The nearest-plant method is robust and powerful enough for different survey teams to monitor change in mesic grassland species composition

A long-term rangeland monitoring programme needs to employ a field survey technique that is practicable, precise, powerful enough to distinguish change, not prone to worker bias, and able to distinguish real change from operator error arising from staff turnover. These criteria were used to evaluate a widely used grassland sampling technique in South Africa – the nearest-plant (with 200 points) method (NP) – against common alternatives, namely NP excluding forbs (NP-nf), the plant number scale (PNS; a cover-abundance method) and quadrat frequency (QF), using multivariate ordination and permutation tests. Four trained teams surveyed four grasslands using each method. PNS took more than twice as long as the other techniques, which were similarly rapid. Estimates of composition using NP methods were the most precise and PNS was least repeatable, with QF intermediate. Compositional differences between sites were most finely distinguished using NP-nf, followed by NP and QF. PNS was able to detect only marked differences and had the greatest potential for surveyor bias. The NP method, with or without including forbs, is therefore recommended for monitoring the species composition of mesic, dense grassland. Some suggestions for monitoring agencies on how best to use multivariate methods are presented.     

棘豆属植物的危害性及其控制对策初探

棘豆属植物对草地畜牧业的危害性主要表现在：与优良牧草竞争水肥、光照及空间，使草地植物学成分简化，生物多样性减少，抗逆性下降，草地退化加速，使用年限缩短，生产率和利用率降低。同时引起家畜中毒、繁殖性能减弱及育种改良难度增大。认为目前棘豆控制应从草地农业生态系统的整体出发，以生态学理论为指导，生态工程控制为基础，生物控制为中心，物理防治、科学管理及政策引导为辅助和补充手段，兼顾开发利用，化学防治为应急措施的综合控制体系。     

区域尺度下气候因子的插值优化及其与草地NPP的相关性

利用甘肃省及周边42个气象站点的气象数据和154个草地样地地上生物量（风干质量）实测数据,在AMMRR插值方法的基础上,加入坡度、坡向两个变量,对甘肃省1996－2005年的年均温和年降水量、不同季节温度和降水量进行空间模拟,并分析了甘肃省年均温和年降水量的空间分布格局,以及草地净初级生产力(NPP)对年均温、年降水量和不同季节温度、降水量的响应。结果表明,1）相对其他插值方法,引入了坡度、坡向等微观地理因子的AMMRR插值方法,可充分体现甘肃省的年均温、年降水量受地形影响的微观变化,更符合实际情况。2）除冬季外,草地NPP与不同时期的温度之间均呈显著负相关（P<0.01）,与不同时期的降水量均呈显著正相关（P<0.01）,而且与降水量的相关性明显高于温度。     

Relationships between denitrification gene expression,dissimilatory nitrate reduction to ammonium and nitrous oxide and dinitrogen production in montane grassland soils

The montane grassland soils of Europe store significant amounts of nitrogen (N), and climate change might drive their volatilization due to the stimulation of gaseous nitrous oxide (N₂O) and dinitrogen (N₂) losses. Hence, a thorough, mechanistic understanding of the processes responsible for N loss and retention such as denitrification and dissimilatory nitrate reduction to ammonium (DNRA) in these soils is urgently needed. Here we aimed to explore the relationships between denitrifier gene abundance and expression with N₂ and N₂O production and the importance of DNRA versus denitrification in nitrate consumption and N₂O production for typical montane grassland soils of Southern Germany. In a laboratory incubation experiment with glucose and nitrate addition, we combined direct measurements of N₂O and N₂ production with a molecular analysis of the denitrifier communities involved in nitrite, nitric oxide (NO) and N₂O reduction and with the quantification of DNRA. The soils originated from a space-for-time climate change experiment, where intact plant-soil mesocosms were exposed for three years either to ambient conditions at a high elevation site (“HE” control treatment) or to predicted climate change conditions (warming, reduced summer precipitation and reduced winter snow cover) by translocation to lower elevation (“LE” climate change treatment).The abundance (DNA) of cnorB genes was significantly reduced in LE soils, whereas the abundance of nosZ genes did not differ between the HE and LE soils. However, the decreased abundance of cnorB genes unexpectedly resulted in slightly increased rather than decreased potential N₂O emissions. This effect could be explained by the increased levels of cnorB mRNA and, therefore, the higher physiological activity of the NO reducers in the LE soils. In contrast with the DNA levels, the dynamics of the cnorB mRNA levels followed N₂O emission patterns, whereas the nosZ expression was strongly correlated with the N₂ emission (R² = 0.83). The potential rates of DNRA were approximately one-third of the rates of denitrification, and DNRA was not a source for N₂O.We conclude that DNRA significantly competes with denitrification in these soils, thus contributing to N conservation. This work demonstrates that the molecular analysis of nosZ gene expression has great potential to contribute to solving the enigmatic problem of understanding N₂ loss from soil.     

