levels near the time of anthesis reduced the growth and reproductive output of both species. Similar experiments in the field revealed that although the critical time of damage was still the same, the plants were less able to tolerate herbivory. Cakile edentula plants exposed to natural herbivory in an unsprayed cabbage field were quickly attacked by large numbers of specialist insect herbivores and completely defoliated in 11 days. The fact that such damage does not occur in its natural habitat suggests that Cakile edentula escapes heavy damage because insects are unable to locate these populations along the shoreline. Key words: white-tailed deer, defoliation intensity, defoliation stage, compensatory response, indeterminate growth.
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Pereira, R. C., B. A. P. da Gama, V. L. Teixeira, and Y. Yoneshigue-Valentin. "Ecological roles of natural products of the Brazilian red seaweed Laurencia obtusa." Brazilian Journal of Biology 63, no. 4 (November 2003): 665–72. http://dx.doi.org/10.1590/s1519-69842003000400013.
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Laboratory and field experiments were performed to assess the ecological roles of natural products produced by the Brazilian red seaweed Laurencia obtusa. Laboratory assays revealed that the natural concentration of the crude organic extract of L. obtusa significantly inhibited feeding by two herbivores: the crab Pachygrapsus transversus and the sea urchin Lytechinus variegatus. It was verified that this chemically defensive action was due to halogenated sesquiterpenoid elatol, found to be the major natural product of this red seaweed. In addition, it was verified that the antifouling property of the chemicals produced by L. obtusa could make this red alga less attractive for fish grazing. Direct protection against two herbivore species and indirect protection against herbivory by fouling inibition constitute evidence that the major natural product from Brazilian L. obtusa plays multiple environmental roles, thereby increasing the adaptive value of these metabolites. On the other hand, the evidence reinforces the idea that marine natural products may have different functions in the sea.
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Baubin, Capucine, Dorothée Ehrich, Virve Ravolainen, Svetlana Sokovina Abdulmanova, Svetlana Ektova, Natalya Sokolova, Rolf A. Ims, and Aleksandr Sokolov. "First results from an experiment excluding three sizes classes of herbivores from tundra vegetation in southern Yamal, Russia." Czech Polar Reports 6, no. 2 (July 1, 2016): 132–40. http://dx.doi.org/10.5817/cpr2016-2-12.
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Plant-herbivore relationships are important for the functioning of tundra ecosystems. Here, we report the first results from an exclosure experiment that, something very few studies have done, separated the impact of three sizes of herbivores (small, medium and large) on nine functional groups of plants in the low arctic tundra of the Yamal Peninsula (Russia). Herbivore faeces counts in the exclosures and pictures from automatic cameras proved that the experimental setup worked. The majority of plant groups did not respond to exclusion of herbivores, supporting our expectation that vegetation responses in tundra are generally too slow to be measured during one growing season. The plant groups with highest growth rates and palatability (forbs and grasses) increased their biomass in meadows associated to tall willow shrubs when reindeer were excluded. This result was expected based on studies from other arctic regions. Our results also suggested that willow meadows and forb tundra, which are focal habitat for herbivores, are resilient and have the capacity to increase their biomass over a short term. We expect this experiment to provide valuable information on how different plant functional types and habitats with different growing conditions and importance to herbivores respond to relaxed grazing pressure from a variety of tundra herbivores.
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Kinga, Geoffrey W., John Mironga, and Wilfred O. Odadi. "Analysis of the Spatial Relationship between Cattle and Wild Ungulates across Different Land-Use Systems in a Tropical Savanna Landscape." International Journal of Ecology 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/2072617.
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In many African savanna landscapes, domestic and wild herbivores cooccur across different land-use systems, but the role of land-use in shaping their spatial relationship is poorly understood. We evaluated the spatial relationship between cattle and wild herbivores categorized by body sizes and feeding habits across different land-use types, namely, private ranches (PR), transitional lands (TRL), and pastoral grazing areas (PGA), in Laikipia County, Kenya. Cattle and wild herbivores spatial distribution data were obtained from Kenya’s Department of Resources Survey and Remote Sensing (DRSRS). Spatial relationships between cattle and different wild herbivore guilds were analyzed using Ripley’s bivariateK12function. In PR, wild herbivore guilds showed significant attraction to cattle at short distances. In TRL, wild grazers, mixed feeders, megaherbivores, and medium-sized ungulates exhibited significant attraction to cattle. Additionally, repulsion was observed between cattle and browsers at short distances under this land-use system. In PGA, wild grazers, mixed feeders, and megaherbivores repelled strongly with cattle at short distances while browsers and medium-sized ungulates were significantly attracted to cattle. Cattle and wild herbivores were more randomly and independently distributed in PR than in TRL and PGA. These spatial relationships imply better coexistence between cattle and wild herbivores in PR than in TRL and PGA.
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Newman, J. A., A. J. Parsons, J. H. M. Thornley, P. D. Penning, and J. R. Krebs. "Optimal Diet Selection by a Generalist Grazing Herbivore." Functional Ecology 9, no. 2 (April 1995): 255. http://dx.doi.org/10.2307/2390572.
