Some aspects of the biology of the garfish Belone belone (L.) from southern Ireland

An account is given of certain aspects of the biology of the garfish, Belone belone , captured by sea anglers from Courtmacsherry Bay, Co. Cork. Fish were aged by otoliths, and found to grow most rapidly in their first 2 years, females attaining a greater mean size than males. Most of the fish caught had already spawned. From examination of their gonads and lengths of juveniles collected in the neuston, spawning would appear to take place there mostly in the month of June.     

High‐throughput sequencing reveals neustonic and planktonic microbial eukaryote diversity in coastal waters

Neustonic organisms inhabit the sea surface microlayer (SML) and have important roles in marine ecosystem functioning. Here, we use high‐throughput 18S rRNA gene sequencing to characterize protist and fungal diversity in the SML at a coastal time‐series station and compare with underlying plankton assemblages. Protist diversity was higher in February (pre‐bloom) compared to April (spring bloom), and was lower in the neuston than in the plankton. Major protist groups, including Stramenopiles and Alveolata, dominated both neuston and plankton assemblages. Chrysophytes and diatoms were enriched in the neuston in April, with diatoms showing distinct changes in community composition between the sampling periods. Pezizomycetes dominated planktonic fungi assemblages, whereas fungal diversity in the neuston was more varied. This is the first study to utilize a molecular‐based approach to characterize neustonic protist and fungal assemblages, and provides the most comprehensive diversity assessment to date of this ecosystem. Variability in the SML microeukaryote assemblage structure has potential implications for biogeochemical and food web processes at the air‐sea interface.     

Northward expansion and climatic factors affecting the distribution limits of Cheilomenes sexmaculata (Coleoptera: Coccinellidae) in Japan

The distributional expansion of the ladybird beetle Cheilomenes sexmaculata (Fabricius) in Japan was analyzed based on literature surveys and observations of 1,312 individual specimens collected from 1918 to 2005. An expansion toward higher latitudes, from Kyushu (33°N) to central Honshu (36°N), was observed between 1910 and the early 1990s. Multiple regression analysis showed that the presence of this beetle was associated with an annual mean temperature but not with the mean minimum temperature in the coldest month, and 95 % occurrence probability of this beetle was obtained in a locality at 15.1 °C annual mean temperature. The northward expansion of this species synchronizes with increasing areas where an annual mean temperature is more than 15 °C. Therefore, climatic warming over the past 100 years is considered as a major factor influencing the northward expansion of this species.     

First account of apochlorotic diatoms from mangrove waters in Florida

ABSTRACT. From January to December 2004, monthly samples were collected from the mangrove salt marsh of J.U. Lloyd State Park, Florida, to examine the spatial and temporal distributions of heterotrophic diatoms in this subtropical region. Four non-pigmented (i.e. apochlorotic), heterotrophic diatom morphotypes were isolated from mangrove neuston and plankton sites. Colorless diatoms were numerically significant in neuston during the fall and winter months and counts peaked at 174 × 10³ cells/L in December. Heterotrophic diatoms were most prevalent in mangrove plankton in October and averaged 55.5 × 10³ cells/L. Valve morphology was detailed for mangrove morphotypes (I, II, V, and VI). However, only one type (I) was named with confidence ( Nitzschia leucosigma ). The other three types failed to conform closely to published diagnostic features suggesting that either characters are more variable than accepted or these types were new species. Growth responses to changes in salinity and irradiance were detailed in the laboratory. All morphotypes were euryhaline, tolerating salinities between 10‰ and 40‰; N. leucosigma was most salt tolerant and grew from 10‰ to 60‰. Maximum growth was achieved between 20‰ and 40‰. Growth was not significantly different for heterotrophic diatoms during light and dark treatments or for diatoms grown with or without bacteria.     

