Studies on Electrolyte Conductivity and Activity of Dehydrogenase of Chinese Fir and Masson Pine Bare—Root Seedling under Water and Cold Stress

The electrolyte conductivity and activity of dehydrogenase of bare-root seedlings of both Chinese fir (Cunninghamia lanceolata (Lamb.)Hook.)and Masson pine (Pinus massoniana Lamb.) under freezing and desiccation treatments were studied.The results showed that needle electrolyte conductivity of both speices increase significantly after freezing treatment and there are no significant differences in needle electrolyte conductivity between the two species.The dehydrogenase activity(ARD) of fine roots of both Chinese fir and Masson pine was negatively correlated with increasing freezing and desiccation.The results suggest that both electrolyte conductivity and dehydrogenase activity could be used as quick indicators of Chinese fir and Masson pine bare-root seedling quality.     

Improving the assessment method of seed vigor in Cunninghamia lanceolata and Pinus massoniana based on oxygen sensing technology

Oxygen sensing technology was employed to study the rapid methods for seed vigor assessment of Chinese fir (Cunninghamia lanceolata) and Masson pine (Pinus massoniana). Firstly, seeds of five lots were performed using accelerated aging (AA) into three vigor levels. Then, four oxygen sensing indices, including increased metabolism time (IMT), oxygen metabolism rate (OMR), critical oxygen pressure (COP), relative germination time (RGT) and the control indices such as laboratory germination indices, dehydrogenase activity (DA), and electrical conductivity (EC) were analyzed by the tests of 15 samples. The results of correlation analysis between these indices and field emergence performances based on two-year and two-spot data showed that RGT and OMR should be indicated as the optimal oxygen sensing indices to rap- idly and automatically evaluate seed vigor of Chinese fir and Masson pine, respectively. On the basis, one-variable linear regression equations were built to forecast their field emergence performances by the two oxygen sensing indices.     

Responses of the seedlings of five dominant tree species in Changbai Mountain to soil water stress

Soil water stress was studied on the potted seedlings of five dominant tree species (Pinus koraienes Sieb.et Zucc.,Fraxinus mandshurica Rupr., Juglans mandshurica Maxim, Tilia amurensis Rupr. and Quercus mongolica Fisch.ex Turcz) from the broadleaved/Korean pine forest in Changbai Mountain. Leaf growth, water transpiration and photosynthesis were compared for each species under three soil moisture conditions: 85%-100% (high water, CK), 65%-85% (Medium water, MW) and 45%-65% (low water, LW) of 37.4% water-holding capacity in field. The results showed that the characteristic of typical drought-resistance of the leaves is significantly developed. The net photosynthetic rate and water use efficiency of Fraxinus mandshurica were higher in MW than those in CK. But for the other four species, the net photosynthetic rate and water use efficiency in CK were lower than those in MW and LW. The transpiration rate responding to soil moistures varied from species to soecies.     

A Study on the Impacts of Climate Change on the Distribution of Pinus tabulaeformis in China

A special interpolation program GREEN has been developed to determine the climatic parameters for the distribution region of Chinese pine (Pinus tabulaeformis Carr.) based on the researches on the distribution of the tree species. The central region, which is the most suitable distribution region, and potential distribution region of the species under current climatic conditions were mapped using a Geographic Information System IDRISI. According to the averaged predictions by 5 GCMs for 2030, a projection was made for the future distribution of the pine. The results show that the potential distribution area of Chinese pine will have a small northward shift, though not significantly. The east part of the northern boundary will move northwards by 1.4 degree, while the southern boundary will move northwards about 0.2 degree in latitude. The east and west edges will both move towards the distribution center. The potential distribution region will shrink by 9.4% compared with the current area. The species wi     

Effects of application date and rate of foliar-applied glyphosate on pine seedlings in Turkey

