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Kerns BK, Day MA. Long-term frequent fire and cattle grazing alter dry forest understory vegetation. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2024; 34:e2972. [PMID: 38751157 DOI: 10.1002/eap.2972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 11/27/2023] [Accepted: 02/06/2024] [Indexed: 07/02/2024]
Abstract
Understanding fire and large herbivore interactions in interior western forests is critical, owing to the extensive and widespread co-occurrence of these two disturbance types and multiple present and future implications for forest resilience, conservation and restoration. However, manipulative studies focused on interactions and outcomes associated with these two disturbances are rare in forested rangelands. We investigated understory vegetation response to 5-year spring and fall prescribed fire and domestic cattle grazing exclusion in ponderosa pine stands and reported long-term responses, almost two decades after the first entry fires. In fall burn areas open to cattle grazing, total understory cover prior to utilization was about 12% lower compared with fall burn areas where cattle were experimentally excluded. This response was not strongly driven by a particular palatable or unpalatable plant functional group. Fire and grazing are likely interacting in a numerically mediated process, as we found little evidence to support a functionally moderated pathway. Post-fire green-up may equalize forage to a certain extent and concentrate herbivores in the smaller burned areas within pastures, constraining a positive understory response to burning. Fall fire and grazing also increased annual forbs and resprouting shrubs. The effects of spring burning were relatively minor, and we found no interaction with grazing. The nonnative annual grass Bromus tectorum (cheatgrass) remains a problematic invader linked to fall burning but not grazing in stands that had higher propagule pressure when the experiment was initiated. At these sites, exotic grass was a major component of the vegetation by 2015, and invasion was also increasing in spring burn and unburned areas. Information from our study suggests that frequent fall fires and cattle grazing combined may reduce understory resilience in similar dry ponderosa pine forests. Consideration of longer fire return intervals, resting areas after fire, virtual fencing, or burning entire pastures may help to mitigate the effects noted in this study.
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Affiliation(s)
- Becky K Kerns
- USDA Forest Service, Pacific Northwest Research Station, Corvallis, Oregon, USA
| | - Michelle A Day
- USDA Forest Service, Rocky Mountain Research Station, Missoula, Montana, USA
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2
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Schwegmann S, Mörsdorf M, Bhardwaj M, Storch I. Effects of understory characteristics on browsing patterns of roe deer in central European mountain forests. Ecol Evol 2023; 13:e10431. [PMID: 37589040 PMCID: PMC10425343 DOI: 10.1002/ece3.10431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 08/03/2023] [Accepted: 08/04/2023] [Indexed: 08/18/2023] Open
Abstract
Selective browsing by deer on young trees may impede the management goal of increasing forest resilience against climate change and other disturbances. Deer population density is often considered the main driver of browsing impacts on young trees, however, a range of other variables such as food availability also affect this relationship. In this study, we use browsing survey data from 135 research plots to explore patterns of roe deer (Capreolus capreolus) browsing pressure on woody plants in mountainous forests in central Europe. We fitted species-specific generalised linear mixed models for eight woody taxa, assessing the potential effects of understory characteristics, roe deer abundance and lying deadwood on browsing intensity. Our study reveals conspecific and associational effects for woody taxa that are intermediately browsed by roe deer. Selective browsing pressure was mediated by preferences of plants, in that, browsing of strongly preferred woody taxa as for example mountain ash (Sorbus aucuparia) and of least preferred woody taxa, for example Norway spruce (Picea abies) was not affected by the surrounding understory vegetation, while browsing pressure on intermediately browsed species like for example silver fir (Abies alba) was affected by understory characteristics. Contrary to our expectations, roe deer abundance was only positively associated with browsing pressure on silver fir and bilberry (Vaccinium myrtillus), while all other plants were unaffected by deer abundance. Finally, we did not find an influence of lying deadwood volume on the browsing pressure on any woody-plant species. Overall, our results indicate that patterns in browsing preference and intensity are species-specific processes and are partly affected by the surrounding understory vegetation. Current management strategies that aim to reduce browsing pressure through culling may be inefficient as they do not address other drivers of browsing pressure. However, managers also need to consider the characteristics of the local understory vegetation in addition to deer abundance and design species-specific plans to reduce browsing on woody plant taxa.
