晋西北黄土丘陵区小叶锦鸡儿人工灌丛营养动态特征研究

研究了小叶锦鸡儿（Caragana microphylla）人工灌丛不同生育期、不同生长年限及不同器官的营养特征。研究结果表明：小叶锦鸡儿枝条和叶片营养丰富．枝条在开花期粗蛋白含量达到19．61％．嫩叶的粗蛋白古量高达27．50％，粗纤维含量仅为12．3％。枝条和叶片的矿质养分含量高且比例合理．Ca／P为1．7：1～2．1：1．接近家畜日粮中Ca／P最佳比例2：1，是优质的灌木饲料。从休眠期到开花期．小叶锦鸡儿的营养元素含量呈上升趋势．以后逐步降低，花期是最佳利用季节。随着小叶锦鸡儿生长年限的延长，各种营养成分逐渐减少．从生态学的角度分析，平茬后第3年是小叶锦鸡儿最佳的利用时间。小叶锦鸡儿枝条氨基酸总量在6．0％左右．高于玉米秸秆饲料，而且维生素含量丰富．是优质的家畜饲料和北方生态建设的优质树种。     

科尔沁沙地小叶锦鸡儿群落生长季土壤水分动态和蒸散量估算

以流动沙丘和不同恢复年限的人工和天然小叶锦鸡儿群落为研究对象,从土壤水分平衡角度对小叶锦鸡儿群落生长季土壤水分动态和蒸散量进行了研究.结果表明,与天然小叶锦鸡儿群落的土壤含水量相比,人工小叶锦鸡儿群落内土壤含水量较低,且呈现出随植被生长发育年限的增加而不断减少的趋势;从土层垂直方向看,流动沙丘土壤含水量较稳定,6年生和天然小叶锦鸡儿群落土壤含水量大致随深度的增加而逐渐增加,但11年生和22年生小叶锦鸡儿群落土壤含水量基本呈下降趋势,绝大多数土层含水量均低于1.50%,水分状况较差;在生长季,人工植被区绝大部分的降雨都通过蒸散丧失,在时间分布上,各样地蒸散量呈现单峰型曲线模式.     

科尔沁沙地人工小叶锦鸡儿群落小气候效应研究

以流动沙丘和小叶锦鸡儿群落为研究对象,通过对各样地内风速、空气温度、空气相对湿度和地温等指标的观测分析,研究了不同恢复年限的人工植被对小气候的改善效应.结果表明:(1)小叶锦鸡儿群落对近地表风速有很大的阻滞作用,在30 cm高度上,6 a生和11a生小叶锦鸡儿灌木林内的风速比流动沙丘分别降低了71.9和76.0％.(2)小叶锦鸡儿林内夏季白天平均温度明显低于流动沙丘,6a生和11a生小叶锦鸡儿林内日均气温分别比流动沙丘低3.7℃和4.9℃.(3)小叶锦鸡儿群落内空气相对湿度较流动沙丘显著提高.(4)小叶锦鸡儿林内土壤浅层温度日变幅较流动沙丘减小.研究结果对于进一步探讨极端干旱条件下人工植被近地表物质和能量交换具有重要意义.     

科尔沁沙地小叶锦鸡儿群落保育土壤作用的研究

以流动沙丘和不同恢复年限的人工和天然小叶锦鸡儿群落为研究对象,从植被重建前后土壤理化性质变化方面分析了小叶锦鸡儿群落保育土壤的作用.结果表明,6 a生、11 a生和22 a生人工小叶锦鸡儿群落对土壤理化性质均有明显的改善作用,且总体上土壤改良效果与恢复年限成正相关.建立人工植被后,土壤中微沙(0.05～0.1 mm)和黏粒(<0.05 mm)的含量增加,表层(0～10 cm)土壤容重减小,孔隙度和饱和含水率增大,土壤持水能力提高;土壤有机碳、全氮、碱解氮、全磷、有效磷和有效钾含量均有不同程度增加,尤以表层增加幅度最大,并且灌丛对养分有明显的富集效应.     

