施肥及刈割对干旱地区紫花苜蓿产量和品质的影响

在黄土高原中部干旱区采用随机区组试验,研究3个施氮水平(0、51.75、103.5 kg·hm^-2)和3个磷水平(0、126、252 kg·hm^-2)下不同刈割次数(3、4次)对“甘农3号”紫花苜蓿种植当年和第2年产量、株高、再生速度及品质的影响,并对紫花苜蓿生长两年中各指标进行比较.结果表明:干旱地区“甘农3号”紫花苜蓿在具备灌溉条件下,种植当年施肥可显著提高产量、株高和再生速度,且4次刈割下显著高于3次刈割;施肥也能增加紫花苜蓿粗蛋白含量,降低中性洗涤纤维和酸性洗涤纤维含量,4次刈割下品质更好;高氮低磷处理(N 103.5 kg·hm^-2+P₂O₅ 126 kg·hm^-2)下效果最好,单施氮肥较单施磷肥效果好.同时,第2年紫花苜蓿产量显著高于第1年,第1年增幅较第2年明显,说明在试验地区,“甘农3号”紫花苜蓿种植当年施肥更有效,第2年施肥仍有益;在灌溉和配施N103.5 kg·hm^-2+P₂O₅ 126 kg·hm^-2条件下,种植当年即可实现4次刈割.     

准噶尔盆地梭梭群落地上生物量及季节变化研究——以克拉玛依农业综合开发区为例

根据样地调查资料,对位于准噶尔盆地的克拉玛依农业开发区外围荒漠植被的生物量及季节变化进行了研究。通过对梭梭自然群落地上生物量的研究表明,梭梭群落在一年的生长周期内没有明显的生长变化,只有两个生长高峰分别在6月下旬和8月下旬出现,但是绿色同化速率快。梭梭地上生物量中,多年生枝条比例最多占地上生物量的60%,当年生绿色同化枝生物量较少,一般占30%以下。5月份梭梭当年生绿色同化枝生长比较缓慢,地上生物量42 052．197g/m~2；7～8月份达到高峰76 457．18～92 922．598g/m~2,这是梭梭当年生绿色同化枝生长最旺盛、最有活力的时期；进入9月份随光合作用的下降生物量也下降至86 794．669g/m~2；10月份生物量迅速下降11月接近零,准备冬眠,脱落大部分枝条被并入非同化系统。梭梭群落地上生物量增长规律符合Logistic增长模型；其地上现存量季节动态呈二次抛物线方程y=a bx cx~2形式；梭梭绿色同化系统(AS)和非同化系统(UAS)的现存量集中分布于地面8～60cm和20～90cm的范围内,属典型的中繁型群落。梭梭群落的生物量及其季节变化与梭梭当年生绿色同化枝的萌发、生长、脱落有密切的关系。     

利用强度对沙地植被恢复能力的影响

在腾格里沙漠南缘,以两种植被恢复状态良好的封育沙地为研究对象,进行不同利用强度试验,通过一个生长季的监测,研究了封育沙地群落物种多样性和生物量的变化,结果表明:(1)两种封育沙地灌木层各处理的优势种均为沙蒿(Artemisia arenaria DC.)或猪毛蒿(Artemisia scoparia Waldst.et Kit.),其重要值在0.47～0.75之间。植物群落的物种组成因不同的封育措施而异,在同一封育措施下利用强度对群落的物种组成无显著影响。(2)两种封育沙地灌木层的多样性指数和均匀度指数均表现为天然封育沙地半刈割沙地全刈割沙地,即随利用强度增加,两封育沙地灌木层群落多样性指数和均匀度指数均呈减少趋势,表明随利用强度的增加,使沙地植被所处的环境异质性增加,促使沙地植被向不同方向发展;但在不同的封育措施区利用强度对草本层多样性指数和均匀度指数的影响不同。(3)相同封育措施不同利用强度群落的相似性指数均很高,最大值可达到2,但不同封育措施各利用强度的相似指数均小于0.3。群落的相似性指数主要受封育措施影响,而利用强度对其影响不大。(4)两种封育沙地全刈割处理的地上生物量均显著小于半刈割处理和对照组,而对照组和半刈割处理之间无显著差异,表明随利用强度的增加,封育沙地群落地上生物量显著减少;而适度降低盖度,群落地上部分生物量变化不大。     