Glyphosate is the herbicide most extensively used for site preparation and conifer release. It is a broadspectrum herbicide and therefore crop safety is a critical issue. This study assessed the early effects of 14 different treatments, including no weed control, manual weed control, and 12 foliar-applied herbicide treatments at low,intermediate, high, and highest application rates and application timing on glyphosate phytotoxicity of containerized seedlings of Austrian pine(Pinus nigra J.F.Arnold.), Scots pine(P. sylvestris L.) and maritime pine(P.pinaster Aiton), conifer species widely used for afforestation and supplementary plantings in Turkish forestry. In general, Scots pine seedlings were tolerant to glyphosate compared to the other species. Glyphosate phytotoxicity varied significantly according to the time and rate of application. Seedlings were relatively tolerant to glyphosate in April whereas they were intolerant in May. The highest herbicide rate(1.2% v:v) was consistently phytotoxic to all species. Moreover, the effect of herbicide rate on seedling survival and growth varied significantly according to application date(i.e., application rate 9 date interaction). Seedlings appeared tolerant to glyphosate at low and intermediate rates(0.2, 0.4% v:v) between midspring and mid-summer, whereas they demonstrated significant sensitivity to the highest rate across all time periods. Glyphosate at the high rate(0.8% v:v) was particularly more phytotoxic when applied in May. Application of glyphosate at rates up to 0.8% could be recommended for weed control without significant pine damage in midspring when the needles presumably have a dense leaf epicuticular wax layer limiting herbicide penetration.Applications of 0.8 and 1.2% v:v are not recommended during May–June.     

Some ecophysiological characteristics of artà (Calligonum comosum Ľ Hérit) in response to drought stress

Water deficit is an important environmental factor restricting plant growth and photosynthesis. The effect of water deprivation on leaf water status, photosynthetic gas exchange, chlorophyll content and fluorescence parameters of artà (Calligonum comosum) was studied. Five-month-old artà seedlings, grown in pots in the open air, were subjected to one of four drought treatments (i.e., mild, moderate, severe and extreme drought stress) and compared to control seedlings (normal watering regime). Results show that leaf water potential, net photosynthesis, stomatal conductance, transpiration, photosynthetic pigment content (chlorophyll a and b) decreased with increasing levels of drought stress. Inactivation of the photosynthetic apparatus was accompanied by changes in the fluorescence characteristics, providing evidence that reduction of photosynthetic rate could be attributed to non-stomatal limitations. Alterations imply changes in photochemical conversion efficiency of photosystem II by which plants could reduce water transpiration or protect their photosynthetic apparatus from destruction. These adaptations are discussed in relation to the strategies developed to grow drought-resistant artà seedlings in desert environments.     

Morphophysiological responses of forest seedling species subjected to different water regimes

Water availability is a limiting factor for the establishment and development of forest species.To understand the appropriate conditions for the initial post-transplanting phase,it is necessary to understand the specific morphophysiological characteristics of the species,such as the leaf water potential and the efficiency of photosystem Ⅱ.We aimed to identify the influence of different water regimes on the morphophysiological aspects of young plants of two forest species(Cedrela.fissilis Vellozo and Eucalyptus saligna Sm.).Two greenhouse experiments were conducted for 28 days;one for each species.The design was completely randomized,and the treatments consisted of six different water regimes.Leaf water potential(Ψw) and chlorophyll a fluorescence were evaluated every 7 days.At the end of the experiment,morphological attributes(height,collection diameter,root volume,and dry matter) were measured and histological blades were made.The water demand of E.saligna was higher than that of C.fissilis and required greater replacement within a shorter period.The rehydration from Ψw=-2 Mpa allowed for a fast recovery of the young C.fissilis plants(Ψw=-1.5,Fv/Fm=0.796),which indicated good physiological plasticity of this species when submitted to water stress at a level that is not severe.The total dry matter allocation was different among species.Seedlings of E.saligna presented the best responses when submitted to a continuous water supply regime,while C.fissilis seedlings presented the best response under intermittent irrigation conditions.     

Field Trial of Copper Treated Moso Bamboo in Southern China

The field trial of Moso bamboo treated with 9 copper preservatives was conducted in Guangzhou, China. The result showed that two formulations of ammonia-based copper azole (F17 and F18 ) and a formulation of amine copper added with boron (F10), as well as 2 kinds of ammonia-based ACQ, at the copper retention of 3.2 kg/m3 or over, were very resistant to decay and termites after the 5- year field test. And the durability of ACQ-B treated Moso bamboo was similar to that of treated Masson pine and slash pine at...     

