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1.
Invasive species management is a critical issue worldwide, but mitigation strategies are slow to develop, and invader populations often expand too rapidly for eradication to be feasible. Thus, reduction in numbers of individuals is the most heavily used management strategy for invasive pests. While long-term biocontrol agents may take years or decades to develop, simple trap modifications can increase capture of targeted demographic groups, such as ovigerous females. The present study identifies the effectiveness of trap modification and use of multiple attractants to capture the invasive cane toad (Rhinella marina). Cane toad traps typically use lights to attract insect prey. Studies suggest that adding a male cane toad advertisement call to attract toads by phonotaxis may be effective. The aims of this study were to determine whether (i) female capture efficiency was influenced by attractants in the same manner as male and juvenile captures, (ii) an acoustic attractant alone (without a light attractant) was sufficient to attract toads, and (iii) the location of an acoustic attractant (inside or on top of the trap) influenced trap success. Male toads were captured more frequently than females and juveniles; combining light and acoustic attractants increased toad capture; and placing the acoustic attractant inside the trap increased the capture of female cane toads. Removal of adult, ovigerous females is a promising strategy to slow population growth of invasive species. Our results suggest that using a sound attractant inside the trap with a UV light is most effective in targeting that particular cane toad cohort.  相似文献   

2.
The development of biological control measures to reduce the impact of invasive species is a desired goal. Rhabdias species have recently been advocated as biological control agents for invasive anurans. This study describes a field-based approach to support laboratory results on the potential impact of the lung nematode Rhabdias pseudosphaerocephala on the prey consumption of its host, the invasive cane toad (Rhinella marina, Bufonidae). Toads were sampled from various populations in the Wet Tropics of Australia during the wet seasons of 2010 and 2012. Consumed prey items were counted in 212 cane toads and identified to class and order levels and the number of lung nematodes was counted for each toad. The number of R. pseudosphaerocephala in free-ranging cane toads affected negatively the diversity of prey items consumed, but was not related to the number of prey items or the number of ants consumed. The results suggest that infection of free-ranging cane toads by the lung nematode reduces their range of prey items. Possible reasons could be a reduced locomotor activity resulting in changes of foraging modes of infected toads which was reported from some laboratory trials. Infection of cane toads by R. pseudosphaerocephala may therefore have the potential to alter the impact of cane toads on invertebrate communities and their competition for food resources with native Australian anurans.  相似文献   

3.
Disturbance has long been a central issue in amphibian conservation, often regarding negative effects of logging or other forest management activities, but some amphibians seem to prefer disturbed habitats. After documenting increased use of recently burned forests by boreal toads (Bufo boreas), we hypothesized that burned habitats provided improved thermal opportunities in terrestrial habitats. We tested this hypothesis by conducting a radio telemetry study of habitat use (reported previously) and by using physical models that simulated the temperature of adult toads. We deployed 108 physical models in and adjacent to a 1-year old burn using a fully-replicated design with three burn severities (unburned, partial, high severity) and four microhabitats (open surface, under vegetation, under log, in burrow). Model temperatures were compared to a range of preferred temperatures in published studies. We found 70% more observations within the preferred temperature range of B. boreas in forests burned with high severity than in unburned areas. Burned forest was warmer than unburned forest across all microhabitats, but the largest relative difference was in burrows, which averaged 3 °C warmer in high-severity burn areas and remained warmer though the night. More than twice as many observations were within the preferred temperature range in high-severity burrows than in unburned burrows. Areas burned with high severity were still warmer than unburned forest 3 years after the fire. Habitat use of toads during the concurrent radio telemetry study matched that predicted by the physical models. These results suggest there are fitness-linked benefits to toads using burned habitats, such as increased growth, fertility, and possibly disease resistance. However, increased soil temperatures that result from wildfire may be detrimental to other amphibian species that prefer cooler temperatures and stable environments. More broadly, our data illustrate the use of physical models to measure and interpret changes that amphibians may experience from disturbance, and highlight the need for research linking vital rates such as growth and survival to disturbance.  相似文献   