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Affiliation(s)
| | | | - Manisha Bhardwaj
- Chair of Wildlife Ecology and ManagementUniversity of FreiburgFreiburgGermany
| | - Ilse Storch
- Chair of Wildlife Ecology and ManagementUniversity of FreiburgFreiburgGermany
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3
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Erfanian MB, Memariani F, Atashgahi Z, Mesdaghi M, Saeedi M, Darrudi M, Hamedian M, Hosseini S, Ejtehadi H. Unpalatable plants induce a species-specific associational effect on neighboring communities. Sci Rep 2021; 11:14380. [PMID: 34257345 PMCID: PMC8277879 DOI: 10.1038/s41598-021-93698-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 06/29/2021] [Indexed: 11/09/2022] Open
Abstract
In grazing conditions, unpalatable species may induce either associational defense or neighbor contrast susceptibility in neighboring communities. Using surveys from eight grasslands, we tested whether various unpalatable species have the same impacts on neighboring communities in response to grazing. The studied unpalatable species were: Phlomis cancellata (an unpalatable nonpoisonous plant), Euphorbia boissieriana, E. microsciadia (poisonous plants), and Seseli transcaucasicum (a highly poisonous plant). Our results showed that, in the ungrazed grasslands, communities containing P. cancellata had lower biodiversity than communities without it. In the moderately- and heavily grazed grasslands, P. cancellata induced associational defense in the neighboring communities. In heavily grazed grasslands, both Euphorbia species promoted neighbor contrast susceptibility in the neighboring communities. Similarly, S. transcaucasicum in a heavily grazed grassland, induced neighbor contrast susceptibility. Different responses of plant community vulnerability among the studied unpalatable plants might be due to herbivore different foraging decisions. Accordingly, grazers selectively choose from other patches when facing P. cancellata and other plant individuals when there is a poisonous plant in a patch. Our results suggested that grazing intensity may not substantially affect the foraging decisions of sheep and goats in response to unpalatable species. We recommend monitoring the abundance of poisonous species to maintain the sustainable use of grasslands.
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Affiliation(s)
- Mohammad Bagher Erfanian
- Quantitative Plant Ecology and Biodiversity Research Laboratory, Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, PO BOX 9177948974, Mashhad, Iran
| | - Farshid Memariani
- Herbarium FUMH, Department of Botany, Research Center for Plant Sciences, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Zohreh Atashgahi
- Quantitative Plant Ecology and Biodiversity Research Laboratory, Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, PO BOX 9177948974, Mashhad, Iran
| | - Mansour Mesdaghi
- Department of Range and Watershed Management, Faculty of Natural Resources and Environment, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Maliheh Saeedi
- Quantitative Plant Ecology and Biodiversity Research Laboratory, Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, PO BOX 9177948974, Mashhad, Iran
| | - Mojtaba Darrudi
- Quantitative Plant Ecology and Biodiversity Research Laboratory, Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, PO BOX 9177948974, Mashhad, Iran
| | - Maliheh Hamedian
- Quantitative Plant Ecology and Biodiversity Research Laboratory, Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, PO BOX 9177948974, Mashhad, Iran
| | - Saeede Hosseini
- Quantitative Plant Ecology and Biodiversity Research Laboratory, Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, PO BOX 9177948974, Mashhad, Iran
| | - Hamid Ejtehadi
- Quantitative Plant Ecology and Biodiversity Research Laboratory, Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, PO BOX 9177948974, Mashhad, Iran.
