Environmental control of daily stem growth patterns in five temperate broad-leaved tree species

Tree ring analysis investigates growth processes at time horizons of several weeks to millennia, but lacks the detail of short-term fluctuation in cambial activity. This study used electronic high-precision dendrometry for analyzing the environmental factors controlling stem diameter variation and radial growth in daily resolution in five co-existing temperate broad-leaved tree species (genera Fraxinus, Acer, Carpinus, Tilia and Fagus) with different growth and survival strategies. Daily stem radius change (SRC(d)) was primarily influenced by the atmospheric demand for water vapor (expressed either as vapor pressure deficit (D) or relative air humidity (RH)) while rainfall, soil matrix potential, temperature and radiation were only secondary factors. SRC(d) increased linearly with increasing RH and decreasing D in all species. The positive effect of a low atmospheric water vapor demand on SRC(d) was largest in June during the period of maximal radial growth rate and persisted when observation windows of 7 or 21 days instead of 1 day were used. We found a high synchronicity in the day-to-day growth rate fluctuation among the species with increment peaks corresponding to air humidity maxima, even though the mean daily radial growth rate differed fivefold among the species. The five -species also differed in the positive slope of the growth/RH relationship with the steepest increase found in Fraxinus and the?lowest in Fagus. We explain the strong positive effect of high RH and low D on radial stem increment by lowered transpiration which reduces negative pressure in the conducting system and increases turgor in the stem cambium cells, thereby favoring cell division and expansion. The results suggest that mechanistic models of tree growth need to consider the atmospheric water status in addition to the known controlling environmental factors: temperature, soil moisture and precipitation. The results further have implications for sensitivity analyses of tree growth to climatic changes.     

Radial stem growth in response to microclimate and soil moisture in a drought-prone mixed coniferous forest at an inner Alpine site

Dendroclimatological studies in a dry inner Alpine environment (750 m a.s.l.) revealed different growth response of co-occurring coniferous species to climate, which is assumed to be caused by a temporal shift in wood formation among species. The main focus of this study therefore was to monitor intra-annual dynamics of radial increment growth of mature deciduous and evergreen coniferous species (Pinus sylvestris, Larix decidua and Picea abies) during two consecutive years with contrasting climatic conditions. Radial stem growth was continuously followed by band dendrometers and modelled using Gompertz functions to determine time of maximum growth. Histological analyses of tree ring formation allowed determination of temporal dynamics of cambial activity and xylem cell development. Daily fluctuations in stem radius and radial stem increments were extracted from dendrometer traces, and correlations with environmental variables were performed. While a shift in temporal dynamics of radial growth onset and cessation was detected among co-occurring species, intra-annual radial growth peaked synchronously in late May 2011 and early June 2012. Moist atmospheric conditions, i.e. high relative air humidity, low vapour pressure deficit and low air temperature during the main growing period, favoured radial stem increment of all species. Soil water content and soil temperature were not significantly related to radial growth. Although a temporal shift in onset and cessation of wood formation was detected among species, synchronous culmination of radial growth indicates homogenous exogenous and/or endogenous control. The close coupling of radial growth to atmospheric conditions points to the importance of stem water status for intra-annual growth of drought-prone conifers.     

Influence of alfalfa (Medicago sativa L.) intercropping and polyethylene mulching on early growth of walnut (Juglans spp.) in central Italy

Combined production of timber and forage species is considered to be a desirable land-use system to offset some of the current land management problems of Italy. This paper reports the early results of a study on intercropping young plants of walnut with alfalfa (Medicago sativa L.), with or without polyethylene mulching, in an experimental plantation in central Italy. Two genotypes of walnut were used:Juglans regia L. and the French hybrid NG23×RA. The seasonal changes of absolute and relative growth rates of walnut stem diameter and apical shoot length were investigated.During both growing seasons, alfalfa intercropping strongly decreased walnut growth, whereas polyethylene mulching promoted stem height and diameter growth. Stem growth of intercropped-and-mulched walnut was the same as that of sole walnut under clean cultivation management. The use of polyethylene mulching reduced or avoided the competitive effect of associated alfalfa on walnut growth. During both growing seasons, the intercropped-and-mulched walnut had higher relative growth rates than intercropped-unmulched walnut. The results show the effectiveness of polyethylene mulching in promoting early growth of walnut, even when intercropped with alfalfa during early stages of plantation establishment.     

