Impact of invasive slash pine (<Emphasis Type="Italic">Pinus elliottii</Emphasis>) on groundcover vegetation at home and abroad

Invasive trees can cause catastrophic reductions in diversity in invaded grasslands and savannas. Such reductions often appear to be particularly severe in the new biogeographic ranges of these invaders. We present results of a field study that examined the effect of slash pine (Pinus elliottii), native to the southeastern US, on savanna groundcover vegetation in the state of São Paulo in Brazil (cerrado) and in its native range in Mississippi (USA) following fire exclusion. We compared the difference in several community attributes between slash pine understories and adjacent open area in both São Paulo and Mississippi, and compared the effects of needle litter on native species in both continents. Slash pine was correlated with lower non-graminoid species richness and plant density in both São Paulo and Mississippi; however, these apparent negative effects were 4.6 and 11 times stronger in the non-native range of Brazil (for richness and density, respectively). Native graminoids were not present in invaded cerrado. Overhead slash pine canopy cover, pine density, and needle depth were 5.2, 3.7, and at 14 times higher, respectively, in Brazil than in Mississippi savannas, for similarly-aged pine stands. One year after implementing needle litter treatments in Brazilian cerrado and restored Mississippi savanna, plant density and non-graminoid species richness were highly suppressed, but to similar degrees in both ranges. Our results suggest that higher rates of needle deposition, associated with higher tree densities, contribute to the stronger suppression of native species in Brazil than in Mississippi.     

澳大利亚亚热带不同森林土壤微生物群落对碳源的利用

为阐明土壤微生物群落对碳源利用类型和强度,采用MicroRespTM方法研究3种森林类型不同土壤含水量微生物群落对不同类型碳源的利用情况,结果表明：湿地松（Pinus elliottii Engelm. var. elliotttii）林地土壤微生物碳源利用率依次为60%WHC>20%WHC>40%WHC,南洋杉（Araucaria cunninghamii）和贝壳杉（Agathis australis）林地土壤微生物对碳源利用的格局相似,为20%WHC>60%WHC>40%WHC。南洋杉和贝壳杉林地土壤对碳源利用率趋势相同,主要是对L-苹果酸、草酸和L-赖氨酸利用比较高。在40%WHC处理中,3种树种对碳源的利用均很低,差异不明显。除精氨酸和L-赖氨酸外,60%WHC处理土壤微生物利用单一碳源能力的大小顺序为：南洋杉>湿地松>贝壳杉。3种树种土壤Shannon多样性指数(H’)、Shannon均匀度(E)和Simpson指数(D)均无显著差异。土壤pH值影响微生物对L-丙氨酸、精氨酸、D-( )-葡萄糖、N-乙酰基-氨基葡萄糖的利用率较大,这些类群的微生物主要分布在贝壳杉林地;分布在南洋杉林地的微生物对柠檬酸、L-苹果酸和γ-酪氨酸利用率较大,且主要是受TP的影响;D-( )-果糖、柠檬酸和L-半胱氨酸-盐酸等受水分、TN和TC等影响较大,这类微生物类群主要分布在湿地松林地。     

不同林相的松针对马尾松毛虫生长发育的影响

为探讨混交林中松树对害虫的生态调控作用机制,研究了不同林分类型下马尾松林和湿地松林对马尾松毛虫生长发育的影响。结果表明,取食马尾松针叶的马尾松毛虫与取食湿地松针叶的相比,其发育历期缩短,死亡率降低,幼虫及蛹（雌、雄）重增加,化蛹率、羽化率和产卵量均提高;且其幼虫的代谢量（取食量与排泄量）更大,对食物的利用与消耗的各项指标均高。取食不同林分类型下的同一种松树（马尾松或湿地松）针叶的马尾松毛虫,以取食纯林松针的幼虫生长发育更快,死亡率更低,化蛹率、羽化率和产卵量更高,对食物的利用、转化和消耗率更强。混交林中的松针不利于马尾松毛虫的生长发育和种群增长。     

Effects of simulated fire on vesicular-arbuscular mycorrhizae in pinyon-juniper woodland soil

Effects of fire on vesicular-arbuscular mycorrhizal fungi were tested using microcosms constructed from soil, litter, and duff collected beneath canopies of pinyon pine, Utah juniper, and in the open space (interspace). Burning was conducted over wet and dry soils. Soil temperatures were monitored continuously throughout the microcosms during burning. Plants grown in soils burned when dry had a lower VAM colonization than soils burned when wet. Juniper soils demonstrated the greatest reduction, over 95%, compared to their respective controls. Plants grown in interspace soils burned when wet were least affected. There was a positive correlation (r²=0.90) between the decrease in VAM colonization and the soil temperature as a result of the fire. Temperature effects, and associated reductions in VAM, were related to amount of litter burned in each microcosm and the moisture content of the soils.     

Linking soil N2O emissions with soil microbial community abundance and structure related to nitrogen cycle in two acid forest soils

Plant and Soil - Tree species and seasonal change influence N2O flux and microbial communities, but the mechanisms are unclear. We studied N2O flux in soils planted with slash pine and oil-seed...     

马尾松毛虫对马尾松和湿地松的选择与适应研究

用马尾松老叶、新叶,湿地松老叶、新叶,当年生马尾松新叶、湿地松新叶和当年生以20％和40％β-蒎烯处理过的马尾松新叶作食料饲养马尾松毛虫。结果表明：马尾松毛虫幼虫在第1代发生期取食马尾松老叶、马尾松新叶、湿地松老叶和湿地松新叶等4种不同质量的食料后,因其食料中10种必需氨基酸含量和挥发性物质β-蒎烯含量的不同,导致幼虫的存活率差异显著。其中,取食马尾松老叶的幼虫成活率最高（44％）,依次为马尾松新叶（32.7％）、湿地松老叶（4％）,而取食湿地松新叶的幼虫全部死亡。通过马尾松针叶增加外援β-蒎烯喂养马尾松毛虫实验,表明增加了外源β-蒎烯的松针饲养的马尾松毛虫幼虫与用同样松针未增加外源β-蒎烯饲养的幼虫相比,死亡率明显提高;松树中β-蒎烯含量的增加与幼虫成活率呈显著负相关。由此,我们阐明了马尾松与湿地松对马尾松毛虫的抗虫机制。     

南方红壤区3种典型森林恢复方式对植物群落多样性的影响

合理的森林恢复方式能提高植物多样性,进而提高生态系统服务功能.在我国南方红壤区研究了3种典型森林恢复方式(引进种恢复的湿地松(Pinus elliottii)人工林本地种恢复的马尾松(Pinus massoniana)人工林和自然恢复的天然次生林)的植物区系构成和植物群落多样性.结果表明:(1)湿地松人工林有155种植物,隶属66科118属,马尾松人工林有137种植物,隶属59科97属;天然次生林有226种植物,隶属86科160属,3种森林恢复方式的乔木层、灌木层和草本层的优势科属明显不同,马尾松人工林的优势物种和天然次生林更相似;(2)天然次生林的植物区系基本构成、植物区系类型种类高于马尾松人工林和湿地松人工林,并且天然次生林的温带成分比例高于湿地松人工林;(3)恢复方式对植物群落的多样性指数有显著影响,天然次生林的物种丰富度、辛普森指数明显高于马尾松人工林和湿地松人工林,两种人工林之间差异不显著;(4)3种森林恢复方式的植物群落结构存在显著差异,相比湿地松人工林,马尾松人工林的植物群落组成与天然次生林更相似.总之,自然恢复的天然次生林植物群落多样性高于人工恢复的马尾松人工林和湿地松人工林,本地种马尾松人工林在维持区域植物群落结构功能上优于引进种湿地松人工林.     

Slash pine genetic transformation through embryo cocultivation with A. tumefaciens and transgenic plant regeneration

Agrobacterium-mediated genetic transformation has been widely used to generate transgenic plants in angiosperms. However, progress in conifer species has lagged because of the recalcitrant nature of gene transfer. In this study, a transgenic plant regeneration system has been established for slash pine (Pinus elliottii Engelm.) using Agrobacterium-mediated transformation. Among the different Agrobacterium tumefaciens strains (EHA105, GV3101, and LBA4404) tested, the highest frequency (60%) of transient β-glucuronidase-expressing embryos was obtained from Agrobacterium strain GV3101 with over 330 blue spots per embryo. To improve the frequency of transformation, different cocultivation conditions were analyzed. Combination of Agrobacterium density at OD₆₀₀?=?0.9, 50 s sonication of embryos, and the addition of 50 μM acetosyringone produced the highest transformation efficiency, in which 56.2% of embryos formed hygromycin-resistant calli. Transient gene expression was observed in cotyledons and hypocotyls, but transgenic plants were only produced from callus cultures derived from embryonic cotyledons of transformed slash pine. Stable integration of transgenes in the plant genome of slash pine was confirmed by polymerase chain reaction, Southern blot, and Northern blot analyses. Transgenic lines with a single T-DNA copy were produced from Agrobacterium strains EHA105 (80.4%), GV3101 (95.7%), and LBA4404 (66%). These results demonstrated that a stable transformation system has been established in slash pine, and this system could provide an opportunity to transfer economically important genes into slash pine.     

Plant regeneration through multiple adventitious shoot differentiation from callus cultures of slash pine (Pinus elliottii)

A plant regeneration system through multiple adventitious shoot differentiation from callus cultures has been established in slash pine (Pinus elliottii). Influences of seven different basal media on callus induction, adventitious shoot formation, and rooting were investigated. Among the different basal media, B5, SH, and TE proved to be suitable for callus induction and plantlet regeneration. Multiple adventitious shoot formation was obtained from callus cultures of slash pine on B5, SH, and TE media containing indole-3-butyric acid, N6-benzyladenine, and thidiazuron. Scanning electron microscopy demonstrated the early development of adventitious shoots derived from callus cultures. These results indicate that an efficient plant regeneration protocol for micropropagation of slash pine had been established. This protocol could be most useful for future studies on genetic transformation of slash pine.     

Relative contributions of crown and phenological traits to growth of a pseudo-backcross pine family ((slash?×?loblolly)?×?slash) and its pure species progenitors

One pseudo-backcross [(slash?×?loblolly)?×?slash] (BC1) and open-pollinated families of the pure species progenitors were established in a single test in North Central Florida. Multivariate analysis was used to estimate the intra-trait correlation among the taxa, and path analyses were used to determine the relative contributions of crown architectural and phenological traits to first-year height growth. The multivariate analysis indicated that BC1, slash, and loblolly pine have different relationships among the traits studied, suggesting that a separate path analysis was required for each taxon. Path analysis coefficients of determination of the final models were 0.69, 0.73, and 0.65 for the pseudo-backcross, loblolly, and slash pine families, respectively. The ranking of traits by relative magnitude of effect on total growth was, for the pseudo-backcross crown projected area (CPA), fascicle length (FL), number of nodes (NN), number of branches (NB), number of needles per fascicle (NF), and fascicle diameter. For loblolly, this was CPA, NB, FL, NN, NF, initiation, and specific leaf area. For slash, this was CPA, NN, FL, NF, and NB. The study indicated that all crown traits considered in the path analysis had moderate effects on first-year height growth, with the exceptions of the consistently large effect of CPA and the minimal effect of the phenological traits.     

多样化松林中昆虫群落多样性特征

马尾松和湿地松是我国南方的2种主要松树。通过对6种不同林分结构下的马尾松林和湿地松林内昆虫群落调查与多样性指数分析,表明2种松树内的昆虫种类和数量无显著差异,混交林中的昆虫群落的种类和数量比纯林多,尤其以捕食天敌类群的种类和数量更为明显。整个昆虫群落和植食类群多样性指数以湿地松林内较大,而天敌(捕食类群和寄生类群)多样性指数则以马尾松林较高。从不同林分结构下昆虫多样性的比较来看,混交林内昆虫群落多样性指数波动较小,明显地高于纯林。但不同林分结构下昆虫多样性随水平分布和垂直分层格局而变化,松树北面和东面各样地之间的昆虫群落多样性指数差异显著,而南、西面之间差异较小;树冠层各样地之间的差异达极显著水平,而枯枝落叶层和树干层之间差异不显著。由此,还进一步讨论了混交林中昆虫群落稳定性问题。     

