Control of Echium plantagineum L.with 2, 4-D and grazing management

This paper describes a field experiment conducted in north-east Victoria investigating the control of Echium plantagineum L. in a pasture with 2, 4–D and grazing management. Spraying with a small dose of 2, 4-D (0–14 kg a.i./ha) in late autumn/early winter, followed about 2 weeks later by heavy grazing, removed E. plantagineum from the pasture, whilst the associated pasture species, Trifoliutn subierraneum L., was retained. Continuous grazing without spraying also resulted in good control of E. plantagineum. Herbage production of the pasture in winter was, however, reduced by spraying. The reasons underlying these observations, and farm management programmes for the longterm control of E. plantagineum, are discussed.     

Effects of grazing intensity on seed production of Caragana stenophylla along a climatic aridity gradient in the Inner Mongolia Steppe,China

As the increases of climatic aridity and grazing intensity,shrubs play an increasingly important role in grassland ecosystem in arid and semi-arid regions,and its abundance also generally increases.However,the effects of climatic aridity and grazing intensity on sexual reproduction of shrubs in grassland remain largely unclear.In order to understand the effects of grazing intensity and climatic drought stress,and their interaction on seed production of shrub species,we examined the seed number,seed weight and seed yield of Caragana stenophylla under three grazing intensities(fenced,mild grazing and severe grazing) across a climatic aridity gradient(semi-arid,arid,very arid and intensively arid zones) in the Inner Mongolia Steppe,northern China during 2012–2013.The seed number,seed weight and seed yield gradually increased from the semi-arid to the very arid zones,but decreased from the very arid to the intensively arid zones in fenced plots.The seed number and seed yield decreased from the semi-arid to the intensively arid zones in mild and severe grazing treatment plots,therefore,grazing enhanced the suppression effect of climatic aridity on seed production of C.stenophylla.The seed number and seed yield gradually decreased as grazing intensity increased.The seed weight was highest in severe grazing plots,followed by the mild grazing plots and then the fenced plots.Precipitation varied interannually during the study period.We observed that the seed number,seed weight and seed yield were lower in the low precipitation year(2013) than in the high precipitation year(2012).As climatic drought stress increased,the negative effects of grazing on seed production of C.stenophylla also gradually increased.Our results indicated that climatic drought stress may contribute to the encroachment of C.stenophylla shrub in arid zones by promoting its seed production.However,grazing had negative effects on sexual reproduction of C.stenophylla,and the combined effects of drought stress and grazing seriously suppressed sexual reproduction of C.stenophylla in the intensively arid zone.     

Effects of dormant insecticide treatments on the San Jose scale (Homoptera: Diaspididae) and its parasitoids Encarsia perniciosi and Aphytis spp . ( Hymenoptera: Aphelinidae )

Populations of the San Jose scale (SJS), Quadraspidiotus perniciosus (Comstock), and its parasitoids, Encarsia perniciosi (Tower) and Aphytis spp. were monitored with double-sided sticky tape and pheromone traps in an almond orchard. A total of 1.21 ha plots within the orchard were treated during winter dormancy with several insecticides, including horticultural mineral oil alone, oil combined with the organophosphate diazinon at different dilution rates, and oil combined with the pyrethroid esfenvalerate in a completely randomized block design. Higher volume diazinon applications (3750 and 1870 l ha -1 ) proved effective against SJS crawlers, as did esfenvalerate. The higher volume applications had greater deposition on Kromecoat ® cards placed in the top of the tree canopy, where SJS is most abundant. The lower-volume (935 l ha -1 ) application of diazinon provided control of first-generation crawlers similar to the other diazinon applications, but it was generally less effective in controlling subsequent generations. All insecticide treatments were associated with a reduction of parasitoid numbers, especially the esfenvalerate application.     

不同放牧制度对荒漠草原短花针茅空间异质性的影响

在不同放牧制度下,以荒漠草原短花针茅植物种群为研究对象,采用GS＋软件和地统计学分析方法对其空间异质性分布进行了研究。结果显示：对照区和划区轮牧区或自由放牧区都表现出很强的空间自相关性,且结构是导致短花针茅空间变异的主要因素。对照区、划区轮牧区和自由放牧区,短花针茅空间格局的分形维数相近,都接近于2。不同放牧制度下短花...     

