Predation on invasive cane toads (Rhinella marina) by native Australian rodents

Journal of Pest Science - The success of an invasive species can be reduced by biotic resistance from the native fauna. For example, an invader that is eaten by native predators is less likely to...     

Effect of Rhabdias pseudosphaerocephala on prey consumption of free-ranging cane toads (Rhinella marina) during Australian tropical wet seasons

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.     

Species-site matching in mixed species plantations of native trees in tropical Australia

Mixed species plantations using native trees are increasingly being considered for sustainable timber production. Successful application of mixed species forestry systems requires knowledge of the potential spatial interaction between species in order to minimise the chance of dominance and suppression and to maximise wood production. Here, we examined species performances across 52 experimental plots of tree mixtures established on cleared rainforest land to analyse relationships between the growth of component species and climate and soil conditions. We derived site index (SI) equations for ten priority species to evaluate performance and site preferences. Variation in SI of focus species demonstrated that there are strong species-specific responses to climate and soil variables. The best predictor of tree growth for rainforest species Elaeocarpus grandis and Flindersia brayleyana was soil type, as trees grew significantly better on well-draining than on poorly drained soil profiles. Both E. grandis and Eucalyptus pellita showed strong growth response to variation in mean rain days per month. Our study generates understanding of the relative performance of species in mixed species plantations in the Wet Tropics of Australia and improves our ability to predict species growth compatibilities at potential planting sites within the region. Given appropriate species selections and plantation design, mixed plantations of high-value native timber species are capable of sustaining relatively high productivity at a range of sites up to age 10 years, and may offer a feasible approach for large-scale reforestation.     

An evaluation of scarification methods for seeds of two leguminous trees

Twenty different methods of seedcoat scarification were tested on Gleditsia triacanthos L. and Robinia pseudoacacia L. to find an alternative to acid scarification for these species. For germination testing, nicking or burning were best, and these same methods could be used in small nurseries with adequate labor. For larger quantities, hot water soaks or heat shock soak treatments yielded satisfactory, though lower, germination.     

澳大利亚辐射松考察报告

通过对澳大利亚辐射松的现场考察参观、学习培训、学术交流与讨论,对澳大利亚在辐射松种源选择、苗木快繁培育、丰产栽培、集约经营、遗传改良、病虫害防治、木材采伐、加工利用等方面进行归纳叙述,了解到澳大利亚的辐射松人工林发展思路和趋势,经营和管理水平,经营理念、技术与方法等,对四川省大规模引种栽培辐射松具有十分重要的借鉴作用。     

Determination of cations and anions in the ashes of some medicinally used tropical woods

Summary The ashes of some medicinally used tropical woods were characterised. These were Afzelia africana, Alstonia congensis, Antiaris africana, Terminalia ivorensis, Azadirachta indica, Ricinodendron heudelotti, Chlorophora excelsa and Daniellia ogea. The ashes were obtained by treating wood in a muffle furnace, after which the ashes dissolved in distilled water. The very alkaline solutions obtained were analysed for Na⁺, K⁺, Ca²⁺, Mg²⁺, Mn²⁺, Fe²⁺, Cu²⁺, Cl^-, SO ₄ ^2- and PO ₄ ^3- . Due to wide medicinal application of these wood species experiments were made to determine the cations and anions which may be active ingredients in the compounds (drugs) used in the treatment of differet ailments.The authors are thankful to A. Amusan of Soil Science Department, Obafemi Awolowo University, Ile-lfe for technical assistance     

Foliar temperature tolerance of temperate and tropical evergreen rain forest trees of Australia

Australian rain forests extend from tropical climates in the north to temperate climates in the south, providing an opportunity to investigate physiological responses to temperature of both temperate and tropical species within the same forest type. Eight, rain forest canopy tree species were selected to cover the 33 degrees latitudinal range of rain forests in eastern Australia. Temperature tolerance was measured in 6-year-old plants grown in a common environment, by exposing leaves to a series of high temperatures during late summer and a series of freezing temperatures during midwinter. Damage was evaluated based on chlorophyll fluorescence measurements made 2 h after exposure and by visual assessment of leaf damage made a week after exposure. Leaves of the tropical species were more heat tolerant and less frost tolerant than leaves of the temperate species, which is consistent with their climate distributions. In contrast, the temperature tolerance of the photosynthetic apparatus was unrelated to climate in a species' native habitat. However, the tropical species underwent significant photoinhibition during winter. All species maintained the integrity of the photosynthetic apparatus and avoided tissue damage over a similar span of temperatures (about 60 degrees C), reflecting the similar annual temperature ranges in Australia's temperate and tropical rain forests. Chlorophyll fluorescence measurements and visual assessment of leaf damage provided different estimates of the absolute and relative temperature tolerances of the species, thus emphasizing the importance of a direct assessment of tissue damage for determining a species' temperature tolerance.     

