封育年限对伊犁绢蒿荒漠土壤活性有机碳及碳库管理指数的影响

以新疆伊犁绢蒿(Seriphidium transiliense)荒漠草地为对象,研究了不同封育年限对草地土壤活性有机碳及碳库管理指数的影响。结果表明,0-5 cm土层,土壤碳密度呈封育9年>对照>封育1年>封育6年,易氧化活性有机碳、碳库管理指数为封育9年>对照>封育6年>封育1年,且封育9年土壤碳密度显著高于封育6年,相对增加了36.51%,而其易氧化活性有机碳、碳库管理指数显著高于其他处理(P<0.05),分别增加了35.81%~84.89%、35.83%~93.96%;土壤有机质、全量养分分别与土壤易氧化活性有机碳、碳库活度、碳素有效率、氧化稳定系数间呈显著(P<0.05)或极显著(P<0.01)相关,而土壤碳库管理指数、易氧化活性有机碳与群落生物量的灰色加权关联度高于土壤有机质和碳密度。土壤碳库活度指数、碳库管理指数能较为敏感地指示土壤碳与草地初级生产力的变化。     

贺兰山自然保护区西坡退牧封育效果分析

贺兰山区自1999年—2004年期间进行退牧还林、封育保护,本文通过对贺兰山退牧还林后不同立地类型及不同地带的森林植被恢复和生长状况的调查,分析了贺兰山退牧还林五年来取得的成效。研究表明,退牧封育可促进植物生长和更新,动植物种群增加,植被盖度和密度增加,从而增强了贺兰山自然保护区的水源涵养、防风固沙、水土保护功能。同时还对贺兰山今后的保护与管理提供了合理建议和措施。     

Grassland Fire Effects on Steel Fence Posts

Rangeland fire effects on flora, fauna, soils, and water have been studied widely. Fire effects information is limited on rangeland developments such as fencing. Fencing is an integral part of rangeland infrastructure and receives much attention when there is a wildfire or even discussion about conducting prescribed fires. Due to known fence age and fire history, we conducted a study on the Oklahoma State University Research Range located near Stillwater, Oklahoma. Five randomly selected individual metal T posts were sampled from a common fence line of known age and fire treatment. The T posts ranged from 4 to 35 yr since fence construction, with fire activity of 0, 1, 3, or 12 prescribed fires and 0, 1, or 2 wildfire occurrences. Each T post was tested in situ at 40 cm, 80 cm, and 120 cm above ground level for hardness and paint adhesion as set forth by American Society for Testing and Materials (ASTM) International standards for hot wrought metal fence posts. Our results found no differences in post hardness, with all posts tested being higher than the ASTM minimum standard of 83 Rockwell B Hardness Scale. We also found that paint adhesion between burned and unburned T posts did not vary, with age of post being the only significant predictor variable for adhesion. Overall, our results provide evidence that T posts exposed to numerous fires and fire types did not suffer negative effects. This shows that concerns about wildfire and prescribed fires in grasslands having negative effects on metal T posts are unfounded.     

Effect of fencing,artificial seeding and abandonment on vegetation composition and dynamics of ‘black soil land’ in the headwaters of the Yangtze and the Yellow Rivers of the Qinghai‐Tibetan Plateau

Rangeland management can affect plant diversity and plant functional groups of native grassland communities. To improve pasture for livestock grazing from the existing poisonous and ruderal vegetation in the ‘black soil land’ grassland in the headwaters of the Yangtze and the Yellow Rivers (HAYYR) of the Qinghai‐Tibetan Plateau, three treatments (fencing‐FT, artificial seeding with local grasses‐ST and abandonment‐AT) were applied during a 5‐year period (2000–2005). Plant diversity and groups (sedges, grasses and dwarf shrubs) in the treated plots were compared with non‐treated control plots. Results showed that (1) FT promoted an increase in forbs species, but there was no change in the other plant functional groups; (2) with ST, species richness of forbs decreased but grass species increased indicating that sowing local grasses could change plant composition of black soil land in the short‐term, and increase the proportion of grasses and, thus, forage for grazing and (3) AT, after plowing, was similar to CK plots, with forbs being the dominant plant functional group for the 5 years. In conclusion, the goal to alter black soil land cover from poisonous and ruderal plants to more useful plants for livestock grazing by either fencing, artificial seeding or abandonment was not successful in the long term. Copyright © 2008 John Wiley & Sons, Ltd.     