An impacts of logging operations on understory plants for the broadleaved／Korean pine mixed forest on Changbai Mountain, China

Natural regeneration of tree species is important to the sustainability of native forest ecosystems in the temperate zone of northeast China. This study compared the densities and heights of seedlings and the diversities of shrubs and herbs on three sites of logging operations: log-skidding trails (LST), logging gaps (LG) and log landing sites (LLS). Sites undisturbed by logging gaps operations were sampied as control. The species, counts and height of tree seedlings and the species, counts, height and percentage coverage of shrubs and herbs were recorded in the field. The highest density and greatest height of regeneration trees were observed at LG and LST. The effects of LST on the densities of broadleaved trees were greater than those of coniferous trees. The difference in seedling density between LLS and control was significant (p=0.05). There was no significant difference in average seedling height for all the tree species between the disturbed sites and control. There were more shrub and herb species at the disturbed sites than at control. The diversity of understory plants at LG was the highest among all the sites. LST and LLS were different in shrub diversity, so were LLS and control. Both LG and LLS were different from control in herb diversity. Active measures need to be taken on the operation sites to protect the coniferous trees and the diversities of understory plants for sustaining the structure and composition of the broadleaved-Korean pine mixed forest on Changbai Mountain of China.Since different operation sites have different effects on different tree species, site-dependent actions must be taken to assure the regeneration of ecologically important tree species.     

Success of three soil restoration techniques on seedling survival and growth of three plant species in the Sahel of Burkina Faso (West Africa)

In the Sahel of Africa, where 90 % of the population depends on natural resources for their livelihood, a large part of the soils are structurally unstable,prone to crusting and hard setting, and have low water holding capacity, which hamper vegetation establishment.The effect of soil restoration techniques on survival and growth of seedlings of Acacia nilotica, Acacia tortilis and Jatropha curcas was tested in completely barren, degraded land in a Sahelian ecosystem in Burkina Faso. A total of522 seedlings(174 plants of each plant species) were planted in a randomized complete block design with three replicates combining three soil preparation techniques:half-moon, za¨? and standard plantation. Survival and growth rates evaluated over 20 months were significantly higher using the half-moon technique compared with the other two techniques. Survival rates of plant species planted using half-moon technique were 62.5, 28.57 and10.71 % for A. nilotica, A. tortilis and J. curcas respectively, but in za¨? and standard planting, seedling survival was zero. The low survival rate of J. curcas using the half-moon technique may indicate that J. curcas is unsuitable for barren and degraded land, whereas A. nilotica and A. tortilis appear to be promising tree species for rehabilitation of degraded land.     

Water relation patterns of bare-root and container jack pine and black spruce seedlings planted on boreal cut-over sites

Water relation patterns and subsequent growth were studied on bare-root and container jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) B.S.P.) seedlings during the first growing season on boreal cut-over sites.Containerized seedlings of both species had greater needle conductance compared to bare-root seedlings over a range of absolute humidity deficits. Needle conductance of containerized seedlings in both species remained high during periods of high absolute humidity deficits and increasing plant moisture stress. Bare-root seedlings of both species had a greater early season resistance to water-flow through the soil-plant-atmosphere continuum (SPAC) than container seedlings. Resistance to water flow through the SPAC decreased in bare-noot seedlings of both species as the growing season progressed, and was comparable to container seedlings 9 through 14 weeks after planting. Four weeks after field planting jack pine container seedlings had greater new root development compared to bare-root seedlings, while at the end of the summer both stock types had similar new root development. Black spruce bare-root seedlings had greater new root development compared with container seedlings throughout the growing season.     

Planting stress in newly planted jack pine and white spruce. 2. Changes in tissue water potential components

Water relations of bare-root jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) planted in a greenhouse and on a boreal cut-over site were examined during the first growing season. In field-planted trees, maximum stomatal conductances (g(wv)) were initially low (< 0.10 cm s(-1)). Base and minimum xylem pressure potentials (Psi(x(base)) and Psi(x(min))) were less than -1.5 and -1.7 MPa for jack pine and -2.0 and -2.6 MPa for white spruce, respectively. During the growing season, maximum g(wv) increased in both species to around 0.2 cm s(-1). Base and minimum xylem pressure potentials also increased in both species to around -0.5 and -1.0 MPa in jack pine and -1.0 and -1.5 MPa in white spruce, respectively. Minimum xylem pressure potentials in white spruce fell below the turgor loss point during the first half of the growing season. Osmotic potential at the turgor loss point Psi(pi(TLP)) decreased after field planting to around -2.7 and -2.3 MPa in jack pine and white spruce, respectively. In the greenhouse, minimum values of Psi(pi(TLP)) were -2.2 and -2.3 MPa in jack pine and white spruce, respectively. Maximum bulk modulus of elasticity was greater in white spruce and underwent greater seasonal change than in jack pine. Relative water content (RWC) at turgor loss ranged between 71 and 74% in jack pine and 80 and 87% in white spruce. Available turgor (T(avail)), defined as the integral of turgor over the range of RWC between Psi(x(base)) and xylem pressure potential at the turgor loss point, was similar in jack pine and white spruce just after field planting. For the rest of the growing season, however, T(avail) in jack pine was two to three times that in white spruce. Diurnal turgor (T(diurnal)), defined as the integral of turgor over the range of RWC between Psi(x(base)) and Psi(x(min)), as a percent of T(avail) was higher in field-planted white spruce than jack pine until the end of the season. Dynamics of tissue water potential components are discussed in relation to plantation establishment.     