沙地冷蒿种群的耐牧机理研究初报

通过调查冷蒿的生物学特性,并以4种不同处理实验研究了耐牧性。处理方法分别为第1组模拟轻牧,剪去植株高度的一半(T₁);第2组模拟重牧,把植株地上部分全部剪掉(T₂);第3组埋土3~5cm(T₃),以模拟沙质草场疏松的地表易被牲畜践踏活化而掩埋植物;第4组做对照(T₄)。试验结果证明,春季对地上部分剪除不影响以后的营养生长和生殖枝的形成发育,但是7月以后做剪除处理则对其营养生长不利,对生殖枝的形成影响更大。生长季多次剪枝可获得更大生物量,不同处理组平均每株的地上部分收获生物量(干重)分别是25.2g(T₁),27.4g(T₂),24.7g(T₃)和22.0g(T₄)。冷蒿枝条密集,在无干扰条件下,平均每株有枝条近百枝。植株地上部被剪除后,不定芽萌发力强,1cm的残枝上可以萌芽2~4个。枝条的基部极易生不定根形成新植株。有性繁殖与无性繁殖并存保证了种群更新。     

半干旱沙区3种优势固沙灌木生物量分配及其生态学意义

为探究科尔沁沙地3种优势固沙灌木生物量的分配特征,以黄柳（Salix gordejevii）、差不嘎蒿（Artemisia halodendron）和小叶锦鸡儿（Caragana microphylla）为对象,采用全挖法在个体水平上研究了固沙灌木生物量构件及其占比、R/S（root-shoot ratio）、地上新生生物量占比、地上新生生物量与老枝生物量占比及其与冠幅的相关性和地下-地上生物量关系。结果表明：（1）科尔沁沙地3种优势固沙灌木生物量构件及其占比存在显著性的种间差异（P<0.05）;黄柳的老枝生物量及其占比居于首位,NAB（new aboveground biomass,新枝生物量）/OBA（old branch biomass,老枝生物量）为43.90%;差不嘎蒿的地上生物量占比居于首位,地上新生生物量是老枝生物量的2.43倍;黄柳和差不嘎蒿地下生物量集中分布在浅土层,不存在深根系（根系长度>100 cm）。（2）小叶锦鸡儿地下生物量及其占比和R/S（root/stem）均居于首位;地下生物量在根系长度>30 cm处的生物量占比达到61.61%,深根系（根系长度>100 cm）层地上生物量占比达到22.33%。（3）黄柳和差不嘎蒿的R/S、NAB/AGB（aboveground biomass,地上生物量）和NAB/OBA均与冠幅呈负线性关系,在固沙后期该两种灌木随着冠幅的增大,地上新生部分锐减,生产力下降,植被出现衰退。（4）通过非线性回归拟合得到3种灌木地上（y）-地下（x）生物量异速生长模型为：黄柳y=2.928x ^1.039（R²=0.901,P<0.01）,差不嘎蒿y=32.802x ^0.685（R²=0.469,P<0.01）,小叶锦鸡儿y=1.337x ^0.066（R²=0.833,P<0.01）。     

半干旱黄土区成熟柠条林地剖面土壤水分环境及影响因子研究

为了探讨柠条群落及环境因子与土壤水分动态响应关系,选择半干旱黄土区流域尺度不同地形条件下成熟柠条林作为观测样地,于2009-2011年生长季节(5月上旬至10月下旬),每15 d1次,对0~220 cm剖面土壤水分进行了连续测定,2010年8月测定了0~600 cm土壤水分,2011年9月调查了柠条林群落结构特征。采用SPSS17.0软件的Duncan进行多重比较、EXCEL软件进行分析作图,对各样地剖面土壤水分差异、不同年度生长季节变异、干燥化程度以及其影响因子进行了综合分析。结果表明:浅层土壤水分含量为北坡东坡南坡,下坡位高于上坡位,坡度越大土壤含水量越低。由表层至深层,地形因子影响土壤水分作用逐渐减弱,植被因子影响土壤水分作用逐渐增强。在一定区域,柠条群落盖度和高度与深层土壤水分含量呈明显的负相关。人工柠条林加重了入渗层以下的土壤干燥化程度,而且连续干旱会造成入渗层范围的临时性土壤干层,而永久性干层是柠条发育至成熟阶段的过程中,逐渐形成并一直存在的一种现象。研究结论将对进一步从多尺度(年际和季节的时间尺度、水平和垂直的空间尺度)、多因子(气候、土壤、植被、微地形等)综合研究半干旱黄土区人工植被群落及其土壤水分环境动态提供重要参考。     

