Dispersal of Quercus mongolica acorns in a broadleaved deciduous forest 2. Scatterhoarding by mice

Acorn transporting and hoarding, distribution, and utilization by mice of hoarded acorns were studied. Apodemus speciosus and A. argentus were observed to transport acorns. An individual A. speciosus observed scatterhoarded at least 49% of acorns transported. The rate of acorn utilization was higher in locations where two or more acorns were buried than where a single acorn was buried. Forty-seven percent of scatterhoarded acorns disappeared before snow cover and 99% before the next spring. Based on the extent of home ranges for mice, dispersal distance is presumed to be from 30 to 40 m.     

净月潭国家级森林公园樟子松生长状况的调查与分析

以长春市净月潭国家级森林公园樟子松人工林为对象,选取不同生长状况的样株制取胸径圆盘进行年轮测定,分析引起大树针叶枯黄、个体死亡的因素,结果表明:林分不同密度或相同密度的植株,不同年份胸径年轮生长量与健康状况存在显著差异,幼龄林和中龄林前期胸径年轮生长十分旺盛,而在中龄林的中后期则生长缓慢,部分年份年轮宽度显著变窄,呈现不规则变化。有大树针叶枯黄、个体死亡现象发生,林分密度大、郁闭度高、林龄大尤为严重;导致针叶枯黄和个体死亡的可能因素有个体的遗传性差异、个别年份的生理干旱、林分密度过大引起光合产物制造与积累受阻、立地环境不适或不良气候胁迫等。     

Mesophyll conductance to CO2 and leaf morphological characteristics under drought stress during Quercus ilex L. resprouting

? Quercus ilex L., the dominant species in Mediterranean forests and one with a great capacity for resprouting after disturbances, is threatened by the expected increase in fire frequency and drought associated with climate change.

? The aim of this study was to determine the contribution of photosynthesis limitants, especially mesophyll conductance (g _mes) during this species’ resprouting and under summer drought.

? Resprouts showed 5.3-fold increased g _mes and 3.8-fold increased stomatal conductance (g _s) at mid-day with respect to leaves of undisturbed individuals. With increased drought, structural changes (decreased density and increased thickness) in resprouts contributed to the observed higher photosynthesis and increased g _mes. However, g _mes only partially depended on leaf structure, and was also under physiological control. Resprouts also showed lower non-stomatal limitations (around 50% higher carboxylation velocity (V _c,max) and capacity for ribulose-1,5-bisphosphate regeneration (J _max)). A significant contribution of g _mes to leaf carbon isotope discrimination values was observed.

? g _mes exhibits a dominant role in photosynthesis limitation in Q. ilex and is regulated by factors other than morphology. During resprouting after disturbances, greater capacity to withstand drought, as evidenced by higher g _mes, g _s and lower non-stomatal limitants, enables increased photosynthesis and rapid growth.

     

Photosynthetic traits around budbreak in pre-existing needles of Sakhalin spruce (Picea glehnii) seedlings grown under elevated CO2 concentration assessed by chlorophyll fluorescence measurements

To assess the effects of elevated CO(2) concentration ([CO(2)]) on the photosynthetic properties around spring budbreak, we monitored the total leaf sugar and starch content, and chlorophyll fluorescence in 1-year-old needles of Sakhalin spruce (Picea glehnii Masters) seedlings in relation to the timing of budbreak, grown in a phytotron under natural daylight at two [CO(2)] levels (ambient: 360?μmol mol(-1) and elevated: 720?μmol mol(-1)). Budbreak was accelerated by elevated [CO(2)] accompanied with earlier temporal declines in the quantum yield of PSII electron transport (Φ(PSII)) and photochemical quenching (q(L)). Plants grown under elevated [CO(2)] showed pre-budbreak leaf starch content twice as high with no significant difference in Φ(PSII) from ambient-CO(2)-grown plants when compared at the same measurement [CO(2)], i.e., 360 or 720?μmol mol(-1), suggesting that the enhanced pre-budbreak leaf starch accumulation might not cause down-regulation of photosynthesis in pre-existing needles under elevated [CO(2)]. Conversely, lower excitation pressure adjusted for the efficiency of PSII photochemistry ((1?-?q(P)) F(v)'/F(m)') was observed in plants grown under elevated [CO(2)] around budbreak when compared at their growth [CO(2)] (i.e., comparing (1?-?q(P)) F(v)'/F(m)' measured at 720?μmol mol(-1) in elevated-CO(2)-grown plants with that at 360?μmol mol(-1) in ambient-CO(2)-grown plants), which suggests lower rate of photoinactivation of PSII in the elevated-CO(2)-grown plants around spring budbreak. The degree of photoinhibition, as indicated by the overnight-dark-adapted F(v)/F(m), however, showed no difference between CO(2) treatments, thereby suggesting that photoprotection during the daytime or the repair of PSII at night was sufficient to alleviate differences in the rate of photoinactivation.     

