The influence of shrub species and fine-scale plant density on arthropods in a semiarid shrubland

2016 ◽  
Vol 38 (4) ◽  
pp. 381 ◽  
Author(s):  
Alan B. C. Kwok ◽  
David J. Eldridge
Keyword(s):  
Plant Density ◽  
Spatial Scales ◽  
Arthropod Community ◽  
Fine Scale ◽  
Arthropod Communities ◽  
Shrub Species ◽  
Multiple Spatial Scales ◽  
Close Proximity ◽  
Semiarid Shrubland

Plant-resident arthropods are closely tied to the distribution of their hosts across multiple spatial scales. Shrubs provide habitat for a range of arthropods, and variations within shrubland ecosystems may affect arthropod communities. We examined the role of shrub species and density in structuring arthropod communities in an encroached Australian woodland using two common and widespread shrub species, Turpentine (Eremophila sturtii) and Silver Cassia (Senna artemisioides subsp. filifolia). We found five times more arthropods (Psocoptera, Collembola and Hemiptera) on Eremophila compared with Senna. Furthermore, Psyllidae were found only on Eremophila. In total we recorded 39 Hemipteran species; 13 from Eremophila, 16 from Senna and 10 common to both shrub species. Each shrub species supported a unique arthropod assemblage, even though they grow in close proximity (<15 m). In contrast, we found limited effects of fine-scale plant density, with plants growing in low and high density supporting similar arthropod communities. Our study indicated that isolated shrubs in these woodlands support a variety of arthropods, and shrub species is a more important driver of arthropod community structure than fine-scale density.

Specialized ecological interactions and plant species rarity: The role of pollinators and mycorrhizal fungi across multiple spatial scales

2014 ◽  
Vol 169 ◽  
pp. 285-295 ◽  
Author(s):  
Ryan D. Phillips ◽  
Rod Peakall ◽  
Michael F. Hutchinson ◽  
Celeste C. Linde ◽  
Tingbao Xu ◽  
...  
Keyword(s):  
Plant Species ◽  
Mycorrhizal Fungi ◽  
Spatial Scales ◽  
Ecological Interactions ◽  
Multiple Spatial Scales ◽  
Species Rarity

scholarly journals Ecotones: Marginal or central areas of transition?

2006 ◽  
Vol 52 (1) ◽  
pp. 29-53 ◽  
Author(s):  
Salit Kark ◽  
Berndt J. van Rensburg
Keyword(s):  
Environmental Gradients ◽  
Spatial Scales ◽  
Small Scale ◽  
Biodiversity Hotspots ◽  
Ecological Communities ◽  
Marginal Populations ◽  
Multiple Spatial Scales ◽  
Scientific Attention

Areas of environmental transition, where ecological communities coincide, are sometimes termed ecotones. These regions often correspond with sharp environmental gradients. Ecotones occur at multiple spatial scales, ranging from transitions between biomes to local small-scale transitions. In recent years ecotones have received increasing scientific attention after being neglected for years, as studies historically often focused on distinct communities. However, it is still debatable whether these transitional regions are speciation and biodiversity hotspots that deserve special conservation interest or are actually areas that hold marginal populations that depend on other parts of the range for the maintenance of their biodiversity and therefore should not deserve primary investment. This paper discusses some of the recent advancements in our understanding of the role of ecotones in ecology, evolution, and conservation.

scholarly journals Spatial Variation in Demographic Processes and the Potential Role of Hybridization to Future Persistence

2021 ◽  
Author(s):  
Meaghan R Gade ◽  
Qing Zhao ◽  
William E Peterman
Keyword(s):  
Spatial Variation ◽  
Spatial Scales ◽  
High Elevation ◽  
Spatially Explicit ◽  
Fine Scale ◽  
Demographic Rates ◽  
Demographic Traits ◽  
Demographic Processes ◽  
Demographic Responses

Abstract CONTEXTSpatial variation in life history traits plays a crucial role in the structure and dynamics of populations. The demographic responses of local populations to fine-scale habitat heterogeneity have consequences for species at a broader scale and responses vary across spatial scales. Yet, the specific nature of such relationships is unclear across taxa.OBJECTIVESWe evaluated the spatial variation in demographic traits of cryptic terrestrial salamanders across the broad scale environmental gradient of elevation (i.e. temperature) and the fine-scale gradient of stream distance (i.e. moisture).METHODSUsing a 4-years of spatial mark-recapture and count data, we implemented a spatially explicit Integrated Population Model to understand demographic rates across scales. We also investigated how hybridization, which occurs in between lungless salamanders at mid-elevations, may influence demographic rates.RESULTSWe found that high elevation animals grow faster and move more, especially far from streams likely as a result of increased temperatures. Survival was highest but recruitment rates were lowest at low elevations and significantly declined with distance to stream. We also found that hybrid animals at low elevations had higher survival probabilities.CONCLUSIONSOur study reveals nuanced spatial variation in demographic rates that differ in magnitude depending on the scale at which they are assessed. Our results also show animals exhibit demographic compensation across abiotic gradients, underscoring the need for further conservation and management efforts to implement spatially explicit and dynamic strategies to match the demographic variation of species and populations of species separated across space.

