Accatino, Francesco

[["dc.bibliographiccitation.firstpage","135"],["dc.bibliographiccitation.journal","Ecological Modelling"],["dc.bibliographiccitation.lastpage","144"],["dc.bibliographiccitation.volume","320"],["dc.contributor.author","Accatino, Francesco"],["dc.contributor.author","Wiegand, Kerstin"],["dc.contributor.author","Ward, David"],["dc.contributor.author","Michele, Carlo de"],["dc.date.accessioned","2017-09-07T11:52:25Z"],["dc.date.available","2017-09-07T11:52:25Z"],["dc.date.issued","2015"],["dc.description.abstract","We develop a model to investigate how trees can invade the grass stratum in humid savannas despite repeated fires. In the literature, it is clear that fire reduces tree canopy in savannas. However, fire alone may not be sufficient to prevent tree invasion because there are ecological mechanisms that hamper fire spread by undermining the continuity and density of the grass stratum, which is the means of fire propagation in savannas. Our model is spatially explicit and individual-based, and includes two important factors characterizing the interactions between fire, trees, and grass in savannas, viz. space and the strategies that trees use to cope with fire. The strategies that trees employ against fire emerge from life history traits. According to these strategies, we classify savanna trees into three categories: resprouters, which are able to resprout after their aboveground biomass is burned\\; resisters, which are able to resist fire due to a thick bark even in the juvenile stages\\; avoiders, which are very fire-vulnerable in the juvenile stages, but are able to grow fast in the absence of fire. Our results show that trees can invade the grass stratum and finally suppress fire spread because one of the following occurs: (1) trees may resprout and form a population that persists despite repeated effective fires\\; (2) trees may be fire-resistant\\; (3) if trees are fire-vulnerable they may cluster and grow in density until fire is prevented. Our results show that fire can be effective in preventing the initiation of the invasion process in the grass stratum. However, once the invasion process has begun, fire alone is not able to reverse this process because of the strategies employed by trees. Furthermore, when a high tree density is reached, grass density is insufficient to allow effective fire spread. From a management point of view, our results imply that fire must be coupled with other factors (browsing, mechanical thinning) to reduce tree density in encroached areas."],["dc.identifier.doi","10.1016/j.ecolmodel.2015.09.014"],["dc.identifier.gro","3148910"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5548"],["dc.notes.intern","Wiegand Crossref Import"],["dc.notes.status","public"],["dc.notes.submitter","chake"],["dc.relation.issn","0304-3800"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.subject.gro","Fire-vegetation feedbacks"],["dc.subject.gro","Individual-based model"],["dc.subject.gro","Resprouting"],["dc.subject.gro","Tree clustering"],["dc.subject.gro","Woody plant encroachment"],["dc.title","Trees, grass, and fire in humid savannas"],["dc.title.subtitle","The importance of life history traits and spatial processes"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","309"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Animal"],["dc.bibliographiccitation.lastpage","317"],["dc.bibliographiccitation.volume","11"],["dc.contributor.author","Accatino, F."],["dc.contributor.author","Ward, D."],["dc.contributor.author","Wiegand, K."],["dc.contributor.author","De Michele, C."],["dc.date.accessioned","2017-09-07T11:44:34Z"],["dc.date.available","2017-09-07T11:44:34Z"],["dc.date.issued","2017"],["dc.description.abstract","Assessing the carrying capacity is of primary importance in arid rangelands. This becomes even more important during droughts, when rangelands exhibit non-equilibrium dynamics, and the dynamics of livestock conditions and forage resource are decoupled. Carrying capacity is usually conceived as an equilibrium concept, that is, the consumer density that can co-exist in long-term equilibrium with the resource. As one of the first, here we address the concept of carrying capacity in systems, where there is no feedback between consumer and resource in a limited period of time. To this end, we developed an individual-based model describing the basic characteristics of a rangeland during a drought. The model represents a rangeland composed by a single water point and forage distributed all around, with livestock units moving from water to forage and vice versa, for eating and drinking. For each livestock unit we implemented an energy balance and we accounted for the gut-filling effect (i.e. only a limited amount of forage can be ingested per unit time). Our results showed that there is