4.
The aim of the study was to monitor the seasonal variation in the sex-specific responses of Ips typographus to a commercial pheromone in relation to the two generations per year occurring in the Southern Alps. The study was carried out over 2 years (2000–2001). Each year, 15 Theysohn traps were baited with Pheroprax. Traps were emptied weekly and the number of beetles determined. In the same forest each year, three spruce logs were set up at the beginning of spring for natural colonisation by Ips typographus and then put in breeding boxes. All adults emerging from the logs or found in the traps were counted and a subsample sexed by genital extraction. Spring captures were always higher than summer captures (second generation). Similarly, the proportion of trapped males was always higher in spring than in summer. Except in the first and second week, the number of females was higher than males. During the first 3 weeks of monitoring, the number of trapped males dropped from above 50 to about 30%. Thereafter, the sex ratio was constant over time, about 33% males. In contrast to trap catches, about 50% of adults emerging from the breeding logs were males. The low proportion of males in traps depends both on discrimination (they avoid strong sources of male pheromone) and on differential mortality of the sex over time. As the pioneer beetles in I. typographus are males, their number is highest in the first part of the flight period when they search for suitable host trees. Such a search can be lethal for several males, decreasing the sex ratio.  相似文献   

5.
Plant invasions of natural communities are commonly associated with reduced species diversity and altered ecosystem structure and function. This study investigated the effects of invasion and management of the woody shrub Lantana camara (lantana) in wet sclerophyll forest on the south-east coast of Australia. The effects of L. camara invasion and management on resident vegetation diversity and recruitment were determined as well as if invader management initiated community recovery. Vascular plant species richness, abundance and composition were surveyed and compared across L. camara invaded, non-invaded and managed sites following L. camara removal during a previous control event by land managers. Native tree juvenile and adult densities were compared between sites to investigate the potential effects of L. camara on species recruitment. Invasion of L. camara led to a reduction in species richness and compositions that diverged from non-invaded vegetation. Species richness was lower for fern, herb, tree and vine species, highlighting the pervasive threat of L. camara. For many common tree species, juvenile densities were lower within invaded sites than non-invaded sites, yet adult densities were similar across all invasion categories. This indicates that reduced species diversity is driven in part by recruitment limitation mechanisms, which may include allelopathy and resource competition, rather than displacement of adult vegetation. Management of L. camara initiated community recovery by increasing species richness, abundance and recruitment. While community composition following L. camara management diverged from non-invaded vegetation, vigorous tree and shrub recruitment signals that long-term community reinstatement will occur. However, secondary weed invasion occurred following L. camara control. Follow-up weed control may be necessary to prevent secondary plant invasion following invader management and facilitate long-term community recovery.  相似文献   

6.
Across the U.S., multiple species of riparian vegetation have proven to be effective filters of sediment and nutrients in agricultural watersheds. Research at Southern Illinois University Carbondale has focused on giant cane [Arundinaria gigantea (Walt.) Muhl.] as a potential candidate to incorporate into riparian buffer designs. In 2001, an exploratory study (i.e., Phase I) monitored nutrient and sediment concentrations from surface runoff and groundwater in the Cypress Creek watershed, while two subsequent studies (i.e., Phase II) focused on groundwater quality and added additional riparian buffer plots in the Big Creek and Cache River Watersheds. The primary objective of this research was to compare nutrient attenuation in groundwater of native giant cane and forest riparian buffers. Results from phase I showed significant nutrient reductions in groundwater over short distances in both the giant cane (~3.0 m) and forest buffers (~6.0 m), thus additional wells were installed at 1.5 and 12.0 m for the second phase. Groundwater NO3 -N was significantly reduced by 90% in the initial 3.0 m of the giant cane buffer, where plant assimilation and microbial denitrification were likely key NO3 -N removal mechanisms. Phase II showed significant reductions in groundwater NO3 -N beneath the forest buffers, whereas little change occurred below the giant cane buffers. However, NO3 -N concentrations beneath giant cane buffers were 3 times less than those observed beneath the forest buffers. Follow-up studies are being conducted on the transport of E. coli through vegetated buffers, and efforts have been expanded to the watershed-scale.  相似文献   

