紫茎泽兰和本地两种伴生植物对氮沉降的响应

通过对入侵植物和当地伴生植物模拟氮沉降,研究了土壤氮含量的增加是否会加剧外来植物的入侵。结果表明:三种植物单种时对氮营养变化表现出很高的可塑性,适量氮素增加会促进植物生长。植物的叶生物量在较少的氮添加范围内会随氮的增加而下降。紫茎泽兰和佩兰的竞争关系小,和山蚂蝗的竞争关系激烈。氮沉降对紫茎泽兰的生长有促进作用,表现在植株总生物量上。土壤氮含量的增加会加剧外来植物紫茎泽兰的入侵,同时,紫茎泽兰和山蚂蝗混种时紫茎泽兰的生长受到竞争抑制作用,此试验的研究,为入侵植物紫茎泽兰的治理提供了一定理论依据。     

峨眉山景区预防紫茎泽兰入侵的生态评估及调查报告

本文采用多种方式结合,调查了紫茎泽兰在乐山峨眉山景区的生长可能性及结果。报道了乐山城区目前紫茎泽兰的生长情况及传播可能,结合紫茎泽兰的生物学特性及峨眉山景区的生态气候特征,对峨眉山景区预防紫茎泽兰入侵的生态条件及风险进行了评估,提出应加强紫茎泽兰的宣传及动态监控。     

紫茎泽兰入侵机理及治理对策

该文通过对紫茎泽兰Eupatorium adenophorum生理生态、入侵环境的生态特征以及入侵林地、牧地、园地、四旁地的过程来阐述紫茎泽兰入侵途径和机理,提出治理对策.     

紫茎泽兰入侵受松小蠹危害的云南松林群落的研究

探讨了紫茎泽兰对松小蠹危害成灾云南松林的入侵状况,对3个受灾云南松群落的结构、生物多样性指数、紫茎泽兰的入侵危害程度进行了研究,分析了松小蠹危害与紫茎泽兰入侵的相互关系.结果表明:松小蠢危害可通过影响群落结构而导致生境变化,增加了群落的可入侵性.群落结构越简单,生物多样性水平越低,对生境资源的利用越不充分,紫茎泽兰成功入侵的机会越大.松小蠹的危害导致云南松林退化,紫茎泽兰的入侵加剧了其生态系统的退化过程,成为影响森林生态系统健康状况的重要生态过程之一.     

接种丛枝菌根真菌对紫茎泽兰生长及氮磷营养的影响

利用西南喀斯特地区常见入侵植物紫茎泽兰进行丛枝菌根真菌(AMF)接种与对照处理试验,研究接种AMF对其形态分化、生物量、光合生理及氮磷营养的影响。结果表明:接种AMF显著提高了紫茎泽兰光合生理,显著影响了紫茎泽兰形态分化(地径、苗高、总叶面积、分蘖数)及生物量;接种AMF显著降低了紫茎泽兰氮浓度,提高了紫茎泽兰磷浓度,氮和磷摄取量均有所提高,磷摄取量达到显著水平;对照条件下紫茎泽兰叶片氮磷比为14.01,接种AMF后降低为8.52,接种AMF使紫茎泽兰的生长更大程度上受氮素限制,而不再受氮素和磷素的共同限制。     

紫茎泽兰入侵地土壤对替代植物竞争力的影响

采用复合取代试验设计研究了拉巴豆、宽叶雀稗与紫茎泽兰的竞争。结果表明,入侵地土壤显著降低了拉巴豆和宽叶雀稗的生物量,但对紫茎泽兰的生物量无显著影响;入侵地土壤也显著降低拉巴豆的竞争攻击力系数(A),但是对宽叶雀稗的A值无显著影响。这说明入侵地土壤对不同的替代植物有不同的影响,对拉巴豆的负面影响大于宽叶雀稗,在替代控制中选择宽叶雀稗可以更好地抑制紫茎泽兰生长。     

