黄土高原丘陵区柠条根系生长发育特性研究

以陇西黄土高原丘陵沟壑区1～3a柠条荒山直播苗为研究对象,应用挖掘法对其根系的形态、生长发育、分布及根瘤特性进行了观测分析。结果表明,幼龄期柠条主根生长速度远大于株高生长,根冠比值在4～6之间;侧根主要发生在主根的5～15cm段;柠条胚根平均向上伸长5cm,合理的播种深度为3cm;根瘤主要集中在10—30cm土层中主根及一级侧根上;速生、发达的根系和根瘤,使得柠条具有超强的抗旱、耐瘠薄能力和蓄水保土、改良土壤的生态功能。柠条秋播较春播能更大程度地与当地的光、热、水等资源相拟合,应大力倡导秋季直播造林。     

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。     

柠条人工林下草本植被特征与土壤特性相关性研究

为探索黄土丘陵沟壑区最佳的柠条（Caragana Korshinskii）平茬措施,本研究以该区柠条人工林为研究对象,对其进行4种不同方式的平茬措施,分析在不同平茬措施的柠条林下草本植被特征与土壤特性的相关关系。结果表明：隔行平茬措施下草本生物量最大,柠条林下各土层土壤含水量与草本地上生物量密切相关,且以负相关关系为主;草本植物多样性各指数均与土壤含水量呈负相关关系,40～80 cm土层的土壤含水量与Simpson指数的相关性显著（P<0.05）,与Shannon-wiener指数的相关性极显著（P<0.01）;土壤养分各指标与草本植物多样性没有显著相关性,在0～60 cm土层内,土壤碱性越大,草本生物量越大,20～40 cm土层土壤有机质越小,草本生物量越大。综合以上结果,在该区域采取柠条隔行平茬措施最佳。     

Soil sterilisation and plant growth-promoting rhizobacteria promote root respiration and growth of sweet cherry rootstocks

Soil microorganisms play important roles in the plant-soil ecosystem, and plant growth-promoting rhizobacterium (PGPR) promotes plant growth through several mechanisms. To investigate the benefits of PGPR for root functions such as respiration, we used the plant model Cerasus sachalinensis Kom., in which root respiration provides a sensitive functional indicator to demonstrate the effect of soil sterilisation (SS) and inoculation with the PGPR Staphylococcus sciuri ss sciuri after SS on seedling root respiration and growth. Root respiration increased in the presence of PGPR inoculation alone, whereas Embden–Meyerhof–Parnas pathway activity decreased due to reduced phosphofructokinase and pyruvate kinase activities. Although cytochrome c oxidase activity decreased and alternative oxidase activity increased, only slight changes were observed in growth indicators such as seedling height. However, SS and PGPR inoculation after sterilisation reduced soil microbial biomass carbon and reduced root respiration. Pyruvate kinase activity as well as plant height and leaf number increased, thus promoting plant growth. Thus, we conclude that SS and PGPR inoculation altered enzymes activities, root respiration and plant growth of cherry rootstocks. The effects of microbial inoculation were altered by SS.     

短脚锦鸡儿灌丛对植物群落和土壤微生物群落的促进效应研究

以内蒙古荒漠区短脚锦鸡儿灌木为研究对象,采用野外调查法分析灌丛对植物群落的影响,采用传统培养法,结合分子鉴定法分析灌丛对土壤微生物群落的影响。结果表明:(1)灌丛内植物群落多度和总生物量显著大于灌丛外,但是物种丰度和Shannon-Wiener指数灌丛内外无显著差异;(2)随土壤深度的增加,表层土与深层土的土壤可培养细菌丰度和真菌多度差异不显著,其余土壤微生物群落多样性特征均表现为:表层土显著大于深层土;(3)灌丛对土壤微生物群落具有正效应,且表层土正效应最大;(4)灌丛对植物群落的促进作用大于对土壤微生物群落的作用。     

Succession of soil bacterial and fungal communities of Caragana korshinskii plantation in a typical agro-pastoral ecotone in northern China over a 50-a period