Inhibition of coral settlement at multiple spatial scales by a pervasive algal competitor

2019 ◽  
Vol 612 ◽  
pp. 29-42 ◽  
Author(s):  
NR Evensen ◽  
C Doropoulos ◽  
KM Morrow ◽  
CA Motti ◽  
PJ Mumby
Keyword(s):  
Spatial Scales ◽  
Coral Settlement ◽  
Multiple Spatial Scales

POLÍTICAS DE ESCALA E A CONFORMAÇÃO DE ESTRATÉGIAS-REDE DAS AÇÕES COLETIVAS NO ESPAÇO SISALEIRO DA BAHIA

GEOgraphia ◽  
2018 ◽  
Vol 19 (41) ◽  
pp. 39
Author(s):  
Agripino Souza Coelho Neto
Keyword(s):  
Political Action ◽  
Spatial Scales ◽  
Spatial Behavior ◽  
Collective Actions ◽  
Collective Behaviors ◽  
Rural Workers ◽  
Scale Levels ◽  
Scale Network ◽  
Comme Point

Resumo: O presente texto pretende analisar o papel das ações coletivas (associações, cooperativas e sindicatos de agricultores) no acionamento e na ativação das escalas geográficas para o desenvolvimento de suas atividades. O estudo foi realizado no Espaço Sisaleiro da Bahia (Brasil), onde um conjunto significativo de associações e cooperativas de agricultores e sindicatos de trabalhadores rurais tem se organizado em torno das escalas espaciais para viabilizar sua ação político-institucional e econômico-produtiva. A ação desses coletivos organizados em rede tem permitido a conformação e o fortalecimento de novas escalas de ação política, como no caso da criação do conselho territorial para viabilização da implantação de políticas de governo. Cooperativas, associações e sindicatos se apoiam nas escalas para compor organizações em diferentes níveis escalares (escala local, escala regional, escala do estado federado e escala nacional), buscando fortalecer seus propósitos e ampliar seu poder de barganha e influência. Analisando o comportamento espacial dessas variadas modalidades de ações coletivas, é possível considerar que elas desenvolvem políticas de escala, ou seja, a escala passa a significar muito mais que uma categoria de análise, mas se torna uma categoria da prática social e política. Nesse sentido, parte-se do pressuposto de que os grupos humanos produzem e tornam efetivas suas próprias escalas visando a alcançar suas metas e organizar seus comportamentos coletivos. Palavras-chave: Escala. Rede. Cooperativismo. Associativismo. Sindicalismo. Espaço Sisaleiro da Bahia. SCALE POLICIES AND THE DEVELOPMENT OF NETWORK STRATEGIES OF COLLECTIVE ACTIONS IN THE SISAL REGION OF BAHIA (BRAZIL)Abstract: This paper aims to analyze the role of collective initiatives of associations, cooperatives and farmers’ unions in the mobilization and activation of geographical scales for the development of their activities. The study was conducted in the Sisal Region of Bahia (Brazil), where a significant number of farmers associations and cooperatives and rural workers’ unions have been organizing their actions around spatial scales to enable their political-institutional and economic-productive influence. The gathering and action of these organized groups in a network have allowed the establishment and strengthening of new scales of political action, as seem in the case of the creation of a territorial council to facilitate the implementation of government policies. Cooperatives, associations, and unions rely on scales to form organizations at different scale levels (local, regional, federal and national scales), seeking to strengthen their performance and increase their bargaining power and influence. After analyzing the spatial behavior of these various forms of collective actions, it’s reasonable to say that they develop scale policies, which means the scale becomes more than a category of analysis, but also a category of social and political practice. In this sense, it’s assumed that human groups produce and utilize the scales in order to reach their goals and organize their own collective behaviors. Keywords: Scale. Network. Cooperativism. Associativism. Syndicalism. Sisal Region of Bahia. POLITIQUES D’ÉCHELLE ET FORMATION DES STRATÉGIES-RÉSEAU DES ACTIONS COLLECTIVES DANS LA RÉGION DU SISAL DE L’ÉTAT DE BAHIA Resumé: Cet article analyse le rôle des actions collectives (associations, coopératives et syndicats d’agriculteurs) dans la prise en compte et l’utilisation des échelles géographiques pour le développement de leurs activités. L’étude a été menée dans la région du sisal à Bahia (Brésil), où un ensemble important d’associations et de coopératives d’agriculteurs et de syndicats de travailleurs ruraux se sont organisés autour d’échelles spatiales pour que puisse être mise en place leur action politique et institutionnelle, économique et productive. L’action de ces groupements organisés en réseaux a permis la conformation et le renforcement de nouvelles échelles d’action politique, comme lors de la création du conseil territorial, pour permettre la mise en œuvre des politiques gouvernementales. Les coopératives, les associations et les syndicats prennent les échelles comme point de départ pour former des organisations à différents niveaux scalaires (échelle locale, échelle régionale, échelle fédérée et échelle nationale), dans le but de renforcer leurs objectifs et d’accroître leur pouvoir de négociation et d’influence. Si nous analysons le comportement spatial de ces diverses formes d’action collective il est possible de considérer qu’ils développent des politiques d’échelle, à savoir l’échelle vient signifier bien plus qu’une catégorie d’analyse, puisqu’elle devient une catégorie de la pratique sociale et politique. En ce sens, on suppose que les groupes humains produisent et rendent efficaces leurs propres échelles pour atteindre leurs objectifs et organiser leurs comportements collectifs. Mots-clés: Échelle. Réseau. Coopérativisme. Associations. Syndicalisme. Région du sisal de l’État de Bahia.