樟子松红斑病引致的生长损失及防治指标研究

通过对大兴安岭新林、富裕、齐齐哈尔３处樟子松红斑病不同病害等级样地的生长量系统调查研究,摸清了不同病情造成的生长量损失及病情与高、径、材积生长量关系,在考虑各地不同的立木材积生长量、木材价格、防治费用、防治效果的基础上,根据防治成本与经济允许水平,建立了应用范围广泛的防治指标动态模型：Ｘ＝ｌｎ（８７．７－ＣＤ·Ｊ·Ｅ×１００）－４．９３９９８－０．０２１０１,同时给出了不同药剂、不同防治效果、不同密度樟子松林分的防治指标。     

Growth and photosynthetic traits of hybrid larch F1 (Larix gmelinii var. japonica x L. kaempferi) under elevated CO2 concentration with low nutrient availability

The hybrid larch F(1) (Larix gmelinii var. japonica × Larix kaempferi) is considered one of the most important tree species not only for timber production but also as an afforestation material for severe conditions such as infertile soil. To predict the ability of hybrid larch F(1) as an afforestation material under potential climates in the future, it is important to understand the response of hybrid larch F(1) to elevated CO(2) concentration ([CO(2)]) under low nutrient availability. Three-year-old seedlings of hybrid larch F(1) were grown under two different levels of [CO(2)], 360 (ambient) and 720 μmol mol(-1) (elevated), in combination with two different levels of nitrogen (N) supply (0 and 30 kg ha(-1)) for one growing season. Elevated [CO(2)] reduced the maximum rates of carboxylation and electron transport in the needles. Net photosynthetic rates at growth [CO(2)] (i.e., 360 and 720 μmol mol(-1) for ambient and elevated treatment, respectively) did not differ between the two CO(2) treatments. Reductions in N content and N use efficiency to perform photosynthetic functions owing to the deficiency of nutrients other than N, such as P and K, and/or increase in cell wall mass were considered factors of photosynthetic down-regulation under elevated [CO(2)], whereas stomatal closure little affected the photosynthetic down-regulation. Although we observed strong down-regulation of photosynthesis, the dry matter increase of hybrid larch F(1) seedlings was enhanced under elevated [CO(2)]. This is mainly attributable to the increase in the amount of needles on increasing the number of sylleptic branches. These results suggest that elevated CO(2) may increase the growth of hybrid larch F(1) even under low nutrient availability, and that this increase may be regulated by changes in both crown architecture and needle photosynthesis, which is mainly affected not by stomatal limitation but by biochemical limitation.     

Comparison of stand structure and growth between artificial and natural forests of Pinus sylvestiris var, mongolica on sandy land

Mongolian pine (Pinus sylvestiris Linnaeus var. mongolica Litvinov) as a valuable conifer tree species has been broadly introduced to the sandy land areas in “Three North” regions (North, northwest and northeast of China), but many prob-lems occurred in the earliest Mongolian pine plantations in 7hanggutai, 7hangwu County, Liaoning Province (ZZL). In order to clarify the reason, comprehensive investigations were carried out on differences in structure characteristics, growth processes and ecological factors between artificial stands (the first plantation established in ZZL in 1950s) and natural stands (the origin forests of the tree species in Honghuaerji, Inner Mongolia) on sandy land. The results showed that variation of diameter-class distributions in artificial stands and natural stands could be described by Weibull and Normal distribution models, respectively.Chapman-Richards growth model was employed to reconstruct the growth process of Mongolian pine based on the data from field investigation and stem analysis. The ages of maximum of relative growth rate and average growth rate of DBH, height, and volume of planted trees were 11,22 years, 8, 15 years and 35, 59 years earlier than those of natural stand trees, respectively. In respect of the incremental acceleration of volume, the artificial and natural stands reached their maximum values at 14 years and 33 years respectively. The quantitative maturity ages of artificial stands and natural stands were 43 years and 102 years respectively. It was concluded that the life span of the Mongolian pine trees in natural stands was about 60 years longer than those in artificial stands. The differences mentioned above between artificial and natural Mongolian pine forests on sandy land were partially attributed to the drastic variations of ecological conditions such as latitude, temperature, precipitation, evaporation and height above sea level. Human beings‘‘ disturbances and higher density in plantation forest may be ascribed as additional reasons. Those results may be potentially useful for the management and afforestation of Mongolian pine plantations on sandy land in arid and semi-arid areas.     