库布齐沙漠沙柳无性快速培育技术对比研究

沙柳是库布齐沙漠重要的生物与生态资源之一。通过对沙柳扦插苗进行生根粉（ABT）、保水剂、有机肥和‘四枝一穴’栽植密度的不同处理后,连续3 a对其高生长、基径生长、生物量及平茬后枝条萌发数进行了测定。对测定结果的分析发现：与对照相比,四种处理都能够不同程度地提高沙柳的高生长、基径生长、生物量及平茬后枝条萌发数量。其中保水剂的作用最好,使沙柳的成活率、平茬后的枝条数和生物量分别提高了61.0%,70.4%和71.4%。     

塔克拉玛干沙漠南缘头状沙拐枣幼苗生长和生物量分配对不同灌溉量的响应

水是荒漠生态系统中首要限制因子。由于水分限制程度不同,植物幼苗在生长过程中表现出不同的适应策略。在塔克拉玛干沙漠南缘的沙漠-绿洲过渡带,设计了0 mm（处理A）、100 mm（处理B）、200 mm（处理C）3种不同的灌溉量,对头状沙拐枣幼苗生长和生物量分配展开实验性研究。结果表明:①处理A比处理B和处理C地下生物量均有所增加;不同灌溉条件下,头状沙拐枣幼苗的根冠比均小于1,随灌溉量的减少头状沙拐枣幼苗的根冠比从0.19增加到0.32;即头状沙拐枣通过改变根系生物量分配适应水分条件变化。②随灌溉量的减少, 头状沙拐枣幼苗主根垂直深度和水平根幅均呈增加趋势。处理A时,头状沙拐枣幼苗根系深度达180 cm以上,处理B和C的根系深度均低于160 cm,表明头状沙拐枣幼苗通过根系的伸长生长来适应水分减少。③在生长过程中,头状沙拐枣通过老同化枝枯落适应土壤水分减少。④株高和冠幅随着灌溉量增加呈先增加后减小趋势,基径随着灌溉量的增加而增加,地上生长指标在不同处理间均无显著差异。     

潜水埋深对疏叶骆驼刺(Alhagi sparsifoli)幼苗生长和叶片形态的影响

研究了潜水埋深(40、80、120、180、220cm)处理对一年生疏叶骆驼刺(Alhagi sparsifoli)幼苗生长和叶片形态的影响。结果表明:随着潜水埋深的增加,疏叶骆驼刺幼苗叶片厚度逐渐增加,叶片厚度在220cm埋深下最大,长度和宽度在120cm埋深下最大,且叶片长度呈优先减小的趋势;潜水埋深变化对疏叶骆驼刺株高生长影响不大,但对冠幅和分枝数的生长影响显著(p0.05);除40cm埋深处理中根系以平均1.24cm·d-1的速率扎入地下水层外,其他4个处理根系生长速率随潜水埋深的增加而增加,且180cm和220cm埋深下根系生长速率明显高于其他3个处理;根系到达220cm潜水埋深的时间为123d;幼苗生物量积累随着潜水埋深变化先增加后减小,茎叶生物量在120cm埋深处理中达到最大值,而根系生物量在180cm埋深下最大。潜水埋深变化对疏叶骆驼刺地上部分和根系生长的影响不同,潜水埋深增加有利于根系生长和根系生物量增加;以120cm为拐点,潜水埋深过浅或过深都会抑制地上部分生长;220cm潜水埋深条件下,疏叶骆驼刺生长缓慢且生物量的累积最小,表明若潜水埋深大于220cm则对幼苗生长不利。     