Radial,Height and Volume Increment Variation in Picea abies (L.) Karst. Stands with Varying Thinning Intensities

Variation in radial increment at different stem heights was compared with stem volume increment and height increment using thinning experiments of Picea abies (L.) Karst. in southern Finland. The magnitude of growth variation was similar on trees from different crown classes and stand densities. However, there was higher autocorrelation in the codominant and intermediate trees and trees on dense plots. The relationship between short-term volume increment and radial increment variation at breast height was not affected by thinnings. While short-term growth variation was similar at different stem heights, some evidence was found for differences in medium-term variation between radial increment at breast height and volume increment. Height increment reacted to unfavourable climatic events later than radial and volume increment. Radial and volume increments were negatively correlated to temperature and positively correlated to precipitation of the current summer. Height increment was positively related to current early summer temperature, but negatively to temperature of the previous summer.     

Weather factors controlling growth of Oriental beech are on the turn over the growing season

A better understanding of the ecophysiological basis of wood formation by monitoring radial growth over the whole vegetation period may help to explain possible discrepancies between long-term average climate–growth relationships and short-term climatic impacts on tree growth. To understand how growth–climate associations of Oriental beech vary throughout a vegetation period, we studied seasonal growth patterns of high-elevation beech trees growing in the north of Iran by collecting wood anatomical micro-cores in 10 to bi-weekly intervals and measuring stem increment with high-resolution electronic dendrometers. Wood formation was for two consecutive years with contrasting inter-annual climate conditions (2011 and 2012). We divided the growing period into three equal time phases and related daily climate variability to the cambial growth in each phase. The pattern of climate–growth relationships varies over a complete growing season and between years: in both study years, trees responded homogenously at the beginning and at the end of the growing season, but showed opposing influence of relative humidity during spring and early summer (June and July). Temperature as the main driver of xylogenesis had a stimulating effect on growth at the beginning of the growing season, but had negative effects on radial increment during late June and July mainly due to the excess of ambient temperatures over an optimum threshold. Higher temperature in late June and July 2011 compared with those of 2012 led to a significantly narrower tree ring in 2011, despite the similar sums/means of annual climate parameters in these two years. Since regional climate change scenarios expect higher temperature and reduced moisture conditions in future, radial growth of beech in the north of Iran may be adversely affected.     

Temporal variation of microfibril angle in Eucalyptus nitens grown in different irrigation regimes

In 1990, a 2-ha plantation of Eucalyptus nitens (Deane and Maiden) Maiden was established in southeastern Tasmania and subjected to different irrigation regimes. Point dendrometers were installed in March 1995 to monitor radial stem movement every 15 min over several growing seasons. In this study, data from two growing seasons (1996-1998) were considered. From these measurements, daily increments of stem radius were determined. At the end of the second growing season, we extracted 12-mm cores and measured microfibril angles (MFA) of the wood at high resolution. Microfibril angles were rescaled on a time axis and mapped to daily and distance-based elements. Among treatments, irrigated trees in particular formed higher MFA early in the growing season (September-November) and lower MFA later in the growing season. Trees subjected to cyclic droughts showed clear relationships between MFA and soil water deficits, with MFA increasing in response to water stress release. Increases in MFA were preceded by accelerations in daily increment of stem radius. Among treatments, trees subjected to severe drought had the smallest MFA and generally low fluctuations in MFA. Irrigated trees were susceptible to changes in climate, whereas growth of the trees in the other treatments was limited by water availability. Use of path-analysis showed that temperature had an effect on stem radius increment but not on MFA; wind speed was the only factor that influenced MFA directly. Microfibril angle was correlated with stem shrinking and expansion phases; growth period length and growth rates were positively related to MFA.     