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Sigaud M, Mason THE, Barnier F, Cherry SG, Fortin D. Emerging conflict between conservation programmes: when a threatened vertebrate facilitates the dispersal of exotic species in a rare plant community. Anim Conserv 2020. [DOI: 10.1111/acv.12579] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Sigaud
- Département de Biologie et Centre d’Étude de la Forêt Université Laval Québec QC Canada
- Primate Research Institute Kyoto University Inuyama Japan
| | - T. H. E. Mason
- Département de Biologie et Centre d’Étude de la Forêt Université Laval Québec QC Canada
- Biological and Environmental Sciences School of Natural Sciences University of Stirling Stirling UK
| | - F. Barnier
- Département de Biologie et Centre d’Étude de la Forêt Université Laval Québec QC Canada
- UMS Patrimoine Naturel Muséum National d'Histoire Naturelle Paris France
| | - S. G. Cherry
- Parks Canada Agency Radium Hot Springs BC Canada
| | - D. Fortin
- Département de Biologie et Centre d’Étude de la Forêt Université Laval Québec QC Canada
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Simon RN, Fortin D. Crop raiders in an ecological trap: optimal foraging individual-based modeling quantifies the effect of alternate crops. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2020; 30:e02111. [PMID: 32112455 DOI: 10.1002/eap.2111] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 01/02/2020] [Accepted: 01/24/2020] [Indexed: 06/10/2023]
Abstract
Crop raiding is an increasing source of human-wildlife conflict that antagonizes humans and can lead to heightened killing of wildlife. Attraction to crops can trigger ecological traps, where animals prefer areas of their range that confer relatively low fitness. Food can be used to draw animals away from problematic areas, but an alternative considered less often is to replace high-quality food with poorer alternatives. In any case, managers often have no means of anticipating by how much such interventions should impact animal use of space. Optimal foraging theory predicts that foragers optimizing their diet should choose food items according to their relative profitability (i.e., digestible energy/ handling time), a theoretical prediction that can orient management actions. Accordingly, we developed an individual-based model (IBM) simulating movement through empirical rules under an optimal foraging framework. Our objective was to quantify the effect size of cultivating alternate crops to reduce crop raiding and the associated human-induced mortality driving an ecological trap for an energy maximizer, plains bison (Bison bison bison). Results showed that almost tripling the area of cultivation of crops of lower profitability (from 24.3% of the bison range outside the protected area in one management scenario to 70.3% in another) only led to a 25% additional decrease in the intensity of crop raiding (from a decrease of 40% in the first scenario to a decrease of 65% in the second). This suggests that localized interventions in the landscape are likely to have a stronger impact in mitigating crop raiding than broad actions ignoring spatial patterns in food distribution. However, we obtained no significant reduction in the number of simulated bison being harvested in the first scenario, and only a small reduction in the second, when the intervention was spatially broad. Our individual-based approach to animal movement informed by optimal foraging demonstrates that linking landscape configuration to mortality rates can help managers anticipate the effectiveness of manipulating food to keep animals away from problematic zones. Yet disarming ecological traps driven by human hunting appears to be a much more challenging undertaking.
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Affiliation(s)
- Ricardo Nouailhetas Simon
- Département de Biologie and Centre d'Étude de la Forêt, Université Laval, Pavillon Alexandre-Vachon, 1045, avenue de la Médecine, bureau 2050, Québec, Quebec, G1V 0A6, Canada
| | - Daniel Fortin
- Département de Biologie and Centre d'Étude de la Forêt, Université Laval, Pavillon Alexandre-Vachon, 1045, avenue de la Médecine, bureau 2050, Québec, Quebec, G1V 0A6, Canada
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Huang Y, Wang L, Wang D, Zeng DH, Li Y, Liu J, Wang Y. Foraging responses of sheep to plant spatial micro-patterns can cause diverse associational effects of focal plant at individual and population levels. J Anim Ecol 2018; 87:863-873. [PMID: 29430651 DOI: 10.1111/1365-2656.12809] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 12/27/2017] [Indexed: 11/29/2022]
Abstract
Multiple-scale foraging decisions by large herbivores can cause associational effects of focal plant individuals neighboured with different species. Spatial micro-patterns between the focal plant and its neighbouring species within patches can affect herbivore foraging selectivity at within- and between-patch scales, which may consequently lead to associational plant effects occurring at both plant individual and population levels. However, these associational effects have not been explored together in the plant-herbivore interaction studies. We aim to evaluate how plant spatial micro-pattern within different quality patches mediate herbivore foraging selectivity, thereby affecting the associational effects of focal plant individuals and population. Using sheep as the model herbivore and a medium preferred species as the focal plant, we conducted a manipulative experiment by allowing sheep grazing freely among three different quality patches, each of which consisted of preferred, unpreferred and focal plant species with different abundances forming spatially aggregated or dispersed micro-patterns. Results showed that, compared with the aggregated plant micro-pattern, dispersed plant micro-patterns within different quality patches increased sheep within-patch selectivity, and caused diverse associational effects of focal plant individuals. Focal plant individuals experienced neighbour contrast defence (i.e. got protection in the high quality patch) and associational defence (i.e. got protection in the low quality patch), respectively, when plants distributed dispersedly in the low and high quality patch. Focal plant individuals simultaneously experienced associational susceptibility (i.e. got damage in the high quality patch) and neighbour contrast susceptibility (i.e. got damage in the low quality patch) when plants distributed dispersedly in the medium quality patch. Furthermore, dispersed plant micro-patterns reduced sheep foraging selectivity between patches, and led to a lower consumption of focal plant population compared with the aggregated plant micro-pattern. Herbivores adopt different within- and between-patch foraging decisions to maintain a high intake of the preferred species in response to various plant micro-patterns, and consequently cause diverse associational effects of both focal plant individuals and population. These associational effects have important implications for understanding the species coexistence and plant community assembly in the grazing ecosystems.