蒋家沟干热河谷区灌草层植被与土壤的养分分布及生态化学计量特征

蒋家沟干热河谷区泥石流与滑坡灾害频发、植被枯败稀疏、土壤结构紊乱、生态环境脆弱,是金沙江上游生态严重退化的典型流域。植被和土壤在退化生态系统修复和治理中扮演着至关重要的角色。对该流域植被与土壤的研究,多侧重从单一物种或土壤酶活性等角度分析植被与土壤的养分耦合关系,缺少对灌草层植物体养分含量与土壤养分含量的耦合机制研究,即植被-土壤耦合机制机理尚不明确。本文选取蒋家沟干热河谷区典型灌草层植被,研究碳(C)、氮(N)、磷(P)、钾(K)元素在植被地上、根系和土壤的养分分布和生态化学计量特征及其相关性。结果显示：(1)与全国陆地植物平均水平相比,干热河谷区灌草层植被地上和根系表现出低C,高N、P、K的特点;土壤表现出低C高P的特点。(2)植被地上部分的C、N、P、K含量均显著高于根系,C、N、P含量均显著高于土壤;土壤K含量(56.05 g/kg)显著高于植被地上(18.43 g/kg)和根系(8.41 g/kg);除P∶K外(地上0.10>根系0.09>土壤0.01),其余5种化学计量比均表现为根系>地上>土壤。(3)灌草层植被地上、根系N、P、K含量及生态化学计量...     

Fe、Mn、Cu在锡林河流域温带草原植被中的含量特征

本文研究了Fe、Mn、Cu三个同周期的植物营养元素在内蒙古锡林河流域三个主要草原群落植被中的含量特征,研究表明:三个元素在凋落物及根系中的含量较高,在立枯中较低,在活体中最低;沿降水、气温和海拔梯度,活体、凋落物中的含量按贝加尔针茅草原、羊草草原、大针茅草原递减,Cu例外,在植物生长末期是递增的;立枯中的元素含量在生长初期递增,在后期递减,Cu也例外,初期和后期都是递增的;在植物系统各组成部分中,生长初期三个元素的含量要高于生长后期;地上部植物体分解程度越高,三个元素的含量也越高;Cu强烈富集于根系中;土壤及降水分别是影响植物元素含量及植物分解的重要因子;三个元素在各草原群落地上部活体中的含量都能够满足牲畜的需要。     

Effects of indole-3-acetic acid and zinc on the growth, osmotic potential and soluble carbon and nitrogen components of soybean plants growing under water deficit

Three-week old soybean (Glycine max) plants were subjected to a factorial combination of four regimes of soil matric water potential (ψ_m=−0·03, −0·5, −1·0 and −1·5 MPa), two levels of supplementary Zn (O and 20 mgl⁻¹) and two levels of foliar IAA application (O and 10 mgl⁻¹). Under control conditions (no Zn, no IAA), increasing soil drying progressively retarded shoot and root growth (length and dry mass production), reduced leaf relative water content (RWC) and decreased the contents of chlorophyll (Chl) and shoot soluble sugars (SS), but increased soluble sugar content of roots and lowered osmotic water potential of shoots and roots (osmotic adjustment). Total free amino acid (TAA) content increased in shoots but decreased in roots whereas contents of soluble proteins (SP) decreased in shoots and roots. The effect of water stress was statistically significant (p<0·05) and had a major effect (as indicated by η²values) on leaf RWC, shoot and root dry masses and osmotic potential. Supplementary Zn improved root growth at all levels of stress and shoot growth under severe stress. Improvement of growth was positively correlated with the internal tissue Zn concentrations (r=0·91 and 0·86 for shoot and 0·94 and 0·82 for root length and dry mass respectively). Exogenous IAA raised (p<0·05) RWC, Chl, DM (slightly), root SS, and SP, whereas shoot TAA was lowered. Effects on root TAA and shoot SS were more complex: they were lowered at zero stress and raised under severe stress. IAA and Zn in combination had additive effects on Chl, growth and osmotic potential, but their combined effects on SP and TAA were more complex. It is concluded that the treatment of soybean plants grown under conditions of low soil water potentials and Zn deficiency with Zn and IAA solutions counteracted the deleterious effects of stress, especially at high stress levels, and helped stressed plants to grow successfully under these adverse unfavourable conditions.     