Daily patterns of stem size variation in irrigated and unirrigated Eucalyptus globulus

High resolution measurements of stem diameter variation provide a means to study short-term dynamics of tree growth and water status. In this 14-month study, daily changes in stem radius of Eucalyptus globulus Labill. seedlings were measured with electronic point dendrometers in a plantation in southern Tasmania, Australia. The daily patterns of stem expansion and shrinkage were classified into three phases: shrinkage; recovery; and increase in diameter from one maximum to the next, or increment. This study showed that rapid onset of even mild drought in irrigated trees caused distinct changes in daily patterns of stem diameter variation, particularly the duration of daily stem increment. The duration of the daily increment phase was directly related to increment magnitude. The dynamics of daily increment were significantly affected by mean minimum temperature, indicating a temperature limitation on metabolic processes underlying diameter growth in these trees. Most likely due to differences in conductance, the duration but not rate of the incremental daily expansion was greater in fast- than in slow-growing trees.     

大青山米老排树干径向生长变化及其对环境因子的响应

【目的】研究南亚热带大青山林区乡土珍贵树种米老排径向生长日变化特征及对环境因子的响应,为理解米老排生长-气候响应的生理机制、森林培育和保护等提供基础数据。【方法】利用点状树木径向生长变化记录仪对米老排径向生长变化进行连续观测,采用气象站同步测量辐射总量、土壤含水量、相对空气湿度、空气温度等环境因子数据。通过径向生长与环境因子的相关分析,研究米老排生长季第一个高峰期(5月)的不同分化等级径向生长日变化规律、不同天气条件下生长变化及径向生长-环境因子相互关系。【结果】1)不同分化等级米老排5月份的径向生长日变化量优势木(17.08μm)>平均木(13.94μm)>被压木(-1.81μm),差异极显著(P<0.01),且不同阶段的起始时间、阶段时长、变化量也有所不同。2)不同天气条件下,三种分化等级米老排径向日净生长量和日变化幅度均表现为雨天>晴天>阴天,受雨水影响,雨天条件下径向变化量远超其自身生长量;同种天气条件下,径向日净生长量优势木最大,日变化幅度则表现为平均木最大。3)不同分化等级米老排径向生长与相对空气湿度、降雨量呈极显著正相关关系,与气温、总辐射呈极显著负相关关系,而20 cm土壤含水率无显著性相关,且各影响因子均存在不同时间滞后效应。【结论】不同分化等级米老排由于林木生长状况的差异,导致其受到环境因子影响程度的不同,进而使得其径向生长变化量产生差异。     

欧美杨新无性系苗期年生长规律的研究

以3个欧美杨(P.×euramericana)无性系为材料,利用Logistic方程对各个无性系的一年生扦插苗木的苗高、地径的年生长节律进行拟合.根据因素列的几何形状发展态势的接近程度,将苗木的生长量与影响苗木生长的气象因子空气温度、空气相对湿度、降水量和日照时数组成一个灰色系统,进行面积关联度分析.结果表明利用Logistic方程拟合效果显著,相关系数皆在0.94以上.并以此将无性系扦插苗的生长过程分为成活期、生长前期、速生期和生长后期四个时期,年生长量表现出明显的"慢-快-慢-快-慢"的节律,其中速生期内的苗高生长量占总生长量的比率平均为58.2%,地径生长量占总生长量的比率平均为70.1%.并对各个生长时期的生长特点进行了分析,探讨了苗木的年生长规律.关联度分析表明空气温度对苗木的高生长影响最大,日照时数影响最小;而日照时数对苗木的粗生长影响最大,降水量影响最小.通过对苗木年生长节律和影响苗木生长主要环境因子进行分析,为加强苗木生产管理,提高苗木的质量和土地的生产力,提供了理论依据.     

幼龄枣树树干液流的动态研究

利用FLGS-TDP插针式植物茎流计,研究了阿克苏市红旗坡农场棉花试验基地中幼龄枣树树干液流的特点及其与环境因子的关系,结果表明:(1)在整个生长季的晴天,枣树树干液流的日变化呈现明显的单峰曲线;液流在10:00迅速上升,在14:00左右达到高峰,17:30又迅速下降;日累计液流为1.43 L/d,白天液流量占全天的91.19%～98.07%,晚上占1.93%～8.81%;由于夜间空气温度的缓慢上升,枣树在夜间有微弱上升液流。(2)4月份液流量最小为7.18 L,7月份最大为29.85 L,4月的累计流量仅为7月的23.96%。(3)生长季液流速率与环境因子逐步回归分析表明,树干液流受环境因子的综合影响,在日变化中大小依次是净辐射、总辐射、空气温度、风速和相对湿度,相关系数为0.68,决定系数为0.48;在季变化中影响大小依次为空气温度、总辐射、净辐射、相对湿度和风速,相关系数和决定系数都是0.89。     