短花针茅荒漠草原土壤种子库对不同放牧强度的响应

在内蒙古短花针茅荒漠草原,采用野外随机定点取样与室内萌发相结合的方法,对不同放牧强度下围封草地土壤种子库的密度、垂直结构、多样性、丰富度、均匀度、以及种子库与地上植被的相似性进行了研究。结果表明,在各试验区土壤种子库主要分布在0～20cm土层,占种子库总密度的87%～96%;随着放牧强度的增加,土壤种子库总密度减少,同时地上植被与土壤种子库的相似物种数减少,种子库组成的相异性增加;轻度放牧对土壤种子库中一二年生草本所占比例影响较小,而中度和重度放牧使土壤种子库中一二年生草本所占比例增加;土壤种子库的物种丰富度、多样性、均匀度均随放牧强度的增加而减小。     

Impacts of livestock grazing on a savanna grassland in Kenya

The dynamics of most rangelands in Kenya remain to be poorly understood.This paper provides baseline information on the response of a semiarid rangeland under different livestock grazing regimes on land inhabited by the Massai people in the east side of Amboseli National Park in Kenya.The data were collected from grasslands designated into four types:(1) grassland from previous Massai settlements that had been abandoned for over twenty years;(2) grassland excluded from livestock grazing for eight years;(3) a dry season grazing area;and (4) a continuous grazing area where grazing occurred throughout all seasons.Collected data included grass species composition,grass height,inter-tuft distance,standing grass biomass and soil characteristics.The results indicated that continuous grazing area in semiarid rangelands exhibited loss of vegetation with negative,long-term effects on grass functional qualities and forage production,whereas grassland that used traditional Maasai grazing methods showed efficiency and desirable effects on the rangelands.The results also showed that abandoned homestead sites,though degraded,were important nutrient reservoirs.     

放牧与封育对沙质草地植被特征及其空间变异性的影响

采用经典统计和地统计学的方法,定量分析了放牧与封育沙质草地植被盖度、丰富度、平均高度、密度和Shannon-Wiener指数的变化及其对植被空间结构特征的影响。结果表明:封育沙质草地植被盖度、平均高度和Shannon-Wiener指数显著大于放牧草地(P<0.01),但两者丰富度变化不显著(P>0.05)。封育草地与放牧草地植被盖度、丰富度和Shannon-Wiener指数的变异系数分别为14.3%,24.4%,13.5%和17.8%,25.7%,21.7%,前者小于后者。在本研究尺度上,封育沙质草地植被盖度以及封育与放牧草地植被密度的空间变异规律均能较好地拟合成球状模型,封育沙质草地植被丰富度和Shannon-Wiener指数以及放牧草地植被盖度、丰富度和Shannon-Wie-ner指数的空间变异规律均能较好地拟合成指数模型。封育与放牧草地植被盖度、丰富度、密度和Shannon-Wiener指数的空间自相关度C/(Co C)分别为70.7%,56.5%,51.0%,68.7%和50.1%,73.3%,70.0%,68.9%,表明封育与放牧草地各变量均具有中等的空间相关性。封育草地所有变量半方差函数值均小于放牧草地。封育草地和放牧草地的植被盖度、丰富度、Shannon-Wiener指数变程分别是36.73 m,85.02 m,161.91 m和24.98 m,5.64 m,51.78m,前者大于后者。放牧草地植被的空间变异性强、破碎化程度高,封育草地植被的空间依赖性强、变异性弱。     

Reduced agent-area treatments (RAAT) for management of rangeland grasshoppers: Efficacy and economics under operational conditions

