Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Mais filtros











Base de dados
Intervalo de ano de publicação
1.
Sci Rep ; 10(1): 14800, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32908193

RESUMO

To ensure integrity of protected areas we need to understand how species respond to anthropogenic borders. We investigate, from a metacommunity perspective, the direct and indirect mechanisms by which transformed areas affect distribution patterns of ground-living arthropod assemblages inhabiting an extensive protected area adjacent to fruit orchards in an important biosphere reserve. Arthropods and environmental variables were sampled along transects perpendicular to natural-orchard edges. Influence of distance from orchard boundary, degree of impermeability of the boundary, orchard habitat quality (local scale land-use intensity), and edge-induced changes in local environmental variables on arthropod species richness and composition in non-crop habitats were assessed. Arthropod groups were assessed in terms of habitat fidelity: species associated with natural habitat (stenotopic species), those within crop habitat (cultural species), and those showing no preference for either habitat (ubiquitous species). Spillover resulted in higher cultural species richness near edges, but not higher overall species richness. Environmental filtering was important for stenotopic species composition, which was influenced by edge-induced changes in environmental variables. Ubiquitous species composition was determined by orchard impermeability. Increased orchard habitat quality was associated with higher cultural and ubiquitous species richness. The effects of orchards on assemblages in natural habitats can be variable, but predictable when using species habitat specificity in conjunction with a metacommunity framework. High intensity orchards may act as sink habitats, especially for species that readily disperse between crop and natural habitats. Here we recommend that local buffer strips are > 85 m wide, which will reduce the influence of cultural species spillover on sensitive natural ecosystems.


Assuntos
Ecologia , Biodiversidade , Ecossistema
2.
J Environ Manage ; 271: 110922, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32778259

RESUMO

Environmental degradation is a global phenomenon with a high likelihood of influencing human quality of life. Effective management responses are needed to achieve societal goals of sustainability. We develop here a new monitoring protocol (Management Check: MATCH) that comprehensively evaluates management outcomes at the operational level. Using the Driver-Pressure-State-Impact-Response (DPSIR) framework, we identified pressures influencing ecosystem integrity inside conservation corridors and commercial compartments of a timber production landscape mosaic. They were 1) domestic livestock grazing (the only exogenous pressure), 2) fire management, 3) invasive alien plants (IAPs), and potential soil erosion from two sources: 4) roads, and 5) harvested timber compartments. We assessed the effects of these on wetland and stream buffers. Environmental incidents accounted for more serious management issues (e.g. oil spills). Management responses were systematically unpacked into point-form questions, which formed the building blocks of our monitoring protocol. We assessed management in twelve plantations in KwaZulu-Natal, South Africa. Answers were compared with Best Operational Practice (BOP), and reworked into a Weighted Index of Compliance (WIC) per section. We found that there was poor management of livestock grazing, but good management of IAPs, roads, and timber compartments. Management of wetland and stream buffers was very good. Fire management presented problems linked to lack of direct effects, measurable at the spatial and temporal scales of operations. We discuss operational outcomes within their respective legislative frameworks, and suggest ways of improving management operations, where needed. MATCH is the first monitoring protocol to comprehensively assess environmental management of commercial forestry at the operational level, and to clearly translate operational activities into measurable progress towards strategic goals. In doing so, MATCH breaks down silos and builds bridges for efficient environmental management in dynamic socio-ecological systems. Moreover, the principles developed here can be applied to build tools that help manage major risks in other economic sectors too. Overall, MATCH strengthened strategic and informed action, which is necessary at multiple levels of an organization, to combat major societal risks, such as environmental degradation.


Assuntos
Ecossistema , Agricultura Florestal , Animais , Conservação dos Recursos Naturais , Monitoramento Ambiental , Humanos , Qualidade de Vida , África do Sul
3.
Ecol Appl ; 29(4): e01883, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30847972

RESUMO

Plants often form the basis of conservation planning and management. The effectiveness of plant diversity as a surrogate for arthropod diversity was assessed in natural areas in the Kogelberg Biosphere Reserve, a floral endemism hotspot in the Cape Floristic Region (CFR), South Africa. Arthropods and plants were sampled across 30 topographically heterogeneous sites in a spatially nested design. The relationship between plants and arthropods were quantified in terms of species richness, assemblage variation, and assemblage turnover. The influence of arthropod trophic groups, habitat association, and spatial scale were also explored. Generalized dissimilarity modelling was used to investigate differential influence of explanatory groups (geology, disturbance, local site characteristics, refuge, mesoclimate, terrain) on arthropod and plant turnover. Congruence in assemblage variation was restricted to local scales, and only present between plants and those arthropods associated with the foliar component of the habitat. Weak congruence in species turnover was due to differences in the relative importance of explanatory groups, with different variables within each explanatory group being important, and similar variables predicting different turnover patterns. For both groups, variables related to geology and fire history were important for assemblage turnover. These variables are already incorporated in conservation planning and management for plant diversity across the CFR. Overall plant diversity was a weak surrogate for the arthropod groups included in this study, suggesting that as an alternative, environmental surrogates for arthropod diversity perform better.