Internal friction measurement of tropical species by various acoustic methods

A batch of 54 tropical species was analyzed using free-vibration and forced-released vibration tests. The free-vibration tests were conducted by bending and compression using nylon thread or elastic thread as supports. The wood species used cover a broad spectrum of density values and were obtained from the CIRAD wood collection. Samples were stabilized at a mean moisture content of 11.1%. The goals of the study were (a) to observe the effects of nylon or elastic supports on the measurement of vibration damping, (b) to compare the damping measurements obtained through free vibration in bending and in compression, (c) to understand the relationship between temporal damping and internal friction based on free-vibration and forced-vibration bending tests, and (d) to observe the effect of frequency on bending free-vibration damping on a rosewood specimen (Dalbergia sp., Madagascar). In this study we were able to demonstrate that (a) the type of support has a significant influence on the measurement of the temporal damping, (b) the temporal damping measurements obtained during bending free vibration are linearly linked to those obtained during compression vibration, (c) the expression of internal friction η _V according to temporal damping α was identical during compression and bending free vibration: η _V = α/(πf), and (d) changes in temporal damping α according to frequency f can be modeled in the form α = β ₁ f ² - β ₂ f ⁴. This form is theoretically justified as the first-order form obtained from the generalized differential equation of linear viscoelasticity.     

An ecosystem approach to biodiversity effects: Carbon pools in a tropical tree plantation

This paper presents a synthesis of experiments conducted in a tropical tree plantation established in 2001 and consisting of 22 plots of 45 m × 45 m with either one, three or six native tree species. We examined the changes in carbon (C) pools (trees, herbaceous vegetation, litter, coarse woody debris (CWD), and mineral topsoil at 0-10 cm depth) and fluxes (decomposition of CWD and litter, as well as soil respiration) both through time and among diversity levels. Between 2001 and 2009 the aboveground C pools increased, driven by trees. Across diversity levels, the mean observed aboveground C pool was 7.9 ± 2.5 Mg ha⁻¹ in 2006 and 20.4 ± 7.4 Mg ha⁻¹ in 2009, a 158% increase. There was no significant diversity effect on the observed aboveground C pool, but we found a significant decrease in the topsoil C pool, with a mean value of 34.5 ± 2.4 Mg ha⁻¹ in 2001 and of 25.7 ± 5.7 Mg ha⁻¹ in 2009 (F_1,36 = 52.12, p < 0.001). Assuming that the biomass C pool in 2001 was negligible (<1 Mg ha⁻¹), then the plantation gained in C, on average, ∼20 and lost ∼9 Mg ha⁻¹ in biomass and soil respectively, for an overall gain of ∼11 Mg ha⁻¹ over 8 years. Across the entire data set, we uncovered significant effects of diversity on CWD decomposition (diversity: F_2,393 = 15.93, p < 0.001) and soil respiration (monocultures vs mixtures: t = 15.35, df = 11, p < 0.05) and a marginally significant time × diversity interaction on the loss of total C from the mineral topsoil pool (see above). Monthly CWD decomposition was significantly faster in monocultures (35.0 ± 24.1%) compared with triplets (31.3 ± 21.0%) and six-species mixtures (31.9 ± 26.8%), while soil respiration was higher in monocultures than in mixtures (t = 15.35, df = 11, p < 0.001). Path analyses showed that, as diversity increases, the links among the C pools and fluxes strengthen significantly. Our results demonstrate that tree diversity influences the processes governing the changes in C pools and fluxes following establishment of a tree plantation on a former pasture. We conclude that the choice of tree mixtures for afforestation in the tropics can have a marked influence on C pools and dynamics.     

林业常用16种杀虫剂对赤眼蜂的急性毒性和安全性评价

采用管测药膜法测定了16种杀虫剂对松毛虫赤眼蜂的急性毒性,并进行安全性评价。急性毒性测定的结果表明:苏云金杆菌、球孢白僵菌、灭幼脲、杀铃脲、甲氧虫酰肼、苦皮藤素对松毛虫赤眼蜂毒性较低,其LR50均高于9.16×10-3mg·cm-2,为低风险性药剂。甲氨基阿维菌素苯甲酸盐、啶虫脒、噻虫啉、辛硫磷、高效氯氟氰菊酯、吡虫啉、氟虫腈和阿维菌素对松毛虫赤眼蜂毒性较高,其LR50分别是2.28×10-4、9.81×10-5、5.23×10-5、2.43×10-5、1.39×10-5、4.33×10-6、2.10×10-6和1.92×10-6mg·cm-2,安全性评价均为高风险性和极高风险性。敌敌畏对松毛虫赤眼蜂的毒性最高,其LR50是1.11×10-6mg·cm-2;其次为虫螨腈,LR50是1.31×10-6mg·cm-2,对松毛虫赤眼蜂伤害均较严重。     