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Turner, Wendy C., Kyrre L. Kausrud, Yathin S. Krishnappa, Joris P. G. M. Cromsigt, Holly H. Ganz, Isaac Mapaure, Claudine C. Cloete, et al. "Fatal attraction: vegetation responses to nutrient inputs attract herbivores to infectious anthrax carcass sites." Proceedings of the Royal Society B: Biological Sciences 281, no. 1795 (November 22, 2014): 20141785. http://dx.doi.org/10.1098/rspb.2014.1785.
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Parasites can shape the foraging behaviour of their hosts through cues indicating risk of infection. When cues for risk co-occur with desired traits such as forage quality, individuals face a trade-off between nutrient acquisition and parasite exposure. We evaluated how this trade-off may influence disease transmission in a 3-year experimental study of anthrax in a guild of mammalian herbivores in Etosha National Park, Namibia. At plains zebra ( Equus quagga ) carcass sites we assessed (i) carcass nutrient effects on soils and grasses, (ii) concentrations of Bacillus anthracis (BA) on grasses and in soils, and (iii) herbivore grazing behaviour, compared with control sites, using motion-sensing camera traps. We found that carcass-mediated nutrient pulses improved soil and vegetation, and that BA is found on grasses up to 2 years after death. Host foraging responses to carcass sites shifted from avoidance to attraction, and ultimately to no preference, with the strength and duration of these behavioural responses varying among herbivore species. Our results demonstrate that animal carcasses alter the environment and attract grazing hosts to parasite aggregations. This attraction may enhance transmission rates, suggesting that hosts are limited in their ability to trade off nutrient intake with parasite avoidance when relying on indirect cues.
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Hutchings, Michael R., Iain J. Gordon, Ilias Kyriazakis, Ewen Robertson, and Frank Jackson. "Grazing in heterogeneous environments: infra- and supra-parasite distributions determine herbivore grazing decisions." Oecologia 132, no. 3 (August 2002): 453–60. http://dx.doi.org/10.1007/s00442-002-0971-z.
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Staver, A. Carla, and Gareth P. Hempson. "Seasonal dietary changes increase the abundances of savanna herbivore species." Science Advances 6, no. 40 (October 2020): eabd2848. http://dx.doi.org/10.1126/sciadv.abd2848.
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African savannas are home to the world’s last great megafaunal communities, but despite ongoing population declines, we only poorly understand the constraints on savanna herbivore abundances. Seasonal diet shifts (except migration) have received little attention, despite a diversity of possible dietary strategies. Here, we first formulate two theoretical models that predict that both mixed feeding and migratory grazing increase population sizes. These predictions are borne out in comprehensive data across African savanna parks: Mixed feeders are the most abundant herbivores in Africa, alongside a few migratory grazer populations. Overall, clear mixed-feeder dominance may reflect a historical pattern or may instead mirror a general global decline in specialists. Regardless, mixed feeders dominate the savannas of the present and future.
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Bloor, Juliette M. G., Antoine Tardif, and Julien Pottier. "Spatial Heterogeneity of Vegetation Structure, Plant N Pools and Soil N Content in Relation to Grassland Management." Agronomy 10, no. 5 (May 16, 2020): 716. http://dx.doi.org/10.3390/agronomy10050716.
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Spatial heterogeneity in plant and soil properties plays a key role for biogeochemical cycling, nutrient losses and ecosystem function. Different management practices are expected to induce varying levels of spatial heterogeneity in agroecosystems, but the effects of contrasting biomass removal regimes and herbivore species on grassland variability and spatial pattern have faced little attention. We carried out a spatially-explicit sampling campaign and geostatistical analyses to quantify the spatial heterogeneity of the biomass and N in plants and soil for three management treatments (mowing, cattle grazing and sheep grazing) within a long-term grassland experiment. All plant and soil properties showed within-site variation, irrespective of management treatment. Within-site variation in plant variables could be ranked as grazing > mowing. Cattle grazing increased variability in vegetation structure, soil mineral N and soil C:N compared with sheep grazing. In addition, the cattle-grazed field had a higher degree of spatial structure and a more coarse-grained pattern of spatial heterogeneity in plant properties than the sheep-grazed field. However, both grazing treatments showed spatial asynchrony in above- and below-ground responses to grazing. These results demonstrate the importance of herbivore species identity as a driver of grassland spatial heterogeneity, with implications for spatial uncoupling of nutrient cycles at the field scale.
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GLIGA, Adrian, and Dumitrița DASCĂLU. "Wild Herbivore Forage Preferences in Semi-Natural Mountain Hay-Meadows." Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture 77, no. 2 (November 20, 2020): 15. http://dx.doi.org/10.15835/buasvmcn-agr:2020.0038.