晋西北黄土丘陵区小叶锦鸡儿人工灌丛土壤水分动态研究

土壤水分是黄土丘陵区植被成活与正常生长的关键因素。对黄土丘陵区不同生长年限小叶锦鸡儿灌丛及其撂荒地土壤水分的动态监测表明,随种植年限延长,小叶锦鸡儿灌丛下土壤水分含量呈持续下降趋势,40年灌丛下土壤含水量明显低于20年和10年的小叶锦鸡儿灌丛,且所有种植年限的灌丛土壤含水量均低于撂荒地。从周年内土壤水分季节变化看,整体呈下降趋势,4~6月不断降低,6~7月达到最低值,8~10月逐渐回升。对0~200cm土体剖面土壤水分分布研究表明,随种植年限增加,小叶锦鸡儿灌丛各深度土层土壤含水量呈递减趋势,在40~80cm土层随种植年限增加土壤含水量减少幅度明显。整个生长季各年限灌丛的土壤水分循环水平不高,40年灌丛只有4.63%,与撂荒地比较相差2.92%,而各年限灌丛土壤水分表观平衡均表现为亏缺状态。表明目前黄土丘陵区人工种植的小叶锦鸡儿灌丛土壤水分环境不容乐观,长期处于水分胁迫状态,不利于其生存生长,存在灌丛衰退甚至死亡的风险。     

留茬高度对小叶锦鸡儿光合生理和生长特征的影响

[目的] 研究不同留茬高度小叶锦鸡儿生长和光合生理的变化规律,揭示不同留茬高度下小叶锦鸡儿生长和光合能力的强弱,探索其平茬时的最适留茬高度,为寻求合理抚育管理措施、指导小叶锦鸡儿生产实践提供理论依据。[方法] 选择2003年人工种植小叶锦鸡儿为研究材料,设置未平茬（CK）、留茬高度5 cm （T₁）,10 cm （T₂）,15 cm （T₃）,20 cm （T₄）,25 cm （T₅）共6个处理于2018年秋季进行平茬,分别测定次年生长季小叶锦鸡儿生长和光合生理指标。[结果] 平茬能显著提高小叶锦鸡儿株高、冠幅、新稍长的增长;不同留茬高度处理净增长量均不同,留茬高度15 cm处理株高、冠幅长和宽度、新稍长净增长量值最高,分别较未平茬处理增加了203.44%,278.10%,292.59%,385.43%;留茬高度5,10和20 cm处理的净增长量次之,留茬高度25 cm的值最低,较未平茬处理分别增加了25.15%,26.38%,25.93%,88.48%;一定留茬高度平茬能显著提高小叶锦鸡儿净光合速率（P_n）、蒸腾速率（T_r）和水分利用效率（WUE）;不同处理小叶锦鸡儿日变化均有不同程度的光合、蒸腾“午休”现象;留茬高度15 cm处理叶片P_n,T_r,WUE日均值均最高,分别比未平茬处理增加了2.52,0.37和1.52倍;留茬高度5,10和20 cm处理次之,留茬高度25 cm处理值最低,其P_n和WUE值分别比未平茬处理增加了0.45和0.32倍,而T_r值比未平茬处理降低了0.02倍。[结论] 平茬后次年生长季内,留茬高度15 cm的平茬小叶锦鸡儿具有较强的生长补偿和光合能力,留茬5,10和20 cm植株的生长补偿和光合能力次之,留茬25 cm植株的生长补偿和光合能力最弱。     

