Change of trunk sap flow of Ginkgo biloba L. and its response to inhibiting transpiration treatment

For this paper, GREENSPAN sap flow system was used to monitor the dynamics of trunk sap flow of Gingkgo biloba. Results indicate that sap flow velocity is significantly different among different heights, depths, and directions of the trunk. Sap flow velocity at the upper position of the trunk is higher than that of the middle and lower position, but cumulative flux is not significantly different among the upper, middle and lower sections. Sap flow velocity at 10 mm reached the most and that at 20 mm the least. However, sap flow velocity at 5 mm and 15 mm was similar and was second among the four depths. Results also showed that sap flow velocity of the south was the highest, and that of the west was next. An Automatic Weather Station of HOBO was synchronously applied to measure these meteorological parameters, and the relationship between these parameters and the changes of trunk sap flow velocity were analyzed. We found that the change of sap flow velocity was a single-crest curve on clear days and multi-crest curve on cloudy and rainy days. In addition, it is also revealed that by stepwise regression analyses photosynthetical active radiation (PAR), temperature and wind speed are the main environmental factors affecting sap flow velocity. The efficient methods of reducing water transpiration of trees, including leaf pruning, overshadowing and antitranspirant spraying, were found by investigating the effects on inhibiting transpiration, which indicated that spraying of antitranspirants, leaf pruning and overshadowing could significantly reduce transpiration but the effects of leaf pruning and overshadowing were far better than that of antitranspirant spraying. Translated from Scientia Silvae Sinicae, 2006, 42(5): 22–28 [译自: 林业科学]     

Nighttime transpiration of Populus euphratica during different phenophases

Evidence exists of nighttime transpiration and its potential impact on plant/water relations for species in a diversity of ecosystems. However, relevant data related to typical desert riparian forest species remains limited Accordingly, we measured sap flow velocity of Populus euphratica using the heat ratio method between 2012 and2014. Nocturnal stem sap flow was separated into nighttime and stem refilling using the ‘‘forecasted refilling'method. Nighttime transpiration was observed for each phenophase. The highest value was during the full foliation period but lowest during leaf expansion and defoliation periods. The contribution of nighttime transpiration to daytime transpiration was an average of 15% but this was comparatively higher during the defoliation period. Relationships between nighttime transpiration, vapor pressure deficits, and air temperatures were more closely associated than with wind speed in all phenophases. Moreover, we found that nighttime transpiration linearly correlated to vapour pressure deficit during the first and the full foliation periods, but nighttime transpiration showed exponential correlations to air temperatures during the same phenophases. Additionally, environmental drivers of transpiration were significantly different between nighttime and daytime(P \ 0.05). Driving forces behind nighttime transpiration were characterized by many factors, and integrated impacts between these multiple environmental factors were complex. Future studies should focus on these integrated impacts on nighttime transpiration, and the physiological mechanisms of nighttime transpiration should be investigated, given that this could also influence its occurrence and magnitude during different phenophases.     

Partition of nocturnal sap flow in Acacia mangium and its implication for estimating the whole-tree transpiration

We analyzed the partition of nocturnal sap flow into refilling of internal water storage and transpiration in Acacia mangium. Sap flow of trees was monitored continuously with Granier’s sensors for estimating the whole-tree transpiration. Possible night transpiration and stomatal conductance at the leaf level in the canopy were measured with a LI-6400 photosynthesis measuring system. For nocturnal leaf transpiration and stomatal conductance were weak, nocturnal sap flow of mature A. mangium trees was mainly associated with water recharge in the trunk. No significant change in night water recharge of the trunk was found at both seasonal and inter-annual scales. Morphological features of trees including diameter at the breast height (DBH), tree height, and canopy size could explain variances of night water recharge. Furthermore, although the contribution of nocturnal sap flow to the total transpiration varied among seasons and DBH classes, the error caused by night water recharge on wholetree transpiration was negligible. __________ Translated from Journal of Plant Ecology (Chinese Version), 2007, 31 (5): 777–786 [译自: 植物生态学报]     

Diversity of soil microorganisms in natural Populus euphratica forests in Xinjiang, northwestern China

To better understand the distribution of soil microorganisms in Populus euphratica forests in Xinjiang, northwestern China, we studied and compared the populations and numbers of bacteria, fungi and actinomycetes in the soil at four different age stages of natural P. euphratica forests, i.e., juvenile forests, middle-aged forests, over-mature forests and degraded forests. Results showed that there were clear differences in the amount of microorganism biomass and composition rates across the four forest stages. Dominant and special microorganisms were present in each of the four different soil layers. The vertical distribution showed that the microorganism biomass decreased with increasing soil depth. The population of microorganisms was the lowest at 31–40 cm of soil depth. The microorganisms consisted of bacteria, actinomycetes, as well as fungi. Bacteria were the chief component of microorganisms and were widely distributed, but fungi were scarce in some soil layers. Aspergillus was the dominant genus among the 11 genera of fungi isolated from the soil in different age stages of P. euphratica forests. __________ Translated from Journal of Beijing Forestry University, 2007, 29(5): 127–131 [译自: 北京林业大学学报]     