多尺度下宝鸡地区干旱动态格局演变及其与植被覆盖的关系

利用宝鸡地区11个气象站点1974—2013年逐月气温和降水量数据,基于标准化降水蒸散指数(SPEI),结合土地利用/覆盖数据,从干旱发生频率、发生强度及与植被NDVI相关性等角度,探讨了近40年来干旱时空变化格局及其对植被覆盖的响应。结果显示:宝鸡地区年均SPEI指数以-2.50%/a的速度下降,干旱趋势明显增强。自20世纪末以来,全区年均干旱指数呈明显的上升趋势,以2007—2010年增大趋势最为显著(超过0.05临界线);近40年来,春季干旱发生频率达60%及以上的有21 a,达90%以上的有9a。1981—1986年起伏变化最为剧烈。秋季平均干旱发生频率为46.29%,为春、夏、秋、冬4个季节中最低。从干旱发生强度来看,全区年际、四季及月6个时间尺度上干旱强度高、低值区域分布均比较集中;秋季强度最弱的区域面积表现最高,占总面积的75.47%。干旱发生最严重的是春季,占总面积的11.90%。全区干旱与植被覆盖相关性均表现较好(均通过0.05显著性水平检验),林地、草地负相关性最为显著(除夏季),夏季、秋季、月尺度上,耕地、水域、城乡地区干旱与植被覆盖的相关性与土地利用类型无关。     

Seasonal variability of ichthyoneuston assemblage on the continental shelf and slope of the Southwest Atlantic Ocean,Brazil (20°–23°S)

Many marine organisms spend the early life history stages in neuston domain. Although the importance of ichthyoneuston, few studies were developed in the Southwest Atlantic Ocean. Therefore, this study aimed to improve the knowledge on ichthyoneuston of the Brazilian coast analyzing the vertical stratification and horizontal distribution of these organisms. Neuston samples were collected in daylight between 20°S and 23°S from February to April 2009 (late summer/early autumn; rainy season) and from August to September 2009 (late winter/early spring; dry season). Eggs of six taxa were identified: Anguilliformes, Engraulidae, Clupeidae, Synodontidae, Trichiuridae, and Maurolicus stehmanni (Sternoptychidae). The neustonic larval fish assemblage was composed by 40 families and 63 species. Mullidae and Myctophidae larvae were the most abundant in the rainy period while Mullidae and Mugilidae dominated in the dry season. Seasonal and spatial variation of larval fish assemblages in the neuston were structured by oceanographic features. The larval fish abundance on the outer slope stations may have been favored by the advection of an anticyclone that encompassed most of the study region during the cruise periods. In the rainy season, salinity and local depth structured the larval fish assemblage in a cross‐shelf gradient, while in the dry season the larval assemblage was structured around temperature and north‐south gradient. In the dry season, the cross‐shelf gradient was less pronounced mainly because of the low abundance and frequency of mesopelagic larvae. The low frequency and abundance of some species are probably related to the net avoidance of fish larvae during the day or dial vertical migration, as many species migrate to deeper layers during the day and ascend to neuston only at night. Nevertheless, the present study presented baseline information about the seasonal and spatial variation of the neustonic larval fish assemblage influenced by the oceanographic conditions in the Campos Basin. We recommend to additionally collect night samples to decrease larval escapement rates and to compare night versus day catches to further investigate the influence of daily migration in the neustonic larval fish in the area.     