7.
Synchrony between development of five corn hybrid varieties of various seasonal growing rates (FAO numbers), seasonal flight pattern of male cotton bollworm, Helicoverpa armigera Hb. (Lepidoptera: Noctuidae), as monitored by pheromone traps, and the subsequent appearance of newly hatched larvae on developing cobs were studied at Mezőhegyes, South-Hungary, in 2003 and 2004. The phenological stages of corn hybrids were evaluated using the Iowa State University Scale (R1–R5), the flight of male moths was monitored by large capacity, funnel type of pheromone traps and the appearance of freshly hatched larvae on developing cobs were counted by visual inspection. The synchrony between the flight peak of male moths and the peak apperance of L1 larvae on cobs was investigated by cross-correlation. In 2003 (average daily temperatures 20.7°C, average daily relative humidity 59.9% for the period of 4–18 July) “DK 391”, “DK 443” and “Maraton” hybrid varieties already reached silking stage (R1) by the time when pheromone traps indicated a peak, at 7 July (peak capture at 3-day intervals 755.5 males/traps). The number of L1 larvae peaked on developing cobs of these varieties also at 7 July (7.0, 4.0 and 3.8 larvae/50 cobs, respectively). The synchrony between the flight peak of male moths and the peak appearance of L1 larvae on cobs was proven (LAG = 0). A rather similar trend was observed in “Vilma” hybrid variety: it reached R1 stage at 7 July, and L1 larvae appeared only a few days later (11 July, 3.8 larvae/50 cobs) (LAG = −1). However, “Maxima” hybrid variety reached R1 stage 1 week later (14 July) than the time of peak captures. Here L1 larvae peaked as late as at 18 July (0.8 larvae/50 cobs), i.e., only after the cob had reached R1 stage (LAG = −3). A reverse order of dates of R1 stage and peak capture was observed in “Maxima” in 2004 (average daily temperatures; 22.5°C, average daily relative humidities 72.6% for the period of 15 July–6 August): it reached R1 stage at 19 July, while peak trap captures were recorded at 6 August (peak capture at 3-day intervals 20.5 males/traps). L1 larvae were found in the highest numbers on 2 August (1.5 larvae/50 cobs), practically in synchrony with peak caputres (LAG = 0). “Káma” reached R1 stage in 16 July, and L1 larvae peaked at 2 August (1.3 larvae/50 cobs) (LAG = 0). On the rest of the corn varieties larvae were found only in too numbers for performing statistical analysis. We conclude that in order to predict the appearance of L1 larvae, the phenological stage of the corn variety and the seasonal flight pattern of moths, as measured by large capacity pheromone traps, should be considered in combination. If the corn variety already reached R1 stage, L1 larvae appear on cobs as early as the time of peak flight of moths. However, no young larvae appear on cobs despite of high trap captures, until the corn reaches the R1 stage. These findings are discussed in the view of specifying optimal timing of a pesticide application.  相似文献   

8.
Local forest landowner associations and broader peer-to-peer learning efforts have received attention–particularly in the United States of America–as ways to increase landowner engagement in forest planning and management. Unlike traditional technical assistance and outreach, knowledge is primarily shared among landowners as opposed to being derived from natural resource professionals. While potentially promising, few studies have investigated these approaches. Through a study of a landowner cooperative in Wisconsin, I report on a finding that considers both the effectiveness of a landowner cooperative in the Upper Midwest (USA) and the social network members rely on in decision-making. The former relies on an importance–performance analysis (IPA) of the services provided by the cooperative and the latter on an egocentric network analysis of members with an emphasis on strong and weak ties. Data were collected via a mail survey to which 146 members (81%) responded. The IPA indicates that the cooperative is providing services with which members are largely satisfied. The network analysis suggests that members, through strong ties, discuss their land with on average three others—primarily natural resource professionals (including cooperative staff), as opposed to other members, neighbors, and kin. However, by virtue of membership, they share weak ties with other members whom they see as trustworthy. The extent to which a network perspective might be applied to similar situations is discussed, as are conceptual implications and future directions. The main conclusion is that the emergence of local landowner associations and peer-to-peer learning requires research methods that better capture the social nature of these new directions.  相似文献   

