草原小知识

<正>什么是草原?草原是指由草本植物和灌木为主的植被覆盖的土地,包括天然草原和人工草地。天然草原包括草地、草山和草坡。人工草地是指通过人工种植牧草而形成的草地,包括改良草地和退耕还草地。为什么要保护和建设草原?我国草原面积近4亿公顷,约占国土总面积的2/5。草原有着重要的生态、经济和社会功能:(1)草原是我国面积最大的绿色生态屏     

西藏人工种草的潜在生态系统服务权衡分析

在现有生态系统及农业生态学理论基础上,从耦合生态过程及人为管理驱动两种驱动机制,分析了西藏人工种草的潜在生态系统服务权衡,并探讨了优化人工种草中生态系统服务权衡的方法。分析表明:人工种草可以大幅提高牧草产量,但由于干物质积累耦合水分能量循环,人工草地初级生产力的大幅增加会提高蒸散,降低地表温度,而植被盖度增加会减少地表反射率,提高白天地表温度,从而影响草地气候调节服务;但若管理不当,会降低土壤碳固定、碳吸收服务、土壤保持服务和水质净化服务,还会造成水源涵养服务的变化。今后研究方向应结合样方尺度实验和景观尺度模型,筛选和研发优化技术和管理体系,降低人工草地生态系统服务权衡。     

北京平原地区不同土地利用类型对土壤颗粒组成及其分形特征的影响

选取农田、撂荒草地、人工乔木林、人工灌木林和次生林5种不同土地利用类型土壤颗粒为研究对象,采用Microtrac S3500激光粒度仪测定土壤样品粒径,利用土壤分形学理论和方法,分析不同土地利用类型对土壤颗粒组成及其分形特征的影响。结果表明,土壤粒径在不同土地利用方式下存在显著差异,其中撂荒草地以砂粒为主,农田、人工乔木林、人工灌木林和次生林以粉粒为主;次生林、人工乔木林黏粒体积分数最大,且显著大于其他土地利用类型,撂荒草地最小;次生林、人工乔木林、人工灌木林粉粒体积分数最大,且显著大于农田与撂荒草地;砂粒体积分数则与粉粒相反。土壤分形维数的大小依次为撂荒草地＜农田＜人工灌木林＜次生林＜人工乔木林;土壤分形维数与土壤黏粒含量、粉粒含量均呈显著正相关,与土壤砂粒含量呈显著负相关。     

不同退化状态高寒草甸人工恢复与自然恢复比较

根据草地植被群落发展规律,利用数学和统计学、投入产出法等方法,对高寒草甸类不同退化状态草地自然恢复和人工恢复进行了经济预测和效益比较,数据证明：在重度→中度恢复中,人工恢复较自然恢复效益高;在中度→轻度恢复中,自然恢复较人工恢复效益高,为草地建设科学决策提供了可靠依据。     

塔尔巴哈台山地不同海拔野生鸭茅植株形态特征的比较

<正>鸭茅是禾本科优良冷季型牧草之一,具有叶量丰富、营养价值高、适应性强等特点,在人工草地建植、水土保持及植被恢复中占有重要地位。鸭茅在北美已有200多年的种植历史,在新西兰、澳大利亚、英国、法国、意大利等国的植被中亦占有重要地位。我国是鸭茅起源地之一,野生鸭茅资源丰富,全国已发现野生鸭茅生长地约26个。其分布较为广泛,主要分布于新疆天山及阿尔泰山、西南地区、江西、湖南、大兴安岭等地海拔1 000～3 000 m以上的森林边缘、灌丛及山坡草地。国内外许多学者研究证明,鸭茅作为栽培种对人工草地的建植具有重要的意义。     

政策法规

<正>我国两成可利用草地实施禁牧休牧轮牧截至2005年底,我国有20％的可利用草地实施了禁牧、休牧和划区轮牧。同时,全国人工种草累计保留面积达1459万hm2,草地改良面积达 1583万hm2,草地围栏面积达3789 万hm2。     

