不同啃食强度对沙拐枣影响的初步研究

在飞播区根据牧畜对沙拐枣啃食程度的不同，采用人工模拟放牧方法对牲畜啃食的绿色部分设置了10％、30％、50％、70％、90％、对照6种不同啃食强度处理，以探讨啃食强度对沙拐枣生长的影响。试验结果表明，30％啃食强度的生物量化90％的高121．37％，比对照高34．85％。沙拐枣的啃食强度在30％－50％时生物量最高，完全不利用或过度利用都会影响其正常生长。     

放牧强度对伊犁绢蒿种群特征及其群落多样性的影响

为探究放牧强度对伊犁绢蒿(Seriphidium transiliense)荒漠草地种群特征及其群落多样性的影响,2012-2014年连续3年采用野外取样和室内分析相结合的方法,对新疆昌吉市阿什里乡处于不同放牧强度下伊犁绢蒿种群特征及其群落多样性进行了研究。结果表明:随着放牧强度增加,伊犁绢蒿种群高度、盖度、生物量呈下降趋势,与对照比,放牧后分别降低了73.7%~90.9%,34.8%~95.9%,67.9%~98.1%;种群密度随放牧强度的增加呈单峰曲线变化,且在轻度放牧达到最高,较对照增加了63.4%以上;群落的Shannon-wiener指数、Pielou指数总体呈逐渐增加趋势,而Patrick指数呈先升后降再升高变化趋势。总之,随放牧强度的增加伊犁绢蒿种群特征逐渐向低矮、退化方向演替,适度放牧有利于群落结构稳定性的保持。     

不同放牧强度对羊草草原近地面反射波谱特征的影响研究

测试并分析了在生长季节不同放牧强度（无牧、中轻度和重度放牧）对羊草草原植被反射波谱特征的影响。羊草草原不同放牧强度群落的种类组成、结构和生物量特征上的明显不同，导致植被反射波谱特征表现出显著差异。不同放牧强度群落的近地面反射特征在6月底的差异最为显著，在5月底的差异最不明显。使用主分量分析（PCA）和模式识别方法，利用多时相的植被反射特征组合数据，对3个不同放牧强度的群落进行了鉴别，后者对退化草地鉴别精度较高。对不同放牧等级群落分类效果最佳的3个反射率组合包括蓝光、红光和近红外光反射率。6月底的鉴别效果最好，最大错误概率小于4％；5月底的鉴别效果最差，最大错误概率高20％左右。     

亚热带中山地区不同放牧强度与草地植物产量和放牧家畜生产性能之间的关系研究

研究了亚热带中山地区草地不同放牧强度与草地植物产量和放牧家畜生产性能之间的关系,试验结果表明,不同放牧强度对草地植物产量和放牧家畜生产性能的影响不同。在A组放牧强度的载畜量水平,草地植物利用率高,植物产量和畜产品产量低;在C组放牧强度的载畜量水平,草地植物利用率低,老草残留,植物再生力降低;在B组放牧强度的载畜量水平,草地植物的利用率为60～70％,对植物生长和利用有利。     

人工草地肉牛放牧系统夏季留茬高度试验

通过探索不同放牧强度对放牧系统人工草地优质牧草再生产力影响,在朗目山混播放牧草地牧草生长旺盛的6-8月开展了不同留茬高度对人工草地质量,牧草生长,牲畜采食量,牧草利用率等影响试验,结果表明,留茬10-12cm的牧草净产量,利用率,草地质量,牲畜采食量均最佳,是实现放牧系统人工草地合理利用和提高效益的理想留茬高度。     

不同轮牧强度对天山北坡低山带蒿属荒漠春秋场土草畜影响研究

1987年至1990年在新疆石河子紫泥泉种羊场,按春秋两季进行了不同强度的分区轮牧试验。研究结果表明,不同轮牧强度对土壤物理性状(0～30厘米)、牧草地上部产量、家畜牧草采食率、再生草产量和绵羊生产性能有显著影响(P<0.05);经本文8项指标分析评价,放牧强度以中牧,即牧草利用率50％,最为适宜,它不仅增加了草地产量(比过牧增产60％)和改善了草地组成结构(优良牧草占总产26.3％),而且有利于绵羊增重(119.5克/日·头)和羊毛生产(5.4公斤/年·头);并在本试验条件下,分四区两季轮牧的载畜量(6头/公顷)比自由放牧提高2倍。该类草地在适度放牧下,其草地群落向蒿类+多年生草本类型方向进展演替;反之,经多年过牧后,则向蒿类+一年生草本类型方向退化演替。     