Assuntos
Artrópodes , Animais , Biodiversidade , Ecossistema , Plantas , África do Sul
4.
J Environ Manage ; 238: 382-395, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30861399

RESUMO

Habitat degradation is a major concern in transformed landscapes, as it reduces complexity by removing species, interactions, and ultimately biodiversity. Degradation is also of concern for ecological networks (ENs) composed of an interconnected system of conservation corridors among South Africa's commercial forestry compartments. These corridors are predominantly grasslands, and used as rangeland, so managed to optimize grazing conditions. Yet, how this management approach influences biodiversity remains unknown. Here, we studied how butterfly assemblages respond to local differences in rangeland quality (low, high and reference sites), and how this effect compared to that of local environmental variables (e.g. rockiness and bare ground), meso environmental gradients (e.g. topographic position and aspect), and landscape composition (i.e. proportion of different land cover types in the surrounding matrix). We calculated species richness and composition, Shannon's diversity index (H'), and the Butterfly Conservation Index (BCIn) representing the proportion of sensitive and range-restricted butterfly species per site. Rangeland quality was considered less important for butterflies than other environmental variables, but it was also significantly confounded with other environmental variables. At the landscape scale, proportion of grassland in the landscape matrix influenced butterfly assemblage composition, while proportion of thicket had a significant positive effect on BCIn. Moreover, the effect of elevation on assemblage composition emphasizes the value of maintaining environmental gradients within these conservation corridors. At the meso spatial scale, butterfly species richness and diversity (H') declined with increased dominance by a single plant species, which usually occurs late in a normal fire cycle. This suggests a reliance by butterflies on recurring natural disturbances for long-term persistence. We recommend moderate patch burning and grazing, as well as occasional hot burns to reduce thicket in Afromontane grassland. This approach would improve local scale vegetation patterns, and increase heterogeneity across the landscape for conserving these butterflies into the future.


Assuntos
Borboletas , Animais , Biodiversidade , Conservação dos Recursos Naturais , Ecossistema , Pradaria , África do Sul
5.
Persoonia ; 28: 138-82, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23105159

RESUMO

Novel species of microfungi described in the present study include the following from Australia: Phytophthora amnicola from still water, Gnomoniopsis smithogilvyi from Castanea sp., Pseudoplagiostoma corymbiae from Corymbia sp., Diaporthe eucalyptorum from Eucalyptus sp., Sporisorium andrewmitchellii from Enneapogon aff. lindleyanus, Myrmecridium banksiae from Banksia, and Pilidiella wangiensis from Eucalyptus sp. Several species are also described from South Africa, namely: Gondwanamyces wingfieldii from Protea caffra, Montagnula aloes from Aloe sp., Diaporthe canthii from Canthium inerne, Phyllosticta ericarum from Erica gracilis, Coleophoma proteae from Protea caffra, Toxicocladosporium strelitziae from Strelitzia reginae, and Devriesia agapanthi from Agapanthus africanus. Other species include Phytophthora asparagi from Asparagus officinalis (USA), and Diaporthe passiflorae from Passiflora edulis (South America). Furthermore, novel genera of coelomycetes include Chrysocrypta corymbiae from Corymbia sp. (Australia), Trinosporium guianense, isolated as a contaminant (French Guiana), and Xenosonderhenia syzygii, from Syzygium cordatum (South Africa). Pseudopenidiella piceae from Picea abies (Czech Republic), and Phaeocercospora colophospermi from Colophospermum mopane (South Africa) represent novel genera of hyphomycetes. Morphological and culture characteristics along with ITS DNA barcodes are provided for all taxa.

6.
Neurosci Lett ; 304(1-2): 13-6, 2001 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-11335043

RESUMO

The effects of lamotrigine on rat neuroma and behavioural paradigms were evaluated to determine a pre-clinical therapeutic index. Lamotrigine blocked neuroma-induced burst pattern firing at a free plasma concentration of 13.7+/-1.7 microM (n=5). Oral dosing of lamotrigine (50-200 mg/kg) had no significant effects on behaviour but measurements of plasma concentrations of free drug showed non-linear oral absorption and lower than predicted drug levels (5-27 microM). Given intravenously (10-100 mg/kg), lamotrigine did affect behaviour at a free plasma concentration of 42.0 microM (n=2). By comparing free plasma concentrations, a therapeutic index of 3 was calculated, which is lower than published data based on comparing oral doses. We propose that a therapeutic index should only be derived with reference to plasma drug concentrations to prevent non-linear or incomplete drug absorption from confounding accurate estimation.