中亚热带湿地松(Pinus elliottii)人工林生长过程

基于树干解析和树轮分析,结合野外调查,揭示了我国主要外来树种--湿地松(Pinus elliottii)的生长规律,从而为人工林经营管理和生态系统服务功能评估提供了依据。2005年调查了1948年江西吉安青原山引种后存留的564株湿地松(1954 1958年生)。胸径(DBH, diameter at breast height)平均值为34.2 cm(18.4-58cm),树高平均值为19.5 m(9-33m)。青原山湿地松树轮分析结果显示:52年间,年树轮宽度增长量平均值为0.32 cm,最大年增长量不超过1.14 cm。胸径年生长量总体上呈下降趋势,直径生长高峰出现在10a左右;林龄达到20a左右时,直径年生长量开始下降;林龄40a后,生长变得极为缓慢。距青原山西南100km的千烟洲湿地松林(20年生)胸径和树高平均值分别为15.9 cm和11.0 m;20a的胸径生长量平均值为0.86 cm;材积方程为V= 0.0000213 D^2.9870924(V为带皮材积,D为胸径)。千烟洲湿地松林生物量低于同期营造的马尾松(Pinus massoniana)林生物量,也明显低于中亚热带地带性植被樟树(Cinnamomum camphora)林的生物量。经比较发现,引种营造的湿地松林,其生长量远不如原产地美国佛罗里达州湿地松林。     

Phenotypic analysis of first-year traits in a pseudo-backcross {(slash x loblolly) x slash} and the open-pollinated families of the pure-species progenitors

A single test, including one pseudo-backcross (Pinus elliottii x Pinus taeda) x P. elliottii and open-pollinated families of the pure species progenitors, was established in North Central Florida in December 2007 to study the transfer of the fast-growing characteristics from a P. taeda L. (loblolly pine) parent into the P. elliottii Engelm. (slash pine) background. Several traits were measured in the first growing season: height growth, phenology, tip moth incidence, stem traits, crown architectural and needle traits. Heterosis was evaluated for each trait using analyses of variance by fitting a linear mixed model. All traits were significantly (p value < 0.05) different among families while the significance for heterosis varied by trait. Positive heterosis was found for average rate of shoot elongation (ASRE), total growth (TG), total height and number of needles per fascicle while the opposite was true for base diameter, top diameter, fascicle length, fascicle diameter, crown projected area and phenological traits (cessation, duration and day to reach 50% of the height). Average performance (i.e., no heterosis) was found for initiation of growth, number of branches, number of nodes, tip moth incidence, sheath length and specific leaf area. The analyses indicated that introgression of loblolly pine alleles into slash pine was effective and novel trait combinations were achieved. The pseudo-backcross had larger variation in early height growth than the slash pine families and was taller than all open-pollinated families at the end of the first season. Tip moth incidence was much lower than the loblolly pine family.     

Mapping quantitative trait loci controlling early growth in a (longleaf pine × slash pine) × slash pine BC<Subscript>1</Subscript> family

Random amplified polymorphic DNA (RAPD) markers were employed to map the genome and quantitative trait loci controlling the early growth of a pine hybrid F₁ tree (Pinus palustris Mill. 2 P. elliottii Engl.) and a recurrent slash pine tree (P. elliottii Engl.) in a (longleaf pine 2 slash pine) 2 slash pine BC₁ family consisting of 258 progeny. Of the 150 hybrid F₁ parent-specific RAPD markers, 133 were mapped into 17 linkage groups covering a genetic distance of 1,338.2 cM. Of the 116 slash pine parent-specific RAPD markers, 83 were mapped into 19 linkage groups covering a genetic distance of 994.6 cM. A total of 11 different marker intervals were found to be significantly associated with 13 of the 20 traits on height and diameter growth using MAPMAKER/QTL. Nine of the eleven marker intervals were unique to the hybrid parent 488 genome, and two were unique to the recurrent parent 18-27 genome. The amount of phenotypic variance explained by the putative QTLs ranged from 3.6% to 11.0%. Different QTLs were detected at different ages. Two marker intervals from the hybrid parent 488 were found to have QTL by environment interactions.     