An evaluation of methods for characterising and monitoring gum arabic of commerce and related Acacia gums

Summary Three methods that have been suggested as inexpensive for characterisation of gum arabic were evaluated in characterising and monitoring gum arabic of commerce. The methods were; physico-chemical and carbohydrate analysis (analytical), determination of molecular mass by gel permeation chromatography (gpc) and an Enzyme Linked Immunosorbent Assay (ELISA). The results revealed that gpc provides quick and consistent information on gum arabic of commerce from Acacia senegal. It was able to detect the three chemical species; Arabinogalactan protein complex (AGP), Arabinogalactan (AG) and Glycoprotein (GP) fractions that are typical of A. senegal and could differentiate gum from the two varieties of A. senegal, i.e., var. senegal and var. kerensis on the basis of the enhanced UV peaks in the later. It was able to distinguish gums from different Acacia species as well as suspected contaminants. The analytical method could differentiate between the two varieties of A. senegal on the basis of optical rotation, protein content and viscosity which were noted as basic parameters for comparison. However, where the proposed FAO (1990) specifiction was applied in its present form, it failed to adequately characterise gum from var. kerensis as gum arabic. Secondly, natural product variability i.e., the observed between sample variation made the method to have limited application in adequately characterising gum arabic from even a single source. The method was able to distinguish gums from the other Acacia species purely on the basis of optical rotation though information on nitrogen and sugar composition was also invaluable. Generating data on the composition of sugars requires time that militates against the method as a slow process. Because of the overlap in the analytical parameters for some samples, it could be adequately characterise two of the samples that were presented as suspected contaminants. Nonetheless, by combining information of gpc and analytical data, a better evaluation of the gums was achieved. The method of Elisa has a future scope but will require refining it by utilising monoclonal antibodies to be developed for it to be more specifc in characterising gum arabic from A. senegal. The authors wish to thank Dr. P. A. Williams of the North East Wales Institute, Deeside, Clwyd, UK for the use of the gpc and Elisa facilities. B.N.C. is grateful to the Kenyan and British governments for financial support.     

A multi-criterion index for the evaluation of local tropical forest conditions in Mexico

Despite the ecological and economical importance of tropical forests they are currently affected by human activities, mainly through deforestation and selective extraction. With the aim of making an opportune diagnosis of the condition of forests, we developed an ecological index based on qualitative and semi-quantitative data, allowing a quick diagnosis in order to manage and conserve tropical forests. We evaluated 44 plots of tree vegetation, measuring canopy height, number of strata, tree cover, dominant trees, number of tree species, as well as the management of and damage to the forest. The data of each parameter was classified in categories of 3, 4 or 5, which were normalized between 0 and 1 for the worst and best characteristics, respectively. For the purpose of analysis, the average, a set of IF–THEN rules, and fuzzy logic were applied and as a result we obtained a model that measures the ecological condition of the tropical forests. The model has the advantages of having an ecological basis, allows data to be gathered quickly and is clear and easy to manage and interpret. When running the model, the value of each intermediate variable is displayed, thus allowing the detection of where necessary action is required to improve the ecological condition of the forest. We expect this index to contribute in evaluating the effectiveness of forest management and possibly offer advice for the short-term management and conservation of the remnants of tropical forests.     

热带四种按树人工林的土壤指标对氮肥反应的评价

较低氮利用性经常会导致桉树人工林的减产.为检验氮矿化的土壤指标的利用并预测桉树对添加氮肥的响应,研究四种桉树人工林(印度海岸低洼地2种细叶桉人工林和和喀拉拉邦高地的2种巨桉人工林)对添加氮肥和相关季节性氮矿化以及其他氮利用率指标的响应,测定几种生化指标对氮肥的响应,包括全氮,土壤C:N比和在厌氧、有氧孵化过程中释放的氮.结果表明,在4块实验地里,增加氮肥可以相应的提高生产率7%至70%;在有氧孵化过程中,释放的氮与氮肥间有最显著相关性(R2=0.92,p<0.01).与有氧孵化过程中释放的氮相比,季节性土壤氮矿化作用是一个较差的肥料响应的指标.虽然有的指标有很好的应用价值,但在广泛应用之前还需验证测试.     

Drought responses of an exotic tree (Eriobotrya japonica) in a tropical cloud forest suggest the potential to become an invasive species

New Forests - Eriobotrya japonica is a non-native tree expanding in secondary forests and threatening the tropical montane cloud forest of central Veracruz, Mexico. Our objective was to investigate...     