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In the context of increasing grassland abandonment we observed wild herbivore impact on the vegetation in order to understand their influence. To quantify semi-natural grassland usage by wild herbivores, we determined grazing intake in semi-natural hay-meadows surrounded by forest vegetation. Grazing exclusion cages were placed at three locations in the Valea Mare village area situated in Bistriţa-Năsăud County, Romania, from 1 April 2014 – 5 October 2014. Sampling took place at two times during this period, first shortly before the hay meadows were mowed and second at the end of the vegetation growing season. Herbage air dry matter yield was measured using two types of observation plots (cage protected plots and unprotected plots). Plant composition on the studied hay-meadows was analyzed using PC-ORD (in order to explain the preference of herbivores for each location. Although herbage production did not vary significantly between locations, the herbage intake of total dry matter production did vary between locations. Wild animals grazed through the entire growing season and based upon the floristic composition analyses we explained differences in herbage intake based on plant species preference. The management of these meadows maintains an offer of good quality forage throughout summer, and the forest surrounding grasslands provides cover when needed. In order to inhibit woody vegetation and to conserve species-rich open landscape further observation need to be made about the optimal deer species densities.
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Bailey, Derek W., John E. Gross, Emilio A. Laca, Larry R. Rittenhouse, Michael B. Coughenour, David M. Swift, and Phillip L. Sims. "Mechanisms That Result in Large Herbivore Grazing Distribution Patterns." Journal of Range Management 49, no. 5 (September 1996): 386. http://dx.doi.org/10.2307/4002919.
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Mysterud, Atle, Ragnar Aaserud, Lars Ove Hansen, Kjetil Åkra, Stefan Olberg, and Gunnar Austrheim. "Large herbivore grazing and invertebrates in an alpine ecosystem." Basic and Applied Ecology 11, no. 4 (June 2010): 320–28. http://dx.doi.org/10.1016/j.baae.2010.02.009.
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Pryke, James S., Francois Roets, and Michael J. Samways. "Wild Herbivore Grazing Enhances Insect Diversity over Livestock Grazing in an African Grassland System." PLOS ONE 11, no. 10 (October 26, 2016): e0164198. http://dx.doi.org/10.1371/journal.pone.0164198.
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Zhang, Hongmao, Yu Wang, and Zhibin Zhang. "Domestic goat grazing disturbance enhances tree seed removal and caching by small rodents in a warm-temperate deciduous forest in China." Wildlife Research 36, no. 7 (2009): 610. http://dx.doi.org/10.1071/wr09001.
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Context. Grazing by large herbivores may have a considerable influence on ground vegetation as well as on the species composition and abundance of granivors (e.g. small rodents) and this may affect forest regeneration. Very few studies have focussed on the effects of herbivore disturbance on forest regeneration by looking at the modified seed-hoarding behaviour of small rodents. Aims. To test the indirect effects that grazing disturbance by domestic animals has on seed dispersal through the modified seed-hoarding behaviour of small rodents. Methods. We looked at the differences in seed removal and caching of Liaodong oak (Quercus liaotungensis) by small rodents between a plot that was grazed and a plot that was ungrazed by domestic goats in a warm-temperate forest in northern China in 2006 (a non-mast-seeding year) and 2008 (a mast-seeding year). Key results. Seed removal and caching by small rodents were significantly higher in the grazed plots, especially in the mast-seeding year (2008). Significantly more seeds were buried in soil during the mast-seeding year (2008) compared with the non-mast-seeding year (2006). Conclusions. Grazing-induced disturbance might stimulate hoarding efforts by seed-caching rodents. Mast seeding benefits seed survival and forest regeneration. Implications. The presence of large herbivores is likely to benefit early seed dispersal in forests by increasing the hoarding activities of rodents.
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Fröberg, Lars, Anette Baur, and Bruno Baur. "Differential herbivore damage to calcicolous lichens by snails." Lichenologist 25, no. 1 (January 1993): 83–95. http://dx.doi.org/10.1006/lich.1993.1015.
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AbstractA laboratory experiment was conducted to determine the damage caused by snail grazing to 35 calcicolous lichen species and cyanobacteria from the Baltic island of Oland, Sweden. Individuals of four species of land snails (Balea perversa, Chondrina cliema, Clausilia bidentata and Helicigona lapicida) were allowed to graze on identified lichen species growing on pieces of limestone. Snail grazing on thalli and ascocarps was classified into four categories ranging from no damage to completely eaten. In general, some lichen species were heavily grazed, whereas others were only slightly damaged or not injured. Aspiciha calcarea, Tephromela atra and Verrucaria nigrescens were preferred by all snail species except Chondrina cliema. In general, lichen thalli that were not immersed in the calcareous rock and cyanobacteria were preferred, whereas ascocarps were avoided by one of the snail species (C. clienta). Immersed perithecia with a carbonized outer layer were avoided by all snail species except C. bidentata. Possibilities of chemical and mechanical defence properties in calcicolous lichens are discussed.
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van Asperen, Eline N., Jason R. Kirby, and Helen E. Shaw. "Relating dung fungal spore influx rates to animal density in a temperate environment: Implications for palaeoecological studies." Holocene 30, no. 2 (September 20, 2019): 218–32. http://dx.doi.org/10.1177/0959683619875804.