入侵生物紫茎泽兰提出香精变害为宝

中国科学院昆明植物研究所经过多年的调查和研究，他们在防治和利用外来入侵植物紫茎泽兰方面取得了新突破。紫茎泽兰可提炼出香味独特的精油，有望成为一种应用于日用化妆品的新型香精原料。紫茎泽兰（Eu-patofium adenophorum）为多年生草本植物，原产墨西哥，上世纪50年代传入我国云南省。     

紫茎泽兰在贵州水城县林地的入侵危害和风险评价

于2018年6-9月对贵州省水城县紫茎泽兰Ageratina adenophora林地分布范围进行的全面调查,结合林业有害植物风险分析指标体系对紫茎泽兰在水城县林地范围内的潜在危害进行风险分析评价。结果表明,紫茎泽兰在水城县发生面积达7 351.76 hm~2,占总调查林地面积的4.07%;紫茎泽兰在水城县的风险综合评价值为2.63,属于特别危险风险等级;紫茎泽兰的分布范围南部地区东部地区中部地区北部地区。灌木覆盖度70%以上的灌木林地和云南松Pinus yunnanensis林紫茎泽兰不发生或少发生,灌木覆盖度50%以下的灌木林地和杉木Cunninghamia lanceolata纯林紫茎泽兰最容易入侵,应将预防工作重点放在北部和东部地区,防治的重点范围放在南部与东部地区。     

3种菊科植物提取物对松材线虫的毒杀作用研究

测定了菊科3种入侵植物乙醇提取物对松材线虫的生物活性。结果表明:飞机草、紫茎泽兰和薇甘菊以1.5g/L处理后72h校正死亡率分别为85.6%、87.6%和74.6%;飞机草、紫茎泽兰和薇甘菊乙醇提取液处理72h后的半致死质量浓度C50分别为0.6892、0.6813、0.7474g/L。即3种入侵植物乙醇提取物对松材线虫毒杀活性顺序强弱依次为紫茎泽兰>飞机草>薇甘菊。     

紫茎泽兰叶片气体交换的气孔调节特性:对其入侵能力的意义

紫茎泽兰是一个典型的外来入侵植物.利用便携式光合测定系统,对分布于四川省凉山州德昌市郊(27°28′36"N,102°12′28″E)的紫茎泽兰的气体交换特性进行测定,并与本地8个伴生种和其他12个分布于我国不同地区和日本的入侵种和本地种进行比较.目的是探讨气孔调节在日变化过程和长期干旱与湿润生境上的差异及其对紫茎泽兰入侵能力的影响.研究发现紫茎泽兰光合午休现象明显,气孔调节和非气孔调节共同控制了紫茎泽兰的光合日进程模式,而以气孔调节最为重要.非气孔调节主要是通过羧化效率的降低,从而影响表观量子效率或其他光合过程来实现的,而气孔调节主要是通过降低胞间CO2浓度,提高气孔限制值来实现的,这与其他种的差异不大.经过长期的野外不同湿度环境适应后,气孔调节出现了一定的弹性变化.在气孔导度相差不大的情况下,土壤有机质、土壤pH值和土壤有效氮含量差异不明显,湿生生境的光合速率和蒸腾速率显著高于干生生境,并导致了叶片含氮量显著提高.气孔在调节紫茎泽兰水分利用效率方面有别于所测定的其他20种植物,在湿生生境下随气孔导度下降,水分利用效率下降,而在干生生境下则显著升高.因此,紫茎泽兰同时兼有"省水"植物和"费水"植物的双重特点,这一灵活水分利用特点保证了它在不利环境中的生存和有利环境中的扩展,对于其在侵入区的生长发育有一定的意义.     