龙里县紫花苜蓿的利用效益初探

龙里县地处苗岭山脉的中段 ,是长江流域乌江水系与珠江流域红水河水系的支流分水岭地区。全县草地面积 540 0 hm2 ,占土地总面积的 35.5% ,其中可利用面积 4 2 6 35hm2 。全县海拔一般在 1 0 80～ 1 50 0 m之间 ,年均气温 1 4 .8℃ ,降雨量为 1 0 89.3mm,4～ 9月为雨季 ,无霜期 2 56 d,日照 1 1 6 0 h。气候条件良好 ,适应各种牧草生长和种植。贵州省林业科学研究院于1 999年在龙里县设立试验点 ,针对原有的草地产量低 ,土地肥力下降 ,缺乏优良牧草的问题。把优良豆科牧草——紫花苜蓿以退耕还草的模式 ,加以推广应用。通过试验示范草场的建…     

昭通市退化草地修复技术研究

昭通市草地以山地草甸为主,草地生态系统脆弱,管理水平和建设能力不高,退化草地修复难度大。昭通市现有草地面积116 079.33 hm²,其中退化草地面积6 992.10 hm²,占全市草地总面积的6.02%。退化草地主要以轻度退化为主,面积4 221.00 hm²。草地退化的原因包括人为因素、有害生物侵入、生态环境脆弱和气候因素。文章给出近自然修复、人工促进修复、人工草地建植和综合修复等退化草地修复措施,并提出加快草种基地建设、规范草地管理、生态优先、因地制宜等草地修复策略。     

防护林对沙地草地的防护功能

１９８７～１９９６年，在阜新市阿尔乡白音花沙地草地系统进行了防护林对沙地草地植物群落的影响；主要牧草蒸腾效率的影响；土壤养分的影响；土壤水分的影响；主要小气候因子的影响；主要牧草物候期的影响；土壤物理特性的影响；产草量的影响；在放牧条件下植被动态的影响；放牧功能的影响等试验，从不同侧面探讨了防护林对沙地草地的功能。     

防护林对沙地草地的防护功能

１９８７～１９９６年，在阜新市阿尔乡白音花沙地草地系统进行了防护林对沙地草地植物群落的影响；主要牧草蒸腾效率的影响，土壤养分的影响，土壤水分的影响；主要小气候因子的影响；主要牧草动候期的影响；土壤物理特性的影响；产草量的影响，在放牧条件下植被动态的影响；放牧功能的影响等试验，从不同侧面探讨了防护林对沙地草地的功能。     

Pasture production and composition under poplar in a hill environment in New Zealand

Traditionally, poplar (Populus spp.) have been planted to control erosion on New Zealand’s hill-slopes because of their capacity to dry out and bind together the soil. Two systems: (1) widely spaced, planted poplar for soil conservation, and (2) non-eroded open pasture were compared to determine the relative effect of the poplar–pasture system on the production, nutritive value and species composition of the pasture, and on the water balance. Measurements were made at three sites with mature poplar (>29 years and 37–40 stems ha⁻¹) and at a replicated experiment with young poplar (5 years, 50–100 stems ha⁻¹). Soil water relations did not suggest strong competition for water between poplar and pasture. Pasture accumulation under mature poplar was 40% less than in the open pasture, but under young poplar was similar to that in the open pasture. Chemical composition of pasture suggested that feed quality of pasture in the open was better than under the poplar canopy, except during spring, when most chemical components were similar. At the most, in vitro digestibility of pasture dry matter was 8.9% lower and metabolisable energy of pasture dry matter was 1.5 MJ kg lower under the poplar canopy than in the open pasture. Shade tolerant species were not dominant in the plant community under the poplar canopy with grasses such as browntop (Agrostis capillaris, L.) and ryegrass (Lolium perenne, L.) being a high proportion of the plant community. Differences in chemical composition were related to differences in the botanical composition between the open pasture and the poplar understorey. It was concluded that the greatest effect of poplar was on pasture production due to shading, and that management of this silvopastoral system needs to focus on control of the tree canopy to lessen the decrease in pasture production.     

不同草场利用方式下土壤物理性状变化的对比研究

以克鲁伦河下游地区典型草原为研究对象,以传统游牧作为对照,研究探讨了围栏放牧草场利用方式下土壤物理性质变化规律,其研究结果如下:土壤含水量为游牧区>打草场区>轮牧区;土壤容重为轮牧区>打草场>游牧区;在夏营盘0～10 cm土层中孔隙度的比较结果为:游牧区>打草场区>轮牧区。在冬营盘各土层中土壤孔隙度比较结果是,游牧区>打草场区>轮牧区。土壤砂粒含量为游牧区<打草场区<轮牧区,细粉粒含量游牧区、轮牧与打草场区间均有显著差异,夏营盘和冬营盘的粘粒含量为轮牧区<打草场区<游牧区。     