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Affiliation(s)
- Yue Huang
- Key Laboratory of Forest and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.,Key Laboratory of Vegetation Ecology, Institute of Grassland Science, Northeast Normal University, Ministry of Education, Changchun, China
| | - Ling Wang
- Key Laboratory of Vegetation Ecology, Institute of Grassland Science, Northeast Normal University, Ministry of Education, Changchun, China
| | - Deli Wang
- Key Laboratory of Vegetation Ecology, Institute of Grassland Science, Northeast Normal University, Ministry of Education, Changchun, China
| | - De-Hui Zeng
- Key Laboratory of Forest and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
| | - Yexing Li
- Key Laboratory of Vegetation Ecology, Institute of Grassland Science, Northeast Normal University, Ministry of Education, Changchun, China
| | - Jun Liu
- College of Horticulture, Shenyang Agricultural University, Shenyang, China
| | - Yue Wang
- College of Veterinary and Animal Science, Heilongjiang Bayi Agricultural University, Daqing, China
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7
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Champagne E, Moore BD, Côté SD, Tremblay J. Spatial correlations between browsing on balsam fir by white-tailed deer and the nutritional value of neighboring winter forage. Ecol Evol 2018; 8:2812-2823. [PMID: 29531697 PMCID: PMC5838068 DOI: 10.1002/ece3.3878] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 12/20/2017] [Accepted: 12/26/2017] [Indexed: 12/03/2022] Open
Abstract
Associational effects, that is, the influence of neighboring plants on herbivory suffered by a plant, are an outcome of forage selection. Although forage selection is a hierarchical process, few studies have investigated associational effects at multiple spatial scales. Because the nutritional quality of plants can be spatially structured, it might differently influence associational effects across multiple scales. Our objective was to determine the radius of influence of neighbor density and nutritional quality on balsam fir (Abies balsamea) herbivory by white-tailed deer (Odocoileus virginianus) in winter. We quantified browsing rates on fir and the density and quality of neighboring trees in a series of 10-year-old cutovers on Anticosti Island (Canada). We used cross-correlations to investigate relationships between browsing rates and the density and nutritional quality of neighboring trees at distances up to 1,000 m. Balsam fir and white spruce (Picea glauca) fiber content and dry matter in vitro true digestibility were correlated with fir browsing rate at the finest extra-patch scale (across distance of up to 50 m) and between cutover areas (300-400 m). These correlations suggest associational effects, that is, low nutritional quality of neighbors reduces the likelihood of fir herbivory (associational defense). Our results may indicate associational effects mediated by intraspecific variation in plant quality and suggest that these effects could occur at scales from tens to hundreds of meters. Understanding associational effects could inform strategies for restoration or conservation; for example, planting of fir among existing natural regeneration could be concentrated in areas of low nutritional quality.