Why do large,nitrogen rich seedlings better resist stressful transplanting conditions? A physiological analysis in two functionally contrasting Mediterranean forest species

We analysed the physiological bases that explain why large and high nitrogen (N) concentration seedlings frequently have improved survival and growth relative to small seedlings in Mediterranean woodland plantations. Large seedlings of Aleppo pine (Pinus halepensis Mill.) and holm oak (Quercus ilex L.) with high N concentration (L+), and small seedlings with either high (S+) or low (S−) N concentration, were planted on two sites of different weed competition intensity that created contrasting stress conditions. Seedling survival, growth, gas exchange, N remobilization (N_R) and uptake (N_U), and water potential were assessed through the first growing season. Weeds reduced survival and growth, but seedling response to weed competition varied among phenotypes and between species. At the end of the first growing season, L+ Aleppo pine seedlings had higher survival than both small seedling types in presence of weeds but no differences were observed in absence of weeds. Mortality differences among phenotypes occurred in spring but not in summer. L+ Aleppo pines grew more than small Aleppo pines independently of weed competition. No holm oak seedling type survived in presence of weeds and no mortality differences among phenotypes where observed in absence of weeds, although L+ holm oak seedlings grew more than small seedlings. Mortality and growth differences in Aleppo pine were linked to marked physiological differences among phenotypes while physiological differences were small among holm oak phenotypes. L+ Aleppo pines had greater root growth, gas exchange, N_R, and N_U than small seedlings, irrespective of their N concentration. Seedling size in Aleppo pine had a greater role in the performance of transplanted seedlings than N concentration. The functional differences among oak phenotypes were small whereas they were large in pine seedlings, which led to smaller differences in transplanting performance in holm oak than in pine. This suggests that the nursery seedling quality improvement for planting in dry sites could depend on the species-specific phenotypic plasticity and functional strategy. Improved transplanting performance in large Aleppo pine seedlings relative to small seedlings was linked to greater gas exchange, root growth and N cycling.     

Vegetation response to intensity of herbaceous weed control in a newly planted loblolly pine plantation

Growth of loblolly pine (Pinus taeda L.) seedlings through three growing seasons after planting increased with intensity of herbaceous weed control using herbicides. Weed control had no effect on pine survival. Two years of complete herbaceous weed control (CHC, control throughout the first two growing seasons after planting) and operational herbaceous weed control (OHC, sulfometuron at 0.42 kg ai/ha at the beginning of the first growing season), resulted in lower biomass of weeds plus trees than with no herbaceous weed control (NHC) during the first growing season. Differences in total biomass during the first year were due to differences in biomass of herbaceous weeds. Total biomass on CHC and OHC plots was at least as great as NHC the second year, and greater by the third year, as pines assumed dominance as a result of increased growth from reduction of herbaceous weeds. The operational herbicide treatment had no significant impact on overall herbaceous weed biomass and cover, and little effect on species composition compared to no herbaceous weed control two and three growing seasons after treatment. The CHC treatment significantly reduced herbaceous weed biomass, cover and composition through three growing seasons.     

Effects of Demand-driven Fertilization on Nutrient Use,Root:Plant Ratio and Field Performance of Betula pendula and Picea abies

Norway spruce [Picea abies (L.) Karst.] and silver birch (Betula pendula Roth) seedlings were grown for one season under three different fertilization regimens in the forest nursery. During the first 50 days the seedlings were grown in a glasshouse, and thereafter outdoors until the beginning of September. Finally, the plants were exposed to 16 h nights in the glasshouse throughout September. When the seedlings were supplied with fertilizers at a rate adjusted to expected plant demand (R_O), less than half as much of each nutrient was applied as in a conventional regimen (R_C), in which equal amounts were supplied per unit time during the growth season, yet the plants still looked healthy. Utilization of N increased by almost 50% in spruce when supply was adjusted to plant demand. In the third treatment (R_L), nutrients were supplied as in the R_O treatment, but at a growth-limiting rate. These plants were loaded with nutrients at the end of the season and had higher root:plant ratios, i.e. root weight in relation to total plant weight, compared with the other treatments. The nutrient status of the plants was not growth limiting at the end of the growing season in any of the treatments. The plants given the different treatments differed in size at planting out, but they had similar heights after 3 yrs in the field. This indicates that the root:plant ratio may be important for growth performance, provided that nutrient status is not at a growth-limiting level. This study suggests that the use of fertilizers can be considerably reduced in Swedish forest nurseries.     

Herbicides and planting date affect early performance of container-grown and bare-root loblolly pine seedlings in Alabama

The survival of bare-root and container-grown loblolly pine (Pinus taeda L.) seedlings exceeded 90% when outplanted in March at two sites in Lee County, Alabama. At both sites, soil moisture and seedling survival were greater in March than in May. A March herbicide application reduced weed biomass by 75–80% at both sites. At the moist site, herbicide application did not affect survival. However, at the drier site, a reduction in weed biomass increased both the percent soil moisture and the survival of May-planted bare-root seedlings. When soil moisture at planting time was less than 13% on a dry weight basis container-grown seedlings survived better than bare-root seedlings. At both sites, reduced weed competition resulted in greater seedling heights and diameters.Alabama Experiment Station Journal Series No. 9-85802.     

Establishing American sycamore seedlings on land irrigated with paper mill sludge

A study was established to evaluate several management practices for improving American sycamore (Platanus occidentalis L.) establishment on land subjected to daily paper-mill sludge spray irrigation, and where a dense herbaceous cover dominated by pokeweed (Phytolacca americana L.) was nearly 2 m tall. Treatments studied included: two sludge application treatments (spray vs no spray), five weed control treatments (control, hand-release, oxyfluorfen, glyphosate and atrazine, and sulfometuron methyl), and two tree shelter treatments (control vs tree shelter). Survival and growth of sycamore seedlings were evaluated after one growing season. Sludge application treatment had the greatest effect on tree survival; survival was greatest on plots that were not sprayed during the year of tree growth. Among the weed control treatments, the hand-release treatment resulted in best survival; survival was 100% when hand release was used on unsprayed plots. Tree shelters provided no benefit to tree establishment.     

Ectomycorrhizae Reduce Damage to Russian Larch by Otiorhyncus Larvae

The effect of ectomycorrhizae on damage caused by Otiorhyncus larvae and on plant growth was evaluated in a 3-yr field experiment. Russian larch seedlings, inoculated with ectomycorrhizal fungi, were compared with uninoculated plants. Assessment of larval damage at the end of the first growing season showed a significant effect of treatment on damage intensity, but not on damage incidence: 11.2% of uninoculated seedlings were severely damaged, but only 3.5% of inoculated plants. There was a significant effect of treatment on plant mortality. The accumulated mortality at the end of the third growing season was 34.5% for uninoculated plants, but 17.6% for inoculated plants. The height increment of inoculated plants (4.5 cm) was significantly greater than that of uninoculated plants (2.7 cm) in the first growing season. No difference in height increment between treatments was observed during the second and third growing seasons.     

Growth responses of six seed sources of Pinus brutia Ten. (Turkish red pine) to herbaceous weed competition

Herbaceous weeds present amajor obstacle to foresters in the earlyestablishment and growth of Turkish red pine (Pinus brutia Ten.), an important coniferof the semi-arid Mediterranean region. Greatgenetic variability of this pine species indrought resistance has already beenwell-studied. The existence of such variationwithin this species in relation to herbaceousweed competition is unknown. This studyinvestigated the effect of herbaceous weedcompetition on the growth of the seedlings ofTurkish red pine seed sources with differentmoisture regimes in their native sites, usingthe rapid screening technique. Two-month-oldTurkish red pine seedlings were grown inindividual pots in a glasshouse either with orwithout joint goose goat grass (Aegilopscylindrica L.). After two simulatedgrowing seasons, grass competitionsignificantly and progressively reduced pinegrowth. Although mean total pine biomass wasreduced by 71% due to weed competition,seedlings of different pine seed sourcesdisplayed significant differences in growthresponses to the weed treatments: dry site seedsource seedlings generally exhibitedsignificantly greater growth than moist siteseed source seedlings under weed competition. These results suggest that competition fromherbaceous weeds is an important factor inreducing the early growth of Turkish red pineseedlings, and that selection ofcompetition-tolerant seed sources can result insubstantial enhancement of the competitivestatus of this pine species against itsherbaceous competitors in early years.     

Weed control measures in Christmas tree plantations of <Emphasis Type="Italic">Abies nordmanniana</Emphasis> and <Emphasis Type="Italic">Abies lasiocarpa</Emphasis> on agricultural land

Abies nordmanniana and Abies lasiocarpa, established for Christmas tree production in southwestern Norway (58°44′N, 5°38′E), were treated with different weed control methods, including chemicals, use of black plastic mulch, grass or clover as ground cover, living mulch and mechanical hoeing. Ground cover with black plastic mulching resulted in the best growth and quality in A. lasiocarpa; the least favourable treatment was when grasses were allowed to grow close to the trees. Unless measures were taken to remove this competing vegetation, the ground cover grew over the trees, smothering 94% of them. A. nordmanniana plants grew to the same height on plots with no weed control as on plots with thorough weed eradication. Stem diameter decreased on plots with ground vegetation compared to seedlings grown in the weed-free environment. The use of Trifolium repens as ground cover decreased height growth by 30% compared to thorough weed control. Both grasses and clover sown as living mulch, damaged the trees more than did natural weed vegetation.     

Soil temperature,gas exchange and nitrogen status of 5-year-old Norway spruce seedlings

Five-year-old Norway spruce (Picea abies (L.) Karst.) seedlings were subjected to three simulated growing seasons in controlled environment chambers. Plants were acclimated to a soil temperature of 16 degrees C during the first and third growing seasons, but were allocated at random to soil temperature treatments of 9, 13, 18 and 21 degrees C during the second growing season. Low soil temperature during the second growing season depressed stomatal conductance and photosynthetic rate (A) per unit of projected leaf area, although intercellular CO2 concentrations did not differ significantly between treatments. At all soil temperatures, total chlorophyll concentration first decreased and then increased, although the rate of increase and the final concentration increased with soil temperature, which may explain the effect of soil temperature on A. Neither chlorophyll a/b ratio nor leaf nitrogen concentration was significantly affected by soil temperature. Treatment differences disappeared during the third simulated growing season when plants were again acclimated to a soil temperature of 16 degrees C.     

Rapid root tip and mycorrhiza formation and increased survival of Douglas-fir seedlings after soil transfer

In order to re-inoculate soil with mycorrhizal fungi, small amounts (about 150 ml) of soil from an established Douglas-fir plantation were added to planting holes when Douglas-fir seedlings were planted on an old, unrevegetated clearcut in the Klamath Mountains of Oregon. Seedlings were lifted throughout the growing season to determine the influence of soil transfer on the rate of root tip initiation and mycorrhiza formation. Six weeks after planting, seedlings receiving plantation soil had formed 62% more root tips than controls; however, no statistically significant differences were apparent 15 weeks after planting. By that time, a small percentage of root tips were visibly mycorrhizal; seedlings receiving transferred soil had the most colonization (13.6 vs 3.5 per seedling, p 0.05). Of seedlings receiving transfer soil, 36.6% survived the first growing season, compared to 11.3% of control seedlings. At this high elevation, soils often remain frozen well into spring, leaving only a brief period betwen the time when soils become warm enough for root growth and the onset of summer drought. Under these conditions, the rapid root growth and mycorrhiza formation stimulated by plantation soil increases the ability of seedlings to survive the first growing season.This is Paper 2341 of the Forest Research Laboratory, Oregon State University.