放牧强度对高寒草甸草场地上生物量和牦牛生长的影响

讨论了放牧强度对高寒草甸草场地上生物量和牦牛生长的影响，结果表明：放牧强度对地上生物量和牦牛生长有显著的影响。随着放牧强度的减轻，优良牧草（禾草＋莎草）比例提高，杂草（可食杂草＋毒杂草）比例降低。在2年的试验期内，三个处理牦牛的平均总增重有显著的差异（F＝5．03＞F0．05＝3．68），进一步做新复极差测验，30％和50％之间差异不显著，但它们和70％之间的差异均显著。     

放牧强度对小叶章草甸植物生长和地上生物量的影响

在东北三江平原小叶章草甸,研究了不同放牧强度下小叶章、苣荬菜、小蓟、垂梗繁缕、蒲公英五个主要植物种群的生长以及地上生物量的季节动态。结果表明:小叶章、苣荬菜、小蓟随放牧强度增大生长速度减缓,中度放牧更能刺激垂梗繁缕的生长,放牧对蒲公英生长影响较小。地上总生物量高峰值在7月,最低值在9月,轻度放牧、中度放牧、重度放牧与不放牧比较,总生物量分别减少了26.85%、28.37%和44.64%。放牧对不同植物种群地上生物量的影响不一致。     

小叶锦鸡儿对牲畜啃食补偿效应的模拟试验研究

采用人工模拟和对比研究的方法,研究了沙地天然和人工小叶锦鸡儿被牲畜啃食后,枝条在生长上的反应.结果表明,小叶锦鸡儿对牲畜的啃食具有一定程度的补偿和超补偿能力,当啃食程度较轻时,可促进枝条的生长,增加其可食部分的生物量,即出现超补偿效应;随着啃食强度的增加,其补偿能力逐渐降低;密度较大的人工小叶锦鸡儿对牲畜啃食的补偿能力明显低于天然植株.建立了小叶锦鸡儿补偿效应模型,对补偿效应机制进行了探讨.     

不同放牧强度对牦牛生长和草地第二生产力的影响

试验研究了６种放牧强度对牦牛生长及草地第二性生产力的影响，结果表明，放牧强度对牦牛日增重有明显影响，日增重以０．２４牦牛单位／ｈｍ＾２处理组最高，达７０７．９ｇ随着放牧强度的增大，牦牛日增重明显降低。其中，放牧强度对１岁牦牛影响最大，２岁牦牛次之，３岁牦牛再次。试验全期当放牧强度于１．２牦牛单位／ｈｍ＾２时，增大放牧强度，草地第二性生产力明显提高，当放牧强度高于１．２牦牛单位／ｈｍ＾２时，增大放牧     

应用灰色关联度分析法综合评价啃食强度对紫穗槐营养价值的影响

应用灰色关联度分析法,对5组人工模拟不同啃食强度,20%,40%,60%,80%,100%(占植株地上部分的比例)下紫穗槐叶、茎,从7个营养指标,粗灰分(Ash)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、可溶性糖(WSC)、粗蛋白质(CP)、磷(P)、钾(K)间的相互关系进行了综合分析, 通过对不同啃食强度处理的关联度比较,探讨啃食强度对紫穗槐营养品质的影响。结果表明,紫穗槐在啃食强度40%时,叶、茎的加权关联度分别为0.781 2和0.651 3,大于其他啃食强度处理,即具有最佳的营养价值。     

Defoliation Effects on Herbage Production and Root Growth of Wet Meadow Forage Species

Root growth is important to the competitive ability of plants, and understanding how herbage defoliation affects root growth has implications for development of management strategies. Objectives were to determine the effects of defoliation intensity and frequency on root characteristics and herbage production of slender wheatgrass (Elymus trachycaulus [Link.] Shinners), Nebraska sedge (Carex nebrascensis C. Dewey), and “Steadfast” birdsfoot trefoil (Lotus corniculatus L.). Plants of each species were transplanted into containers that had been placed in the ground at wet meadow field sites the prior year. There were eight replications of a control and five defoliation treatments, which were combinations of different frequencies (two or five times) and intensities (light or heavy) and haying. Treatments were applied for a single growing season, and aboveground biomass was collected. Containers were extracted in October, and plant crowns, rhizomes, and roots were separated from the soil. Defoliation treatment did not affect total root weight, length, and surface area of Nebraska sedge or birdsfoot trefoil (P>0.10). Slender wheatgrass total root weight was less when defoliated five times (4.46 g·container^?1) than when defoliated twice (6.62 g·container^?1) during the growing season. More frequent defoliation of slender wheatgrass also reduced length (20%) and surface area (21%) compared to less frequent defoliation. However, defoliation frequency did not affect aboveground biomass. Defoliation intensity did not affect aboveground production or root characteristics of the three species. Abundant soil moisture in meadows likely buffers negative effects of defoliation. For all species, two defoliation events (e.g., haying followed by grazing) does not appear to negatively affect root growth and herbage production.     

