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1.
Russell Fairfax Rod Fensham Don Butler Kelvin Quinn Bernice Sigley James Holman 《Landscape Ecology》2009,24(10):1363-1373
There is circumstantial evidence that grasslands on the Bunya Mountains were once maintained by Aboriginal burning, and with
lack of fire under European management are being colonised by trees. To assess the efficacy of burning for maintaining grasslands,
119 fires were lit between 1996 and 2006. The total area of unburnt grasslands decreased by 27%, while grasslands burnt at
least once decreased by 1%. The density of invading trees was recorded from fixed plots on 23 grasslands burnt between one
and six times. Cassinia was virtually eliminated and the density of the Rainforest species guild slowly but continually declined. Acacia irrorata exhibited a humped response, with initial increases resulting from vegetative resprouting and gradual decline with persistent
burning. Phyllodinous Acacia and Woodland trees were the least fire sensitive guilds, having stable or increased density with repeated burning. Multi-factor
regression modelling detected no significant relationships between changes in woody plant density and the interval between
fires, fire intensity, the initial density of large trees, an index of soil moisture, or the cumulative number of fires for
any species guild. The survivorship of both Cassinia and Rainforest guilds was significantly lower with summer burning than winter burning, but a seasonal effect of burning was
not evident for other guilds. The findings suggest that regardless of fire conditions, frequent burning will reduce the number
of adult trees, maintain resprouts in an immature state, facilitate further fire and reduce the rate of grassland loss. Woodland
species are especially resilient to fire, and burning to maintain grassy ecosystems will be most successful where the main
colonisers are rainforest species and burning is conducted in summer. The findings suggest that the montane grasslands of
the Bunya Mountains were maintained by anthropogenic burning and active fire management will prolong their existence. 相似文献
2.
1. The most important area in Singapore for native aquatic fauna and flora is a relatively intact 5 km2 patch of freshwater swamp forest in Nee Soon. 2. The Nee Soon Swamp Forest contains 48% of the primary freshwater fish, 71% of the amphibian, 28% of the reptile and 34% of the bird fauna of Singapore. The swamp also has the highest percentage of native and threatened freshwater fish and crustacean species on the island, as well as being the main (if not the only) habitat of the aquatic plant Hydrostemma. It is also the last refuge of two mammals, the Banded Leaf Monkey, Presbytis femoralis femoralis, and the Cream-coloured Giant Squirrel, Ratufa affinis affinis. 3. The threats to the swamp forest are discussed, and proposals are made to establish the swamp forest as Singapore's second major nature reserve. 4. Study of the swamp forest is essentially still at a survey and discovery phase. The research priorities are to establish detailed species lists, the status of endangered species and the extent of buffer zones. 5. The swamp forest is administered primarily by the newly established National Parks Board, but several other government organizations also have jurisdiction over the land, causing some problems in the management of the swamp. The roles of the university and non-governmental organizations in conducting surveys, drafting recommendations and educating the general public are detailed. 相似文献
3.
We compared the composition and structure of primary forest avifauna among primary forests, selectively logged forests and mixed-rural areas (e.g. villages and agricultural areas) of Peninsular Malaysia. We found that forests that were selectively logged at least 30 years ago contained only 73-75% of the 159 species of extant primary forest birds, with an increased proportion of dominant species. We estimated that only 28-32% of the primary forest species utilized the mixed-rural habitat, and that the number of species that bred in the agricultural landscapes might be even lower. The microhabitat of different species most affected their vulnerability to disturbance. Most small, arboreal frugivores and omnivores, and insectivores that fed from tree trunks, showed greater persistence in the mixed-rural habitat than ground dwelling bird species, which were affected most by disturbance. Resource abundance and variables that were closely related to forest disturbance such as the density of large trees, density of dead trees, canopy cover density and shrub volume influenced the distribution of the primary forest birds. Large primary forest reserves and a revision of short-cycle logging regimes (ca. 30 years) are needed if we are to conserve the lowland rainforest avifauna of Peninsular Malaysia and other parts of Southeast Asia. 相似文献
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5.
Thamm DH Rose B Kow K Humbert M Mansfield CD Moussy A Hermine O Dubreuil P 《Veterinary journal (London, England : 1997)》2012,191(1):131-134
Masitinib, a selective tyrosine kinase inhibitor, has previously been shown to enhance the antiproliferative effects of gemcitabine in human pancreatic cancer, demonstrating potential as a chemosensitizer. This exploratory study investigated the ability of masitinib to sensitize various canine cancer cell lines to doxorubicin, vinblastine, and gemcitabine. Masitinib strongly sensitized histiocytic sarcoma cells to vinblastine (>70-fold reduction in IC(50) at 5 μM masitinib), as well as osteosarcoma and mammary carcinoma cells to gemcitabine (>70-fold reduction at 5-10 μM). In addition, several cell lines were sensitized to doxorubicin (2-10-fold reduction at 10 μM). These data establish proof-of-concept that masitinib in combination with chemotherapeutic agents can generate synergistic growth inhibition in various canine cancers, possibly through chemosensitization. The findings justify further investigation into those combinations that may potentially yield therapeutic benefit. 相似文献
6.