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The management of the remainder of Europe’s once extensive forests is hampered by a poor understanding of the character of the vegetation and drivers of change before the onset of clearance for farming. Pollen data indicate a closed-canopy, mixed-deciduous forest, contrasting with the assertion that large herbivores would have maintained a mosaic of open grassland, regenerating scrub and forested groves. Coprophilous fungal spores from sedimentary sequences are increasingly used as a proxy for past herbivore impact on vegetation, but the method faces methodological and taphonomical issues. Using pollen trap data from a long-running experiment in Chillingham Wild Cattle Park, UK, we investigate the first steps in the mechanisms connecting herbivore density to the incorporation of fungal spores in sediments and assess the effects of environmental variables on this relationship. Herbivore utilisation levels correlate with dung fungal spore abundance. Chillingham is densely populated by large herbivores, but dung fungal spore influx is low. Herbivores may thus be present on the landscape but go undetected. The absence of dung fungal spores is therefore less informative than their presence. Dung fungal spores likely enter the sediment record through a different pathway from wind-borne pollen and thus dung fungal abundance is better expressed as influx rates than as percentage of total pollen. Landscape openness, vegetation type and site wetness do not distort the impact of utilisation levels on dung fungal spore representation. However, dung fungal spore influx varies markedly between seasons and years. Spores travel, leading to a background level of spore deposition across the landscape, and at times a depletion of spores, especially under wet weather conditions. Animal behaviour, as well as husbandry practices, can lead to the accumulation of dung, and thus fungal spores, in specific locations on the landscape that do not directly reflect grazing pressure.
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Kirathe, Joseph Nderitu, John Maina Githaiga, Robert Mutugi Chira, and Daniel Rubenstein. "Land use influence on distribution and abundance of herbivores in Samburu-Laikipia, Kenya." Journal of Sustainability, Environment and Peace 4, no. 1 (July 12, 2021): 21–29. http://dx.doi.org/10.53537/jsep.2021.07.003.
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The distribution and abundance of different wildlife herbivores was studied in Samburu-Laikipia landscape. The study sites included; Mpala and Oljogi, both commercial ranches in Laikipia district; Oldonyiro and Kipsing community areas in Isiolo district; West Gate Conservancy, Ngaroni Community area, Kalama Community area and Sessia-Barsalinga Community area in Samburu district; and Buffalo Spring National Reserve and Samburu National Reserve both protected areas in the landscape. The objectives of the study were: 1) Determine the influence of different land use on seasonal abundances and distribution wildlife species and 2) Examine the influence of livestock, human settlements and water on wildlife species in Samburu-Laikipia landscape. Distance sampling was used to estimate wildlife, livestock and bomas densities. Distance to nearest water was projected from GPS coordinates for both wildlife and livestock sighting using ARCGIS. Our analysis showed non-uniform distributions of wildlife groups across the Samburu-Laikipia ecosystem largely driven by seasonal rainfall patterns and land use types. Like predicted, most wildlife groups occurred in higher abundances on protected areas, Laikipia commercial ranches and community conservancies unlike in community grazing areas in both dry and wet season. However, large grazers increased substantially in community grazing areas over the wet season when livestock grazing was heavy, stimulating growth of short annuals plants of high-quality nutrients. Human activities had negative influences on all wildlife groups. Our findings indicate that the type of land -use influenced herbivore distribution and abundance in Samburu-Laikipia landscape. This suggests that human activities, including pastoralism, in conjunction with season rainfall patterns and land-use shape herbivore distribution and abundance in the area. Conservation strategies for successfully increasing survival of wildlife therefore, requires maintenance of a mixture of land-use types with well controlled and sustainable development.
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Yang, Fan, Quanqin Shao, and Zhigang Jiang. "A Population Census of Large Herbivores Based on UAV and Its Effects on Grazing Pressure in the Yellow-River-Source National Park, China." International Journal of Environmental Research and Public Health 16, no. 22 (November 11, 2019): 4402. http://dx.doi.org/10.3390/ijerph16224402.
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Using the Yellow-River-Source National Park (YRSNP) as a study site, an unmanned aerial vehicle (UAV) remote sensing and line transect method was used to investigate the number of wild herbivorous animals and livestock, including the kiang (Equus kiang) and Tibetan gazelle (Procapra picticaudata). A downscaling algorithm was used to generate the forage yield data in YRSNP based on a 30-m spatial resolution. On this basis, we estimated the forage–livestock balance, which included both wild animals and livestock, and analyzed the effects of functional zone planning in national parks on the forage–livestock balance in YRSNP. The results showed that the estimates of large herbivore population numbers in YRSNP based on population density in the aerial sample strips, which were compared and validated with official statistics and warm season survey results, indicated that the numbers of kiangs and Tibetan gazelles in the 2017 cold season were 12,900 and 12,100, respectively. The numbers of domestic yaks, Tibetan sheep, and horses were 53,400, 76,800, and 800, respectively, and the total number of sheep units was 353,200. The ratio of large wild herbivores and livestock sheep units was 1:5. Large wild herbivores have different preferences for functional zones, preferring ecological restoration areas consisting mainly of sparse grassland. The grazing pressure indices of the core reserve areas and ecological restoration areas were 0.168 and 0.276, respectively, indicating that these two regions still have high grazing potential. However, the grazing pressure index of the traditional utilization areas was 1.754, indicating that these grasslands are severely overloaded. After the planning and implementation of functional zones, the grazing pressure index of YRSNP was 1.967. Under this measure, the number of livestock was not reduced and the grazing pressure nearly doubled, indicating that forage–livestock conflict has become more severe in YRSNP.