Defoliation Intensity and Simulated Grazing Strategy Effects on Three C4 Rangeland Bunchgrasses

Defoliation intensity and timing are two important factors determining plants response to grazing. These factors can be managed by adjusting stocking rate and applying a grazing strategy. In a 6-yr clipping experiment conducted in northwestern Argentina, we assessed the effect of different defoliation intensities (~ 30%, ~ 50%, and ~ 70% removal of the annually produced aboveground biomass) and simulated grazing strategies (continuous grazing, two-paddock rest-rotation, three-paddock rest-rotation, dormant season grazing) on plots of three C4 native bunchgrasses (Pappophorum vaginatum, Trichloris crinita, and Digitaria californica). Response variables were mean and trend of clipped-off biomass during the 6 yr of treatments, number of inflorescences, and aboveground biomass produced on the year following treatments end (to evaluate residual effect of treatments). Results were species dependent. Mean clipped-off biomass increased with defoliation intensity in T. crinita and D. californica. However, defoliation intensity negatively affected clipped-off biomass trend in T. crinita and the production of P. vaginatum and T. crinita during “residual effect” evaluation. The three species responded positively at least in one response variable to the amount of rest periods in the grazing strategy. Our results are not fully consistent with the concept that forage production is more influenced by defoliation intensity than by grazing strategy: In two of the three species, grazing strategy presented greater impact on response variables than defoliation intensity. When significant “defoliation intensity × grazing strategy” was detected, intensity tended to be more detrimental as grazing strategy allows fewer rest periods. We observed a residual effect of treatments in the three species (generally, negative effect of defoliation intensity and positive effect of grazing strategies with more rest periods). Our results show that dormant season utilization and rest periods are beneficial for maximizing mean clipped-off biomass and ensuring clipped-off biomass trend. High defoliation intensities can maximize short-term clipped-off biomass, but it may produce negative residual effects and trends.     

Effect of intensity and frequency of defoliation on aerial growth and carbohydrate reserve levels in Acacia karroo plants

Acacia karroo trees were defoliated by goats at two intensities and four frequencies; 2, 4, 8 and 12‐weekly. Leaf accumulation and carbohydrate reserve levels were compared to a non‐defoliated control, and to plants (defoliation controls) which were defoliated for the first time that season each time a frequency treatment was defoliated. These plants are activated by defoliation in such a manner that successive defoliations can result in this activation being additive. There is clearly a defoliation level below which they are not activated. Activation appears to be negated to a degree by defoliations at 2 and 4‐weekly frequencies, relative to the 8‐weekly defoliation frequency. The 12‐weekly frequency at heavy defoliation produced less than the same defoliation at 8‐weekly frequency. The 2‐weekly frequency treatments produced as much leaf as the 4 and 12‐weekly defoliations at the same defoliation intensity. The more frequently plants were defoliated, the more carbohydrate reserves dropped. However, plants adjusted to cope with very frequent defoliations. There was no connection between leaf accumulation and carbohydrate reserve levels following the different frequencies and intensities of defoliation.     

建植第1年刈割对黑麦草+白三叶草地杂草空间格局的影响

栽培草地稳定性是近年来草地建植与管理的核心问题之一,其中草地抗杂草入侵是其稳定性的重要表现形式。本研究应用地统计学分析方法,分析了刈割处理下多年生黑麦草(Lolium perenne)+白三叶（Trifolium repens）混播草地杂草生物量空间分布的异质性。结果表明,不同刈割强度下,多年生黑麦草+白三叶混播草地入侵杂草地上生物量空间格局异质化程度及其相关范围变化比较明显。变异函数的基台值(C0+C)在不同刈割强度下的变化表明,在重度刈割条件下,杂草地上生物量空间分布异质性最高(12.530),对照条件下次之(4.751),轻度刈割条件下较低(4.557),中度刈割条件下最低(3.149)。变异函数的相关范围(A0)表明,在重度刈割条件下空间相关范围最大(1 004.1 cm),中度刈割条件下最小(122.1 cm),轻度刈割 (161.9 cm)和对照(219.1 cm)条件下居中。空间变异比分析表明,由空间自相关因素引起的空间异质性占主要部分(50.3%～93.5%)。空间分布格局图(Kriging map)分析进一步显示,不同刈割强度下多年生黑麦草+白三叶混播草地杂草地上生物量格局变化显著。     