A hotspot for cold crenarchaeota in the neuston of high mountain lakes

We have surveyed the first 1 m of 10 oligotrophic high mountain lakes in the Central Pyrenees (Spain) for both abundance and predominant phylotypes richness of the archaeaplankton assemblage, using CARD-FISH and 16S rRNA gene sequencing respectively. Archaea inhabiting the air-water surface microlayer (neuston) ranged between 3% and 37% of total 4,6-diamidino-2-phenylindole (DAPI) counts and were mainly Crenarchaeota of a new freshwater cluster distantly related to the Marine Group 1.1a. Conversely, most of the Archaea from the underlying waters (the remaining first 1 m integrated) were mainly Euryarchaeota of three distantly related branches ranging between 0.4% and 27% of total DAPI counts. Therefore, a consistent qualitative and quantitative spatial segregation was observed for the two main archaeal phyla between neuston and underlying waters at a regional scale. We also observed a consistent pattern along the lakes surveyed between lake area, lake depth and water residence time, and the archaeal enrichment in the neuston: the larger the lake the higher the proportion of archaea in the neuston as compared with abundances from the underlying waters ( n  = 10 lakes; R ² > 0.80; P  < 0.001, in all three cases). This is the first report identifying a widespread non-thermophilic habitat where freshwater planktonic Crenarchaeota can be found naturally enriched. High mountain lakes offer great research opportunities to explore the ecology of one of the most enigmatic and far from being understood group of prokaryotes.     

我国草地螟轻发年份时空特征及其气候背景

揭示我国草地螟在长时间序列上的年度间变化规律,探明轻发年份特点和研究意义,阐释气候变化背景对草地螟发生的影响方式。分析了1949—2012年我国草地螟发生面积的时间序列和轻重年份差异,利用2006—2012年北方主发区每年各代次各虫态发生期出现时间、有效持续时间和发生县点数等数据分析了轻发年份的时空分布特征。在1951—2012年可追溯的时间序列上,研究了北方草地螟主发区(169个具有连续气象资料的发生站点)年平均气温、1月月平均气温、6—8月累计降雨量等气候背景变化趋势与草地螟年度发生动态的相关性。结果表明:(1)在62年的长时间序列上,我国草地螟轻发年份频次多于重发年份;(2)轻发年份的总体特征是发生期迟、发生盛期短、发生区域少;(3)大尺度气象条件变化是引起草地螟年度发生动态波动的重要因素,与1951—2012年年度发生面积进行相关分析发现,年平均气温和1月份月平均气温与草地螟发生面积呈显著正相关关系,6—8月累计降雨量与发生面积呈显著负相关关系。分析指出,轻发年份是草地螟种群长期消长动态中不可忽视的环节,对轻发年份的研究是揭示其年度发生变化规律的重要途径;在长时间序列的分析方法上,可采用年度发生(幼虫)面积作为判断轻重年份发生程度的主要量化指标;利用草地螟发生区多点大尺度气象数据,与年度发生面积进行相关性分析,可作为阐释气候背景影响草地螟长期发生趋势的方法之一。     

Heterotrophic bacteria of the freshwater neuston and their ability to act as plasmid recipients under nutrient deprived conditions

Significantly higher numbers of Gram-negative heterotrophic bacteria were present at the air-water interface (neston) of freshwater lakes than in the bulk water. Neuston bacteria were distinguished as a population distinct from bacteria in the bulk water by a higher incidence of pigmented colony types and significantly greater levels of multiple resistance to antibiotics and heavy metals. The incidence of plasmids in 236 neuston and 229 bulk water strains were similar (14 and 16.2%, respectively). Nine of 168 plasmid-free strains and 2 of 14 plasmid carrying strains, isolated from both bulk water and neuston, acted as recipients of plasmid R68.45 in plate matings with aPseudomonas aeruginosa donor strain PAO4032 at 21°C, but at frequencies below that of matings with a restriction-minus recipient strain ofP. aeruginosa, strain PAO1168. In a model system composed of nutrient-free synthetic lake water, plasmid R68.45 was shown to transfer betweenP. aeruginosa strains at frequencies between 10⁻³ and 10⁻⁵. Transconjugants were detected about 100 times more frequently at the interface than in the bulk water, which in part reflected a greater enrichment of the donor at this site. None of the aquatic isolates were able to act as recipients of plasmid R68.45 in this model system with strain PAO4032 as donor. The results suggest that under nutrient deprived conditions, the spread of plasmid R68.45 and similar plasmids by lateral transfer into this particular aquatic population would be a rare event.     