9.
During the last few years following the invasion of European tomato crops by the invasive South American tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), several indigenous larval parasitoid species were recorded as natural enemies of this pest. Necremnus cf. artynes (Walker) and to a lesser extent Stenomesius sp. nr. japonicus (Ashmead) (Hymenoptera: Eulophidae) have been frequently reported attacking T. absoluta in tomato greenhouses in Europe and they are considered as possible biocontrol agents. Few biological data are available on these two species, notably when they parasitize T. absoluta. Therefore, the present study documents their biology when parasitizing T. absoluta, and provides scientific bases for potential development of biological control programs relying on larval ectoparasitoids in invaded areas. We demonstrated the ability of the two parasitoid species to reproduce on T. absoluta as host on tomato plants. On average, N. cf. artynes female parasitized 28.5 larvae and killed 26.2 larvae during its life time whereas S. sp. nr. japonicus female was more long-lived and consequently more efficient; it parasitized 144.3 larvae and killed 90.1 larvae. In a second step, we also explored the effect of T. absoluta larvae instar on parasitism by S. sp. nr. japonicus and subsequent development of the parasitoid offspring. Best results were obtained with the third larvae instar with a higher number of offspring produced, bigger individuals and a higher proportion of females. Our results support the hypothesis that the two species are good candidates for biological control programs targeting T. absoluta in Europe.  相似文献   

10.
Fuel hazards have increased in forests across the United States because of fire exclusion during the 20th century. Treatments used to reduce fuel buildup may affect wildlife, such as shrews, living on the forest floor, especially when treatments are applied repeatedly. From mid-May to mid-August 2006 and 2007, we used drift fences with pitfall traps to capture shrews in western North Carolina in 3 fuel reduction treatment areas [(1) twice-burned (2003 and 2006), (2) mechanical understory cut (2002), and (3) mechanical understory cut (2002) followed by 2 burns (2003 and 2006)] and a control. We captured 77% fewer southeastern shrews (Sorex longirostris) in mechanical + twice-burned treatment areas than in mechanical treatment areas in 2006, but southeastern shrew captures did not differ among treatment areas in 2007. Total shrew captures did not differ among treatment areas in either year. Decreases in leaf litter, duff depth, and canopy cover in mechanical + twice-burned treatment areas may have decreased ground-level moisture, thereby causing short-term declines in southeastern shrew captures. Prescribed fire or mechanical fuel reduction treatments in the southern Appalachian Mountains did not greatly affect shrew populations, though the combination of both treatments may negatively affect some shrew species, at least temporarily.  相似文献   

11.
The invasive mealybug Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae) is a plant feeding insect believed to be native to Southern Asia or Australia. This mealybug has become established in many regions throughout the world (including the Caribbean and North America) in the past 100 years and is currently expanding its range in South America. Because this insect is of concern as a potential pest of many plant species, this review is provided to summarize knowledge of M. hirsutus based on past research that may be most useful for addressing the current invasion of South America by the species, and to identify gaps in information that may need to be addressed to inhibit the spread of the insect and improve management methods for this and similar organisms. In most areas into which M. hirsutus has expanded its range it is commonly suppressed by native or introduced natural enemies. Therefore, besides preventing introduction, establishment and spread of this potential pest, efforts should be made to determine if natural enemies of M. hirsutus are present in areas of concern (i.e., where the mealybug may be introduced and become established). Such information will enable determination of the need for introduction or augmentation of biological control agents in response to possible entry and establishment of the mealybug in new areas. Methods developed in response to the recent invasion of the Caribbean and North America by M. hirsutus may serve as models for addressing the threat of this and similar invasive pests in South America and elsewhere.  相似文献   

12.
Sika deer (Cervus nippon) sometimes cause extensive damage to planted tree seedlings. To evaluate the effects of culling on the spatial distribution patterns of sika deer and browse damage to planted seedlings, we compared the data collected before and after experimental culling in a cool, temperate, mixed forest on Kyushu Island, Japan. Experimental culling, conducted in an area of 1 km2, removed five, four and two sika deer in April, June and October 2011, respectively. During the year before culling, the spatial pattern of the number of sika deer caught on camera corresponded to the predicted sika deer density. Sika deer immediately browsed planted seedlings after the initial planting. The cumulative number of browsed seedlings increased over time, especially in winter. The spatial pattern of the cumulative number of sika deer caught on camera corresponded to that of browsed seedlings at the year’s end. During the year when culling was conducted, the number of sika deer caught on camera decreased around the center of the study site where the culling was conducted and the number of browsed seedlings decreased. During the year following culling, the cumulative number of browsed seedlings was very similar to that in the year before the culling, while the same low number of sika deer was caught on camera. These results indicate that the effects of deer culling resulted in decreased levels of sika deer appearance and browse damage for more than 1 year and for several months, respectively.  相似文献   