scholarly journals Effects of Vector Maturation Time on the Dynamics of Cassava Mosaic Disease

2021 ◽  
Vol 83 (8) ◽  
Author(s):  
F. Al Basir ◽  
Y. N. Kyrychko ◽  
K. B. Blyuss ◽  
S. Ray
Keyword(s):  
Time Delay ◽  
Plant Density ◽  
Plant Viruses ◽  
Mosaic Disease ◽  
Plant Diseases ◽  
Cassava Mosaic Disease ◽  
Maturation Time ◽  
Negative Effect ◽  
Dynamical Regimes

AbstractMany plant diseases are caused by plant viruses that are often transmitted to plants by vectors. For instance, the cassava mosaic disease, which is spread by whiteflies, has a significant negative effect on plant growth and development. Since only mature whiteflies can contribute to the spread of the cassava mosaic virus, and the maturation time is non-negligible compared to whitefly lifetime, it is important to consider the effects this maturation time can have on the dynamics. In this paper, we propose a mathematical model for dynamics of cassava mosaic disease that includes immature and mature vectors and explicitly includes a time delay representing vector maturation time. A special feature of our plant epidemic model is that vector recruitment is negatively related to the delayed ratio between vector density and plant density. We identify conditions of biological feasibility and stability of different steady states in terms of system parameters and the time delay. Numerical stability analyses and simulations are performed to explore the role of various parameters, and to illustrate the behaviour of the model in different dynamical regimes. We show that the maturation delay may stabilise epidemiological dynamics that would otherwise be cyclic.

scholarly journals Ecological Connectivity in Agricultural Green Infrastructure:  Suggested Criteria for Fine Scale Assessment and Planning

Land ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 807
Author(s):  
Simone Valeri ◽  
Laura Zavattero ◽  
Giulia Capotorti
Keyword(s):  
Land Cover ◽  
Green Infrastructure ◽  
Rural Areas ◽  
Urban Areas ◽  
Landscape Heterogeneity ◽  
Agricultural Landscapes ◽  
Spatial Pattern Analysis ◽  
Fine Scale ◽  
Unique Type

In promoting biodiversity conservation and ecosystem service capacity, landscape connectivity is considered a critical feature to counteract the negative effects of fragmentation. Under a Green Infrastructure (GI) perspective, this is especially true in rural and peri-urban areas where a high degree of connectivity may be associated with the enhancement of agriculture multifunctionality and sustainability. With respect to GI planning and connectivity assessment, the role of dispersal traits of tree species is gaining increasing attention. However, little evidence is available on how to select plant species to be primarily favored, as well as on the role of landscape heterogeneity and habitat quality in driving the dispersal success. The present work is aimed at suggesting a methodological approach for addressing these knowledge gaps, at fine scales and for peri-urban agricultural landscapes, by means of a case study in the Metropolitan City of Rome. The study area was stratified into Environmental Units, each supporting a unique type of Potential Natural Vegetation (PNV), and a multi-step procedure was designed for setting priorities aimed at enhancing connectivity. First, GI components were defined based on the selection of the target species to be supported, on a fine scale land cover mapping and on the assessment of land cover type naturalness. Second, the study area was characterized by a Morphological Spatial Pattern Analysis (MSPA) and connectivity was assessed by Number of Components (NC) and functional connectivity metrics. Third, conservation and restoration measures have been prioritized and statistically validated. Notwithstanding the recognized limits, the approach proved to be functional in the considered context and at the adopted level of detail. Therefore, it could give useful methodological hints for the requalification of transitional urban–rural areas and for the achievement of related sustainable development goals in metropolitan regions.

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