Assuntos
Potenciais de Ação/efeitos dos fármacos , Anticonvulsivantes/farmacologia , Comportamento Animal/efeitos dos fármacos , Neuroma/fisiopatologia , Triazinas/farmacologia , Potenciais de Ação/fisiologia , Animais , Anticonvulsivantes/sangue , Anticonvulsivantes/uso terapêutico , Comportamento Animal/fisiologia , Avaliação Pré-Clínica de Medicamentos , Lamotrigina , Masculino , Destreza Motora/efeitos dos fármacos , Destreza Motora/fisiologia , Neuroma/tratamento farmacológico , Ratos , Ratos Sprague-Dawley , Nervo Isquiático/efeitos dos fármacos , Nervo Isquiático/lesões , Nervo Isquiático/fisiologia , Triazinas/sangue , Triazinas/uso terapêutico
7.
J Neurochem ; 73(2): 849-58, 1999 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10428084

RESUMO

The alpha subunits of Shaker-related K+ channels (Kv1.X) show characteristic distributions in mammalian brain and restricted coassembly. Despite the functional importance of these voltage-sensitive K+ channels and involvement in a number of diseases, little progress has been achieved in deciphering the subunit composition of the (alpha)4(beta)4 oligomers occurring in human CNS. Thus, the association of alpha and beta subunits was investigated in cerebral grey and white matter and spinal cord from autopsy samples. Immunoblotting established the presence of Kv1.1, 1.2, and 1.4 in all the tissues, with varying abundance. Sequential immunoprecipitations identified the subunits coassembled. A putative tetramer of Kv1.3/1.4/1.1/1.2 was found in grey matter. Both cerebral white matter and spinal cord contained the heterooligomers Kv1.1/1.4 and Kv1.1/1.2, similar to grey matter, but both lacked Kv1.3 and the Kv1.4/1.2 combination. An apparent Kv1.4 homooligomer was detected in all the samples, whereas only the brain tissue possessed a putative Kv1.2 homomer. In grey matter, Kvbeta2.1 was coassociated with the Kv1.1/1.2 combination and Kv1.2 homooligomer. In white matter, Kvbeta2.1 was associated with Kv1.2 only, whereas Kvbeta1.1 coprecipitated with all the alpha subunits present. This represents the first description of Kv1 subunit complexes in the human CNS and demonstrates regional variations, indicative of functional specialisation.


Assuntos
Química Encefálica , Canais de Potássio de Abertura Dependente da Tensão da Membrana , Canais de Potássio/análise , Canais de Potássio/química , Adulto , Idoso , Sequência de Aminoácidos , Anticorpos , Especificidade de Anticorpos , Córtex Cerebral/química , Humanos , Canal de Potássio Kv1.1 , Canal de Potássio Kv1.2 , Canal de Potássio Kv1.3 , Canal de Potássio Kv1.4 , Pessoa de Meia-Idade , Dados de Sequência Molecular , Mutação , Canais de Potássio/imunologia , Testes de Precipitina , Superfamília Shaker de Canais de Potássio , Medula Espinal/química
10.
Planta ; 132(3): 279-84, 1976 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24425091

RESUMO

We did this work to see if there is a correlation between lignin synthesis and the activity of the pentose phosphate pathway. Excision of the third internode of the stem of Coleus blumei Benth. followed by incubation on sucrose and indoleacetic acid led to extensive formation of tracheids. During this lignification we determined the activities of glucose-6-phosphate dehydrogenase and fructose-1,6-diphosphate aldolase, and the extent to which [1-(14)C]-,[3,4-(14)C]-, and [6-(14)C]glucose labelled CO2 and the major cellular components. The results indicate that the pentose phosphate pathway was active during lignification, and that the activity of this pathway relative to glycolysis increased at the onset of lignification. Explants of storage tissue of Helianthus tuberosus L. were cultured under conditions which caused extensive lignification. (14)CO2 production from [1-(14)C]-, [3,4-(14)C]-, and [6-(14)C]glucose indicated activity of the pentose phosphate pathway during tracheid formation. We suggest that lignification is accompanied by appreciable activity of the pentose phosphate pathway and that this could provide the reducing power for lignin synthesis.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA