Growth rate of mosses and their environmental determinants in subalpine coniferous forests and clear-cuts at the eastern edge of the Qinghai-Tibetan Plateau, China

Mosses cover most of the forest floor of subalpine forests at the eastern edge of the Qinghai-Tibetan Plateau, the origin of many important rivers in China. They play a crucial role in preventing soil erosion and conserving large amounts of water thereby regulating the water budget of local ecosystems. This area has a harsh climate due to low temperatures and low air pressure at high elevations. But the temperature varies considerably during the growing season, which does not favor the regeneration of spruce seedlings on clear-cuts after logging. Leaves of mosses have a single layer of cells and are thus sensitive to environmental changes. This attribute may be useful for monitoring environmental conditions and guide artificial regeneration. The growth of mosses has never been studied in this area and the variables indicating their growth in the subalpine forest ecosystems still needs investigation. Growth rates of mosses have been rarely studied worldwide because the methods are time consuming and often inaccurate. A more simple and accurate method for measuring moss growth would help and encourage relevant research. We have found a method that will promote the efficiency in field measurements. Because of the special growth properties of mosses, the apical cell of branches initiates growth and the preceding leaves will stay where they were as the tips grow. Once mosses are marked with red oil at the tip of branches surrounded by young leaves, that portion of the branch above the marked leaves represents growth after labeling. Two plots, one in an old-growth spruce forest and another in a nearby clear-cut, were selected to label mosses in a subalpine area of western Sichuan Province during the growing season in 2001. The labeling was done on May 7 and measurements were made on August 7. Microclimate measurements on both sites were simultaneously carried out. Of the six mosses, five species were present in both the forest and on the clear-cut. One species, Entodon conncinus, was found only on the clear-cut. The growth rates of mosses varied among species and habitats. Hylocomium splendens grew the fastest while Dicranum assamicum had the slowest growth rate. Habitat conditions have a distinct effect on the growth of Hylocomium splendens, Dicranum assamicum and Thuidium lepidoziaceum and their growth rates were higher in forests than on clear-cuts. The growth rates of these mosses increased as their habitat approached the forest. Actinothuidium hookeri and Rhytidiadelphus triquetrus have moderate growth rates and is almost entirely independent of the type of habitat. The mosses can therefore be classified into habitat-sensitive and habitat-insensitive types. Analysis of microclimate characteristics shows that from May to July, the solar radiation level is lower and the environment is drier in the forest than those on the clear-cut. But a vapor pressure deficit (VPD) regime shows that the VPD in the morning is almost always lower in the forest than that on the clear-cut. With lower radiation and VPD, forests are more favorable to moss growth. For habitat-insensitive species, favorable micro-topographic factors might have offset the effect of habitat type. VPD is strongly correlated with the growth of mosses. Eco-physiological characteristics, such as poikilohydry, play an important role in the survival and growth of mosses under harsh climatic conditions. Temperature and humidity are two factors critical for seedling establishment in artificial regeneration processes in the subalpine areas of western Sichuan. Since the growth of mosses is a function of the two factors, moss growth rates can be used to indicate the more favorable habitats. Therefore, the status of moss growth can be used to indicate habitats potentially favorable to the growth of tree seedlings. __________ Translated from Journal of Plant Ecology, 2007, 31(3): 464–469 [译自: 植物生态学报]     

不同沙埋深度对刺叶墙藓植株碎片生长的影响

采用撒茎法对构成古尔班通古特沙漠苔藓结皮的优势种刺叶墙藓(Tortula desertorum Broth.)进行室内沙培实验,探讨不同沙埋深度对刺叶墙藓无性繁殖的影响.结果表明:(1) 在不添加任何营养元素或激素的原沙基质培养条件下,刺叶墙藓的植株碎片仍然能够生长并发育成完整的植物体.(2)在所设置的不同沙埋厚度条件下,刺叶墙藓的植株碎片在2 mm沙埋厚度时生长较好,生长趋势表现为:前12 d内生长较快,之后生长缓慢.第22 d以后,未见新生植株,苔藓植株数趋于稳定.大于2 mm的沙埋厚度则抑制其生长.同时指出,沙埋也是影响古尔班通古特沙漠苔藓植物生长和分布的因素之一.     

邳州苔干绿色生产技术

苔干肉质肥厚,清脆可口,富含多种氨基酸、维生素及锌、铁、硒等微量元素,有“天然海蜇”“健康食品”等美称,在江苏邳州等地广泛种植,是江苏邳州市一个珍贵稀有品种。通过阐述邳州苔干特征特性、生育周期对环境条件的要求、病虫害防治、适期采收等绿色生产栽培技术,为苔干的高效生产提供科学依据。     

滋生青苔对柑橘叶际生物多样性的影响

本文利用Illumina Miseq高通量测序技术对重庆地区有青苔病症和无病症的柑橘叶际真核生物的群落组成、结构、多样性及差异进行了研究,旨在找到可能的病原物类群,为更好地防治柑橘青苔病奠定基础。结果表明13个柑橘叶片样本共检测到303个OTU,多样性较为丰富;优势门为链形植物门Streptophyta、子囊菌门Ascomycota、绿藻门Chlorophyta等;通过分析发现可能的病原物为不可培养的虚幻球藻属球藻uncultured Apatococcus sp.、黄绿异小球藻Heterochlorella luteoviridis、无柄杯梗孢Cyphellophora sessilis、海南橡胶藻Heveochlorella hainangensis、Coniochaetales sp. GMG C4、椭圆球藻Chloroidium ellipsoideum、Kalinella bambusicola等;不同区县表现出青苔病症状的柑橘叶片上疑似病原物的种类和丰度都差异很大。柑橘青苔病可能是由多种藻类及真菌复合侵染造成的,病原物和柑橘叶片间的相互作用有待进一步研究。     

黄土丘陵区生物结皮土壤温度年内动态特征及其对土壤水分的响应

[目的] 明确黄土丘陵区粉砂质壤土上生物结皮土壤温度年内动态以及其与土壤水分的关系，为进一步理解生物结皮在黄土丘陵区生态系统中的功能提供科学依据。[方法] 于2016年1月1日至2018年12月31日在陕西省吴起县退耕封禁地进行野外长期定位监测试验。[结果] ①生物结皮土壤温度具有明显的年内动态。一般生物结皮层月均温最高出现在6月，为27.1℃；结皮层下5 cm土壤月均温最高在7月，为22.7℃；生物结皮层和结皮层下5 cm土壤月均温均在1月最低，分别为-1.7和-1.4℃。②生物结皮层和结皮层下5 cm土壤温度日动态均为正弦曲线。生物结皮层和结皮层下5 cm土壤温度最大日较差均出现在6月，分别为32.0和17.2℃；10月生物结皮层温度日较差最小，为17.3℃，1月结皮层下5 cm土壤温度日较差最低为8.5℃。③年内生物结皮土壤温度与气温呈显著正相关；3-10月生物结皮土壤温度与土壤水分呈显著负相关，11-12月生物结皮土壤温度与土壤水分呈显著正相关。④1月和7月土壤含水量的增加导致生物结皮层和结皮层下5 cm土壤温度日较差下降。[结论] 黄土丘陵区粉砂质壤土上生物结皮土壤温度与土壤含水量密切相关，且不同月份土壤水分对生物结皮土壤温度的影响程度不同。     

不同青苔发病程度下柑橘叶片营养及叶际生物特征分析

为探讨不同青苔发病程度下柑橘叶片矿质营养元素含量和叶表生物群落结构的变化特征之间的关系,本研究对重庆江津区李市和白沙两个不同地点柑橘果园中的W·默科特叶片青苔病发生程度按G0~G5分级并进行病情指数统计,测定各病情等级下叶片的氮(N)、磷(P)、钾(K)、钙(Ca)、镁(Mg)、锌(Zn)、铜(Cu)、铁(Fe)、锰(Mn)、硼(B)这10种矿质营养元素含量,同时利用高通量测序技术测定叶片叶际真核生物的群落组成、丰度、差异,分析了不同病情等级下叶际生物特征与营养之间的关系。结果表明:两样地的柑橘青苔发病程度和病情特征较为一致。李市和白沙两个果园W·默科特叶片青苔病病情等级均与P、Mg含量显著负相关,与K、Ca含量显著正相关。不同病情等级下叶际真核生物在属水平上存在明显差异,病情等级1下优势属是Heterochlorella、Sporidiobolus和Cladosporium,病情等级2下优势属是Heterochlorella、Symmetrospora和Microsporomyces,病情等级3下优势属是Heterochlorella、Cladosporium和Sporidiobolus,病情等级4下优势属是Heterochlorella、Cladosporium和Heveochlorella,病情等级5下优势属是Heterochlorella、Cladosporium和Microsporomyces;在种水平上,主要病原生物uncultured Apatococcus、Cladosporium herbarum、Heveochlorella hainangensis的相对丰度较高,且与病情等级呈极显著正相关关系。进一步分析显示,叶片中P、Fe、Mg、Mn、Cu、N含量与叶片生物群落结构之间关系密切,主要病原生物uncultured Apatococcus、Cladosporium herbarum与P含量极显著负相关,与Ca含量极显著正相关。综上所述,柑橘青苔病与叶片P和Ca两种元素关系最为密切,青苔病发生程度高低可直接影响叶片中P和Ca的含量。     