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Herder, Michael den, Samuli Helle, Pekka Niemelä, Heikki Henttonen, and Timo Helle. "Large Herbivore Grazing Limits Small-Mammal Densities in Finnish Lapland." Annales Zoologici Fennici 53, no. 3-4 (August 2016): 154–64. http://dx.doi.org/10.5735/086.053.0404.
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Day, T. A., and J. K. Detling. "Grassland Patch Dynamics and Herbivore Grazing Preference Following Urine Deposition." Ecology 71, no. 1 (February 1990): 180–88. http://dx.doi.org/10.2307/1940258.
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Leavitt, P. R., and S. R. Carpenter. "Regulation of Pigment Sedimentation by Photo-Oxidation and Herbivore Grazing." Canadian Journal of Fisheries and Aquatic Sciences 47, no. 6 (June 1, 1990): 1166–76. http://dx.doi.org/10.1139/f90-136.
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Reversed-phase high pressure liquid chromatography was used to show that algal carotenoid sedimentation is regulated by photo-oxidation and herbivore grazing in three unproductive, north-temperate lakes. Comparison of algal carotenoid and biovolume standing stocks revealed that carotenoid concentrations in epilimnetic waters were influenced by nonplanktonic inputs of pigments as well as phytoplankton community composition. Sediment traps did not record weekly events in the water column. Pigments that were incorporated in zooplankton feces and sank rapidly (e.g. alioxanthm and pheophorbide a) were overrepresented in trap material relative to epilimnetic pigment standing stocks. Differential decay of pigments in traps could not account for this observed bias. Chlorophyll mass–balance budgets corroborated the important influence of grazing by large-bodied zooplankton on pigment sedimentation. Interannual differences in pigment sedimentation were caused by changes in zooplankton community structure and the vertical zonation of phytoplankton communities. In the absence of fecal transportation, photo-oxidation destroyed carotenoids prior to their sedimentation from the photic zone. Therefore, sedimentary carotenoid composition is regulated by loss processes as well as changes in algal community composition.
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Lewis, Sara M., and Peter C. Wainwright. "Herbivore abundance and grazing intensity on a Caribbean coral reef." Journal of Experimental Marine Biology and Ecology 87, no. 3 (May 1985): 215–28. http://dx.doi.org/10.1016/0022-0981(85)90206-0.
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BêTY, Joël, Maude Graham-Sauvé, Pierre Legagneux, Marie-Christine Cadieux, and Gilles Gauthier. "Fading indirect effects in a warming arctic tundra." Current Zoology 60, no. 2 (April 1, 2014): 189–202. http://dx.doi.org/10.1093/czoolo/60.2.189.
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Abstract Indirect interactions in food webs can strongly influence the net effect of global change on ecological communities yet they are rarely quantified and hence remain poorly understood. Using a 22-year time series, we investigated climate-induced and predator-mediated indirect effects on grazing intensity in the tundra food web of Bylot Island, which experienced a warming trend over the last two decades. We evaluated the relative effects of environmental parameters on the proportion of plant biomass grazed by geese in wetlands and examined the temporal changes in the strength of these cascading effects. Migrating geese are the dominant herbivores on Bylot Island and can consume up to 60% of the annual production of wetland graminoids. Spring North Atlantic Oscillation, mid-summer temperatures and summer abundance of lemmings (prey sharing predators with geese) best-explained annual variation in grazing intensity. Goose grazing impact increased in years with high temperatures and high lemming abundance. However, the strength of these indirect effects on plants changed over time. Grazing intensity was weakly explained by environmental factors in recent years, which were marked by a sharp increase in plant primary production and steady decrease in grazing pressure. Indirect effects do not seem to be reversing the direct positive effect of warming on wetland plants. We suggest that cascading effects on plants may lag considerably behind direct effects in vertebrate dominated arctic communities, especially where key herbivore populations are strongly affected by factors outside of the Arctic.
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Morgan, Helen R., Guy Ballard, Peter J. S. Fleming, Nick Reid, Remy Van der Ven, and Karl Vernes. "Estimating macropod grazing density and defining activity patterns using camera-trap image analysis." Wildlife Research 45, no. 8 (2018): 706. http://dx.doi.org/10.1071/wr17162.