草地利用和管理方式对地木耳生物量的影响

地木耳(Nostoc commune)是一种固氮蓝藻,其固氮活性是可逆的,在天然草地氮素循环中起着非常重要的作用。本研究分析了放牧、刈割、烧荒以及围封对地木耳生长动态的影响,以期为合理利用和管理天然草地提供理论依据。结果表明,围栏封育样地地木耳的生物量最高,适度放牧和刈割样地次之,重度放牧显著抑制了地木耳生长,其总生物量仅相当于围栏封育的11.2%～35.1%;烧荒处理当年地木耳生长受到抑制,但随着凋落物的积累,其生长量逐渐增加;地木耳生物量与凋落物、立枯物的量呈显著正相关（P<0.05）,凋落物和立枯物的量是影响地木耳生长的主要因素。因此,适度放牧和围栏封育有利于草地固氮蓝藻--地木耳的生长和增加草地氮素供应。     

科技是云南草地畜牧业可持续发展的关键因素

针对云南草地资源的现状及面临的问题，进行了草地畜牧业持续发展综合配套技术的研究，试验、示范、推广效果突出、效益明显，从而提出了科技是草地畜牧业可持续发展的基础和关键因素，以及加快科技推广的一系列建议。     

降水对青海同德高寒草地牧草产量影响的积分回归分析

利用积分回归的基本原理,并以青海省同德县巴滩高寒草地牧草产量为例,运用积分回归分析气象要素与牧草产量的关系,确定了青海省同德县巴滩高寒草地不同生育时段的降水对牧草产量的影响效应。结果表明,降水对高寒天然草地牧草产量的影响正效应为4月上中旬、5月下旬—7月上旬和8月下旬3个阶段,降水量每增加1mm,牧草产量最大增加138.2,80.1,53.8kg/hm2;负效应为4月下旬—5月中旬和7月中旬—8月中旬2个阶段,降水量每增加1mm,牧草产量相应最多减少23.1,43.7kg/hm2。     

充分利用石山灌草丛草地资源发展广西马山县山羊优势产业

在阐述广西马山县石山灌草丛草地的自然环境、草地饲草资源以及马山黑山羊生产性能和现状的基础上。分析了制约马山黑山羊生产发展的主要因素,提出了饲草资源开发利用的对策．并针对马山县发展山羊优势产业的现状和存在的问题提出了相关建议,以期达到充分利用马山黑山羊的品牌优势、突破制约发展山羊产业的饲料瓶颈、指导当地农民增收致富的目的。     

我国草原确权承包及信息化管理探讨

草原是我国重要的自然资源,对维护生态系统稳定具有十分重要的意义。草原确权承包工作是草原生态保护和建设的制度保障,是落实中央有关要求的具体举措。从已有对草原确权的报道来看,由于我国草原牧区的特殊情况,草原确权工作在地区间推进速度不一,整体推进不平衡,部分地区确权工作推进相对缓慢。在对草原确权承包工作的背景、现状进行分析的基础上,梳理了推进我国草原确权承包需要的基础工作,包括基础信息收集、承包合同完善、颁发草原权属证书、开展培训、加强信息管理和健全草场纠纷解决机制等,提出了信息管理平台的构建思路,包括主要构成模块、基本功能、工作流程、采用的主要技术等。在此基础上,提出了下一步推进草原“三权分置”的思考和建议,对于推动我国草原确权承包和信息化管理具有重要意义。     

扁穗牛鞭草人工草地中空心莲子草杂草防除效果研究

利用水花生净除莠剂可有效地防除扁穗牛鞭草人工草地中的杂草空心莲子草,平均株防效达26.7%～99.8%,并且在较高防效下药剂对扁穗牛鞭草较为安全。在空心莲子草杂草生长盛期,14%的水花生净乳油以浓度为675ml/hm2～900ml/hm2、各处理对水600ml的防除效果最佳,可达到100%。综合考虑,以525ml/hm2～675ml/hm2的浓度为宜。