毛乌素沙地气候因子对樟子松、油松生长的影响

调查了毛乌素沙地沙漠研究中心樟子松、油松人工林的生长状况,选取可能影响其生长的气候因子并运用双重筛选逐步回归的方法,对樟子松和油松高生长与气候因子间的关系进行了逐步判别分析.结果表明：影响樟子松树高生长量的主导气候因子依次是前一年的降雨量、≥10℃积温、年蒸发量;影响油松生长的气候因子主要是前一年降雨量与当年降雨量;该区樟子松的生长表现明显好于油松,并且在干旱年份表现出更强的抗旱特性,所以该地区的气候条件更适合樟子松的生长.     

2种密度下樟子松单株生物量和生长量的比较

以章古台22年生1 420株·hm-2樟子松林一次性间伐成密度为404株·hm-2和810株·hm-2并采取封育措施的2种林分为调查对象,调查单株生物量、生长量及林下植被。结果表明:404株·hm-2与810株·hm-2相比,11a后樟子松单株生物量干质量前者为后者的1.64倍,根系粗壮程度、草本盖度前者高于后者;14a后胸径生长量前者为后者的1.11倍;有无垂直主根取决于土壤的质地;810株·hm-2林分在林内出现衰弱死亡林木以后才侵入灌木。     

切根、中耕对沙地樟子松人工林生长与健康的影响

通过研究切根和中耕措施对沙区樟子松人工林生长与健康的影响得出:切根和中耕措施能明显减轻樟子松近熟林的感病情况,控制成熟林病情的发展,同时也能促进近熟林胸径生长,但对成熟林胸径生长影响并不明显；樟子松细根主要分布区在地下0 ～ 80 cm,切根和中耕措施能促进近熟林细根量的增加.     

不同起源沙地樟子松林结构与生长比较研究

樟子松已成为三北沙区防护林主要乔木造林树种,但是,最早于20世纪50年代在科尔沁沙地引种的沙地樟子松却出现了生长衰退、枯梢直至死亡的现象,而天然状态的樟子松在该阶段却正处于旺盛生长期。为了比较沙地人工樟子松林与天然林的林分结构、生长特点及所处立地的生态因子的异同,对辽宁省彰武县章古台(最早引种沙地樟子松区)和内蒙古自治区红花尔基(天然樟子松分布区)的樟子松林进行了综合调查。结果表明,Weibull分布函数可较好地模拟人工林树木直径分布,正态分布函数可用于模拟天然林树木直径分布。基于树干解析的树木生长模型(Chapman-Richards)分析,人工林胸径、树高与材积的相对生长率与平均生长率的最大值比天然林分别提早11、22年,6、18年和35、59年。人工林材积的生长加速度高峰值出现在14年,而天然林则出现在33年;人工林的数量成熟龄为43年,天然林为102年;因此,可以推断天然林的寿命比人工林要长近60年。这一结果可以归纳为以下综合作用:1)两种起源地生态因子的巨大的差异,主要包括:人工林区的纬度、平均气温、降水量、蒸发量、海拨高度等较天然林区高;2)人工林的林分密度较天然林大;3)人工林区的干扰强度较天然林强。图4表6参23。     

钾对淹水胁迫下樟子松光合特性和保护酶活性的影响

为了研究钾对缓解樟子松苗木淹水胁迫的生理效应。该试验在盆栽条件下,以2a生樟子松为试材,设置0(CK)、4、8、12g/株4个钾肥施用量处理,3次重复。试验结果显示：(1)随淹水时间延长,樟子松光合速率降低,施用钾肥提高了光合速率,第7～10天,8g/株和12g/株处理显著高于4g/株;(2)施钾提高了第4～10天的蒸腾速率和气孔导度,第10天,8g/株和12g/株处理显著高于4g/株处理,且两者之间无显著差异;(3)施钾降低了淹水胁迫第4～10天的胞间CO₂浓度,第10天8g/株和12g/株处理显著低于4g/株;(4)施钾提高了第7～10天SOD和POD活性,第10天8g/株和12g/株处理显著高于4g/株和对照。(5)钾肥可以提高淹水胁迫下樟子松光合能力和保护酶活性,且随淹水时间延长效果越显著。表明：钾能够提高樟子松植株在淹水状态下的光合能力,也会通过影响植株保护酶活性来改善其胁迫状态。不同施用量分析认为钾肥施用量为8g/株可以有效缓解樟子松的淹水胁迫。     