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Context When measuring grazing impacts of vertebrates, the density of animals and time spent foraging are important. Traditionally, dung pellet counts are used to index macropod grazing density, and a direct relationship between herbivore density and foraging impact is assumed. However, rarely are pellet deposition rates measured or compared with camera-trap indices. Aims The aims were to pilot an efficient and reliable camera-trapping method for monitoring macropod grazing density and activity patterns, and to contrast pellet counts with macropod counts from camera trapping, for estimating macropod grazing density. Methods Camera traps were deployed on stratified plots in a fenced enclosure containing a captive macropod population and the experiment was repeated in the same season in the following year after population reduction. Camera-based macropod counts were compared with pellet counts and pellet deposition rates were estimated using both datasets. Macropod frequency was estimated, activity patterns developed, and the variability between resting and grazing plots and the two estimates of macropod density was investigated. Key Results Camera-trap grazing density indices initially correlated well with pellet count indices (r2=0.86), but were less reliable between years. Site stratification enabled a significant relationship to be identified between camera-trap counts and pellet counts in grazing plots. Camera-trap indices were consistent for estimating grazing density in both surveys but were not useful for estimating absolute abundance in this study. Conclusions Camera trapping was efficient and reliable for estimating macropod activity patterns. Although significant, the relationship between pellet count indices and macropod grazing density based on camera-trapping indices was not strong; this was due to variability in macropod pellet deposition rates over different years. Time-lapse camera imagery has potential for simultaneously assessing herbivore foraging activity budgets with grazing densities and vegetation change. Further work is required to refine the use of camera-trapping indices for estimation of absolute abundance. Implications Time-lapse camera trapping and site-stratified sampling allow concurrent assessment of grazing density and grazing behaviour at plot and landscape scale.
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NYAHONGO, J. W., M. L. EAST, F. A. MTURI, and H. HOFER. "Benefits and costs of illegal grazing and hunting in the Serengeti ecosystem." Environmental Conservation 32, no. 4 (December 2005): 326–32. http://dx.doi.org/10.1017/s0376892906002566.
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Two forms of natural resource use (meat hunting and livestock grazing) were investigated at three sites in the western region of the Serengeti ecosystem, Tanzania. Statutory management of natural resources in this region was designated as National Park, Game Reserve or village council. A quasi-experimental design examined factors likely to alter the cost and benefit of illegal use by ranking areas within sites in relation to these factors. Factors likely to alter costs were the chance of arrest, determined by the presence or absence of guard posts, and the distance travelled to the site of exploitation. As all sites experienced large fluctuations in the density of migratory herbivores, it was assumed that the benefit acquired from hunting increased with wild herbivore density. Marked seasonal changes in precipitation were considered likely to alter the value of forage and water to livestock owners. Hunting effort (density of snares) increased as the density of wild herbivores increased. The distribution of hunting effort across sites was more consistent with the prediction that high travel costs were more likely to curtail hunting than a high potential cost of arrest. Unlike hunters, livestock owners mostly avoided the use of resources in protected areas probably because of the high potential cost of arrest and confiscation of stock. Natural resources within protected areas were exploited when benefits outweighed likely costs.
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Zimmer, Heidi C., Singarayer K. Florentine, Rita Enke, and Martin Westbrooke. "Rainfall and grazing: not the only barriers to arid-zone conifer recruitment." Australian Journal of Botany 65, no. 2 (2017): 109. http://dx.doi.org/10.1071/bt16104.
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An understanding of the drivers of infrequent recruitment is fundamental in managing for species persistence. Callitris glaucophylla Joy Thomps. & L.A.S. Johnson (white cypress-pine) is a slow-growing, long-lived conifer, with a distribution that extends across arid Australia. Arid populations of C. glaucophylla are endangered in New South Wales, and are characterised by infrequent recruitment. We examined recruitment patterns of C. glaucophylla in differential grazing exclosures (excluding rabbits, excluding large herbivores or excluding both) and in unfenced areas. More recruitment occurred in rabbit-proof exclosures, compared with nearby large herbivore and control exclosures, although some rabbit-proof exclosures recorded no recruitment. Increases in recruitment at several long-term exclosures were associated with wet periods, as was recruitment at some unfenced sites. Apart from grazing and rainfall, recruitment was related to mature tree size and stand density (probably because of their influence on seed availability). These endangered arid C. glaucophylla woodlands are all that remains of a once extensive distribution, and are habitat for a suite of threatened species. Reduction in grazing pressure, particularly from rabbits, is clearly critical to maintain recruitment in these remnant populations. Chances of recruitment appear to be enhanced in low-density stands, around large trees, and in dune blow outs – fencing should focus on these areas.
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Mutze, G. "Barking up the wrong tree? Are livestock or rabbits the greater threat to rangeland biodiversity in southern Australia?" Rangeland Journal 38, no. 6 (2016): 523. http://dx.doi.org/10.1071/rj16047.