沙丘先锋植物——沙蓬生长可塑性的研究

 无论是大尺度降水的分异还是小尺度土壤湿度的差异都影响植物的生长可塑性。比较科尔沁沙地和腾格里沙漠沙蓬的生长分异, 并用地统计学方法探讨了腾格里沙漠沙蓬生长可塑性的空间变化, 结果表明：科尔沁沙地和腾格里沙漠沙蓬的地上部生物量和地下部生物量都呈线性正相关关系, 地上部生物量和根长都呈对数递增关系;与科尔沁沙地相比, 腾格里沙漠沙蓬的根长增加20％, 根冠比大33.3％, 显然降水分异导致了地区间沙蓬的生长可塑性。地统计学方法进一步分析表明, 腾格里沙漠沙蓬植株因土壤湿度产生的空间异质性是地上部生物量小于根长但大于根重, 说明干旱逆境时沙蓬生长可塑性变化趋势的顺序依次是根长>地上部生物量>地下部生物量, 沙蓬这种生长可塑性特点是其对干旱生境的适应。     

Effects of increased summer precipitation and N deposition on Mojave Desert populations of the biological crust moss Syntrichia caninervis

Climate change in the Mojave Desert (USA) may result in a greater intensity of summer (monsoon) rain events and greater atmospheric N deposition. Patches of the dominant biological crust moss Syntrichia caninervis were exposed to field treatments of low and high nitrogen supplementation, added summer rain, and combinations thereof, for a period of five years. In the lab, shoots were subjected to a moderate (single rapid-dry treatment) and a severe (double rapid-dry treatment) desiccation stress. Shoots were then hydrated and allowed to regenerate for 6 weeks on sterile sand. Shoots exhibited lower aboveground biomass from the +monsoon treatment, indicating carbon balance deficits under conditions of recurring summer rainfall. The low N treatment and the severe desiccation stress promoted shoot burning (chlorosis) and negatively affected regeneration responses. High N treatment, however, only adversely affected the resumption of apical meristematic growth. Summer irrigation and N application interacted to mitigate the effects of later protonemal emergence time, lower protonemal cover, and lower shoot numbers. Increased monsoonal frequency and higher N deposition as forecast for the northern Mojave Desert may result in declines in shoot biomass and reduced regenerational vigor in S. caninervis.     

不同坡向梭梭幼苗的生长状况和适应特征

以古尔班通古特沙漠南缘一年生梭梭移栽苗为研究对象,对梭梭幼苗的地上部分生长状况、蒸腾速率日变化趋势以及根系形态进行了调查,探讨不同坡向梭梭幼苗的生长和适应特征。结果表明,平地、阴坡和阳坡表层0~30 cm土壤含水量无显著差异,40~100 cm土壤含水量阳坡<阴坡<平地。梭梭幼苗同化枝生长速率和含水量均表现为阳坡<阴坡<平地,其生长速率和含水量可能与根层土壤含水量高低有关。不同坡向梭梭幼苗蒸腾速率日变化均呈“单峰型”,12:00-16:00阳坡梭梭幼苗蒸腾速率显著高于阴坡与平地。 阳坡梭梭幼苗主根不发达,侧根较多但较短;平地和阴坡梭梭幼苗根系主根发达,以单根为主。这反映出根系对相应生境下土壤水分的适应特征。     