引种火炬松家系的速生性和稳定性综合分析

以湿地松和马尾松为对照,对福建省引种的5年生火炬松家系生长情况进行调查分析,结果表明,引种火炬松的树高、胸径和材积的家系方差及家系与地点互作方差均达显著水平,火炬松家系在福建省的平均生长表现优于马尾松和湿地松。利用系统聚类法可将测试的25个火炬松家系分为速生、较速生、中等和较差4类,其相对于当地树种马尾松的实际增益分别为83.2%、63.4%、48.5%和33.7%。运用基因型分组法对火炬松家系的速生性和稳定性进行综合评价,最终确定19、25、18、21、10号家系为增产且变异小,具有理想基因型的稳定型家系。     

Responses of Antioxidative Systems to Drought Stress in Pendunculate Oak and Maritime Pine as Modulated by Elevated CO2

The aim of the present study was to investigate the effects of an enhanced CO2 concentration alone or in combination with drought stress on antioxidative systems of a deciduous (oak; Quercus robur) and an evergreen (pine; Pinus pinaster) tree species. The seedlings were grown for one season in a greenhouse in tunnels supplied with 350 or 700 [mu]L L-1 CO2. The experiment was repeated in a second year. Antioxidants, protective enzymes, soluble protein, and pigments showed considerable fluctuations in different years. Elevated CO2 caused significant reductions in the activities of superoxide dismutases in both oak and pine. The activities of ascorbate peroxidase and catalase were also reduced in most cases. The activities of dehydroascorbate reductase, monodehydroascorbate radical reductase, glutathione reductase, and guaiacol peroxidase were affected little or not at all by elevated CO2. When the trees were subjected to drought stress by withholding water, the activities of antioxidative enzymes decreased in leaves of pine and oak grown at ambient CO2 and increased in plants grown at elevated CO2 concentrations. The present results suggest that growth in elevated CO2 might reduce oxidative stress to which leaf tissues are normally exposed and enhance metabolic flexibility to encounter increased stress by increases in antioxidative capacity.     

土壤水分对湿地松幼苗光合特征的影响

通过设置常规供水(CK)、轻度干旱(T1)、水饱和(T2)、水淹(T3)4个处理组,研究湿地松当年实生幼苗在不同土壤水分条件下的光合生理响应及叶绿素荧光特性。结果表明:不同水分处理对湿地松幼苗的叶片气体交换参数、水分利用效率(WUE)、光合色素、叶绿素荧光参数等指标有不同的影响;其中,T3的光合色素含量最低;T2、T3组的湿地松幼苗表现出较低的净光合速率(Pn)、电子传递速率(ETR)和PSⅡ光化学的量子效应(ΦPSⅡ),但与其他耐水淹植物相比,T3条件下的湿地松幼苗仍具有较高的Pn,说明湿地松幼苗具有较强的耐水淹能力;在T1条件下,湿地松幼苗具有较高的WUE和较低的蒸腾速率(Tr)、气孔导度(Gs)以对抗干旱的逆境,其Pn、PSⅡ最大光化学效率(Fv/Fm)、ETR和ΦPSII均有所下降,但仍能维持在相对正常的水平。研究证明,湿地松幼苗具有一定的耐淹耐旱特性,可运用于三峡库区消落带的植被重建。     

湿地松和马尾松人工林土壤甲烷代谢微生物群落的结构特征

土壤甲烷代谢微生物影响甲烷的产生和氧化,然而关于林型对土壤中甲烷代谢微生物群落结构影响的研究较少。采用基因芯片GeoChip 3.0研究了湿地松人工林和马尾松人工林土壤甲烷代谢微生物群落结构特征。结果如下,(1)两种林型的甲烷代谢微生物群落结构存在极显著差异(P=0.008),林型能解释其34.9%的变异;(2)产甲烷菌(包含甲基辅酶M还原α亚基基因mcrA的微生物)的优势菌群发生了变化,湿地松人工林的的优势菌为Methanocorpusculum labreanum Z,马尾松人工林的优势菌群除Methanocorpusculum labreanum Z外,还包括产甲烷古菌和Methanosarcina mazei Gol;(3)甲烷营养菌(包含甲烷单加氧酶基因pmoA基因的微生物)的优势菌为Ⅱ型,有3种不可培养细菌只在湿地松人工林检测到,在马尾松人工林中未检测到;(4)mcrA基因丰度或同源基因数量与土壤容重正相关,与土壤粘粒含量呈显著负相关;pmoA基因信号强度或多样性指数与土壤全碳含量、全磷含量和速效氮含量显著正相关。总之,相比本地种马尾松人工林,引进种湿地松人工林的土壤甲烷代谢微生物群落结构发生了显著变化。     