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Increasing provision of permanent water points has put most Australian pastoral rangelands within grazing distance of sheep, cattle, kangaroos and large feral herbivores, and there is concern that grazing-sensitive native plants will be lost as a result. Proposals have been developed to conserve plant biodiversity by permanently excluding livestock from any areas that are remote from permanent water, or to buy back pastoral properties and remove existing water points to create large reserves. There is, however, little evidence that water-remote areas provide refuge for grazing-sensitive plants, nor consistent evidence of plant biodiversity loss along gradients of increasing livestock grazing pressure in proximity to water. One of the reasons why that evidence might be lacking is that most livestock studies have not considered the grazing impact of sympatric European rabbits, the most widespread and abundant wild herbivore in southern Australia. Numerous studies have shown that rabbit grazing has a major impact on rangeland vegetation and can prevent regeneration at densities which may be too low to be thought important. Plant biodiversity gradients are readily discernible along gradients of rabbit density in livestock-free reserves. Rabbits are therefore likely to be a significant confounding factor when assessing livestock impacts, or possibly the primary cause of observed patterns of plant diversity. If so, attempts to preserve plant biodiversity by removing livestock are destined to fail in rabbit-grazed areas. Public funds for biodiversity conservation in the pastoral zone might be better spent on co-investment with pastoralists for rabbit control on conservatively stocked properties, rather than on restricting pastoral use of land in livestock-free, rabbit-infested reserves.
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Davis, Naomi E., Julian Di Stefano, Graeme Coulson, Jim Whelan, and John Wright. "Vegetation management influences habitat use by mammalian herbivores in shrub-encroached grassy woodland." Wildlife Research 43, no. 5 (2016): 438. http://dx.doi.org/10.1071/wr15218.
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Context Restoration of disturbed vegetation communities commonly involves altering vegetation composition and structure, attributes that can influence the suitability of habitat for fauna. Feedbacks may occur whereby changes to the vegetation affect mammalian herbivores, and unintended changes may prevent managers from achieving conservation goals. Aims To understand how vegetation management affects habitat use by five mammalian herbivores, namely eastern grey kangaroo (Macropus giganteus), swamp wallaby (Wallabia bicolor), common wombat (Vombatus ursinus), European rabbit (Oryctolagus cuniculus) and hog deer (Axis porcinus). Methods A management experiment (mechanical slashing of the encroaching shrub Leptospermum laevigatum) at Wilsons Promontory National Park, Australia, created slashed swales in addition to untreated dune and scrub woodland. In each vegetation stratum, we estimated the cover of L. laevigatum and quantified herbivore abundance by counting the standing crop of faecal pellets. Key results Relative to untreated vegetation, mechanical slashing of L. laevigatum substantially reduced cover of this species above 200 cm, but increased its cover below 30 cm. On the basis of faecal-pellet counts, multispecies use of managed and unmanaged parts of the landscape differed substantially, with the differences principally driven by higher abundance of European rabbits and eastern grey kangaroos at slashed sites. Conclusions The responses of three grazing species (kangaroo, rabbits and wombats) to vegetation management were predicted well by prior knowledge of diet and habitat preferences. This was not the case for the browser (swamp wallaby), nor for the grazer that consumes substantial amounts of browse in the study area (hog deer), and additional knowledge of the processes underlying their responses to vegetation change is required. Implications Our findings highlighted that vegetation management can influence herbivore abundances in the managed system. An improved understanding of these associations will allow vegetation management plans to incorporate herbivore responses.
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Lee, S. Y. "Herbivory as an ecological process in a Kandelia candel (Rhizophoraceae) mangal in Hong Kong." Journal of Tropical Ecology 7, no. 3 (August 1991): 337–48. http://dx.doi.org/10.1017/s0266467400005605.
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ABSTRACTNatural levels and consequences of insect herbivory were studied for a Kandelia candel (Rhizophoraceae) dominated mangal at the Mai Po Marshes, Hong Kong. Grazing insects (mainly lepidopteran larvae) consumed, on average, 10.3% of the leaf area on K. candel, with >90% of the leaves suffering <30% loss. Natural median leaf longevity was significantly different between winter and summer-exposed leaves, being, respectively, 423.2 and 269.6 days. Observations showed that herbivore damage caused a reduction of leaf longevity, as severely damaged leaves were abscissed before intact, older leaves on the same branch. Experimental leaf area removal suggested that leaf life span reduction was significantly influenced by leaf age and degree of damage. However, the reduction was only significant (>40 days) when area loss was >40%. Leaves produced in summer were also more sensitive to damage than those produced in winter. As <5% of the leaves suffered >40% of area removal by insect grazing in nature, insect herbivory is considered an unimportant regulator of leaf litter dynamics for K. candel. At this intensity level, herbivory consumes 2.8–3.5% of the net above-ground primary production of the mangrove. There was also no significant difference in the final number of leaves and twigs produced by the branches with various degrees of leaf area removal. Other observed impacts of insects on the structure and function of the K. candel mangal are discussed.
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Cerling, Thure E., Samuel A. Andanje, Scott A. Blumenthal, Francis H. Brown, Kendra L. Chritz, John M. Harris, John A. Hart, et al. "Dietary changes of large herbivores in the Turkana Basin, Kenya from 4 to 1 Ma." Proceedings of the National Academy of Sciences 112, no. 37 (August 3, 2015): 11467–72. http://dx.doi.org/10.1073/pnas.1513075112.