a temporal threshold above which livestock begin to experience energy deficit and burn fat reserves. We demonstrated that such a temporal threshold increases with the number of animals and decreases with the rangeland conditions (amount of forage). The temporal threshold corresponded to the time livestock take to consume all the forage within a certain distance from water, so that the livestock can return to water for drinking without spending more energy than they gain within a day. In this study, we highlight the importance of a time threshold in the assessment of carrying capacity in non-equilibrium conditions. Considering this time threshold could explain contrasting observations about the influence of livestock number on livestock conditions. In case of private rangelands, the herd size should be chosen so that the spatial threshold equals (or exceeds) the length of the drought."],["dc.identifier.doi","10.1017/s1751731116001531"],["dc.identifier.gro","3148929"],["dc.identifier.pii","S1751731116001531"],["dc.identifier.pmid","27452875"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5570"],["dc.language.iso","en"],["dc.notes.intern","Wiegand Crossref Import"],["dc.notes.status","final"],["dc.notes.submitter","chake"],["dc.relation.issn","1751-7311"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.rights","CC BY-NC-ND 4.0"],["dc.subject.gro","drought"],["dc.subject.gro","energy deficit"],["dc.subject.gro","foraging"],["dc.subject.gro","optimal herd size"],["dc.subject.gro","water point"],["dc.title","Carrying capacity in arid rangelands during droughts: the role of temporal and spatial thresholds"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1272"],["dc.bibliographiccitation.issue","8"],["dc.bibliographiccitation.journal","Animal"],["dc.bibliographiccitation.lastpage","1281"],["dc.bibliographiccitation.volume","8"],["dc.contributor.author","Accatino, Francesco"],["dc.contributor.author","Sabatier, Rodolphe"],["dc.contributor.author","Michele, Carlo de"],["dc.contributor.author","Ward, David"],["dc.contributor.author","Wiegand, Kerstin"],["dc.contributor.author","Meyer, Katrin M."],["dc.date.accessioned","2017-09-07T11:44:40Z"],["dc.date.available","2017-09-07T11:44:40Z"],["dc.date.issued","2014"],["dc.description.abstract","Rangelands provide the main forage resource for livestock in many parts of the world, but maintaining long-term productivity and providing sufficient income for the rancher remains a challenge. One key issue is to maintain the rangeland in conditions where the rancher has the greatest possibility to adapt his/her management choices to a highly fluctuating and uncertain environment. In this study, we address management robustness and adaptability, which increase the resilience of a rangeland. After reviewing how the concept of resilience evolved in parallel to modelling views on rangelands, we present a dynamic model of rangelands to which we applied the mathematical framework of viability theory to quantify the management adaptability of the system in a stochastic environment. This quantification is based on an index that combines the robustness of the system to rainfall variability and the ability of the rancher to adjust his/her management through time. We evaluated the adaptability for four possible scenarios combining two rainfall regimes (high or low) with two herding strategies (grazers only or mixed herd). Results show that pure grazing is viable only for high-rainfall regimes, and that the use of mixed-feeder herds increases the adaptability of the management. The management is the most adaptive with mixed herds and in rangelands composed of an intermediate density of trees and grasses. In such situations, grass provides high quantities of biomass and woody plants ensure robustness to droughts. Beyond the implications for management, our results illustrate the relevance of viability theory for addressing the issue of robustness and adaptability in non-equilibrium environments."],["dc.identifier.doi","10.1017/s1751731114000913"],["dc.identifier.doi","10.1017/S1751731114000913"],["dc.identifier.gro","3148934"],["dc.identifier.pii","S1751731114000913"],["dc.identifier.pmid","24780528"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5575"],["dc.language.iso","en"],["dc.notes.intern","Wiegand Crossref Import"],["dc.notes.status","public"],["dc.notes.submitter","chake"],["dc.relation.issn","1751-7311"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.subject.gro","adaptability"],["dc.subject.gro","herding strategy"],["dc.subject.gro","resilience"],["dc.subject.gro","robustness"],["dc.subject.gro","viability"],["dc.title","Robustness and management adaptability in tropical rangelands: a viability-based assessment under the non-equilibrium paradigm"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]