The Reduced Agent-Area Treatment (RAAT) approach involves applying low rates of insecticides in intermittent swaths to control grasshopper infestations in an effort to achieve a more economically and environmentally sound pest management strategy compared to traditional blanket applications at high rates. Operationalscale (>250 ha) insecticide tests on Wyoming rangeland grasshopper infestations (18-56 grasshoppers/m2) at two sites in 1997 revealed that carbaryl yielded 94% control as a blanket treatment (560 g/ha) and 81% control as a RAAT application (280 g/ha applied to 50% of the infested land). Malathion yielded 90% control as a blanket treatment (683 g/ha) and 91% control as an RAAT application (342 g/ha applied to 80% of the infested land), and fipronil (4 g/ha) yielded 98% control as a blanket treatment and 92% control when applied to 33% of the infested land. One year after treatment, the RAAT and blanket-treated plots had 2-4% (Pollet Ranch) of the densities in untreated plots. Economic analysis showed that the greatest benefit:cost ratio was obtained with the fipronil-RAAT method, followed by carbaryl-RAAT, malathion-RAAT, malathion-blanket, fipronil-blanket, carbaryl-blanket. The worst-case outcome of fipronil and carbaryl with a RAAT approach had a greater economic return than the best-case outcome of no treatment. Following blanket treatments, non-target arthropod abundance was highest in the fipronil plots, followed by carbaryl and malathion; arthropod biomass was higher in the carbaryl plots than fipronil and malathion. In RAAT plots, arthropods were generally less impacted than in the blanket plots, with the least reduction caused by fipronil and carbaryl. Thus, the RAAT tactic appears to be economically and environmentally superior to blanket treatments under large-scale, operational conditions.     

连续放牧对沙质草地植被盖度、土壤性质及其空间分布的影响

在科尔沁典型沙质草地,设置不同放牧强度的4块样区:重牧区、中牧区、低牧区和封育对照区。连续放牧4年后,通过统计学分析及方差均值比、秩相关系数和分维数等方法,分析了植被平均盖度、多样性指数和土壤颗粒组分、土壤养分含量(有机碳和全氮)在各样区的变化及其空间分布。结果表明,(1)沙质草地的植被平均盖度、多样性指数均随放牧强度的增加而降低,植被平均盖度对放牧的反应比多样性指数更为敏感,变化幅度更大;植被在各样区均为聚集分布,但随聚集程度随放牧强度的降低而降低;(2)不论放牧强度大小,植被平均盖度在4个样区均受到土壤养分的制约作用,而土壤颗粒组分对植被的影响随放牧强度的降低逐渐减弱;(3)通过比较植被平均盖度和土壤某些指标在4个样区的分维数值认为,在科尔沁沙质草地,放牧强度应保持在低牧水平,更高的放牧强度将导致植被和土壤特征的空间分布格局产生大的改变,可能导致沙漠化。     

Response to the insecticide chlorpyrifos by arthropods on maize canopy

We assessed the response of maize canopy arthropods to the insecticide chlorpyrifos. Four 0.3 ha (18 2 180 m) plots were divided into two subplots, a control and a treated area. During tasseling of the plants, the treated area was sprayed twice, with an interval of 3 days. Ten plants were sampled: 1 day before spraying, and 7, 14, 21 and 28 days after spraying. The insecticide had no effect on insect herbivores: a high density of Spodoptera frugiperda larvae was present in the treated plots. A few predator arthropod species were negatively affected by the insecticide, but their numbers or activity increased 2 weeks after the treatment of the plots. A canonical variate analysis showed no pronounced effect of the insecticide on arthropod communities; the largest variations on species abundance were related to sampling occasion. These results can be explained by the combination of the short period of chlorpyrifos residual activity on the plant surface and the great potential for recolonization of the areas by most of the monitored arthropods.     

放牧和封育条件下科尔沁沙地小叶锦鸡儿群落土壤种子库特征

以科尔沁沙地小叶锦鸡儿群落为研究对象,对比分析了放牧干扰和不同封育年限下土壤种子库特征。结果表明:①放牧和封育样地土壤种子库均以一年生植物为主,物种丰富度没有明显差异;②放牧样地土壤种子库密度为(3 475±519)粒/m2,封育6年和封育12年样地土壤种子库密度分别为(20 241±1 714)粒/m2和(28 777±3 946)粒/m2,显著高于放牧样地;③Shannon-W iener多样性指数、S impson多样性指数和P ielou均匀度指数在放牧样地分别为1.36,0.68和0.56,并随着封育年限的增加而降低;④放牧和封育样地土壤种子库主要分布于0~2 cm的土壤表层,封育样地各层的种子库密度均显著高于放牧样地;⑤放牧和封育样地土壤种子库均为聚集分布,但放牧样地种子库的空间异质性高于封育样地。     

