Agreil, Cyril

Chambon-Dubreuil, E.

Jarry, M.

Magda, D.

Meuret, Michel

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings 21st International Grassland Congress / 8th International Rangeland Congress A Resource‐Explicit Population Model for the Management of a Dominant Shrub that Takes into Account the Ruminants' Feeding Strategy D. Magda INRA, France Cyril Agreil INRA, France E. Chambon-Dubreuil INRA, France M. Jarry Université de Pau et des Pays de l'Adour, France Michel Meuret INRA, France Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/21/4-2/9 The 21st International Grassland Congress / 8th International Rangeland Congress took place in Hohhot, China from June 29 through July 5, 2008. Proceedings edited by Organizing Committee of 2008 IGC/IRC Conference Published by Guangdong People's Publishing House This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅰ 　 瞯 ]617　 瞯Grasslands/Rangelands Resources and Ecology ——— Indicators for Sustainable Use and Conservation of Grasslands/Rangelands ResourcesA resource‐explicit population model for the management of a dominant shrub that takes intoaccount the ruminants摧 feeding strategyD . Magda1 , C . A greil2 , E . Chambon‐Dubreuil 1 , M . Jarry 3 , M . Meuret21 INRA‐SA D , UMR 1248 AG IR , B .P . 52627 31326 Castanet Tolosan , France , E‐mail : magda＠ toulouse .inra .f r ,2 INRA‐SA D , Unité Ecodévelop pement , A v ignon , France ,3 Université de Pau et des Pays de l摧A dour , UMR ECOBIOP ,64310 Saint P e sur N ivelle , FranceKey words : pastoral resources , dominant shrub species , population demography , grazing , feeding strategyIntroduction European environmental policies encourage the livestock farmers to graze their animals on shrubby rangelands tomaintain plant communities in states that are favorable to the protected wild fauna and flora species and then of ten provideincentives to slow down the encroachment of shrub species with strong dominance ability .Current scientific knowledge and technical references are often insufficient to encompass uncertainties about the feed value ofshrubs and the real impact of grazing on encroachment dynamics . In order to propose management practices at paddock level ,conciliating seasonal resources renewal for flock and long term control of shrub dynamics , we propose a new conceptual modelof plant population capable of linking the population demography of a dominant plant species and the functional feedingresources offered to the flock .Materials and methods We carried out direct observations of small ruminant ( sheep ) feeding behaviour at bite scale andcontinuously during each meal per day and during whole grazing sequences in paddock ( １０‐１５ days) ( Parker et al . １９９３ , Agreiland Meuret , ２００４ ) . Focusing on scotch broom ( C . scoparius ) as a model of grazed dominant shrub species , we identify thediversity of organs potentially consumed and defined their functional role in the feeding strategy with regards to the potentialbite mass they offer ( Agreil et al , ２００５ ) . Observations and experimentations on C . scoparius populations also allowed us tobuild a basic model of population structure based on the demographic strategy of this species with identification of maindevelopmental stages ( juveniles , adults , seedlings , non dormant seeds , dormant seeds , . .) and quantitative estimation oftransition between stages ( Caswell , ２００１ ) . We relate explicitly feed items defined by ruminant feeding strategy withdemographic items organizing the population dynamics pattern .Results Our results show that the feeding strategy of small ruminant is to exploit the diversity of the species‐structures throughcombining small and large bite masses , allowing the maintenance of intake levels until the end of the stay in the paddock .Several organs of scotch broom ( Flowers , young pods , young shoots , mature stems) provide feed items but with differentfunctional status for animal feeding according to their mass . ( Figure １ ) . It shows that two main stages ( juvenile and adult )produce each , different feed items . As cumulative impact of repeated grazing seems to change adult demographic behaviourtowards a long term vegetative status , we create a new demographic item as �vegetative adult " revealing through thismodification of the population structure possible irreversible impact of grazing .Figure 1 L i f e cycle o f Cytisus scoparius population built on development stages (seedling , adult , j uvenile . . .) and f eedingresources f or herbivores (small bites , big bites ) . The vegetative adult stage , not p resent in ungrazed population , is created byrepeated browsing .Conclusions Such a conceptual model , taking in account the ruminant feeding strategy at bite level , allows us to model the realimpact of gazing on shrub population dynamics . It reveals the diversity of the possible ways of regulation as severaldemographic processes are impacted by grazing according to organs consumed ( fecundity , survival rate , maturation age . . .) .Modelling is now in progress to simulate the impact of different management scenarios .ReferencesAgreil , C . , Meuret , M . ( ２００４ ) . An improved method for quantifying intake rate and ingestive behaviour of ruminants indiverse and variable habitats using direct observation . Small Rumin . Res . ５４(１‐２) : ９９‐１１３ .Agreil , C . , Fritz , H . , and Meuret , M . ( ２００５ ) . Maintenance of daily intake through bite mass diversity adjustment indomestic sheep grazing on heterogeneous vegetation . A p p lied A nim . Behav . Sci . ９１ (１) : ３５‐５６ .Caswell , H . (２００１ ) . Matrix population models . Sinauer Associates , Inc publishers . Sundermand Mass . ６２２p .~Seedling Seed bank 0 ~ V ~~ L Access,ble Ad ult 8888 Juvenile BB lnnaccessible Adult BB 

A Resource‐Explicit Population Model for the Management of a Dominant Shrub that Takes into Account the Ruminants\u27 Feeding Strategy

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A Resource‐Explicit Population Model for the Management of a Dominant Shrub that Takes into Account the Ruminants\u27 Feeding Strategy

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