甘肃省兴隆山天然林下苔藓凋落物蓄积量及持水特性

2010年,采用野外实地观测与室内浸水法,对甘肃兴隆山青杄林、青杄—白桦林林下苔藓和凋落物的累积量、持水量、持水率和吸水速率进行了研究。结果表明:(1)青杄—白桦林和青杄林下苔藓及凋落物层总厚度7.10~8.30cm,总重量24.66~30.69t/hm2,青杄—白桦林均高于青杄林;(2)苔藓层最大持水率明显高于凋落物层,但凋落物层最大持水量是苔藓层的11.15倍;(3)苔藓层和凋落物层持水率在开始浸水时增加较快,0.5h后增幅逐渐减慢,浸水10h后基本趋于某一稳定值;(4)凋落物层最大拦蓄量、有效拦蓄量分别是苔藓层的10.41和10.27倍;凋落物层在对降水二次分配及在吸持降水过程中发挥着重要作用,并且位于主导地位。     

外源添加物对沙地苔藓结皮扩繁发育的促进作用

人工苔藓结皮作为一种新型的防风固沙潜在途径而备受关注，为进一步优化现有的培育扩繁技术，采用4因素2水平正交试验设计，探讨了菌类（放线菌和巨大芽孢杆菌）、藻类（小球藻和具鞘微鞘藻）、沙蒿胶（有和无）和基质类型（沙土基质和配方基质）对沙地苔藓结皮室内发育扩繁的影响。结果表明：（1）4因素中仅基质类型显著影响了苔藓结皮的盖度和株密度（P<0.05），沙土基质处理的苔藓结皮盖度和株密度均值比配方基质处理分别提高61.04%和17.48株/cm²；（2）藻类、菌类和基质类型显著影响了苔藓的生理特性（P<0.05），而沙蒿胶影响不显著。沙土基质、放线菌和小球藻的添加显著提高了苔藓的过氧化物酶（POD）活性和可溶性蛋白含量，降低了丙二醛（MDA）含量；（3）最适扩繁组合为"沙土基质+放线菌（1 g/kg基质）+小球藻（2 g/m²）"，在30天内，上述组合在培养箱条件下（光照设定为6 000 lx，光周期12 h/d，温度20℃，空气湿度75%），可将1 m²野外苔藓种源培育为4 m²盖度达97.14%的苔藓结皮，实现4倍扩繁。研究结果将为今后大规模工厂化高效扩繁苔藓种源提供技术支撑。     

林下地被物保水保土作用研究进展

 较为系统地总结了部分前人关于林下枯落物和苔藓对水土保持、环境保护等方面作用的研究成果,林下枯落物和苔藓均具有较强的吸持降水、涵养地表径流、增加地表糙率、改良土壤特性等作用。部分学者的研究成果还表明,苔藓对环境变化具有指示和监测作用。     

中国四省未开垦表土硫源识别研究

The analysis of stable isotopes of sulfur(δ34S) is a useful tool for identifying sources of sulfur in soils. Concentrations and sulfur(S)isotopes of water-soluble sulfate(WSS), adsorbed sulfate(AS), residual sulfur(RS), and total sulfur(TS) in uncultivated surface soils of four Chinese provinces were systematically analyzed for identifying sources of S in the soils. Green and healthy mosses(Haplocladium microphyllum) were sampled as bioindicators. The mean WSS concentration(27.8 ± 23.4 mg kg-1) in the surface soils was lower than those of AS(101.4 ± 57.0 mg kg-1) and RS(381.5 ± 256.7 mg kg-1). The mean δ34S values of WSS and AS were very similar(about2.0‰), lower than those of RS(8.0‰) and TS(6.1‰). A significant linear correlation was found between the δ34S values of AS and WWS(y = 1.0002x- 0.0557, P 0.0001), indicating that sulfate adsorption in the soils did not markedly fractionate S. All S species in the soils of Guizhou Province were characterized by the lowest δ34S values, consistent with the most34S-depleted rainwater sulfate reported at Guiyang of Guizhou Province. The δ34S values of sulfate in mosses and rainwater previously reported were significantly linearly correlated with those of both WWS and AS in surface soils, suggesting that atmospheric S input was an important source for soil WSS and AS. However, there were no significant correlations between isotopic composition of rainwater sulfate and RS or TS.The slopes of all these significant linear correlations(soil/rainwater or soil/moss isotopic ratio) were 0.4–0.6, indicating that inorganic sulfate in the surface soils should be a result of mixing of deposited atmospheric sulfate with a more34S-depleted sulfate component possibly from mineralization of RS.