沙漠人工植物群落的根系分布及动态

2004年植物生长季,利用根钻取样研究了沙漠4种不同配置类型油蒿与柠条植物群落的根系分布及生长动态;另外,采用挖沟分层取样研究了半固定沙丘两种植物的粗根剖面结构,结果表明：尽管4个样地高峰值和低峰值出现的时间不一致,但沙漠植物细根的生长动态表现为双峰型;整个生长季纯油蒿样地细根密集分布于0~40 cm,其余样地密集分布于10~60 cm;受一年生植物的影响,9月份4个样地表层（0~30 cm）细根的根长密度和根重密度均出现最大值。采用边灌水边取样的办法获得4个样地300 cm深的根系数据,4个样地90%以上的细根分布在0~200 cm层次,其中纯油蒿样地的根系的最大深度是270 cm,其余3个样地均在300 cm以下;细根的根长密度和根重密度随深度而减小且呈指数递减形式（P<0.01）。除纯油蒿样地外的其他3个样地,根瘤的最高值出现在4月份;粗根的根长密度远远小于细根的根长密度。挖沟分层取样研究表明,与柠条相比油蒿具有较高的根冠比;柠条的粗根长主要分布于0~60 cm,粗根重主要分布在0~40 cm;油蒿的粗根分布比柠条的更浅,粗根长主要分布于0~40 cm,粗根重主要分布在0~20 cm。     

Micropropagation of Acacia seyal Del. in vitro

In vitro mass propagation of Acacia seyal Del. was achieved using seedling shoot tip explants on Murashige and Skoog (MS) medium supplemented with 6-benzyladenine (BA) or Thidiazuron (TDZ) with ∝-Naphtalene acetic acid (NAA). The best result was obtained with BA in the presence of NAA. The greatest shoot multiplication with long shoots was observed on media containing (mg l^-1) 2·0 BA with 0·1 or 0·5 NAA and 4·0 BA with 0·1 NAA; with 6·4 and 6·7 mean number of shoots, respectively. TDZ also induced multiple shoots but most of the shoots were stunted. Microshoots were rooted better on half-MS salts supplemented with Indole-3-butyric acid (IBA). The highest rooting percentage (80%) and root number (4·9 roots/microshoot) were promoted by 4·0 mg IBA. The plantlets (90%) successfully survived acclimatization ex vitro.     

Biogeomorphological influence of slope processes and sedimentology on vascular talus vegetation in the southern Cascades, California

The vascular vegetation of alpine talus slopes between 2035 and 3095 m altitude was studied at Lassen Volcanic National Park (California) in the Cascade Range. Taluses show a diverse flora, with 79 plant species; growth forms include coniferous trees, shrubs, suffrutices, herbs, graminoids, and ferns. Spatial patterns of plant distribution were studied along 40 point-intercept transects. Plant cover was low (0-32.7%) on all slopes, spatially variable, and showed no consistent trends. Sedimentological characteristics were determined by photosieving next to 1500 plants; this census indicated preferential plant growth on blocks and cobbles, with 43.2% and 23.3% of the plants growing on these stones, respectively; fewer specimens were rooted on pebbles (13%) or on stone-free gravel areas (20.5%). Growth forms displayed different substrate preferences: 92.5% of the shrubs and 83% of the suffrutices colonized blocks or cobbles, but only 57.2% of the herbs and 59.8% of the graminoids grew on large stones. Plants are associated with large clasts because (1) coarse talus is more stable than fine sediment areas, which are more frequently disturbed by various geomorphic processes, and (2) large stones help conserve substrate water beneath them while moisture quickly evaporates from fine debris.Root patterns were studied for 30 plant species; 10 specimens for each species were excavated and inspected, and several root growth ratios calculated. All species exhibited pronounced root asymmetry, as roots for most plants grew upslope from their shoot base. For 23 species, all specimens had 100% of their roots growing upslope; for the other 7 species, 92.2-99.3% of below-ground biomass extended uphill. This uneven root distribution is ascribed to continual substrate instability and resulting talus shift; as cascading debris progressively buries roots and stems, plants are gradually pushed and/or stretched downhill. Various disturbance events affect root development. Slope erosion following rubble removal often exposes plant roots. Debris deposition can completely bury plants; some may survive sedimentation, producing new shoots that grow through accumulated debris. Shrubs may propagate by layering, as adventitious roots develop along buried stems; or produce new clones along their roots. Slope processes may damage and transport plant pieces downhill; some species can sprout from severed, displaced root or stem fragments. Vegetation interacts with several geomorphic processes, including debris flows, grain flows, rockfall, snow avalanches, frost creep, and runoff. Larger plants may alter local patterns of debris movement and deposition, damming cascading debris on their upslope side and deflecting sediments laterally to plant margins, where they form narrow elongated stone stripes.