欧美杨新无性系苗期年生长模型的研究

以3个欧美杨(P.×euramericana)无性系为材料,利用Logistic方程对各个无性系的一年生扦插苗木的苗高、地径的年生长节律进行拟合。根据因素数列的几何形状发展态势的接近程度,将苗木的生长量与影响苗木生长的空气温度、空气相对湿度、降水量和日照时数组成一个灰色系统,进行面积关联度分析。结果表明:利用Logistic方程拟合效果显著,相关系数皆在0.92以上。并以此将无性系扦插苗的生长过程分为成活期、生长前期、速生期和生长后期4个时期,年生长量表现出明显的"慢快慢快慢"的节律,其中速生期内的苗高生长量占总生长量的比率平均为60.3%,地径生长量占总生长量的比率平均为63.7%。关联度分析表明空气温度对苗木的高生长影响最大,降水量影响最小;而日照时数对苗木的粗生长影响最大,降水量影响最小。通过对苗木年生长节律和影响苗木生长的主要环境因子进行分析,为加强苗木生产管理,提高苗木的质量和土地的生产力,提供了理论依据。     

1年生楸树无性系苗期生长特性

楸树(Catalpa bungei C.A.Mey.)为紫葳科(Bignoniaceae)梓树属(Catalpa Scop.),原产我国,适应性强、分布范围广、栽培历史悠久,至今已有2 600年,是我国传统栽培的珍贵优质用材树种和著名园林观赏树种,喜温暖湿润,适生于年均气温10～15℃,年降水量500～1 000 mm的气候条件.楸材作为优质上等木材可以满足国内对高级木材的需要,缓解上等材供不应求的矛盾.     

Six-year time course of light-use efficiency, carbon gain and growth of beech saplings (Fagus sylvatica) planted under a Scots pine (Pinus sylvestris) shelterwood

Two-year-old Fagus sylvatica L. saplings were planted under the cover of a Pinus sylvestris L. stand in the French Massif Central. The stand was differentially thinned to obtain a gradient of transmitted photosynthetically active radiation (PAR(t); 0-0.35). Eighteen Fagus saplings were sampled in this gradient, and their growth (basal stem diameter increment) was recorded over six years. Over the same period, morphological parameters (leaf area, number and arrangement in space) were monitored by 3D-digitization. Photosynthetic parameters were estimated with a portable gas-exchange analyzer. Photosynthesis was mainly related to light availability, whereas sapling morphology was mainly driven by sapling size. Annual stem diameter increment was related to the amount of light-intercepting foliage (silhouette to total leaf area ratio (STAR) x total sapling leaf area (LA)) and light availability above the saplings (PAR(t)). However, light-use efficiency, i.e., the slope of the relationship between STAR x LA x PAR(t) and stem diameter increment, decreased over time as a result of a relative decrease in the proportion of photosynthetic tissues to total sapling biomass.     

红豆树等6种珍贵用材树种的生长特性和材性分析

利用浙江龙泉和庆元两地在较好立地上营造的21 36年生红豆树、江南油杉、伯乐树、闽楠、刨花楠和乐东拟单性木兰6种珍贵用材树种的片林,以研究其生长、干形和木材基本密度的变化规律。研究结果表明,红豆树是一个树高和胸径生长量大、径生长速生持续期长、木材基本密度中等及其径向均匀性较高的珍贵用材树种,平均年轮宽度达到0.8 1.2 cm,36年生时按宽度和面积计算心材比例分别为60.57%和37.47%。因红豆树分叉干特性明显,在栽植的第2年就应及时修枝抹芽和施肥,以培育树干通直、心材比例高的优质干材。江南油杉和闽楠等其它5种珍贵用材树种皆较少分叉干,其树干通直。闽楠以材质优良而闻名,木材密度中等,虽然其生长速度较慢,但生长势很强,年生长量稳定,加之树冠窄小,适宜长周期大径材的培育;伯乐树生长速度中等,木材密度略低,但其径向均匀性较高,宜作为优质的工艺材来培育;树冠窄小的乐东拟单性木兰生长速度中等,但其木材密度大、径向均匀性高,是优良的珍贵用材树种;江南油杉是个早期生长快而后期生长慢,木材密度中等的针叶树种,可通过加强经营管理延长速生期和提高木材密度的径向均匀性;刨花楠虽然生长速度中等,但其木材密度却较低,浸水有粘液,不宜作为珍贵用材树种培育。     