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Affiliation(s)
- Emilie Champagne
- Département de biologieCentre d’études nordiques & Chaire de recherche industrielle CRSNG en aménagement intégré des ressources de l’île d'AnticostiUniversité LavalQuébecCanada
- Centre d’étude de la forêtUniversité LavalQuébecCanada
| | - Ben D. Moore
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityRichmondNSWAustralia
| | - Steeve D. Côté
- Département de biologieCentre d’études nordiques & Chaire de recherche industrielle CRSNG en aménagement intégré des ressources de l’île d'AnticostiUniversité LavalQuébecCanada
| | - Jean‐Pierre Tremblay
- Département de biologieCentre d’études nordiques & Chaire de recherche industrielle CRSNG en aménagement intégré des ressources de l’île d'AnticostiUniversité LavalQuébecCanada
- Centre d’étude de la forêtUniversité LavalQuébecCanada
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8
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Champagne E, Tremblay J, Côté SD. Spatial extent of neighboring plants influences the strength of associational effects on mammal herbivory. Ecosphere 2016. [DOI: 10.1002/ecs2.1371] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- Emilie Champagne
- Département de Biologie & Centre d’études NordiquesUniversité Laval Québec Québec G1V 0A6 Canada
| | - Jean‐Pierre Tremblay
- Département de Biologie & Centre d’études NordiquesUniversité Laval Québec Québec G1V 0A6 Canada
- Centre d’étude de la forêtUniversité Laval Québec Québec G1V 0A6 Canada
| | - Steeve D. Côté
- Département de Biologie & Centre d’études NordiquesUniversité Laval Québec Québec G1V 0A6 Canada
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Fortin D, Buono PL, Schmitz OJ, Courbin N, Losier C, St-Laurent MH, Drapeau P, Heppell S, Dussault C, Brodeur V, Mainguy J. A spatial theory for characterizing predator-multiprey interactions in heterogeneous landscapes. Proc Biol Sci 2016. [PMID: 26224710 DOI: 10.1098/rspb.2015.0973] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Trophic interactions in multiprey systems can be largely determined by prey distributions. Yet, classic predator-prey models assume spatially homogeneous interactions between predators and prey. We developed a spatially informed theory that predicts how habitat heterogeneity alters the landscape-scale distribution of mortality risk of prey from predation, and hence the nature of predator interactions in multiprey systems. The theoretical model is a spatially explicit, multiprey functional response in which species-specific advection-diffusion models account for the response of individual prey to habitat edges. The model demonstrates that distinct responses of alternative prey species can alter the consequences of conspecific aggregation, from increasing safety to increasing predation risk. Observations of threatened boreal caribou, moose and grey wolf interacting over 378 181 km(2) of human-managed boreal forest support this principle. This empirically supported theory demonstrates how distinct responses of apparent competitors to landscape heterogeneity, including to human disturbances, can reverse density dependence in fitness correlates.
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Affiliation(s)
- Daniel Fortin
- Chaire de Recherche Industrielle CRSNG-Université Laval en Sylviculture et Faune, Département de Biologie, Université Laval, Québec, G1V 0A6, Canada
| | - Pietro-Luciano Buono
- GIREF, Chaire de Recherche Industrielle du CRSNG en Calcul Scientifique, Département de Mathématiques et de Statistique, Université Laval, Québec, G1V 0A6, Canada Faculty of Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario, Canada
| | - Oswald J Schmitz
- Yale School of Forestry and Environmental Studies, 370 Prospect Street, New Haven, CT 06511, USA
| | - Nicolas Courbin
- Chaire de Recherche Industrielle CRSNG-Université Laval en Sylviculture et Faune, Département de Biologie, Université Laval, Québec, G1V 0A6, Canada
| | - Chrystel Losier
- Chaire de Recherche Industrielle CRSNG-Université Laval en Sylviculture et Faune, Département de Biologie, Université Laval, Québec, G1V 0A6, Canada
| | - Martin-Hugues St-Laurent
- Département de Biologie, Chimie et Géographie, Centre d'Études Nordiques, Université du Québec à Rimouski, Rimouski, Canada
| | - Pierre Drapeau
- Chaire de Recherche Industrielle CRSNG-Université du Québec en Abitibi-Témiscamingue et Université du Québec à Montréal en aménagement forestier durable, Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Canada
| | - Sandra Heppell
- Direction de la gestion de la faune de la Côte-Nord, Ministère des Forêts, de la Faune et des Parcs (MFFP), Baie-Comeau, Canada
| | - Claude Dussault
- Direction de la gestion de la faune du Saguenay-Lac-St-Jean, MFFP, Jonquière, Canada
| | - Vincent Brodeur
- Direction de la gestion de la faune du Nord-du-Québec, MFFP, Chibougamau, Canada
| | - Julien Mainguy
- Direction de la faune terrestre et de l'avifaune, MFFP, Québec, Canada
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Huang Y, Wang L, Wang D, Zeng DH, Liu C. How does the foraging behavior of large herbivores cause different associational plant defenses? Sci Rep 2016; 6:20561. [PMID: 26847834 PMCID: PMC4742796 DOI: 10.1038/srep20561] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 01/06/2016] [Indexed: 11/09/2022] Open
Abstract
The attractant-decoy hypothesis predicts that focal plants can defend against herbivory by neighboring with preferred plant species when herbivores make decisions at the plant species scale. The repellent-plant hypothesis assumes that focal plants will gain protection by associating with nonpreferred neighbors when herbivores are selective at the patch scale. However, herbivores usually make foraging decisions at these scales simultaneously. The net outcomes of the focal plant vulnerability could depend on the spatial scale at which the magnitude of selectivity by the herbivores is stronger. We quantified and compared the within- and between-patch overall selectivity index (OSI) of sheep to examine the relationships between associational plant effects and herbivore foraging selectivity. We found that the sheep OSI was stronger at the within- than the between-patch scale, but focal plant vulnerability followed both hypotheses. Focal plants defended herbivory with preferred neighbors when the OSI difference between the two scales was large. Focal plants gained protection with nonpreferred neighbors when the OSI difference was narrowed. Therefore, the difference in selectivity by the herbivores between the relevant scales results in different associational plant defenses. Our study suggests important implications for understanding plant-herbivore interactions and grassland management.