Studies have shown that increasing diversity has a positive influence on many ecosystem functions and services, for example, biomass productivity. However, most diversity–functioning studies have derived their conclusions (1) from considering only random species assemblages, (2) from small spatial scales – often micro- and mesocosm experiments, (3) from studying merely a single trophic level, and (4) studies from a small number of biomes dominate. Critics argue that these studies provide little basis to evaluate the consequences for biodiversity loss in the real world. Here we re-consider the latest research focusing on each limitation in turn to highlight the possible lessons for real-world conservation from recent biodiversity–ecosystem function (BEF) research. Tentative general lessons from recent research include: (1) the need to urgently forestall human-induced extinction (i.e., non-random extinction) over large areas, in order to avert large negative functional consequences which may be more pronounced at larger scales and (2) preserve relatively intact communities because biotic interactions across the multi-trophic levels may have a synergistic contribution to the overall functioning of a system. However, considering the complexity of the community dynamics of natural systems, we recommend using natural systems – and understanding the basic physiological features and ecological roles of the species within them – because they implicitly include realistic extinction process, trophic structures and spatial–temporal scales as a useful way of increasing the relevance of future BEF studies to conservation. 相似文献
7.
The effects of 6, 10 and 14 days of skip-a-day feed removal during the starter and grower periods on the growth performance
of Ross 308 and Hubbard broiler chickens were studied in a 49-day production period. Ross 308 was superior to Hubbard in weight
gain, market weight and feed utilization but consumed more feed, deposited more abdominal fat and had a higher mortality rate.
Overall, feed removal improved feed efficiency, had insignificant effects on abdominal fatness and mortality rate and reduced
feed intake, weight gain and market weight. On each restricted-feeding regime, the birds gained as much weight as their fully
fed counterparts during the period of resumed full feeding but were unable to compensate fully for the weight loss and were
lighter at the end of the trial. It is suggested that for profitable broiler production under tropical conditions, Ross 308
and skip-a-day feed removal for less than 6 days from 7 to 17 days of age be considered. 相似文献
8.
ABSTRACT Phytophthora ramorum is a recently described pathogen causing bleeding cankers, dieback, and leaf blight on trees and shrubs in parts of Europe and North America, where the disease is commonly known as sudden oak death. This article describes the development of a single-round real-time polymerase chain reaction (PCR) assay based on TaqMan chemistry, designed within the internal transcribed spacer 1 region of the nuclear ribosomal (nr)RNA gene for detection of P. ramorum in plant material. Unlike previously described methods for the molecular detection of P. ramorum, this assay involves no post amplification steps or multiple rounds of PCR. The assay was found to have a limit of detection of 10 pg of P. ramorum DNA, and could detect P. ramorum in plant material containing 1% infected material by weight within 36 cycles of PCR. The assay also was used to test DNA from 28 other Phytophthora spp. to establish its specificity for P. ramorum. A quick and simple method was used to extract DNA directly from host plant material, and detection of P. ramorum was carried out in multiplex with an assay for a gene from the host plant in order to demonstrate whether amplifiable DNA had been extracted. Amplifiable DNA was extracted from 84.4% of samples, as demonstrated by amplification of host plant DNA. The real-time protocol was used to test 320 plant samples (from 19 different plant species) from which DNA extraction had been successful, and was shown to give results comparable with a traditional isolation technique for diagnosis of P. ramorum in plant material from common U.K. hosts. 相似文献
9.
K. A. Wirth K. Kow M. E. Salute N. J. Bacon R. J. Milner 《Veterinary and comparative oncology》2016,14(3):281-294
Yunnan Baiyao is a Chinese herbal medicine that has been utilized for its anti‐inflammatory, haemostatic, wound healing and pain relieving properties in people. It has been utilized in the veterinary profession to control bleeding in dogs with hemangiosarcoma (HSA) and has been anecdotally reported to prolong survival times in dogs with this neoplasm. This study evaluated the in vitro activity of Yunnan Baiyao against three canine HSA cell lines after treatment with increasing concentrations of Yunnan Baiyao (50, 100, 200, 400, 600 and 800 µg mL?1) at 24, 48 and 72 h. Mean half maximum inhibitory concentration (IC50) at 72 h for DEN, Fitz, SB was 369.9, 275.9 and 325.3 µg mL?1, respectively. Caspase‐3/7 activity increased in correlation with the IC50 in each cell line which was confirmed by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL, APO‐BRDU Kit; BD Biosciences, San Jose, CA, USA) assay. VEGF in cell supernatant was also quantified. Overall, the study found that Yunnan Baiyao causes dose and time dependent HSA cell death through initiation of caspase‐mediated apoptosis, which supports future studies involving Yunnan Baiyao. 相似文献
10.
Crop loss due to plant pathogens has provoked renewed interest in bacteriophages as a feasible biocontrol strategy of plant diseases. Phage cocktails in particular present a viable option for broadening the phage host range, limiting the emergence of bacterial resistance while maintaining the lytic activity of the phages. It is therefore important that the design used to formulate a phage cocktail should result in the most effective cocktail against the pathogen. It is also critical that certain factors are considered during the formulation and application of a phage cocktail: their stability, the production time and cost of complex cocktails, the potential impact on untargeted bacteria, the timing of phage application, and the persistence in the plant environment. Continuous monitoring is required to ensure that the efficacy of a cocktail is sustained due to the dynamic nature of phages. Although phage cocktails are considered as a plausible biocontrol strategy of phytobacteria, more research needs to be done to understand the complex interaction between phages and bacteria in the plant environment, and to overcome the technical obstacles. © 2019 Society of Chemical Industry 相似文献