13.
Shrinkage of green cane (Arundo donax L.) was measured during air-drying at room temperature. The cane began to shrink at 150% moisture content due to a remarkable collapse of parenchyma cells. The collapse recovered after boiling in water, but more serious collapse (recollapse) was induced by the following drying. On the other hand, the collapse recovered almost completely after steaming with saturated water vapor at 92°–96°C without recollapse. By comparing the thickness of cane specimens before and after steaming, the degree of cell collapse remaining in dry cane was evaluated. When the green cane was frozen prior to drying, the degree of collapse was reduced whereas the drying rate remained unchanged. The effect of prefreezing was interpreted as the generation of air bubbles in the cell lumen which hinder the effective loading of liquid tension on the cell wall. Even when the cane was carefully dried using a conventional method used by reed manufacturers, the degree of collapse was very large and it increased with elevating internode position.  相似文献   

14.
薇甘菊的危害与防除研究   总被引:1,自引:0,他引:1  
薇甘菊作为我国南方重要的入侵危害植物,近年来迅速蔓延。对农业、林业发展造成了极大危害。本文对薇甘菊的危害、防除的最新研究进展进行了综述。为进一步有效防除薇甘菊提供参考。  相似文献   

15.
To determine whether Monochamus alternatus can use the Japanese cedar (Cryptomeria japonica) as a host tree, experiments were conducted in a laboratory using three insect populations of different localities. Adult females chose Pinus densiflora bolts as oviposition substrate when supplied with cedar and pine bolts simultaneously, whereas some females from one locality oviposited on cedar bolts when supplied with them exclusively. Seventy-three percent of 40 eggs hatched in cedar bolts. When the first instar larvae were inoculated on cedar bolts, the development was stunted greatly and all died during the larval stage. Two of 20 larvae that were inoculated on cedar bolts at the third instar entered the diapause and one larva developed into an adult female, which produced viable eggs but was much smaller than those obtained from pine bolts. The results did not exclude the possibility that M. alternatus can use recently killed C. japonica trees as a host.  相似文献   

16.
While early efforts to establish protected areas often excluded local people, modern approaches in many countries now seek to involve local communities in ways that are appropriate to the objectives for the protected area. In the Lao People's Democratic Republic (Lao PDR), a protected area management system was established in 1993. In many cases, the new protected areas had land-use conflicts with inhabitants who depended on the areas for their living. This study was undertaken in a protected area in the northwest of the Lao PDR. The primary objective was to identify and gain experiences from a feasible approach for improvement and implementation of protected area management with a positive interaction between people and the natural environment. An integrated land-use planning approach was adopted. It included participatory methods for data capture and analysis, including the use of a simple simulation model, the ‘Area Production Model’ (APM) aiming at evaluating different options for land use and primary production. The outcome of the study was positive in the sense that this integrated land-use planning approach was found to be well adapted to the needs of the protected area management system.  相似文献   

17.
Abstract

Research indicates that natural resources managed in common, resembling traditional commons such as the Swedish forest commons, could be a type of regime with the potential to stimulate successfully sustainable use conditions. This is supported by findings regarding the characteristics of Swedish forest commons, their claimed concern for the environment and relatively high proportion of old forest in two out of three regions. Swedish environmental policy is directed towards environmental quality objectives and the Sustainable Forests objective states, among other things, that biological diversity must be maintained and enhanced. Swedish National Forest Inventory data for the period 2003–2006 were used to analyse differences between forest commons in northern Sweden and other ownership categories regarding the proportion of forestland with a large deciduous element, the proportion of forest older than 80 years with a large (> 25%) deciduous element, the volume of dead wood and the proportion of forest older than 140 years, parameters corresponding to the interim targets for enhanced biological diversity. The results show no consistent differences in indicator variables between the forest commons and other ownership categories, signifying that forests managed in common have been conducted in ways promoting biodiversity more effectively than in other ownership categories. Further studies of different ownership categories regarding driving forces and forest status are warranted.  相似文献   