平茬对吉兰泰盐湖花棒防护林植被特征和土壤理化性质的影响

为探究平茬措施对吉兰泰盐湖防护林植被和土壤的影响,以吉兰泰荒漠绿洲过渡带不同平茬年限(1,2,3年)的人工花棒林为研究对象,对比分析不同平茬年限的花棒林植被生长特征和土壤理化性质。结果表明:(1)平茬有利于花棒自我更新。平茬后花棒株高、基径随平茬年限增加而增大,新生枝数与之相反。(2)平茬增加林下草本生物量和草本植物多样性,不同平茬年限花棒林间植物生活型均以一年生植物和多年生植物为主。林下植被盖度、密度、株高、地上生物量、Shannon-Wiener多样性指数、Simpson优势度指数和Margalef丰富度指数均以平茬3年最高。(3)平茬初期的风蚀作用导致地表部分细颗粒被吹蚀,0—30 cm土层土壤机械组成均以细砂和中砂为主,其值为77.63%~88.02%。(4)平茬促进土壤水分蓄积,0—200 cm土层土壤含水量按平茬年限由大到小依次为3年>2年>1年>未平茬,但土壤水分稳定性变差。(5)平茬有利于土壤养分积累,花棒林下土壤有机碳、全氮、全磷、碱解氮和速效磷以平茬后3年最高,较未平茬分别增加6.67%,12.90%,20.00%,115.51%,66.24%。研究结果表明适当平茬可以改善林间生境,但是在平茬初期,需要对地表进行覆盖,防止土壤水分蒸散。     

黄土高原丘陵区不同土地利用方式对土壤理化性质的影响

对晋西北黄土高原丘陵区持续利用30年的小叶锦鸡儿人工林、农田、杨树林、小叶锦鸡儿和杨树的混交林地以及撂荒地的土壤理化性状进行了研究。结果表明,不同土地利用方式对土壤理化性质影响很大。小叶锦鸡儿和杨树的混交林以及小叶锦鸡儿人工林可以降低土壤容重,提高土壤酶活性、有机质和全N含量,从而改善土壤肥力。混交林和小叶锦鸡儿人工林的土壤培肥作用高于杨树纯林。粗放的农业耕作措施提高土壤容重,降低土壤养分含量,使土壤退化。撂荒地一定程度上可以起到培肥土壤的作用。在黄土高原丘陵区,种植小叶锦鸡儿人工林以及小叶锦鸡儿和杨树的混交林是较好的生态重建和植被恢复方式。     

黄羊滩沙地不同造林措施对植被恢复和土壤风蚀的影响

为给黄羊滩及类似地区流动沙地人工造林提供科学依据,在黄羊滩流动沙地营造不同树种的人工林,探讨不同人工林地天然植被恢复效果和防止风蚀的差异。造林7年后调查资料表明：从物种丰富度衡量,小叶锦鸡儿和侧柏人工林加快了天然植被的恢复进程,新疆杨和欧美杨107人工林延缓了天然植被的恢复进程,沙枣和榆树人工林对天然植被恢复的影响不大;欧美杨107和新疆杨人工林1年生草本占绝对优势,随林地环境条件的改善,1年生草本逐渐减少,多年生草本、灌木逐渐增加,侧柏和小叶锦鸡儿人工林地天然植物种生活型结构已趋于多样化。新疆杨和欧美杨107人工林地处于流动沙地阶段,沙枣和榆树人工林地处于半固定沙地阶段,侧柏和小叶锦鸡儿人工林地处于固定沙地阶段。相同沙漠化阶段林地间天然植被的相似性系数较大,不同沙漠化阶段林地间相似性系数较小。该地区人工造林树种以小叶锦鸡儿和侧柏最佳,沙枣和榆树次之,不宜选择新疆杨和欧美杨107等杨树品种。     