水杨酸对NaCl胁迫樟子松抗氧化酶活性及MDA含量的影响

通过研究水杨酸(SA)对NaCl胁迫下樟子松的生理响应机制,以期为降低樟子松育苗中NaCl胁迫危害提供理论依据。试验在盆栽条件下,设置了清水(对照T1)、NaCl胁迫(T2)、NaCl胁迫+SA(T3)、清水+SA(T4)4个处理。结果表明:5～8月,T2、T3 SOD活性显著高于对照,T3分别比T2提高了5.59%、7.19%、10.49%、6.22%,T4与T1之间无显著差异;5～9月,POD活性T2、T3显著高于对照,T3比T2提高了53.86%、38.58%、16.25%、19.32%、13.75%;5～9月,CAT活性T2、T3显著高于对照,T3显著高于T2、T4与对照无显著差异;5～9月,T2显著提高了MDA含量,T3与T2相比分别降低了4.95%、11.56%、9.32%、12.61%、8.30%。综合分析认为:1.0mmol/L的水杨酸可以有效提高NaCl胁迫下樟子松保护酶活性并缓解盐胁迫。     

Oak powdery mildew changes growth patterns in its host tree: host tolerance response and potential manipulation of host physiology by the parasite

Context

Parasites can induce strong effects on their host’s growth, not only as a result of host resource exploitation (growth loss) but also with a potential adaptive value for host (tolerance response) and themselves (increased transmission).

Aims

We assessed these three types of phenotypic changes in oak seedlings infected by powdery mildew.

Methods

A manipulative field experiment with three levels of parasite inoculum was designed in order to tease apart infection from genetic effects on oak growth. Seedlings were monitored during 3 years for height growth, phenology and infection.

Results

Powdery mildew infection induced both significant growth loss and qualitative changes in plant architecture. The most striking and unexpected change was increased growth polycyclism in infected seedlings. This benefitted both the host as a form of compensation for infection-caused height loss, and the pathogen, by increasing sporulation.

Conclusion

The study highlights the effect of parasites in the expression of plant phenotypic traits, such as phenology and ultimately tree architecture. Both host tolerance and parasitic manipulation may be involved in the observed changes in growth patterns. These results suggest a complex interplay between development and defence in trees and emphasize the need to better assess tolerance mechanisms when considering the defence strategies of trees against pathogens.     

Effects of an ectomycorrhizal fungus on the growth and physiology of Pinus sylvestris var. mongolica seedlings subjected to saline-alkali stress

This research investigates the mechanism of increased salinity tolerance of ectomycorrhizal fungiinoculated P. sylvestris var. mongolica to provide a theoretical basis for the application of the fungus in saline soils.Growth effects due to inoculation of seedlings with Suillus luteus(a symbiotic ectomycorrhizal fungus), were determined in four kinds of saline–alkali soils. Growth and physiological indicators, including photosynthetic characteristics, plant height, biomass, photosynthetic pigments,catalase(CAT) and superoxide dismutase(SOD) enzyme levels, and malondialdehyde(MDA), an organic marker for oxidative stress, and soluble protein levels were determined. Mycorrhizal colonization rate decreased with increasing saline–alkalinity and growth of inoculated seedlings was significantly enhanced. Biomass and chlorophyll contents also increased significantly. SOD and CAT activities were higher than in non-inoculated seedlings. However, MDA content decreased in inoculatedseedlings. Soluble protein content did not increase significantly. Inoculation with a symbiotic ectomycorrhizal fungus could enhance the saline–alkali tolerance of P. sylvestris var. mongolica. Growth and physiological performance of inoculated seedlings were significantly better than that of uninoculated seedlings. The results indicate that inoculated P. sylvestris var. mongolica seedlings may be useful in the improvement of saline–alkali lands.     

不同盐梯度处理下沼泽小叶桦的生理特征及叶片结构

设计盐梯度(0,2‰,4‰,6‰,8‰盐溶液的质量比为NaCl:Na2SO4:NaHCO3=75%:15%:10%)试验分析沼泽小叶桦生理表现和叶片解剖结构。结果显示:在低于4‰盐度时沼泽小叶桦能正常生长,6‰盐度时沼泽小叶桦生长发育不良,当盐度8‰时沼泽小叶桦只能存活30天左右;在低盐度处理下沼泽小叶桦光合生理表现和叶片解剖结构正常;随着盐度增加,其叶片净光合速率、气孔导度、胞间CO2浓度、蒸腾速率、叶绿素含量等指标均下降,而叶片中可溶性糖含量、脯氨酸含量、蛋白质含量升高;当盐度≥0.4%时,沼泽小叶桦叶片栅栏细胞逐渐纵向伸长且排列更紧密,叶绿体从椭圆形变成球形,叶绿体中出现粗大的淀粉粒和脂质球,表明其对滨海盐土具有一定的适应能力。     

