Impact of Grazing Regimes, Landscape Aspect, and Elevation on Plant Life Form Types in Managed Arid Montane Rangelands

Arid steppes, with scattered vegetation, are commonly qualified as degraded ecosystems. Their natural vegetation cover is affected by both abiotic stresses and human activities and, therefore, suitable managements are needed for their sustainability. This study was carried out in the mountain rangeland chain of Matmata (southern dryland of Tunisia) during the springs of 2 rainy yr, 2019 and 2020. Our aims were to evaluate the impact of three grazing regimes (grazing exclusion [over 42 ys; 1978−2020]; seasonal [protected in spring and summer and grazed in autumn and winter, since the 1960s]; and continuous grazing [control; grazed over time]) on the cover of some plant life forms (Raunkiaer, Noy-Meir, and Grime types), under various conditions (sites, aspects, and elevations). To achieve this goal, the pseudoreplicated-nested design was applied, taking into account the site locations (grazing regimes), aspects (exposure to sunlight), and elevations. The cover of the retained plant life forms was measured using the quadrat point method. The main results showed that plant life forms are strongly affected by the grazing regime since the chamephytes (Ch_R), arido-active (AA_NM), and competitive stress-tolerant species (CS_G) are higher under seasonal grazing than control. All these species are qualified as less resistant to grazing. However, arido-passive (AP_NM), ruderal stress-tolerant (RS_G), and therophytes (Th_R) seem to be more resistant to grazing. Studying the impact of grazing management on the plant life form types provides useful information to find the most adapted species for rangeland sustainability all around the world

P2P Logging and Timestamping for Reconciliation

In this report, we address data reconciliation in peer-to-peer (P2P) collaborative applications. We propose P2P-LTR (Logging and Timestamping for Reconciliation) which provides P2P logging and timestamping services for P2P reconciliation over a distributed hash table (DHT). While updating at collaborating peers, updates are timestamped and stored in a highly available P2P log. During reconciliation, these updates are retrieved in total order to enforce eventual consistency. In this report, we first give an overview of P2P-LTR with its model and its main procedures. We then present our prototype used to validate P2P-LTR. To demonstrate P2P-LTR, we propose several scenarios that test our solutions and measure performance. In particular, we demonstrate how P2P-LTR handles the dynamic behavior of peers with respect to the DHT

XWiki Concerto: A P2P Wiki System Supporting Disconnected Work

International audienceThis paper presents the XWiki Concerto system, the P2P version of the XWiki server. This system is based on replicating wiki pages on a network of wiki servers. The approach, based on the Woot algorithm, has been designed to be scalable, to support the dynamic aspect of P2P networks and network partitions. These characteristics make our system capable of supporting disconnected edition and sub-groups, making it very flexible and usable

P2P Logging and Timestamping for Reconciliation

ISBN : 978-1-60558-306-8/08/08Dans VLDB 2008International audienceIn this paper, we address data reconciliation in peer-to-peer (P2P) collaborative applications. We propose P2P-LTR (Logging and Timestamping for Reconciliation) which provides P2P logging and timestamping services for P2P reconciliation over a distributed hash table (DHT). While updating at collaborating peers, updates are timestamped and stored in a highly available P2P log. During reconciliation, these updates are retrieved in total order to enforce eventual consistency. In this paper, we first give an overview of P2P-LTR with its model and its main procedures. We then present our prototype used to validate P2P-LTR. To demonstrate P2P-LTR, we propose several scenarios that test our solutions and measure performance. In particular, we demonstrate how P2P-LTR handles the dynamic behavior of peers with respect to the DHT

Estampillage et Journalisation P2P pour XWiki

Dans NOTERE 2008International audienceLes systèmes pair-à-pair sont de plus en plus utilisés pour développer des applications distribuées au sein des entreprises. Les réseaux pair-à-pair permettent de construire des applications fiables, performantes, disponibles et passant à l'échelle en répliquant les données sur plusieurs pairs du réseau. Dans cet article nous nous intéressons à la réplication des données de l'application XWiki dans un réseau pair-à-pair. Pour ce faire, nous proposons un nouveau mécanisme de réplication optimiste combinant un algorithme de réconciliation de données basé sur une approche de transformées opérationnelles et une extension du service KTS qui intègre un mécanisme d'estampillage fiable et réparti fonctionnant sur un modèle de réseau à base de DHT pour gérer la fraîcheur des répliques. Le travail présenté est en partie financé par l'Agence Nationale de la Recherche dans le cadre du projet RNTL XWiki Concerto (2007-2009), projet de wiki P2P supportant la mobilité