不同治理措施下科尔沁沙地南缘土壤质地与持水特性研究

[目的]研究不同治理措施下土壤结构及土壤水分的分异特征,为合理选择沙化土地治理方式提供科学参考。[方法]结合空间代替时间和相邻样地比较法,利用压力膜仪和烘干法对科尔沁沙地治理过程中形成的樟子松人工林地、小叶杨人工林地、小叶锦鸡儿林地、围封草地、天然恢复的固定沙地以及流动沙地(CK)土壤水分特征曲线及土壤结构进行研究。[结果](1)各种治理措施均能明显增强土壤水分持蓄能力,小叶锦鸡儿林地土壤有效水含量最高,为0.05cm~3/cm~3。(2)各治理措施土壤沙粒含量、土壤容重降低;小叶锦鸡儿对土壤粉粒恢复效果最高,较流动沙地增加7.49%;围封措施下土壤黏粒含量最高,为1.08%。(3)土壤黏粒是影响土壤有效水含量和过剩水含量的主要因素,回归系数分别达到2.54和-2.65。[结论]小叶锦鸡林地和围封措施能较好地改善沙化土地土壤结构和土壤水分持蓄能力。     

Reclamation of degraded cocoa lands using Albizia Zygia

The structure of the population of Albizia zygia and the regeneration potential of the species from seed were studied in three site conditions (mature cocoa stand, fallow and intact natural forest) in the moist semi-deciduous forest zone in Ghana. The potential of the species to regenerate vegetatively was also assessed. Different population structures and different natural regeneration status were observed for each site. Regeneration from seed appeared to be of a little importance in the fallow site, whereas vegetative regeneration was found to be a major mechanism of secondary succession in abandoned cocoa farms. The population of Albizia zygia in the forest appeared to be stable, while in the mature cocoa fields it was in decline. Efficient seed pretreatment techniques and vegetative propagation methods using juvenile cuttings, which are useful for enhanced management of the species, are also presented. Management strategies using the species for the rehabilitation of degraded cocoa farms are discussed.     

人工油松林中跳虫群落恢复状况

Large areas of forest plantations have been developed in China.It is important to evaluate the soil fauna in plantations and the conditions needed for their recovery in view of the large areas of plantations in China.Three Pinus tabulaeformis forests,a 26-year-old plantation (P26) and a 45-year-old plantation (P45),exposed to clear-cutting before plantation,and an 80-260-year-old natural forest (N260),were chosen to study the effects of different forest ages/types on Collembola community in the litter and soil layers during 2008 and 2009.Soil conditions in P26 and P45 were significantly deteriorated when compared to N260.A higher value of soil bulk density and lower values of soil organic matter,soil N,litter depth,soil pH,and soil water content were observed in P26 and P45.Totally,the same genera of Collembola tended to occur in the forests of all ages studied;however,the Collembola community structure was significantly impacted by the differences in forest age.Both in the litter and soil layers,the density and generic richness of the Collembola were the highest in N260 and the lowest in P26.Some collembolan groups were sensitive to soil conditions in particular forest ages.N260 was associated with relatively high abundance of Plutomurus collembolans and P45 with relatively high abundance of Pseudofolsomia collembolans.The canonical correspondence analysis showed that the community structure of Collembola was mainly affected by forest age in both litter and soil layer.The ordination analysis of non-metric multidimensional scaling also found that the Collembola community did not recover to the level of natural forests in 26-year regeneration after clear-cutting.Even in 45-year regeneration after clear-cutting,the Collembola community only showed a slight recovery to the level of natural forests.Our results clearly showed that both Collembola community and soil conditions did not recover in 26-and 45-year regeneration after clear-cutting in P.tabulaeformis plantations;however,they might have the potential to recover in the future because the same genera of Collembola were distributed in the plantations and natural forests.     

Intense fragmentation and deep burial reduce emergence of Rumex crispus L.