褐环乳牛肝菌对轻基质营养包樟子松和油松苗的促生效应

为提高轻基质营养包樟子松和油松幼苗的出棚成活率以及对恶劣环境的适应能力,有效的增强其抗逆性,人工接种外生菌根真菌技术可以有效解决以上难题.用实验室生产的褐环乳牛肝菌优良菌株Suillus luteus SP4,SP7,SP8以及SP4、SP7、SP8的混合液体菌液,应用蘸根的方法对1年生轻基质营养包樟子松幼苗和1年生轻基质营养包油松幼苗进行接种,试验结果表明,SP4、SP7、SP8的混合液体菌剂接种两种幼苗的菌根侵染效果好于单独使用一种菌剂侵染,且接种油松幼苗的效果好于樟子松幼苗;相应的用SP4、SP7、SP8的混合液体菌剂接种的樟子松幼苗和油松幼苗的生长指标提高幅度最大.     

Relationships between mass mortality of two oak species (Quercus mongolica Turcz. var.grosseserrata Rehd. et Wils. andQ. serrata Thunb.) and infestation by and reproduction ofPlatypus quercivorus (Murayama) (coleoptera: Platypodidae)

This study investigated the number of adults ofPlatypus quercivorus (Murayama) captured on host oak (Quercus spp.) trees, the attack density (the number of entry holes per 100 cm²), and the number of emerging adults to clarify the relationships between the beetle’s colonization on trees in oak stands and tree mortality. The initial attack ofP. quercivorus, which was the most intense attack, was observed on most living trees simultaneously. Although some attacked trees died within the year of the attack or in the next year, a high density of attack did not usually cause the death of host trees. Surviving trees suffered low levels of consecutive attack after the initial attack. BecauseP. quercivorus successfully produced broods only in the dead trees, the population of the insect seems to be maintained only in stands where oak mortality occurs. However, the adults that landed on most of the surviving trees appeared unable to reproduce probably due to degradation of host quality. Thus, oak mortality probably ceases within 3 or 4 years after the start of infestation in a stand, with subsequent reductions in population density of the borer.     

Effects of CO2 enrichment at varying photon flux density on the growth of picea abies (L) karst. seedlings

Seedlings of Norway spruce (Picea abies (L.)) were grown at 335 and 1000 μl CO₂ 1^?1 for 118 days in growth rooms at different irradiance levels. Photon flux density ranging from 8.6 to 34.6 mol m^?2 day^?t (PAR) was given either as constant light or as alternating levels in intervals of two or six hours. CO₂ enrichment increased the plant dry weight from 36% to 105% by increasing photon flux density from 8.6 to 25.9 mol m^?2 day^?1. At constant light the dry weight apparently reached its maximum at a photon flux density of 25.9 mol m^?2 day^?t. At the lower radiation levels alternating in CO₂ enriched air gave slightly higher dry weights compared to constant light levels. At the highest radiations the effect on dry weight was the opposite. High CO₂ concentration and 300 μmol m^?2 s^?1 constant light (25.9 mol m^?2 day^?1) gave the best growth and quality of plants. Top, root, stem and foliage weight were proportionally affected. Shoot length was enhanced by CO₂ enrichment. Shoot weight per cm was substantially increased both by CO₂ enrichment and increasing photon flux density.     

Carbon allocation, root exudation and mycorrhizal colonization of Pinus echinata seedlings grown under CO(2) enrichment

Increased exudation of carbon compounds from roots may provide a mechanism for enhancement of nutrient availability to plants growing in a CO(2)-enriched atmosphere. Therefore, the effect of atmospheric CO(2) concentration on carbon allocation and root exudation was investigated in Pinus echinata Mill. (shortleaf pine) seedlings. After 34 and 41 weeks, seedlings growing in 695 microl l(-1) CO(2) allocated proportionately more (14)C-labeled photosynthate to fine roots than did seedlings growing in ambient air. This was associated with greater fine root mass and mycorrhizal density in CO(2)-enriched plants after 34 weeks. Exudation of soluble, (14)C-labeled compounds from roots also was greater in these plants at 34 weeks, but the effect of CO(2) concentration on exudation did not persist at 41 weeks.