千烟洲针叶林的比叶面积及叶面积指数

根据实测数据计算了湿地松(Pinus elliotii)、马尾松(P. massoniana) 和杉木(Cunninghamia lanceolata)不同年龄、不同类型叶片的生物量和比叶面积,并结合样地调查数据和相对生长方程计算了中国科学院千烟洲试验站20年生湿地松林、马尾松林、杉木林和针叶混交林的叶面积指数。根据拟合结果,选择如下方程计算3个树种的叶生物量:湿地松W=12.074 1D^{2.151 5}、马尾松W=6.972 7D^{2.197 3}和杉木W=5.261 9D^{2.302 7}。湿地松林的叶生物量(0.822 kg·m^-2)最大,其次为针叶混交林(0.679 kg·m^-2),马尾松林和杉木林相差不大(分别为林0.528和0.572 kg·m^-2)。不同树种、不同年龄、不同类型叶片的比叶面积比较发现,新叶的比叶面积大于老叶,三针一束叶的比叶面积略大于两针一束叶,马尾松的平均半比表面积(8.62 m²·kg^-1)大于湿地松(6.04 m²·kg^-1)和杉木(7.91 m²·kg^-1)。胸径与单木叶片半表面积之间的经验方程为:湿地松LA=0.073D^{2.151 5}、马尾松LA=0.060D^{2.197 3}和杉木LA=0.042D^{2.302 7}。据此计算湿地松林的叶面积指数为5.03,马尾松林和杉木林为4.31,针叶混交林为4.77,该结果比利用CI-110植被冠层数字图像仪测得的结果偏大。     

Slash Pile Burning Effects on Soil Biotic and Chemical Properties and Plant Establishment: Recommendations for Amelioration

Ponderosa pine forest restoration consists of thinning trees and reintroducing prescribed fire to reduce unnaturally high tree densities and fuel loads to restore ecosystem structure and function. A current issue in ponderosa pine restoration is what to do with the large quantity of slash that is created from thinning dense forest stands. Slash piling burning is currently the preferred method of slash removal because it allows land managers to burn large quantities of slash in a more controlled environment in comparison with broadcast burning slash. However burning slash piles is known to have adverse effects such as soil sterilization and exotic species establishment. This study investigated the effects of slash pile burning on soil biotic and chemical variables and early herbaceous succession on burned slash pile areas. Slash piles were created following tree thinning in two adjacent approximately 20‐ha ponderosa pine (Pinus ponderosa) restoration treatments in the Coconino National Forest near Flagstaff, Arizona. We selected 30 burned slash pile areas and sampled across a gradient of the burned piles for arbuscular mycorrhizal (AM) propagule densities, the soil seed bank, and soil chemical properties. In addition, we established five 1‐m² plots in each burned pile to quantify the effect of living soil (AM inoculum) and seeding amendments on early herbaceous succession in burned slash pile areas. The five treatments consisted of a control (no treatment), living soil (AM inoculum) amendment, sterilized soil (no AM inoculum) amendment, seed amendment, and a seed/soil (AM inoculum) amendment. Slash pile burning nearly eliminated populations of viable seeds and AM propagules and altered soil chemical properties. Amending scars with native seeds increased the cover of native forbs and grasses. Furthermore adding both seed and living soil more than doubled total native plant cover and decreased ruderal and exotic plant cover. These results indicate that seed/soil amendments that increase native forbs and grasses may enhance the rate of succession in burned slash pile areas by allowing these species to outcompete exotic and ruderal species also establishing at the site through natural regeneration.