Abstract

Mechanical control through different tillage methods is a common measure against perennial weeds. However, non-optimal tillage can potentially increase the vegetative regeneration instead of reducing it. Aspects of regenerative capacity in the perennial weed species Rumex crispus L. was studied in three pot and box experiments as follows: (1) regeneration from different root fragments under varying test conditions; (2) effects of root size and burial depth on time of emergence and emergence rate; and (3) effects of burial depth and cutting on biomass production and seed production. In experiment 1, sprouting occurred mainly from the neck of the roots, consisting of underground stem tissue. A few shoots were observed also from the upper half of the true taproot and from a side root. No difference in sprouting was found between test conditions. In experiment 2, total emergence rate was positively related to root size and negatively related to burial depth. Time to first emergence was defined by an interaction between the two factors. Roots larger than 100 g gave rise to a high degree of emergence from all burial depths, while emergence from roots weighing 20–30 g was less than 30% from 12 cm and nonexistent from 18 cm. When emergence and shoot production were tested under different cutting regimes (experiment 3), the separated top fragments of the roots sprouted faster and produced more shoot biomass than intact rootstocks, even at a second harvest. Our results indicate that fragmentation can stimulate sprouting from the regenerative tissue of the taproot. Hence, if tillage is carried out as weed control it is important that root fragments are buried at ploughing depth, especially if the population consists of adult plants.     

小叶锦鸡儿固沙群落土壤微生物生物活性的季节动态

为探讨科尔沁沙地小叶锦鸡儿固沙群落土壤微生物生物量和酶活性的季节动态规律,选取6,11,24年生人工群落和天然群落为对象,研究了不同土层深度微生物生物量(C、N、P)和脲酶、蛋白酶、蔗糖酶、磷酸单酯酶、脱氢酶和多酚氧化酶的活性随季节的变化特征。土壤按5层取样:0-10cm,10-20cm,20-30cm,30-40cm,40-50cm。结果表明,6～24年生小叶锦鸡人工固沙群落及天然群落土壤微生物生物量表现出明显的季节性变化,微生物生物量C和N为夏季>秋季>春季;微生物生物量P为夏季>秋季;6种土壤酶的活性也随季节发生显著变化,夏季显著高于春季和秋季。土壤微生物生物量和6种酶的活性随群落发育年限的增长而升高,但人工群落土壤的生物活性始终低于天然群落。6种土壤酶活性和微生物生物量最高值均出现在土壤表层(0-10cm),随着土层的加深生物活性逐渐降低。     

小麦抗穗发芽酶反应生化标记选择法研究

以穗发芽抗性不同的小麦品种（系）及不同杂交组合的F2为试材，用邻苯二酚作底物进行多酚氧化酶生化染色标记，对小麦抗穗发芽酶反应标记选择法进行了研究。结果表明，种子染色标记的最佳条件是：0.125%的邻苯二酚溶液，在气温18~25℃条件下浸种10~15min，覆膜保湿酶反应4~6h，晒干后进行比色分级。对不同色级的种子进行抗穗发芽、酚酶活性鉴定，表明小麦穗发芽率与酶反应生化标记后的种子色级存在极显著的正相关，生化标记后颜色越深的材料越不抗穗发芽，不染色或染色浅的低酚酶活性种子则具有较强的抗穗发芽性。用该法成功选育出抗穗发芽小麦新品种宝麦8号（冀审麦2004012号）。     

Response of Chamecytisus palmensis to drought stress induced by polyethylene glycol during germination

Abstract

Seed germination and subsequent changes in Chamecytisus palmensis were studied under water limiting conditions, imposed by increasing concentrations of polyethylene glycol (PEG-6000) (0, 5, 10, 15, 20, 25, and 30%). Six water stress conditions (C. palmensis. Seed germination was completely inhibited under the drought stress of 30% (?1.20?MPa). Similar to the seed germination, the growth of radicles and hypocotyls after seed germination was also restricted by PEG-simulated drought stress, especially when water potential was lower than ?0.12?MPa (25%). In the same way, the ratio of radicles and hypocotyls significantly decreased with the increase of PEG concentrations, demonstrating strong adaptability to drought stress. Moreover, the decline of radicles and hypocotyls lead to a decrease in the number of root hairs. This would seriously affect the water absorption ability of the young roots. It was concluded that drought stress might be one of the causes for obstructed natural regeneration of C. palmensis plantations on sandy land.     