伊犁绢蒿(Seriphidium transiliense)个体功能性状对短期禁牧的可塑性响应

为了探讨禁牧对植物个体功能性状的影响,在新疆呼图壁县、玛纳斯县及昌吉市阿什里乡对短期禁牧下蒿类荒漠草地建群种伊犁绢蒿(Seriphidium transiliense)的个体表型特征、构件生物量及其分配比进行了测定。结果表明:伊犁绢蒿个体功能性状对短期禁牧的响应因禁牧地点的差异而有所不同,呼图壁和玛纳斯样地的大多性状如株高、地上生物量、叶片数、叶生物量均呈显著增加(P 0. 05),而昌吉样地多数功能性状虽为增加,但均不显著。总体分析可知,短期禁牧后伊犁绢蒿的株高、地上生物量、叶片数、茎生物量、叶生物量依次显著增加21. 32%、48. 97%、104. 50%、50. 18%、100. 00%(P 0. 05),根颈直径、一级及三级分枝数出现显著下降,而二级分枝数、生殖生物量、各构件生物量分配比变化不显著。伊犁绢蒿个体表型性状与其构件生物量及分配比间均具有显著的联动效应,且短期禁牧可引起其部分个体功能性状间的相关关系发生显著改变。研究表明,短期禁牧促进伊犁绢蒿个体功能性状的恢复,利于退化蒿类荒漠草地的恢复。     

A World-Wide Organization to Promote the Development of Biological Control

Abstract

Three experiments were conducted to evaluate the efficacy of metribuzin in tea fields. These were a field trial in plots infested with a wide range of weeds, a pot experiment using Paspalum conjugatum and a microplot experiment with 100 Ageratum conyzoides plants/plot. Metribuzin at 0.70, 1.05, 1.40 and 2.10 kg a.i./ha was applied in 450 l water/ha. All rates were satisfactory after 1 week but residual activity increased with application rate; metribuzin at 2.10 kg a.i./ha was significantly superior after 6 weeks. Control after 8 weeks was reduced due to the presence of resistant species. Against Paspalum conjugatum metribuzin at 1.40 kg/ha gave good control for 8 weeks but 2.10 kg/ha was necessary for 12 weeks control. All rates compared favourably with dalapon (4.48 kg a.i./ha). Against Ageratum conyzoides metribuzin at all rates gave good control for up to 12 weeks and significantly better than 2, 4-D at 1.12 kg a.i./ha. Most other grass and broadleaved weeds were satisfactorily controlled at 1.40 kg a.i./ha. Metribuzin with its marked post-emergent effect and prolonged soil residual activity from 6-12 weeks after application, depending on weed species, may become an important tool in pre-monsoon weed control programmes in tea fields. It did not induce any phytotoxic symptoms on mature tea.     

围栏与不同放牧强度对东祁连山高寒草甸植被和土壤的影响

在东祁连山高寒草地,对围栏7年和不同放牧强度的草地进行了物种数、地上生物量、地下生物量、土壤理化性质等研究。结果表明,围栏7年的高寒草地鲜草产量为425.8 g·m-2,显著高于夏季中牧159.3 g·m-2和夏季重牧91.0 g·m-2,但与冬季轻牧、夏季轻牧差异不显著。围栏条件下的物种数为26.3种·16 m-2,显著低于其他放牧条件下的物种数,但显著高于夏季重牧条件下的物种数23.0种·16 m-2;轻度或重度放牧都会使物种数减少,夏季中牧下的物种数最高(33.5种·16 m-2)。在0~10 cm的表层土壤中,围栏7年的草地根系生物量显著高于其他放牧强度。随着放牧强度的增加,根系生物量在0~10 cm土壤中呈下降趋势,在30~40 cm土壤中则表现为升高趋势。围栏7年的土壤容重低于其他放牧强度下的土壤容重,但差异不显著;夏季重牧的土壤容重显著高于围栏7年和其他放牧强度的土壤容重。随着放牧强度的增加,0~10 cm土壤碱解氮增加,围栏7年草地最低。围栏封育可有效改善和恢复草地植被,但不能长时间禁牧不进行放牧利用。合理的放牧能够维护高寒草甸草地生态系统功能、促进物种丰富度和土壤营养的均衡。     