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Affiliation(s)
- Yue Huang
- Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, 5268 Renmin St., Changchun 130024, P.R. China.,State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, P.R. China
| | - Ling Wang
- Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, 5268 Renmin St., Changchun 130024, P.R. China
| | - Deli Wang
- Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, 5268 Renmin St., Changchun 130024, P.R. China
| | - De-Hui Zeng
- State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, P.R. China
| | - Chen Liu
- Northwest Polytechnical University, Centre for Ecological and Environmental Sciences, Xi'an, 710072, P.R. China
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Stutz RS, Banks PB, Dexter N, McArthur C. Herbivore search behaviour drives associational plant refuge. ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY 2015. [DOI: 10.1016/j.actao.2015.05.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Merkle JA, Cherry SG, Fortin D. Bison distribution under conflicting foraging strategies: site fidelity vs. energy maximization. Ecology 2015; 96:1793-801. [DOI: 10.1890/14-0805.1] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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13
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Bonnet OJF, Meuret M, Tischler MR, Cezimbra IM, Azambuja JCR, Carvalho PCF. Continuous bite monitoring: a method to assess the foraging dynamics of herbivores in natural grazing conditions. ANIMAL PRODUCTION SCIENCE 2015. [DOI: 10.1071/an14540] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Accurate estimates of bite mass and variations in the short-term intake rate of grazing herbivores has been historically considered as a fundamental methodological difficulty, a difficulty that increases with the complexity of the feeding environment. Improving these methodologies will help understand foraging behaviours in natural grazing conditions, where habitat structure and interactions among different forages influence feeding decisions and patterns. During the past 30 years, we have been developing the ‘continuous bite-monitoring’ method, an observational method that allows continuous assessment of foraging behaviours, including bite mass, instantaneous intake rate and food selection, in simple to complex feeding environments. The centrepiece of the method is a ‘bite-coding grid’ where bites are categorised by structural attributes of the forage to reflect differences in bite masses. Over the years, we have been using this method with goats, sheep, llamas and cattle across a range of different habitats. After reviewing the development of the method, we detail its planning and execution in the field. We illustrate the method with a study from southern Brazilian native Pampa grassland, showing how changes in the forages consumed by heifers strongly affect short-term intake rate during meals. Finally, we emphasise the importance of studying animals grazing in their natural environments to first identify the relevant processes that can later be tested in controlled experiments.
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14
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Fortin D, Merkle JA, Sigaud M, Cherry SG, Plante S, Drolet A, Labrecque M. Temporal dynamics in the foraging decisions of large herbivores. ANIMAL PRODUCTION SCIENCE 2015. [DOI: 10.1071/an14428] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The foraging decisions involved in acquiring a meal can have an impact on an animal’s spatial distribution, as well as affect other animal species and plant communities. Thus, understanding how the foraging process varies over space and time has broad ecological implications, and optimal foraging theory can be used to identify key factors controlling foraging decisions. Optimality models are based on currencies, options and constraints. Using examples from research on free-ranging bison (Bison bison), we show how variations in these model elements can yield strong spatio-temporal variation in expected foraging decisions. First, we present a simple optimal foraging model to investigate the temporal scale of foraging decisions. On the basis of this model, we identify the foraging currency and demonstrate that such a simple model can be successful at predicting animal distribution across ecosystems. We then modify the model by changing (1) the forager’s option, from the selection of individual plants to the selection of food bites that may include more than one plant species, (2) its constraints, from being omniscient to having incomplete information of resource quality and distribution and (3) its currency, from the maximisation of energy intake rate (E) to the maximisation of the ratio between E and mortality risk (u).We also show that, where the maximisation of E fails, the maximisation of E/u can explain the circadian rhythm in the diet and movements of bison. Simple optimal foraging-theory models thus can explain changes in dietary choice of bison within a foraging patch and during the course of a day.