黄土高原典型草原区草地土壤种子库的动态分析

采用野外调查取样和室内试验相结合的方法,研究了黄土高原典型草原区草地土壤种子库的物种组成、密度、时空格局和物种多样性等特征。结果表明,（1）土壤种子库中共统计到37个物种,隶属于16科,其中禾本科、菊科、唇形科、豆科和毛茛科的植物占优势。（2）从返青期到枯黄期,种子库中豆科、禾本科、堇菜科所占比例呈下降趋势,唇形科和菊科所占比例明显提高,种子库的密度也显著提高。（3）种子库中种子数量在垂直分布上呈现出由表层土壤向深层逐层减少的变化规律;在水平分布上的变化规律为：封禁〉放牧;阴坡〉阳坡;下坡〉中坡〉上坡。（4）封禁地土壤种子库中的Margalef丰富度和Shannon--Wienner指数都高于放牧地,Pielou均匀性指数低于放牧地。从返青期到枯黄期,封禁地和放牧地土壤种子库的Margalef丰富度、ShannonWienner指数、Pielou均匀性指数都呈下降趋势。     

高寒草甸植被群落特征及其营养品质对围栏封育的响应

为探究长期封育对高寒草甸植被功能群落特征和营养品质年际动态的影响,本研究以围封11年和连续放牧高寒草甸为研究对象,采用3年连续野外群落调查和室内牧草营养品质分析相结合的方法,比较了长期围封和连续放牧2种草地管理措施对5个植被功能群特征和营养品质的影响。结果表明：围封样地禾本科（Grass group,GG）、莎草科（Sedge group,SG）、豆科（Leguminous group,LG）和杂类草（Forbs group,FG）4个功能群盖度和地上生物量显著高于放牧样地（P<0.05）,功能群密度、物种丰富度指数、Shannon-Wiener指数、粗蛋白（Crude protein,CP）和体外干物质消化率（In vitro dry matter digestibility,IVDMD）显著低于放牧样地（P<0.05）;围封样地4个功能群的密度、群物种丰富度指数、Shannon-Wiener指数、CP和IVDMD表现出不受年际降雨量影响而逐渐下降的趋势。研究建议对围封11年的高寒草甸可进行适当的放牧以增加植被功能群物种多样性和牧草营养品质。     

围封对希拉穆仁草原植被和土壤种子库的影响

围栏封育有利于受损草地生态系统的恢复。通过在希拉穆仁草原进行5年的围封试验,对样地的植被和土壤种子库进行连续监测的方法,研究围封对退化草地的地上植被与土壤种子库的综合修复效果。结果表明:①围封样地植被产量、盖度和高度等生产性能明显高于重牧样地。种类数和Shannon-Wiener生物多样性指数则围封样地低于重牧样地。围封样地中克氏针茅和羊草等优质牧草占优势,重牧样地中冷蒿、银灰旋花和猪毛菜等劣质牧草占优势。②降水量是影响年际间土壤种子库状况的主要因素。围封可促进草地土壤中各种植物种子的积累。围封样地土壤种子库中克氏针茅占多数,重牧样地劣质牧草种子占多数。围封可提高草地生产性能和土壤种子库的积累,但长此以往不利于草地生物多样性,因此应适当中轻度放牧以提高草地的生物多样性。     

植物在高速公路边坡防护中的应用

高速公路的建设带来了一系列的生态问题。植物应用于边坡的防护和绿化是防止水土流失、改善公路生态环境、减少生境片段化、保护生物多样性的有效方法。简述了边坡防护的三种方法（工程防护、生物防护、工程结合生物防护），重点介绍了植物在高速公路边坡防护中的作用。讨论了三种方法的适用范围，并阐述了施工中应注意的问题以及后期管理。同时，还提出了植物配置、景观设计中应遵守的一些原则，以及今后的研究方向。     

封闭时间对模拟践踏的沟叶结缕草草坪质量的影响

在春季、梅雨季和盛夏季对践踏胁迫的沟叶结缕草草坪进行封闭15和30 d处理,研究封闭对践踏胁迫下沟叶结缕草草坪坪用性状的影响,结果表明,春季封闭显著提高了结缕草垂直高度和叶片长度(P<0.05),而梅雨和盛夏季封闭仅分别显著提高了草坪的垂直高度和叶片长度(P<0.05);春季封闭明显提高了草坪的密度和地上活生物量(P<0.05),封闭30和15 d的草坪密度分别比对照提高136.4%和40.3%,地上活生物量分别提高173.9%和42.0%;与盛夏季封闭相比,梅雨季节封闭更有助于减缓草坪密度下降的趋势,且地上活生物量在整个生长季几乎都大于盛夏季节封闭;垂直高度、叶片长度、草坪密度和地上活生物量,封闭30 d的效果均比15 d好;综合各项指标,阶段封闭措施对改善践踏胁迫下沟叶结缕草草坪的坪用质量效果显著,其中春季封闭的效果比梅雨季好,梅雨季比盛夏季好,封闭30 d的效果比15 d好.     

新疆昭苏草原围栏封育效果研究

从2004~2005年对新疆昭苏草原76团场天然草地围栏内、外植被特征进行了调查,结果表明:从2003年封育到2004年,围栏封育处理与对照相比草层高度增加36.5%,总盖度增加12.5%,鲜草产量增加56.2%;从2003年封育到2005年,围栏封育处理与对照相比草层高度增加138.5%,总盖度增加54.3%,鲜草产量增加109.1%.在围栏内0~5 cm土层,土壤水分含量较对照增加63.6%,氨态氮含量增加26.7%;在10~20 cm土层,土壤水分含量较对照增加85.1%,由此可见,围栏对草场恢复效果明显.