Herbicide Research on Groundnut and Sorghum under Farmer Conditions in the Indian Semi-arid Tropics

Abstract

Plots 17 × 5 m were laid out in farmers' fields in three villages. Treatments (replicated thrice) included atrazine (0.5 or 1.0 kg a.i./ha) on sorghum and nitrofen (0.75 and 1.5 kg a.i./ha) on groundnuts with or without hand-weeding or farmers normal weed control. Groundnuts were unfertilized, sorghum received 20 or 80 kg N/ha. Cooperating farmers were allocated plots for traditional weed control, other operations were carried out by research staff. Some plots were discounted because farmers withdrew cooperation or did not participate correctly or because of flooding. In groundnuts nitrofen alone was inferior to nitrofen + one hand-weeding. In sorghum there were no differences between high and low fertilizer regimes. Atrazine gave superior yields to farmers' weed control. All treatments were better than the unweeded control. Generally farmers fields had low weed populations due to good, timely control and low soil fertility. Herbicides are not economic at present. Problems associated with research in farmers fields included: selection of farmers who would participate correctly, variability between different farmers' weeding practices and between different fields due to previous crops and cultural practices; lack of control of farmers weeding operations and the distance of experimental plots from the research station. The authors suggest that small experiments with only 4-6 treatments are easier for participating farmers to comprehend, selecting suitable size and shape of plots is important and that if many farmers are involved the number of replicates can be reduced.     

内蒙古半干旱地区沙质过牧草地的沙漠化过程

为了掌握我国北方半干旱地区沙质放牧草地的沙漠化过程，在内蒙古东部的科尔沁沙地进行了为期5年的放牧试验。结果表明，在牧草利用率为70％的过牧条件下，草地植被盖度、高度、个体大小和根量急剧降低，第5年分别只有10.1％、1.0cm、2.5cm^3／株和18.7g/m^2（0－30cm土层内），是禁牧区的12.0％．3.02％．0.86％和22.1％。同时，家畜觅食活动增加，对草地践踏作用增强，如第5年其单位面积的蹄印6数和每只羊单位面积的蹄印数达到36.4n/m^2和8.5n/m^2，分别是轻牧区的9.6倍和8.25倍，土壤紧实度是禁牧区的3.75倍。植被盖度、高度、根量和植物个体普遍降低，家畜喜食植物首先从草地中退出后，草地开始出现小块裸斑，随着过牧的继续，这种裸斑迅速增加和扩大，使之相互连接成为大片裸地，如试验当年过牧区裸斑数仅为19个，而且73.7％≤2.5m的裸斑，到第3年裸斑数迅速增至358个，＞2.5m的裸斑比例从26.3％增加到31.3％，裸地率由1.8％增加到35.8％，第5年裸斑平均长度由2.4m增加到4.1m，＞2.6m的裸斑比例增至45.7％，裸地率达到了51.6％。当地面出现裸斑后，即使冬季不进行放牧，在风力的作用下草地中的裸地面积也会自然扩大，如第5年秋季过牧区的裸地率为51.6％，到第6年春季自然扩展到71.6％。裸地出现以后，冬春季在风力作用下地面迅速出现风蚀，过牧区第3年70％的测点发生风蚀，平均风蚀深度8.5cm，第5年90％的测点发生风蚀，平均风蚀深度25cm，最大风蚀深度90cm，地面呈现出凹凸不平的风沙地貌。研究结果表明，试验期间夏季放牧啃食对地表裸露的贡献率为41.3％，而冬春季节土壤风蚀对地表裸露的贡献率高达58.7％，这说明在内蒙古半干旱风沙区地表一旦裸露，马上就会因风蚀而迅速扩大。     

放牧对荒漠灌丛草地土壤团聚体组成及其稳定性的影响

以内蒙古阿拉善盟荒漠草地为研究对象,分析了不同放牧强度对土壤理化性质、团聚体组成、养分含量及其稳定性的影响.结果表明:与轻度放牧相比,重度放牧使0～5 cm、5～10 cm和10～20 cm土层土壤有机C和全N含量显著降低,土壤容重显著增加;各土层中土壤团聚体以0.053～0.25 mm粒径为主,放牧强度的增加造成土壤...     