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Villalba JJ, Provenza FD, Catanese F, Distel RA. Understanding and manipulating diet choice in grazing animals. ANIMAL PRODUCTION SCIENCE 2015. [DOI: 10.1071/an14449] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Conventional models of foraging, such as optimal foraging theory, generally take the univariate approach to explain the decisions of consumers on the basis of the intrinsic properties of foods, including nutrient concentration and abundance. However, the food environment is inherently diverse and, as a consequence, foraging decisions are influenced by the interactions among multiple food components and the forager. Foraging behaviour is affected by the consumer’s past experiences with the biochemical context in which a food is ingested, including the kinds and amounts of nutrients and plant secondary compounds in a plant and its neighbours. In addition, past experiences with food have the potential to influence food preference and intake through a mechanism, namely, food hedonics, which is not entirely dependent on the classical homeostatic model of appetite control. Research on the impacts of experience with food context and its behavioural expression in natural settings should pioneer innovative management strategies aimed at modifying food intake and preference of herbivores to enhance their nutrition, health and welfare, as well as the health and integrity of the landscapes they inhabit.
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Mládek J, Mládková P, Hejcmanová P, Dvorský M, Pavlu V, De Bello F, Duchoslav M, Hejcman M, Pakeman RJ. Plant trait assembly affects superiority of grazer's foraging strategies in species-rich grasslands. PLoS One 2013; 8:e69800. [PMID: 23922805 PMCID: PMC3724891 DOI: 10.1371/journal.pone.0069800] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 06/12/2013] [Indexed: 11/18/2022] Open
Abstract
Background Current plant – herbivore interaction models and experiments with mammalian herbivores grazing plant monocultures show the superiority of a maximizing forage quality strategy (MFQ) over a maximizing intake strategy (MI). However, there is a lack of evidence whether grazers comply with the model predictions under field conditions. Methodology/Findings We assessed diet selection of sheep (Ovis aries) using plant functional traits in productive mesic vs. low-productivity dry species-rich grasslands dominated by resource-exploitative vs. resource-conservative species respectively. Each grassland type was studied in two replicates for two years. We investigated the first grazing cycle in a set of 288 plots with a diameter of 30 cm, i.e. the size of sheep feeding station. In mesic grasslands, high plot defoliation was associated with community weighted means of leaf traits referring to high forage quality, i.e. low leaf dry matter content (LDMC) and high specific leaf area (SLA), with a high proportion of legumes and the most with high community weighted mean of forage indicator value. In contrast in dry grasslands, high community weighted mean of canopy height, an estimate of forage quantity, was the best predictor of plot defoliation. Similar differences in selection on forage quality vs. quantity were detected within plots. Sheep selected plants with higher forage indicator values than the plot specific community weighted mean of forage indicator value in mesic grasslands whereas taller plants were selected in dry grasslands. However, at this scale sheep avoided legumes and plants with higher SLA, preferred plants with higher LDMC while grazing plants with higher forage indicator values in mesic grasslands. Conclusions Our findings indicate that MFQ appears superior over MI only in habitats with a predominance of resource-exploitative species. Furthermore, plant functional traits (LDMC, SLA, nitrogen fixer) seem to be helpful correlates of forage quality only at the community level.
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Affiliation(s)
- Jan Mládek
- Department of Botany, Palacký University, Olomouc, Czech Republic.
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Axelsson EP, Stenberg JA. Associational resistance in a multiple herbivore system: differential effects of mammal versus insect herbivores. Ecol Res 2012. [DOI: 10.1007/s11284-012-0985-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Ostoja SM, Schupp EW, Klinger R. Seed harvesting by a generalist consumer is context-dependent: Interactive effects across multiple spatial scales. OIKOS 2012. [DOI: 10.1111/j.1600-0706.2012.19969.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Courant S, Fortin D. Time allocation of bison in meadow patches driven by potential energy gains and group size dynamics. OIKOS 2011. [DOI: 10.1111/j.1600-0706.2011.19994.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kimball BA, Russell JH, Ott PK. Phytochemical variation within a single plant species influences foraging behavior of deer. OIKOS 2011. [DOI: 10.1111/j.1600-0706.2011.19515.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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