Preservation of seed viability during 25 years of storage under standard genebank conditions

Maintaining sufficient viability is critical to the sustainability of ex situ conserved seed collections. For this reason, accessions are regenerated when viability falls below a predefined threshold. Viability is monitored by determining the germination ability of accessions at predefined time intervals. Optimizing the frequency of these germination tests, in order to avoid waste of resources, is hampered by the scarce availability of data about seed longevity, particularly for material maintained under genebank conditions. Here we report on the analysis of nearly 40,000 germination test results collected for a wide range of crop species over a 25-years period by the centre for genetic resources, the Netherlands (CGN), where seeds of genebank accessions are dried to 3–7 % moisture content and stored for the long term under near-vacuum in aluminium foil bags at ?20 °C. The results indicate that seed viability is well maintained for the large majority of seed lots during the first 25 years after regeneration as only 3.3 % of the monitoring tests revealed below-threshold germination values. It is argued that the majority of these sub-standard seed lots are due to other causes than seed ageing, including dormancy problems and estimation error in germination testing. For material, maintained under the seed management procedures and storage conditions practiced by CGN, it is therefore recommended to delay the first germination monitoring tests to 25 years after regeneration.     

黄土丘陵半干旱区人工柠条林土壤固碳特征及其影响因素

为了探讨黄土丘陵区不同生长年限的人工柠条林地土壤有机碳含量的变化特征及其影响因素,更好地阐明黄土丘陵区柠条林土壤的固碳机理,本文采用时空替代法,以撂荒2 a的坡耕地为对照,对黄土丘陵半干旱区不同林龄(10 a、17 a、26 a、34 a、40 a、50 a)人工柠条林地土壤有机碳(SOC)、全氮(STN)、全磷(STP)及柠条林的根系生物量和枯落物现存量进行了分析。结果表明:1)在0~60 cm的土层剖面上,0~20 cm土层SOC含量明显高于其他土层,并随土层深度的增加逐层递减,其中柠条林地0~20 cm土层SOC含量变化幅度为2.68~11.44 g·kg-1,而40~60 cm土层SOC含量仅在1.64~2.73 g·kg-1波动;与对照相比,随林龄增加柠条林地0~60 cm土层平均SOC含量先减小后增加最后趋于平稳:10 a和17 a柠条林SOC含量比对照显著降低了34.5%和26.9%,26 a柠条林的SOC含量显著升高,其值是对照的1.43倍,40 a和50 a柠条林SOC含量处于积累与消耗相对稳定的状态。2)对SOC含量与STN、STP含量及根系生物量和枯落物现存量进行相关性分析表明,SOC含量与STN含量、根系生物量及枯落物现存量之间存在极显著线性相关,但与STP含量相关性不明显,说明土壤中氮含量的增加能明显提高土壤的固碳能力,而根系生物量和枯落物现存量的多少能够决定土壤的固碳水平。     

Influence of Growing Medium and Seed Size on Germination and Seedling Growth of Pinus gerardiana Wall.

Pinus gerardiana Wall. is an important nut-producing pine having restricted distribution in the world. It has been observed that natural regeneration in the species is extremely poor or entirely lacking. The species has erratic and infrequent seed years, dormancy-related problems, and slow growth of seedling, which reduces its regeneration process in natural habitats. Therefore, we investigated the effect of growing medium and seed size on germination and seedling growth of the Pinus gerardiana. The seeds were categorized into two sizes, viz, small (<2.35 cm) and large (>2.35 cm) and five growing medium treatments were used, viz, Soil:Sand:FYM; Soil:Sand:Moss:FYM; Soil:Moss:Vermicompost; Soil:Sand:Vermicompost; and Soil:Sand:Moss:Vermicompost, for assessing their impact on germination and seedling growth. It was observed that, among different growing medium treatments, higher germination and seedling growth parameters were recorded, when Soil:Sand:Moss:Vermicompost was used for the study. Between different seed sizes, higher germination and seedling growth were recorded when seed size was large.