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A large stable isotope dataset from East and Central Africa from ca. 30 regional collection sites that range from forest to grassland shows that most extant East and Central African large herbivore taxa have diets dominated by C4 grazing or C3 browsing. Comparison with the fossil record shows that faunal assemblages from ca. 4.1–2.35 Ma in the Turkana Basin had a greater diversity of C3–C4 mixed feeding taxa than is presently found in modern East and Central African environments. In contrast, the period from 2.35 to 1.0 Ma had more C4-grazing taxa, especially nonruminant C4-grazing taxa, than are found in modern environments in East and Central Africa. Many nonbovid C4 grazers became extinct in Africa, notably the suid Notochoerus, the hipparion equid Eurygnathohippus, the giraffid Sivatherium, and the elephantid Elephas. Other important nonruminant C4-grazing taxa switched to browsing, including suids in the lineage Kolpochoerus-Hylochoerus and the elephant Loxodonta. Many modern herbivore taxa in Africa have diets that differ significantly from their fossil relatives. Elephants and tragelaphin bovids are two groups often used for paleoecological insight, yet their fossil diets were very different from their modern closest relatives; therefore, their taxonomic presence in a fossil assemblage does not indicate they had a similar ecological function in the past as they do at present. Overall, we find ecological assemblages of C3-browsing, C3–C4-mixed feeding, and C4-grazing taxa in the Turkana Basin fossil record that are different from any modern ecosystem in East or Central Africa.
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Davies, Hugh F., Stefan W. Maier, and Brett P. Murphy. "Feral cats are more abundant under severe disturbance regimes in an Australian tropical savanna." Wildlife Research 47, no. 8 (2020): 624. http://dx.doi.org/10.1071/wr19198.
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Abstract ContextThere is an increasing awareness that feral cats play a key role in driving the ongoing decline of small mammals across northern Australia; yet, the factors that control the distribution, abundance and behaviour of feral cats are poorly understood. These key knowledge gaps make it near-impossible for managers to mitigate the impacts of cats on small mammals. AimsWe investigated the environmental correlates of feral cat activity and abundance across the savanna woodlands of Melville Island, the larger of the two main Tiwi Islands, northern Australia. MethodsWe conducted camera-trap surveys at 88 sites, and related cat activity and abundance to a range of biophysical variables, either measured in the field or derived from remotely sensed data. Key resultsWe found that feral cat activity and abundance tended to be highest in areas characterised by severe disturbance regimes, namely high frequencies of severe fires and high feral herbivore activity. ConclusionsOur results have contributed to the growing body of research demonstrating that in northern Australian savanna landscapes, disturbance regimes characterised by frequent high-severity fires and grazing by feral herbivores may benefit feral cats. This is most likely to be a result of high-severity fire and grazing removing understorey biomass, which increases the time that the habitat remains in an open state in which cats can hunt more efficiently. This is due to both the frequent and extensive removal, and longer-term thinning of ground layer vegetation by severe fires, as well as the suppressed post-fire recovery of ground layer vegetation due to grazing by feral herbivores. ImplicationsManagement that reduces the frequency of severe fires and the density of feral herbivores could disadvantage feral cat populations on Melville Island. A firm understanding of how threatening processes interact, and how they vary across landscapes with different environmental conditions, is critical for ensuring management success.
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J. Page, Manda, and R. J. S. Beeton. "Is the removal of domestic stock sufficient to restore semi-arid conservation areas?" Pacific Conservation Biology 6, no. 3 (2000): 245. http://dx.doi.org/10.1071/pc000245.
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Increasingly, conservation areas are proclaimed in non-pristine environments that have biodiversity values and the issue of how to change the management regime to restore such landscapes arises. Before gazettal in 1992, Currawinya National Park (28�52'S, 144�30'E) in south-west Queensland's mulga lands was grazed by domestic stock for over 130 years. Following gazettal, the area was destocked and a monitoring programme initiated to determine the response by the vegetation. This paper describes the grass dynamics in three vegetation communities on Currawinya National Park with three different grazing regimes. Data are presented for an on-park site (native and feral herbivores present), an off-park site (domestic, native and feral herbivores were present), and an exclosure (no mammalian herbivores present). The results show that removal of domestic livestock alone is not sufficient to promote rapid recovery of grass populations, and suggest that conservation area managers must reduce native herbivore numbers as well if the desired outcome is a return to the supposed "natural" condition.
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Dumont, Bertrand, Nicolas Rossignol, Francis Decuq, Priscilla Note, and Anne Farruggia. "How does pasture size alter plant–herbivore interactions among grazing cattle?" Grass and Forage Science 75, no. 4 (October 23, 2020): 438–46. http://dx.doi.org/10.1111/gfs.12503.
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Wood, Kevin A., Richard A. Stillman, Francis Daunt, and Matthew T. O’Hare. "Evaluating the Effects of Population Management on a Herbivore Grazing Conflict." PLoS ONE 8, no. 2 (February 6, 2013): e56287. http://dx.doi.org/10.1371/journal.pone.0056287.
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