Correlates of molt in golden lion tamarins (Leontopithecus rosalia)

In this paper we describe the timing and correlates of molt for a native population of golden lion tamarins (Leontopithecus rosalia). We conducted 820 examinations of 267 adult tamarins over a 7.75 year period to determine the annual molting cycle in this population. Dorsal molt was an annual event for most individuals in the study population; however, 10% of sampled individuals apparently molted twice in a 12 month period. Duration of molt was estimated at 5–6 weeks. The proportion of samples in which tamarins were in molt was significantly greater during the wet season than the dry season and positively correlated with mean monthly precipitation and minimum temperature but not tamarin births, suggesting an environmental component to timing of molt. We found no sex differences in the occurrence of molt during wet or dry seasons. However, the relative frequency of samples in molt was significantly less for gravid females than for nongravid females. In four polygynous groups, socially dominant females gave birth before subordinate females, and younger reproductive females completed molt before older reproductive females. © 1995 Wiley-Liss, Inc.     

1961-2010年中国东部林区降水的完整日值序列建立与变化特征

高精度地对各气象站缺测降水资料进行插补,从而获得完整序列的降水资料,对于提高气候变化影响分析的时空精度具有十分重要的意义.本文利用空间相关和逐步回归法,对东部林区月内有单日缺测或不多于7 d缺测的降水资料进行插补,最终建立了853个站自1961-2010年完整序列的降水资料.在此基础上,应用趋势分析法,分析了1961-2010年降水量、降水日数和极端降水事件的变化特性.结果表明： 1961-2010年,研究区年降水量略呈不显著增加趋势,倾向率为5.58 mm·(10 a)^-1,年代际变化明显;年降水日数呈显著减少趋势.极端降水日数和极端降水量呈显著上升趋势,倾向率分别为0.12 d·(10 a)^-1、10.22 mm·(10 a)^-1.尤其是20世纪90年代以后,该区极端降水事件明显偏多偏强,极端降水量对总降水量的比率也呈显著增加趋势.极端降水日数和极端降水量均在1993年发生突变.     

内蒙古草原区植被净初级生产力及其与气候的关系

利用NOAA/AVHRR GIMMSNDVI数据、土地覆盖分类数据、气象数据等,基于改进的基于光能利用率的净初级生产力(Net Primary productivity,NPP)遥感估算模型对内蒙古草原区1982-2006年的NPP进行估算,并分别以年、季节和月为时间单位,计算基于像元的NPP与降水、温度之间的相关及偏相关系数,分析不同时间单位及尺度上NPP与气候的关系。结果表明,1982-2006年内蒙古草原区NPP总量呈波动增加的趋势,平均增加值为0.861Mt C/a。以年为时间单位,内蒙古草原区年NPP与降水的关系比较明显。以季节为时间单位,年际春季和夏季NPP与降水的关系比较明显,秋季二者关系相对较弱,春季和秋季NPP与温度的相关系数和偏相关系数空间格局比较一致,且相关性明显高于夏季。以月为时间单位的相关水平明显高于年际水平,多年平均年内月NPP与降水、温度的相关程度明显增强,除去降水的影响,月均温对NPP的影响明显下降,且空间格局也有明显的变化,说明以月为时间单位在年内尺度上降水对植被生长的影响比温度要大。而以4、7、10月份为例,在年际尺度上,虽然各月份NPP均受降水的影响较大,但与降水关系最为密切的是4月份和10月份NPP,与之相比,7月份NPP与温度的关系明显高于其他两月。     

降水对新疆马铃薯甲虫分布的影响

为明确降水在中国新疆地区对马铃薯甲虫分布的影响,揭示制约马铃薯甲虫分布扩散的关键环境因子,为马铃薯甲虫的持续防控和综合治理提供理论依据。该研究结合新疆历史降水数据,对马铃薯甲虫现有分布区内的降水时空格局展开分析,比较了马铃薯甲虫危害程度与降水时空格局的关系。结果表明:马铃薯甲虫现主要分布于新疆年降水量在150 mm以上地区,早期定殖的地区降水量大于后期定殖区,其扩散方向为自西向东,同时年降水量也逐渐减少。马铃薯甲虫危害程度也随着经度增加而递减,早期发现马铃薯甲虫的地区受危害程度较重。降水量减少导致的水分缺乏对马铃薯甲虫的分布扩散具有一定的制约作用。     