水分和热胁迫处理对三个针叶树种苗木叶绿素荧光的影响

本文测定了三个周期水分和热胁迫处理对杉木、马尾松和北美乔柏苗木叶绿素荧光的影响。结果表明：三个树种的可变荧光与最大荧光之比值(Fv／Fm)对水分胁迫的反应不同。水分胁迫处理后北美乔柏的(Fv／Fm)值大大降低，而杉木的(Fv／Fm)值只有轻微下降，马尾松的(Fv／Fm)值则没有显著变化。实验结果还表明：热胁迫处理对三个树种的(Fv，Fm)值都有显著影响。就三个水分和热胁迫周期而言，研究发现：在每个水分和热胁迫周期结束时测定的杉木和马尾松(Fv／Fm)值没有显著差异。但随着胁迫时间的延长，北美乔柏的(Fv／Fm)值显著下降。图4表4参20。     

Water relations and morphological development of bare-root jack pine and white spruce seedlings: seedling establishment on a boreal cut-over site

Bare-root jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) seedlings were planted on a boreal cut-over site and subsequent growth and seedling water relation patterns were monitored over the first growing season. Comparison of morphological development between white spruce and jack pine showed jack pine seedlings had greater new root development and a lower new shoot/new root ratio, while white spruce seedlings had greater new shoot development. Seasonal water relation patterns showed white spruce seedlings to have a greater decrease in xylem pressure potential (_x) per unit increase in transpirational flux density in comparison to jack pine seedlings. These results suggest that the greater resistance to water flow through the soil-plant-atmosphere continuum in white spruce seedlings compared to jack pine seedlings may be due to the relative lack of new root development in white spruce. Stomatal response of the seedlings showed that as absolute humidity deficit between the needles and air (AHD) increased, needle conductance (gwv) decreased in both species, but at low AHD levels white spruce had gwv approximately 35% higher than jack pine. For white spruce seedlings, gwv decreased as _x became more negative in a predictable curvilinear manner, while gwv of jack pine seedlings responded to _x with a threshold closure phenomenon at approximately - 1.75 MPa. Tissue water potential components for jack pine and white spruce seedlings at the beginning and end of the growing season showed jack pine to reach turgor loss at 76% relative water content while white spruce reached turgor loss at 88% relative water content. White spruce seedlings showed osmotic adjustment over the growing season, with an osmotic potential at turgor loss of - 1.27 MPa and - 1.92 MPa at the beginning and end of the growing season, respectively. Jack pine did not show any osmotic adjustment over the growing season. The implication of morphological development on water relation patterns are discussed with reference to successful seedling establishment.     

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.     

马尾松、杉木容器苗培育基质研究

以１０种培养基质，对马尾松和杉木两种树种进行容器育苗研究，结果表明，以竹叶为基本材料配制基质，比纯黄心土基质培育的马尾松和杉木百日苗，干物质重分别增加９３．２％和５３．９％，与蛭石配制的基质相比，分别增加４３．９％和１０４．０％，与松树皮配制的基质相比，分别增加２５．０％和４２．９％，以松针为基本材料配制的基质效果似于竹叶。两者对苗木生长的影响，与各处理相比较，均达到了极显著水平，通过培养基质理化     

Soil water content and water relations in planted and naturally regenerated Pinus halepensis Mill. seedlings during the first year in semiarid conditions