18.
Relative to closed-canopy tropical forests, tree seedlings planted in open grown areas are exposed to higher light intensity, air temperatures, vapor pressure deficit, and greater seasonal fluxes of plant available water than mature tropical forests. The species-specific adaptive capacity to respond to variable precipitation and seasonality in open grown conditions, therefore, is likely to affect species performance in large-scale reforestation efforts. In the present study, we compared the photosynthetic characteristics of eight tropical tree species within and between seasons at two study sites with contrasting dry season intensities. All species except Pseudosamanea guachapele reduced leaf physiological function between the wet and dry seasons. The contrasting severity of seasonal drought stress at the study sites constrained growth rates and photosynthetic characteristics differently. Variation of photosynthetic characteristics at the species level was high, particularly in the dry season. Faster growing species at the less seasonal site, Terminalia amazonia, Inga punctata, Colubrina glandulosa, and Acacia mangium, exhibited a greater adaptive capacity than the other species to down-regulate leaf photosynthesis between seasons. As the dry season was more severe at the more seasonal site, most species strongly reduced physiological function regardless of relative growth rates, except two species (Tectona grandis and P. guachapele) with widespread distributions and relatively high drought tolerance. Our results underscore the need to consider seasonal drought tolerance when selecting tree species for specific reforestation sites.  相似文献   

19.
Trends in global wildfire potential in a changing climate   总被引:1,自引:0,他引:1  
The trend in global wildfire potential under the climate change due to the greenhouse effect is investigated. Fire potential is measured by the Keetch-Byram Drought Index (KBDI), which is calculated using the observed maximum temperature and precipitation and projected changes at the end of this century (2070–2100) by general circulation models (GCMs) for present and future climate conditions, respectively. It is shown that future wildfire potential increases significantly in the United States, South America, central Asia, southern Europe, southern Africa, and Australia. Fire potential moves up by one level in these regions, from currently low to future moderate potential or from moderate to high potential. Relative changes are the largest and smallest in southern Europe and Australia, respectively. The period with the KBDI greater than 400 (a simple definition for fire season in this study) becomes a few months longer. The increased fire potential is mainly caused by warming in the U.S., South America, and Australia and by the combination of warming and drying in the other regions. Sensitivity analysis shows that future fire potential depends on many factors such as climate model and emission scenario used for climate change projection. The results suggest dramatic increases in wildfire potential that will require increased future resources and management efforts for disaster prevention and recovery.  相似文献   

20.
We compared the effects of three fuel reduction techniques and a control on the relative abundance and richness of reptiles and amphibians using drift fence arrays with pitfall and funnel traps. Three replicate blocks were established at the Green River Game Land, Polk County, North Carolina. Each replicate block contained four experimental units that were each approximately 14 ha in size. Treatments were prescribed burn (B); mechanical understory reduction (M); mechanical + burn (MB); and controls (C). Mechanical treatments were conducted in winter 2001–2002, and prescribed burns in March 2003. Hot fires in MB killed about 25% of the trees, increasing canopy openness relative to controls. Leaf litter depth was reduced in B and MB after burning, but increased in M due to the addition of dead leaves during understory felling. The pre-treatment trapping period was short (15 August–10 October 2001) but established a baseline for post-treatment comparison. Post-treatment (2002–2004), traps were open nearly continuously May–September. We captured a total of 1308 species of 13 amphibians, and 335 reptiles of 13 species. The relative abundance of total salamanders, common salamander species, and total amphibians was not changed by the fuel reduction treatments. Total frogs and toads (anurans) and Bufo americanus were most abundant in B and MB; however, the proximity of breeding sites likely affected our results. Total reptile abundance and Sceloporus undulatus abundance were highest in MB after burning, but differed significantly only from B. Mean lizard abundance in MB was highest in 2004 and higher than in other treatments, but differences were not statistically significant. Our results indicate that a single application of the fuel reduction methods studied will not negatively affect amphibian or reptile abundance or diversity in southern Appalachian upland hardwood forest. Our study further suggests that high-intensity burning with heavy tree-kill, as in MB, can be used as a management tool to increase reptile abundance – particularly lizards – with no negative impact on amphibians, at least in the short-term.  相似文献   

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