近50年京津冀气候舒适度的区域时空特征分析

受气候变化影响,区域气候舒适期势必会发生不同程度的变化。从气候舒适性的视角出发,利用京津冀地区1966—2015年的170个观测站点50年逐日气象资料,以温湿指数、风效指数、着衣指数及其综合指数为气候舒适性的评价指标,统计分析区域气候舒适期的起止日期、天数及其年际间变化规律,揭示京津冀区域气候舒适度的时空变化特征,为区域人口合理分布和气候资源评价提供科学依据。此外,以日为时间尺度进行气候舒适期分析,有利于气候变化背景下区域间横向和区域内纵向的比较研究。结果显示:(1)京津冀气候舒适度指数近50年来的变化趋势基本相同,综合指数呈显著增加趋势;但各地间变幅存在一定差异,其中天津气候舒适度指数变化幅度最为明显,北京变化相对平稳。(2)从气候舒适度综合指数来看,京津冀地区气候舒适期年内分布呈"M"型,舒适期相对集中在4—5月、9—10月,舒适和较舒适等级的月累计日数均达到28 d以上,其中5月气候最为舒适,舒适等级日数最多,达到24—26 d;北京年平均舒适天数最多(100 d),天津最少(91 d)。(3)从单一气候舒适度指数来看,京津冀舒适和较舒适等级的初始日期大多呈显著的提前趋势;终止日期和天数大多略有增加,但变化趋势不显著。而综合指数显示,1966—2015年较舒适等级的初始日期变化最为显著,大约每10年提前3—4 d;天津和河北终止日期变化也达到显著水平,大约每10年推迟1—2 d,北京增加趋势不明显。(4)京津冀气候舒适期的空间分布显示,舒适等级的日数从西北向东南地区呈减少特征,河北北部舒适等级的年平均日数最多达115—120 d,东南部最少,不足90 d。     

Cetaceans of Southeast Alaska: distribution and seasonal occurrence

Aim To assess the distribution, group size, seasonal occurrence and annual trends of cetaceans. Location The study area included all major inland waters of Southeast Alaska. Methods Between 1991 and 2007, cetacean surveys were conducted by observers who kept a constant watch when the vessel was underway and recorded all cetaceans encountered. For each species, we examined distributional patterns, group size, seasonal occurrence and annual trends. Analysis of variance (anova F) was used to test for differences in group sizes between multiple means, and Student’s t‐test was used to detect differences between pairwise means. Cetacean seasonal occurrence and annual trends were investigated using a generalized linear model framework. Results Humpback whales (Megaptera novaeangliae) were seen throughout the region, with numbers lowest in spring and highest in the fall. Fin whale (Balaenoptera physalus) and minke whale (Balaenoptera acutorostrata) distributions were more restricted than that reported for humpback whales, and the low number of sightings precluded evaluating seasonal trends. Three killer whale (Orcinus orca) eco‐types were documented with distributions occurring throughout inland waters. Seasonal patterns were not detected or could not be evaluated for resident and offshore killer whales, respectively; however, the transient eco‐type was more abundant in the summer. Dall’s porpoise (Phocoenoides dalli) were distributed throughout the region, with more sightings in spring and summer than in fall. Harbour porpoise (Phocoena phocoena) distribution was clumped, with concentrations occurring in the Icy Strait/Glacier Bay and Wrangell areas and with no evidence of seasonality. Pacific white‐sided dolphins (Lagenorhynchus obliquidens) were observed only occasionally, with more sightings in the spring. For most species, group size varied on both an annual and seasonal basis. Main conclusions Seven cetacean species occupy the inland waters of Southeast Alaska, with distribution, group size, seasonal occurrence and annual trends varying by species. Future studies that compare spatial and temporal patterns with other features (e.g. oceanography, prey resources) may help in identifying the key factors that support the high density and biodiversity of cetaceans found in this region. An increased understanding of the region’s marine ecology is an essential step towards ensuring the long‐term conservation of cetaceans in Southeast Alaska.     