Bacterial and fungal communities play critical roles in reestablishing vegetation structure, function and biodiversity in ecosystem restoration in arid and semi-arid areas. However, the long-term successional changes in bacterial and fungal communities that occur with artificial vegetation development are not fully understood. In this study, we investigated the successional changes in bacterial and fungal communities in Caragana korshinskii Kom. plantation over a period of 50 a (6, 12, 18, 40 and 50 a) and their relationships with key soil environmental factors in a typical agro-pastoral ecotone, northern China. The results showed that bacterial and fungal diversities (α- and β-diversity) were significantly affected by plantation age; moreover, the change in fungal community was more evident than that in bacterial community. Soil samples from 12 a plantation had the highest (P<0.05) bacterial and fungal α-diversity (i.e., abundance-based coverage estimator (ACE) and Chao1 index) at 0-10 cm depth compared with other samples. However, soil samples from plantation at the late recovery stage (40-50 a) had the highest α-diversity at 10-20 cm depth. Soil bacterial community was not significantly affected by plantation age at the genus level; but, soil fungal community was significantly affected at the genus level. Overall, Mortierella and Chaetomium were the dominant genera at natural recovery stage (0 a); Inocybe was the dominant genus at the early recovery stage (6-12 a); Inocybe and Mortierella were the dominant genera at the mid-recovery stage (12-40 a); And Mortierella, Cladosporium and Humicola were the dominant genera at the late recovery stage (40-50 a). Redundancy analysis (RDA) showed that β-glucosidase activity, total nitrogen and soil organic carbon were closely associated with bacterial community composition, while alkaline phosphatase, urease activity and total nitrogen were associated with fungal community composition, indicating that changes in enzyme activity and soil nutrients were the most important determinants of dominant genera. Furthermore, pathogenic microorganisms (Cladosporium and Humicola) were dominant in soils from 40-50 a plantation, which may affect plant growth, resulting in the decline of C. korshinskii plantation. Overall, the findings of this study improve the understanding of ecological patterns of bacterial and fungal communities in artificial vegetation and provide an important scientific basis for comprehensive ecological restoration management in arid and semi-arid areas.     

水分缓释在柠条复合型包衣种子中的研究

飞播包衣种子技术是沙区植被恢复与重建的重要手段,但目前该技术存在一个亟需解决的问题,即飞播种子的成活率低。本文以沙生先锋植物柠条种子为材料,利用正交试验设置不同包衣材料组合,再通过研究不同组分的包衣种子发芽率、苗质量以及包衣种子的多项物理指标,确立了适合柠条种子的丸化包衣剂最佳配方,即乙基纤维素1.5%、凹凸棒黏土和滑石粉的比例为2∶1和10%的“旱可舒”保水剂,并且最终的丸化倍率为1.0。该丸化包衣种子具有一定的吸水功能,在丸化包衣的基础上,再筛选出“尤特奇 (Eudragit) RS 30D”为成膜材料,制成厚度为10%的包衣薄膜,该薄膜可以有效“控制”柠条种子在不适合成苗的降雨量下的萌发,同时不影响在丰富降雨量条件下正常萌发与成苗。毛乌素沙漠实地播种试验结果表明,经过丸化包衣处理的柠条种子,其成苗率提高了22%;对丸化包衣处理的柠条种子,再经过外敷薄膜包衣处理后,其成苗率提高了88%,明显高于丸化包衣处理的种子。这种复合型的丸化薄膜包衣种子可为毛乌素沙区的飞播治沙提供新的思路。      

黄土丘陵区柠条灌木林合理平茬期的研究

本文根据柠条(Caragana korshinskii)生长的特点,即生长速率随灌木林龄的变化呈近似正态分布的特征曲线,根据曲线的几何特征,提出以柠条生长速率与峰值和右拐点连线的斜率相等的点为平茬始点,以几何曲线的右拐点为平茬终点的平茬方案。长期观测结果表明,柠条生长指标符合Logistic方程,本文以Logistic生长函数为例,说明了柠条灌木林平茬时间确定方法的具体推导过程。最后结合柠条生长指标(株高、分枝和生物量),对不同立地条件下柠条灌木林的合理平茬时间进行了探讨,结果表明,不同立地条件下柠条的合理平茬时间存在一定的差异,这种现象是由不同立地条件下水热环境的差异造成的。     

小叶锦鸡儿花棒固沙林生物生产力及适宜经营密度

通过对半固定沙地小叶锦鸡儿、花棒固沙林生物量的调查,初步确定了2个树种的生产力范围及适宜密度。调查结果表明,在嫩江沙地12年生小叶锦鸡儿林分最佳营林配置方式为带状,带距6m,穴距2．0m,花棒林分的稳定性远不如小叶锦鸡儿林分,在固定流沙方面,最好采用小叶锦鸡儿作为主栽树种。     

桦树柠条混交林生长效应的试验

通过对桦树柠条混交林及桦树纯林、柠条纯林的林木生长量、林分生物量、根系分布规律等的调查研究,结果表明,混交林的桦树高生长量比纯林桦树提高47．6％～119．5％,胸径提高44．1％～143．1％;混交林的林木生长量及单株生物量均高于纯林;混交林中桦树根系分布比纯林均匀,使林木充分利用土壤养分、水分、空间,利于林木的生长。