Silvicultural alternatives in an uneven-sized forest dominated by Picea abies

In this article, we report on the increments in basal area and tree diameter as well as the structural development observed in variously thinned plots that underwent either uneven- or even-sized treatment. The experimental forest was originally an uneven-sized mixed stand dominated by Picea abies. Twenty-eight randomized sample plots underwent each treatment, and the trees were monitored for 15 growing seasons after thinning. The uneven-sized plots retained a reverse J-shaped diameter distribution, but this was changed into a bell shape by low thinning in the even-sized plots. Absolute basal area increment was positively correlated with basal area in the even-sized treatment but not in the uneven-sized treatment. In the latter, all of the plots grew almost equally well, and only the basal area of broadleaves explained slightly positively the increment variation. Relative basal area increment was negatively correlated with basal area in both treatments. Additionally, the basal area of Scots pine was a positive explanatory variable in the relative increment variation in the even-sized treatment. For the dominant Norway spruce trees, diameter increment was negatively correlated with basal area in both treatments and, conversely, heavy removal increased the diameter increment. Relative basal area increment averaged 5% annually in uneven-sized plots representing the “target selection.” This was more than double the increment observed for the even-sized plots that represented the “prevailing practice.” Likewise, the diameter increment of Norway spruce trees was 48% greater in the uneven-sized compared to the even-sized plots.     

Geographical variation in age–height relationships for dominant trees in Japanese cedar (Cryptomeria japonica D. Don) forests in Japan

In this study, we analyzed Japanese National Forest Inventory data to investigate the geographical variation in the relationship between tree height and age for dominant trees, and the effects of climatic conditions on these relationships. Our analysis focused on Cryptomeria japonica forests in 13 regions of Japan. The age–height relationships were classified into two regional groups that were distinguished by their climatic conditions. Several categories of climatic variables (warmth, solar radiation, precipitation, and snow depth) were significantly correlated with the parameters of a model for the age–height relationships. Our results also suggest the existence of a latitudinal cline for the maximum tree height of C. japonica in Japan. In regions with cold temperatures, deep snow, low solar radiation, and low summer precipitation, C. japonica shows a late-maturity pattern for height increase, with slow initial growth and a large maximum size. In regions with the opposite climatic conditions, it shows an early-maturity pattern with fast initial growth and small maximum size.     

Dynamics of diameter and height increment of Norway spruce and Scots pine in southern Finland

Key message

Onset and cessation of radial and height increment of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) in southern Finland were independent phenomena. They both contributed to the increment period duration, which was a more crucial factor defining the magnitude of annual radial and height increment.

Context

Phenology of diameter and height increment is a critical component of growth, also contributing to damage and survival of trees.

Aims

We quantified annual variation in intra-annual tracheid production and height increment of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.).

Methods

The number of tracheids and the day of the year for the onset and cessation of tracheid production were monitored from microcores collected repeatedly during growing seasons 2001–2012 in southern Finland. Weekly height increment was also measured in an adjacent sapling stand in 2008–2012.

Results

The first tracheids in pine were found around mid-May and in spruce a week later. The cessation of the tracheid production occurred during the last week of August for both tree species. Increment onset and cessation were independent phenomena, both contributing to the magnitude of tracheid production via increment period duration, which appeared to be a more crucial factor defining the number of tracheids. Duration of the height increment period was also related to shoot length but the connection was less tight than the link between the duration of tracheid production and the number of tracheids. A thermal threshold around 100 d.d. (degree days) was found for the onset of radial increment. No single environmental factor triggered the cessation of tracheid production, but in some years, soil water availability appeared to play a role.