Rehabilitation Experiment at Menzel Habib,Southern Tunisia

This long - term rehabilitation experiment is located near Menzel Habib, in the arid zone of southern Tunisia in a site with unambiguously degraded vegetation and soil, caused by a decades - old practice of overexploitation (grazing and plow agriculture). The fundamental premise is that by reintroducing an appropriate combination of native perennial plants, a simplified version of a previously occurring vegetation (and ecosystem) could be reinstated that would utilize the sparse and irregular water resources available in an efficient and complementary fashion, while also showing considerable resistance and resilience to moderate livestock grazing. The long - term goal is, on the basis of such a simplified system, to progressively achieve, through additional reintroductions and other manipulations, a state similar to that of the "ecosystem of reference," an example of which is provided in the nearby Bou Hedma National Park. In this paper we report various aspects of the experiment related to germination and establishment of four supposed keystone species (Rhanterium suaveolens, Plantago albicans, Stipa lagascae, and Cenchrus ciliaris) sown in field conditions, and compared to the ecosystem of reference for a number of parameters related to the structure and functioning of the ecosystems under study. Over a 4 - year period, distinct changes in the desired direction were observed in the experimental plots, and positive effects of controlled grazing were also recorded.     

Studies on the effect of deltamethrin sprays on the numbers of epigeal predatory arthropods occurring in arable fields

The effect of spraying winter rape and winter wheat with deltamethrin on the numbers of epigeal Carabidae, Staphylinidae and Linyphiidae caught in pitfall traps was studied in Northern Germany in 1980 and 1981. Two experiments were performed with each crop, deltamethrin being sprayed at 7.5 g a.i. ha^?1 in 300 litres of water in springtime on rape, and in midsummer on wheat. Sprayed plots were rectangles of 2 and 3 ha; unsprayed plots were squares of 0.5 ha each (two replicates). Ten pitfall traps were placed per replicate at least 3 weeks before spraying and were left for at least 3 weeks after spraying, the traps being emptied weekly. Beneficial Carabid species which have been shown already to have an economic significance, were rare during this study, but four other species (three of them were autumn breeders) were not affected by deltamethrin. At the spraying dates the autumn breeders were hidden in the soil as pupae. Three Staphylinid species, studied in only one experiment each, appeared to be strongly reduced in numbers by deltamethrin. The Linyphiid spiders were affected most heavily by deltamethrin sprayed in spring or in midsummer; the initial mortality of more than 92% lasted longer than 4 weeks, and an adverse effect was still significant in winter wheat 6 weeks after spraying. Overall, deltamethrin appears to have a broad spectrum effect concerning the epigeal predatory arthropods.     

放牧对短花针茅草原土壤微生物和土壤养分的影响及其季节动态

研究了短花针茅草原不同季节、不同放牧梯度内土壤微生物数量、土壤养分的变化及土壤微生物与土壤养分之间的相关性,结果表明:轻度放牧区(LG)和重度放牧区(HG)内土壤微生物数量春季最高,土壤微生物数量(0-10 cm)在三个放牧区内随着季节的变化均呈下降趋势。而在10-20 cm,对照区内土壤微生物数量的高峰期出现在夏季然后开始下降,轻度放牧区和重度放牧区土壤微生物随着季节的变化而下降。土壤微生物数量到了秋季在三个放牧梯度内均呈现显著性的差异,土壤养分也是在秋季出现了显著性差异(P<0.05)。土壤微生物总数在不同放牧梯度内的变化规律是对照和轻度放牧区均大于重度放牧区。土壤微生物与土壤有机质和土壤全氮呈较强的正相关。