Infrastructure P2P pour la Réplication et la Réconciliation des Données

In this thesis, we address the problem of optimistic replication for collaborative text editing in Peer-to-Peer (P2P) systems. This problem is challenging because of concurrent updating at multiple peers and dynamic behavior of peers. Operational transformation (OT) is a typical approach used for handling optimistic replication in the context of distributed text editing. However, most of OT solutions are neither scalable nor suited for P2P networks due to the dynamic behavior of peers. In this thesis, we propose a scalable P2P reconciliation infrastructure for OT that assures eventual consistency and liveness despite dynamicity and failures. We propose a P2P logging and timestamping service, called P2P-LTR (P2P Logging and Timestamping for Reconciliation) that exploits a distributed hash table (DHT) for reconciliation. While updating replica copies at collaborating peer editors, updates are stored in a highly available P2P log. To enforce eventual consistency, these updates must be retrieved in a specific total order to be reconciled at the peer editors. P2P-LTR provides an efficient mechanism for determining the total order of updates. It also deals with the case of peers that may join and leave the system during update operations. We evaluated the performance of P2P-LTR through simulation; the results show the efficiency and the scalability of our solution.Dans notre thèse, nous nous intéressons à la construction d'une infrastructure Pair-à-Pair (P2P) pour la réconciliation des données des applications d'édition de texte collaborative. Cependant, cette tâche est difficile à réaliser étant donné le comportement dynamique des pairs. Au regard de l'état de l'art, le modèle des transformées opérationnelles (OT) est une approche typiquement utilisée pour la gestion de la réplication optimiste dans le contexte d'édition de texte distribuée. Toutefois, la plupart des solutions d'OT ne passent pas à l'échelle et ne sont pas adaptées aux réseaux P2P. Pour répondre à ce problème, nous proposons une nouvelle approche appelée P2P-LTR (Estampillage et Journalisation P2P pour la Réconciliation) pour la réconciliation des données à base d'OT, qui assure la cohérence à terme malgré la dynamicité et les cas de pannes. P2P-LTR offre un service de journalisation P2P et un service d'estampillage fiable et réparti fonctionnant sur un modèle de réseau à base de DHT. Dans notre approche, les mises à jour sont estampillées et stockées en P2P dans des journaux à forte disponibilité. Lors de la réconciliation, ces mises à jour sont récupérées selon un ordre total continu afin d'assurer la cohérence à terme. En outre, P2P-LTR traite les cas où les pairs peuvent rejoindre ou quitter le système pendant les opérations de mise à jour. Nous avons évalué les performances de P2P-LTR par simulation. Les résultats montrent l'efficacité et le passage à l'échelle de notre solution

Infrastructure P2P pour la réplication et la réconciliation des données

Dans notre thèse, nous nous intéressons à la construction d une infrastructure Pair-à-Pair (P2P) pour la réconciliation des données des applications d édition de texte collaborative. Cependant, cette tâche est difficile à réaliser étant donné le comportement dynamique des pairs. Au regard de l état de l art, le modèle des transformées opérationnelles (OT) est une approche typiquement utilisée pour la gestion de la réplication optimiste dans le contexte d édition de texte distribuée. Toutefois, la plupart des solutions d OT ne passent pas à l échelle et ne sont pas adaptées aux réseaux P2P. Pour répondre à ce problème, nous proposons une nouvelle approche appelée P2P-LTR (Estampillage et Journalisation P2P pour la Réconciliation) pour la réconciliation des données à base d OT, qui assure la cohérence à terme malgré la dynamicité et les cas de pannes. P2P-LTR offre un service de journalisation P2P et un service d estampillage fiable et réparti fonctionnant sur un modèle de réseau à base de DHT. Dans notre approche, les mises à jour sont estampillées et stockées en P2P dans des journaux à forte disponibilité. Lors de la réconciliation, ces mises à jour sont récupérées selon un ordre total continu afin d assurer la cohérence à terme. En outre, P2P-LTR traite les cas où les pairs peuvent rejoindre ou quitter le système pendant les opérations de mise à jour. Nous avons évalué les performances de P2P-LTR par simulation. Les résultats montrent l efficacité et le passage à l échelle de notre solution.In this thesis, we address the problem of optimistic replication for collaborative text editing in Peer-to-Peer (P2P) systems. This problem is challenging because of concurrent updating at multiple peers and dynamic behavior of peers. Operational transformation (OT) is a typical approach used for handling optimistic replication in the context of distributed text editing. However, most of OT solutions are neither scalable nor suited for P2P networks due to the dynamic behavior of peers. In this thesis, we propose a scalable P2P reconciliation infrastructure for OT that assures eventual consistency and liveness despite dynamicity and failures. We propose a P2P logging and timestamping service, called P2P-LTR (P2P Logging and Timestamping for Reconciliation) that exploits a distributed hash table (DHT) for reconciliation. While updating replica copies at collaborating peer editors, updates are stored in a highly available P2P log. To enforce eventual consistency, these updates must be retrieved in a specific total order to be reconciled at the peer editors. P2P-LTR provides an efficient mechanism for determining the total order of updates. It also deals with the case of peers that may join and leave the system during update operations. We evaluated the performance of P2P-LTR through simulation; the results show the efficiency and the scalability of our solution.NANTES-BU Sciences (441092104) / SudocSudocFranceF

Scalable P2P Reconciliation Infrastructure for Collaborative Text Editing

International audienceWe address the problem of optimistic replication for collaborative text editing in Peer-to-Peer (P2P) systems. This problem is challenging because of concurrent updating at multiple peers and dynamic behavior of peers. Operational transformation (OT) is a typical approach used for handling optimistic replication in the context of distributed text editing. However, most of OT solutions are neither scalable nor suited for P2P networks due to the dynamic behavior of peers. In this paper, we propose a scalable P2P reconciliation infrastructure for OT that assures eventual consistency and liveness despite dynamicity and failures. We propose a P2P logging and timestamping service called P2P-LTR (P2P Logging and Timestamping for Reconciliation) which exploits a distributed hash table (DHT) for reconciliation. While updating réplica copies at collaborating peer editors, updates are stored in a highly available P2P log. To enforce eventual consistency, thèse updates must be retrieved in a specific total order to be reconciled at the peer editors. P2P-LTR provides an efficient mechanism for determining the total order of updates. It also deals with the case of peers that may join and leave the system during the update operation. We evaluated the performance of P2P-LTR through simulation; the results show the efficiency and the scalability of our solution