Silvopastoralism in New Zealand: review of effects of evergreen and deciduous trees on pasture dynamics

Complex interactions between livestock, trees and pasture occur in silvopastoral systems. Between trees and pasture, competition for soil resources (nutrients and water) occurs, becoming especially relevant when one of them is in scarce supply. Trees reduce light and water reaching the understorey layers according to tree density and canopy size. However, they may ameliorate extreme climatological features (reducing wind speed and evapotranspiration, and alleviating extreme temperatures), and improve soil properties, for example, deciduous tree litter may contribute to increased pH and soil nutrient concentrations. During tree establishment, there are generally negligible effects on pasture, irrespective of tree type. However, there is a decline in pasture production and nutritive value under shade with increasing tree age and higher stand density. Under the same conditions, deciduous trees affect pasture later (extinction point of pasture occurs at 85% of canopy closure) than evergreen trees (about 67% for Pinus radiata D. Don). This is mainly because deciduous trees have a leafless period that enables pasture recovery, and their litter smothers pasture less intensely because of its relatively fast decomposition. Silvopastoral studies conducted in New Zealand are reviewed to discuss these effects, and differences in the effects of evergreen and deciduous trees are shown using the examples of P. radiata, and Populus and Salix spp. respectively, which exist in many temperate countries. Future research needs are outlined.     

Liveweight changes of sheep grazing a range of herbage allowances underPinus radiata agroforestry regimes

A range of improved pasture herbage feed allowances (1 to 5 kg dry matter/head/day) were offered to young sheep, grazing underPinus radiata grown at 0, 50, 100 and 200 stems per hectare. Six trials were conducted, each for 30 days duration between spring 1986 and autumn 1988, at tree age 13–15 years. Mean liveweight gain over all trials for 0 (open pasture), 50, 100 and 200 stems per hectare were 170, 155, 136 and 94 g/sheep/day, respectively. Liveweight gain increased curvilinearly with increasing pasture allowance at all tree stockings and tended to level off above 3 kg green dry matter/head/day. Green matter pasture in vitro digestibility of the green pasture fraction changed little with increasing tree stocking despite changes in pasture composition. Pine needle accumulation under the higher tree stockings depressed the quality of the total feed on offer. Livestock performance under low tree stocking agroforestry regimes can be satisfactory, providing pasture management encourages fresh nutritious feed.     

Developing a canopy closure model to predict overstorey/understorey relationships in Pinus radiata silvopastoral systems

Silvopastoral models require the development of the relationship between understorey pasture production, and the overstorey tree production. The Tikitere agroforestry trial, located near Rotorua in the Bay of Plenty, was established in Pinus radiata at a range of stockings in 1973, and monitored for stand parameters, understorey pasture production, and livestock carrying capacity between 1976 and 1992. A canopy closure model, developed for radiata pine plantations in the Bay of Plenty, shows a strong relationship (R2 ≈ 0.92) between canopy closure and the stand parameters of basal area and the ratio of green crown length to mean top height. Canopy closure was predicted for the Tikitere stands using the canopy closure model. A strong linear relationship (R2 ≈ 0.89) was shown to exist between the measured pasture production, and the predicted canopy closure. This indicates that direct assessment of canopy closure combined with a measurement of understorey pasture production, may be a simpler and more cost effective research technique than relying entirely on the continuous measurement of understorey pasture in the development of understorey/overstorey relationships. This revised version was published online in June 2006 with corrections to the Cover Date.     

辽西北地区林草及林药综合开发技术研究

林草、林药间作,林木为牧草和药材提供蔽阴条件,同时,林下间作牧草、药材,有利于改良林地土壤理化性质,增加肥力,促进林木生长。采取林草、林药间作的杨树,经精耕细作,与未采取林草、林药杨树对比,平均每年胸径增加了78.31%,高生长增加了186.58%。因此,在辽西北地区林草、林药间作是可推广的配置模式。奇可利、蒙古冰草、羊草是适于本地区种植的优良牧草;林间种植牧草、药材可获得较好经济效益。     

Planting slash pine in a dense pasture sod

Recommendations for planting pines usually include providing a competition-free site to assure establishment and good early growth. When combining pines and pasture in agroforestry systems, the possibility of planting pines directly into a pasture sod without site treatment would be economically desirable. In south Georgia, USA, slash pine (Pinus elliottii) was planted into a pasture sod and on well-disked sites; both with and without annual fertilization. Partial weed control was maintained in subsequent years on the cultivated treatments and the pasture sod was mowed periodically.Slash pine establishment and growth rate through 5 years generally was not different among treatments. Survival was 96% intially and 86% after 5 years. The pines grew rapidly with no measurable advantage from cultivation or fertilization.This alternative to providing a competition-free environment needs to be tested under differing climates, soils, tree species, and pasture species. It could be a suitable technique in various situations and of special interest to small, nonindustrial landowners.Cooperative study between the Coastal Plain Experiment Station, University of Georgia, and USDA Forest Service, Tifton, GA 31794, USA.     