Influence of forest clearing methods on nutrient uptake of some tropical food crops

The adverse effects of forest clearing on crop yield have often been directly ascribed to decline in soil fertility. However, the effect of various forest clearing methods on crop nutrient uptake as reflected by the content in the leaf tissues has been the subject of few scientific investigations. A study to determine the effect of forest clearing on nutrient content of some arable crops was, therefore, carried out in the tropical rainforest of south-western Nigeria. Three forest clearing methods—mechanical, semi-mechanical and manual clearing—were used, while maize, cowpea, and cassava were the test crops. Nutrient content in the tissues of these crops was assessed by sampling maize ear leaves at silking, youngest mature leaves (YML) of cowpea at flowering and YML of 3-month-old cassava for analysis. Correlation analysis was carried out to establish the relationship between nutrient content and crop yield. The method of forest clearing had no significant effect on the nutrient content of maize and cowpea during the first cropping cycle. However, nutrient content of maize in the manually cleared plots was higher than those in the semi- and mechanically cleared plots for all elements analyzed except Mg. Nitrogen content of cowpea was much higher than that of maize. Except for P and K, the nutrient content of cassava was not markedly different among the forest clearing methods. Calcium and P content in the leaves of maize and cassava varied inversely with their levels in the soil, implying that crop uptake could have accounted for the differences in their availability within the soil. Nitrogen, P and K had significant positive correlations with maize yield (r = 0.77, 0.89, and 0.71). Potassium content also had significant positive correlation with cassava root yield (r = 0.69). This is not surprising because compared with other crops, cassava requires large amounts of K for starch formation and root development. It is concluded that differences observed in crop yields under different forest clearing methods are a function of nutrient uptake and availability within the soil. However, the uptake of some nutrients does not seem to be determined by the level of soil availability alone. This study was supported with a research grant from the International Foundation for Science (IFS), Sweden.     

Mechanical relaxation processes due to sugars in cane (Arundo donax L.)

The storage modulus and the mechanical loss tangent of untreated, extracted, and sugar- impregnated canes (Arundo donax L.) were measured over a temperature range of –150° to 0°C at low frequencies. Two relaxation processes, labeled and , were detected in the ranges –60° to 0°C and –120° to –100°C, respectively. The and processes shifted to lower temperatures with increasing moisture content. The process was detected only in the canes containing sugar. The magnitude of its loss peak increased with an increase in sugar content. It was speculated that the process was due to some interactive molecular motions of the adsorbed water and sugar. The process, detected in all of the canes, was attributed to the motion of the adsorbed water in the amorphous cell wall substances.     

Components of the water balance for tree species under evaluation for agroforestry to control salinity in the wheatbelt of Western Australia

The soil water balance technique was used to study evaporation from two fodder tree species, tenEucalyptus species and annual pasture over a three year period after planting in the Western Australian wheatbelt. Evaporation is the total water loss by the processes of transpiration, evaporation from the soil surface and evaporation of water intercepted by plant canopies.Evaporation from both fodder trees and from seven of theEucalyptus species was greater than from pasture for one or more of the study years. The maximum difference in evaporation between trees and pasture was 82, 84 and 70 mm in the first, second and third study years, respectively. Higher evaporation from trees was associated with greater depletions in soil water than occurred beneath pasture. Upward movement of water from wet soil beneath the root zone was found under trees, with a maximum flux of 30 mm observed over a one year period beneathE. camaldulensis.The water use efficiency of fodder trees was significantly higher than for mostEucalyptus species, due to greater yields from fodder trees. Biomass production was found to be a good indicator of the water use of eucalypts over the first two years of growth, but the relationship between productivity and water use was found to differ for species with tree and mallee forms. In the third year of study, obvious differences in the relation between water use and yield were observed for some species of eucalypts with high evaporation.     

土地复垦适宜性评价方法

以土地复垦适宜性评价研究的发展为主线,着重介绍了5类方法,即:极限条件法、指数和法、模糊综合评价法、可拓法、人工神经网络模型法.通过对不同方法的优缺点进行分析比较,并对土地复垦适宜性评价研究的最新发展趋势进行了预测和展望,为土地复垦工作提供了有效的工具.     

A case study of shelterbelt effect on potato (Solanum tuberosum) yield on the Atherton Tablelands in tropical north Australia

An experimental study was conducted on the Atherton Tablelands of tropical north Australia to quantify the shelterbelt benefit to the production of potato (Solanum tuberosum). Wind speed, wind direction and potato yield were measured at various distances from the leeward side of the shelterbelt. Non-linear modelling was used to describe the relationship between potato yield and distance from the shelterbelt. With the developed model, definite integral was used to calculate the net increase percentage of potato yield.Wind speed was greatly reduced by the shelterbelt. Potato yield was increased by 6.7% due to the shelterbelt.It appears that fitting non-linear models is a useful method to determine an accurate net increase of crops from shelterbelts, providing an accurate assessment of the average crop yield on the open areas is achieved.