Conclusion

The results indicate that extending growing seasons due to the climatic warming may increase growth in the Finnish forests.

     

Additive mixed models to study the effect of tree age and climatic factors on stem radial growth of Eucalyptus trees

The effect of tree age and climatic variables on stem radial growth of two hybrid clones of Eucalyptus was determined using longitudinal data from eastern South Africa.The stem radius of was measured weekly as the response variable.In addition to tree age,average weekly temperature,solar radiation,relative humidity and wind speed were simultaneously recorded with total rainfall at the site.An additive mixed effects model that incorporates a non-parametric smooth function was used.The results of the analysis indicate that the relationship between stem radius and each of the covariates can be explained by nonlinear functions.Models that account for the effect of clone and season together with their interaction in the parametric part of the additive mixed model were also fitted.The interaction between clone and season was not significant in all cases.For analyzing the joint effect all the covariates,additive mixed models that included two or more covariates were fitted.A significant effect of tree age was found in all cases.Although tree age was the key determinant of stem radial growth,weather variables also had a significant effect that was dependent on season.     

Mapping the effect of spatial and temporal variation in climate and soils on Eucalyptus plantation production with 3-PG,a process-based growth model

In the wet tropics, near the Atlantic Coast of Brazil, drought may reduce plantation yields by as much one-third over a six-to-seven-year rotation. For land owners, annual variation in production cannot be estimated with empirical models. In this paper, we examine whether the process-based growth model, 3-PG is sufficiently sensitive to climatic variation to provide a virtual record of changes in growing stock across 180,000 ha eucalypt plantation estate. We first mapped variation in climate and soil properties, and then ran simulations for the current planted forest with ages varying from one to seven years. Model predictions of stand volume and mean tree diameter agreed closely with measurements acquired on 60 reference plots monitored over the test period; the prediction of mean annual increment (MAI) was less reliable. Available soil water (ASW) and leaf area index (LAI) were also measured and compared with the model estimations. Vapour pressure deficit (VPD) and ASW accounted for most of the variation in yields. We conclude that this spatial modelling approach offers a reasonable alternative to extensive ground surveys, particularly when climatic variation extends beyond the historical average for a region.     

Performance of loblolly pine (Pinus taeda L.) seedlings and micropropagated plantlets on an east Texas site: I. Above- and belowground growth

East Texas contains the western extent of the natural range of loblolly pine (Pinus taeda L.) and, therefore, many planted seedlings there experience water deficit sometimes leading to plantation failure. One solution may be to regenerate with clonally propagated drought-hardy planting stock. The objective of this research was to compare the field performance of loblolly pine seedlings and plantlets of diverse genetic origin, produced via micropropagation technology.Two adjacent sites were established (Site I in 1993 and Site II in 1994) with trees produced from four genetic families: Liberty (LIB) and Montgomery (MON) Counties from southeast Texas, and Fayette (FAY) and Bastrop (BAS) Counties from the “Lost Pines” in Central Texas. Height, groundline diameter (GLD), leaf area, survival, root/shoot ratio, and root system architecture were measured throughout the 1994 and 1995 growing seasons. In addition, height and diameter at breast height on Site II were measured at the end of 1999 and 2000 growing seasons.Height and GLD growth for seedlings was significantly greater than for plantlets on both sites. However, mean relative growth rates for height were greater for plantlets during the first growing season, but comparable thereafter. Survival for all treatments was >85% on Site I and >90% on Site II at the end of the 1995 growing season. Survival was significantly different, but by a negligible margin, between families and stock types on Site II at the end of the 1995 growing season, and by a margin of 7% (89% for seedlings vs. 82% for plantlets) at the end of the 2000 growing season. Seedlings had greater leaf area growth than plantlets after two growing seasons. Root/shoot ratio was significantly greater for plantlets after two growing seasons, whereas their specific root length was significantly smaller than that of seedlings. This was attributed to root system architecture. Whereas plantlets produced thicker roots with less length per unit dry weight, seedlings produced more branching with thinner roots for similar dry weights.