Numerical analysis of surface and fossil pollen spectra from northern Fennoscandia

Aim Determination of the main directions of variance in an extensive data base of annual pollen deposition, and the relationship between pollen data from modified Tauber traps and palaeoecological data. Location Northern Finland and Norway. Methods Pollen analysis of annual samples from pollen traps and contiguous high‐resolution samples from a peat sequence. Numerical analysis (principal components analysis) of the resulting data. Results The main direction of variation in the trap data is due to the vegetation region in which each trap is located. A secondary direction of variation is due to the annual variability of pollen production of some of the tree taxa, especially Betula and Pinus. This annual variability is more conspicuous in ‘absolute’ data than it is in percentage data which, at this annual resolution, becomes more random. There are systematic differences, with respect to peat‐forming taxa, between pollen data from traps and pollen data from a peat profile collected over the same period of time. Main conclusions Annual variability in pollen production is rarely visible in fossil pollen samples because these cannot be sampled at precisely a 12‐month resolution. At near‐annual resolution sampling, it results in erratic percentage values which do not reflect changes in vegetation. Profiles sampled at near annual resolution are better analysed in terms of pollen accumulation rates with the realization that even these do not record changes in plant abundance but changes in pollen abundance. However, at the coarser temporal resolution common in most fossil samples it does not mask the origin of the pollen in terms of its vegetation region. Climate change may not be recognizable from pollen assemblages until the change has persisted in the same direction sufficiently long enough to alter the flowering (pollen production) pattern of the dominant trees.     

Analysis of temporal changes in fish assemblages in Serpentine Creek,Queensland

Synopsis From November 1975 to April 1977 nocturnal dermersal fish were sampled fortnightly at ten sites in Serpentine Creek using a three meter beam trawl with a 3.2 cm mesh net. Forty-five species from thirty-four families were obtained totalling 14 518 individuals with the six most abundant species comprising approximately 72% of the catch. Using multiple regression techniques with Fourier transformations, the mean number of species (S) and abundance (N) of all fish were found to conform to a regular annual cyclical pattern with maxima in April and May. A trend toward declining abundances of individuals and species was present. Shannon (H′) and Gleason (G) diversity indices showed no regular seasonal trends and are considered poor indicators of pollution. In comparison with other estuarine studies at different latitudes Serpentine Creek conforms to the theory that more tropical waters have the greatest faunal diversity. Seventeen of the 22 most abundant species demonstrated a regular annual cycle of abundance. The number of species, abundance and diversity measures were greatest about 1 km from the mouth of the creek and gradually declined upstream. This was the region with highest macrobenthos diversity and with the most stable abiotic values. Temperature and/or salinity were positively correlated with the abundance of eleven species. The species were placed in five groups according to their periodic characteristics. The proportion of ‘resident’ species was low and this is consistent with Tyler's (1971) theory of temperature stabilized fish assemblages. The known biology of six species is related to their occurrence. Salinity and temperature values in the creek exhibit an annual cycle which preceeds that of Bramble Bay by approximately one month. Rainfall in the watershed was correlated with observed salinity values. It is postulated that salinity is the common feature between temperate and tropical estuaries in the maintenance of community cycles.     