刈割频次对高寒草甸群落特征和初级生产力的影响

在甘南州玛曲县典型高寒草甸区,对不同刈割频次下草地初级生产力基本特征的变化进行研究。结果表明:莎草科和禾本科的物种对多次刈割的耐受性较高,而杂类草较为敏感,部分物种甚至会在高频次刈割下消失,毒害草则会在多次刈割的干扰下得到促进。在生长季内,对草地实施2~3次刈割利用,不仅不会对物种多样性造成不利影响,反而有利于物种多样性的提高;相反,若仅于生长季后期(9月中旬)刈割1次或刈割次数超过4次,则可对物种多样性产生明显的负面影响。就地上生物量而言,最佳刈割频次为2次(7月15日和9月15日)和3次(6月15日、7月30日和9月15日);就粗蛋白产量而言,最佳刈割频次为3次,且显著高于刈割2次的处理。采用在牧草产量峰值期1次性测产的方法核定草地载畜量,必须考虑在实际利用方式下所产生的草地超补偿效应,并以相应的差异率对牧草产量进行校正。     

The response of Acacia karroo plants to defoliation of the upper or lower canopy

The response of Acacia karroo trees to defoliation of either the upper or lower canopy only, was compared experimentally with that of plants whose whole canopies had been defoliated at a range of defoliation levels. These plants were very sensitive to defoliation of the upper canopy. A 100% defoliation of the upper canopy only, resulted in the same amount of growth as 100% defoliation of the whole canopy. This was considerably less than the growth of plants defoliated overall, at 25% and 50% leaf removal. In contrast, defoliating the bottom half of the canopy only, stimulated growth in the whole canopy to the same degree as defoliation of the whole canopy at 25–50%. The increases of growth were due largely to increased growth in the top half of the canopy. Plants were very sensitive to defoliation in the early‐flush phenophase. This probably masked the positive effects of the partial defoliations applied at this phenophase.     

三华李化学脱叶药剂筛选试验研究初报

迫使三华李提早落叶,可以实现三华李二次开花,从而进行反季节促早栽培。以4～5年生三华李果树为对象,通过喷施脱落酸、乙烯利、噻苯隆、石硫合剂等药剂进行生长季脱叶试验。结果表明：全株喷施45%石硫合剂10～15倍液总体效果最好,药后30天脱叶率可达80%以上,老叶脱叶彻底,只剩树体顶端嫩叶,且脱叶速度较缓,有利于树体营养的积累,同时还可起到清园的作用;乙烯利脱叶速度快,效果好,喷药后15天脱叶率达到100%,但易产生药害,对三华李树体影响较大,不推荐后续使用。     

不同放牧强度下绵羊采食方式的变化特征

本研究将绵羊对禾本科植物的采食方式主要分为摘叶、拔芯和去顶3种类型.研究发现采食方式受植物种类、季节和放牧压的影响.对羊草(Leymus chinensis)的采食方式以去顶和摘叶为主, 对芦苇(Phragmites communis)的采食方式以去顶和拔芯为主.具体表现为,羊草的去顶率,8月以前随放牧强度减小、季节推移而降低,8月后则相反;摘叶率随放牧压增加和时间推移大致是先增加后减少;拔芯率随放牧压的增加而增大,6月最高,9月最低;总体上,未被采食的羊草比例随放牧压降低而增大,在生长季后期相应增加.芦苇去顶率随时间推移先降低后增加;拔芯率在6月随放牧压减小而降低,其它月份里主要随放牧压减小而升高,从整个生长季看,芦苇拔芯率在6月初最大;芦苇摘叶率的变化受前2种采食方式制约;未被采食的芦苇比例随放牧压降低而增加,但在7月后中牧要比轻牧和重牧低,在放牧干扰下,生长季里未被采食的芦苇比例在8月达最大.     

Effect of the intensity and phenophase of defoliation and water stress on the rate of photosynthesis and the recovery of carbohydrate reserves in acacia karroo hayne

Abstract

A field study was conducted with Acacia karroo plants to determine changes in relative photosynthetic rates, the extent of carbohydrate reserve depletion and the rate reserves take to recover, following defoliation by goats at different intensities and phenophases, at a “wet” and a “dry” site.

The rate of photosynthesis of fully expanded leaves increased markedly following defoliation. Light defoliation increased photosynthetic rate the most. Total non‐structural carbohydrate levels dropped significantly after defoliation. The magnitude of decrease was directly related to the intensity of defoliation.

Following the heavy defoliations, recovery of carbohydrate levels was much faster than after the light defoliations. Rates of recovery were also faster following defoliation in the second half of the growing season, than in the first half. However, the plants that had been heavily defoliated in the second half of the growing season had not fully recovered carbohydrate levels before leaf fall in late autumn.

Moisture stress had very little effect on carbohydrate levels in comparison with the defoliation treatments.