The capacity of Aleppo pine (Pinus halpensis Mill.) seedlings to overcome the planting shock in dry conditions was assessed by firstly studying the survival and water status during the first year after planting in relation to soil water content. In spite of receiving only 177 mm rainfall during the year studied, survival of planted Aleppo pine was very high (88.5%). Soil water during summer months (after receiving 67 mm rainfall in winter and spring) was only available at 30–60 cm depth, with tension values of –1.1 and –1.3 MPa in July and August respectively; in these conditions, July predawn xylem water potential measured was –2.5 MPa, and midday potential was –3.6 MPa. According to different authors, these values don't jeopardize the survival of Aleppo pine. In addition, acclimation of outplanted seedlings to environmental conditions was followed by comparing their water relations with those of naturally regenerated seedlings on the site. Predawn and midday xylem water potential showed differences in favour of outplanted seedlings since June, indicating an adjustment to this dry site. Compared to naturally regenerated trees, nursery grown stock of the same age before field planting had much more biomass and higher N and P concentrations and contents; although shoot:root balance and Dickson quality index were not significantly different. Finally, planted seedlings acclimation level during first year was also evaluated by Transplant Stress Index, which value (–0.1278) indicated a slight planting impact.     

基于国家森林资源清查数据的不同生物量和碳储量估计方法的对比分析

[目的]通过对不同生物量和碳储量的估计方法进行对比分析,为确定在国家森林资源清查中生物量和碳储量的具体估计方法提供依据。[方法]以广东省2012年森林资源清查的100个杉木林和80个马尾松林的实测样地资料为基础,利用近年来我国建立的主要树种立木生物量模型,对改进IPCC法、生物量模型法和转换因子连续函数法(即方精云法)3种方法按一元和二元模型共6种方案进行了对比;同时,基于改进IPCC法一元和二元模型的生物量估计值,用平均含碳系数法、组分含碳系数法和固定含碳系数(0.5或0.47)法分别对碳储量进行估计。[结果]用二元生物量模型法得到的杉木林和马尾松林样地的总生物量分别为320 Mg和331 Mg,一元生物量模型法的结果分别相差0.9%和6.2%;改进IPCC法的估计结果,采用二元和一元模型时杉木林分别相差-3.6%和-11.9%,马尾松林分别相差-8.5%和-19.6%;而方精云法的估计结果,采用二元和一元模型时杉木林分别相差6.65倍和6.60倍,马尾松林分别相差-14.3%和-18.0%。平均含碳系数法和组分含碳系数法的碳储量估计结果,杉木林仅相差0.2%,马尾松林相差约0.4%;固定含碳系数法的估计结果因树种而异,对杉木林要低估0.6%5.4%,对马尾松林要低估3.3%9.1%。[结论]对生物量的估计,采用生物量模型法准确性最高,而林木水平的生物量模型其预估精度要高于林分水平的模型;IPCC法是基于材积源的通用方法,将其中的缺省参数改进为可变参数模型,可大大提高方法的适应性;方精云法只是基于IPCC法所建立的林分水平模型在大尺度上的一种具体应用方法,其精度要低于林木水平的生物量模型法,不适于中小尺度应用。对碳储量的估计,采用平均含碳系数法与组分含碳系数法差异很小,但采用固定含碳系数法则误差较大。     

Effects of dessication on post-planting stress in bare-root Corsican pine seedlings

We examined the post-planting consequences of pre-planting exposure stress on two-year-old, bare-root Corsican pine (Pinus nigra Arnold. ssp. laricio var. Corsicana) seedlings. Seedlings were lifted from a nursery and exposed to ambient conditions for periods of up to 192 h before being planted in minirhizotrons. Exposure decreased seedling water potential, CO(2) assimilation rate, leaf conductance and new root elongation, and increased mortality after planting. During exposure, needle total nonstructural carbohydrates (TNC) concentration (expressed on a dry mass basis) decreased by 0.31 mg g(dm) (-1) h(-1); however, needle and root TNC concentrations remained high (> 100 mg g(dm) (-1)) at planting, even in those treatments leading to severe seedling mortality. More than 90% of the seedlings with predawn water potentials lower than -1.3 MPa at planting did not elongate new roots and did not survive, whereas a similar percentage of seedlings with a predawn water potential above this value at planting elongated new roots and survived, suggesting that this value corresponds to a turgor threshold below which new root formation is inhibited. At planting, embolization of xylem conduits in roots and shoots was low for seedlings in all of the exposure treatments.