降水年内分配不均匀性指标

径流量及其分配过程依赖于降雨特征,它关系到水利设施规模和水资源合理配置。本文借鉴水文界经验,应用降雨集中度、降雨不均匀系数和调节系数概念,并对后2个系数进行修订,使其值域介于0～1。利用中原地区有代表性的4个气象台站1951—2005年的日降雨资料,计算并分析比较了降雨集中度、降雨不均匀系数和调节系数在河南省的适用性。结果表明:降水集中度、降水不均匀系数和调节系数从不同侧面反映了降水量的年内分布特征。3个指标具有一定的可比性,但数值上用同样资料计算的调节系数都要大于不均匀系数;4站候、旬和月的降水不均匀系数有相同的分布规律,随着时段的延长,不均匀系数增大,其变幅也增大,而调节系数则不同,随着时段的延长,降水调节系数减小,而相应的变幅则增大;分别采用候、旬和月的降水资料计算的降水集中度、不均匀系数和调节系数之间具有很好的一致性,最小的相关系数为0.60(P<0.001),说明3个指标间可互为代替;采用候、旬和月计算的降水集中度两两之间呈显著相关,相关系数为0.98;候、旬和月不均匀系数之间的相关系数为0.75;候、旬和月的调节系数之间的相关系数与不均匀系数相当。表明这3个指标在不同时间尺度间具有明显的一致性,在河南区域只应用月降水量就能反应降水的不均匀性。     

中国林蛙胸腺类肌细胞的细胞学研究

目的通过对中国林蛙胸腺的组织细胞结构研究,探讨胸腺类肌细胞的结构特点及年周变化规律。方法选用崂山产中国林蛙(Rana chensinensis),雌雄兼有,逐月取材,应用H-E、铅苏木精、Grimelius嗜银和PAS等染色方法进行染色,超微结构用日立透射电子显微镜进行观察。结果类肌细胞是中国林蛙胸腺髓质中恒定出现的一种特征性细胞。细胞质包含许多类似于骨骼肌内的典型结构——肌纤维,根据结构特点可将细胞分为未成熟、成熟以及退化3种类型。肌细胞的出现伴有明显的年周变化,2、3月份开始逐渐增多,到9月份肌细胞的大小与数量达到最大,不同月份所含细胞类型也大有不同。结论类肌细胞是胸腺实质组织中的一种正常细胞,具有不同发育阶段的3种形态结构类型,细胞数量和类型具有年周变化特点,推测与胸腺的正常功能有密切关系。     

Distribution of Indole-3-Acetic Acid and the Occurrence of Its Alkali-Labile Conjugates in the Extraxylary Region of Pinus sylvestris Stems

Free and conjugated indole-3-acetic acid (IAA) were measured by quantitative gas chromatography-selected ion monitoringmass spectrometry in the extraxylary region of the stem of large Pinus sylvestris (L.) trees during the annual cycle of cambial activity and dormancy. The extraxylary region at the stem top and bottom was divided into 3 and 4 fractions, respectively, for the free IAA measurements, while the entire extraxylary region was extracted when the IAA-conjugates were analyzed. The effect on the distribution pattern of expressing IAA level as a concentration (per gram fresh weight or dry weight) and as total amount (per square centimeter) was examined. The IAA level was much higher in the cambial region than in the fractions that contained the nonfunctional phloem and the periderm. The largest IAA concentration occurred in the fraction that included the cambium, whereas the total amount of IAA was greatest in the phloemcontaining fraction. The significance of the nonuniform radial distribution of IAA for estimating the IAA concentration in the cambial region is discussed in relation to how the cambial region is sampled. A slight Iongitudinal gradient in IAA concentration, decreasing from the top to the bottom of the stem, was observed in the cambial region when the cambium was in the grand period of activity, but not at the end of the cambial growing period. In all fractions, the total amount of IAA was highest when the cambium was active. However, the IAA concentration in the cambial region did not follow the same pattern, actually being lowest during the tracheid production period at the stem bottom. IAA conjugates were detected on all sampling dates except June 23, but their concentrations were always less than 14% of that of free IAA, and their occurrence did not obviously vary during the year. In general, there was a higher concentration of ester conjugates than of amide conjugates, and the ester conjugates were more abundant at the top of the stem than at the bottom.