Effects of active pasture,teak (Tectona grandis) and mixed native plantations on soil chemistry in Costa Rica

In this study soil samples were taken from the O/A and B horizons of undisturbed forest, active pasture, and 8- to 12-year-old teak and mixed native plantations. Samples were analyzed for K, Ca, Mg, soil organic carbon, pH, exchangeable acidity, bulk density, and compared with a fertility equation. Bulk density was significantly lower in the undisturbed forest than other land uses, suggesting that after approximately 10 years of growth neither plantation lowered bulk density significantly from that of the active pasture. Teak plantations had significantly higher Mg and K (B horizon) and Ca (O/A horizon) concentrations than the undisturbed forest. This trend suggests that exchangeable base concentrations increase when land use changes from undisturbed forest to pasture, then pasture to plantation, with the most pronounced effect of this in teak plantations exhibiting more high fertility plots than other land uses. Soil organic carbon concentration was similar for all land uses except for a significantly lower concentration in teak plantations than in active pasture (O/A horizons). These results suggest that teak plantations may be advantageous for increasing soil fertility but, with respect to restoration of undisturbed forest conditions, present significant deviations in soil chemistry. Options for improved plantations soil management are discussed.     

Tree windbreaks and shelter benefits to pasture in temperate grazing systems

The effects of windbreaks on pastures are reviewed, with an emphasis on temperate grazing systems. Mechanisms of plant response to shelter are dealt with in brief. Few papers on measured responses of pasture species to shelter were located in a search of the global literature for the period 1972–97. Except in cold climates, where the benefits of snow-trapping on water availability can be demonstrated, there were few reports of increased production of pasture in response to shelter. A significant result was obtained in a summer rainfall environment in Australia, where a 43% increase in wool production was obtained over three years in small plots sheltered with iron sheeting on the fences. The gain was attributed to increased pasture growth. In New Zealand, one study over three years with a narrow, permeable shelterbelt in a windy, dry summer environment showed a 60% increase in pasture growth in the sheltered zone. However, another study on a high rainfall site with a dense, wide shelterbelt found no substantial shelter effect on pasture. In dry, hot and windy climates there appears to be scope for protecting spray-irrigated pasture with windbreaks. The feasibility of evaluating shelter effects on pastures or crops from old windbreaks is questioned. Variability of soil over the site can not be satisfactorily accounted for and there are problems in defining the true ‘unsheltered’ yield. Shelter effects on pastures could best be determined by comparing production in small completely sheltered plots and open plots. Effects in and near the competitive zone should be measured for living windbreaks. Modelling could then be used to evaluate windbreak systems. We are not yet in a position to provide unequivocal advice to farmers on windbreak outcomes for particular purposes or regions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Pasture production under densely planted young willow and poplar in a silvopastoral system

New Zealand is subject to summer and autumn droughts that limit pasture growth. The planting of willow and poplar trees is one option used to provide green fodder during drought. However, there is a wide concern that such an option can reduce the overall understorey pasture growth. This study evaluated the comparative establishment and growth of densely planted young willow and poplar and their effects on understorey pasture growth. Two experiments were established for 2 years in Palmerston North and Masterton, North Island, New Zealand. In the first experiment, densely planted willow and poplar significantly reduced understorey pasture growth by 24 and 9%, respectively, mainly due to shade, but coupled with soil moisture deficit in summer. In the second experiment, pasture growth in a willow browse block was 52% of that in open pasture as a result of shade and differences in pasture species composition and management. Willow and poplar survival rates were similar (P > 0.05) after 2 years of establishment (100 vs. 90.5%, respectively). However, willow grew faster than poplar in height (1.90 vs. 1.35 m), stem diameter (43.5 vs. 32.6 mm), canopy diameter (69 vs. 34 cm) and number of shoots (8.7 vs. 2.3) at the age of 2 years.