Comparison of stomatal characteristics and photosynthesis of polymorphic Populus euphratica leaves

The leaf shapes of adult Populus euphratica vary from lanceolate to dentate broad-ovate. In order to find the mechanism regarding the ecological adaptation of the polymorphic leaves, the dentate broad-ovate, broad-ovate, and lanceolate leaves were chosen to study their stomatal and photosynthetic characteristics. It is observed that the stomas on the adaxial and abaxial epidermis of the same leaves open non-uniformly with similar densities. The stomatal densities are different among the three typical leaves, which decrease from broad-ovate to lanceolate leaves. Their stomatal sunken degree varied obviously, decreasing from broad-ovate to lanceolate leaves. The changes of the diurnal photosynthetic rate of the three typical leaves follow a single peak curve. The mean diurnal photosynthetic rates of these leaves rank from high to low as broad-ovate > dentate broad-ovate > lanceolate leaves. The light compensation points are similar in the three typical leaves, while the light saturation points vary obviously. The efficiency of solar energy conversion and potential activity of the PSII in the leaves differ significantly, with the dentate broad-ovate leaves the highest. The results suggest that their leaf shapes, anatomic structures, and photosynthetic characteristics change during the leaf development. __________ Translated from Scientia Silvae Sinicae, 2006, 42(8): 20–24 [译自: 林业科学]     

Spatial distribution characteristics of fine roots of Populus euphratica in a desert riparian forest

The soil-plant system is a very important subsystem of the soil-plant-atmosphere continuum (SPAC). The water uptake by plant roots is an important subject in the research on water transport in this SPAC and is also the most active study direction in the fields of ecology, hydrology and environment. The study of the spatial distribution pattern of fine roots of plants is the basis of constructing a water absorption model of plant roots. Our study on the spatial distribution pattern of fine roots of Populus euphratica in a desert riparian forest shows that the density distribution of its root lengths can be expressed horizontally as a parabola. The fine roots are concentrated within the range of 0–350 cm from the tree trunk and their amount accounts for 91.9% of the total root mass within the space of 0–500 cm. In the vertical direction, the density distribution of the fine root lengths shows a negative exponential relation with soil depth. The fine roots are concentrated in the 0–80 cm soil layer, accounting for 96.8% of the total root mass in the 0–140 cm soil layer. __________ Translated from Chinese Journal of Ecology, 2007, 26(1): 1–4 [译自: 生态学杂志]     

Response of canopy stomatal conductance of Acacia mangium forest to environmental driving factors

Granier’s probes were applied to measure the sap flow of 14 sample trees in an Acacia mangium forest on the hilly lands in Heshan City, Guangdong, during the time period of October, 2003. The photosynthetically active radiation (PAR), air relative humidity (RH) and temperature of air (T) above the forest canopy were recorded. The sap flow measurement was used in combination with morphological characteristics of tree and forest structure to calculate the whole-tree transpiration (E), stand transpiration (E _t), and mean canopy stomatal conductance (g _c). Analyses on the relationships between tree morphological characters and whole-tree water use, and on the responses of g _c to PAR and vapor pressure deficit (D) were conducted. The results showed that whole-tree transpiration correlated significantly and positively with tree diameter at breast height (DBH) (p<0.0001), with sapwood area (p<0.0001), and with canopy size (p = 0.0007) logarithmically, but exponentially with tree height (p = 0.014). The analyses on the responses of canopy stomatal conductance showed that the maximum g _c (g _cmax) changed with PAR in a hyperbolic curve (p<0.0001) and with D in a logarithmic one (p<0.0001). The results obtained with sap flow technique indicate its reliability and accuracy of the methods of estimation of whole-tree and stand transpirations and canopy stomatal conductance. __________ Translated from Chinese Journal of Applied Ecology, 2006, 17(7): 1149–1156 [译自: 应用生态学报]     

Genetic diversity of Populus euphratica populations in northwestern China determined by RAPD DNA analysis

Five Populus euphratica Oliver populations in northwestern China were analyzed using RAPD DNA markers to determine genetic diversity among and within populations. One hundred-and-five polymorphic bands were observed, ranging in size from 250 bp to 1700 bp, using 10 primers. Only one population on the north side of the Tianshern Range had a unique band common to all individuals that was not found in individuals from populations in the Tarim River valley. Intra-population genetic diversity was high in two populations along the Tarim River and low in the other three populations. There was no significant correlation between genetic distances and geographic distances. The result of correspondence analysis shows that the individuals from the three populations with low genetic diversity are isolated from each other. The result of cluster analysis based on genetic distance shows that the population in the Tianshern Range is genetically distant from the other populations. These results suggest that the Tianshern Range population was genetically isolated from the other populations.     

胡杨蒸腾耗水的单木测定与林分转换研究

利用热脉冲技术,在黑河下游额济纳天然绿洲内测定胡杨单木边材液流在不同位点、方位的变化,结果表明:液流速率随深度的增加而增大,在15 mm处达到最大值,随后随深度增加而减小,越靠近形成层,液流启动越早,减小滞后;在4个方位上,南、西面液流速率远远高于北、东面;南面比西面液流启动较早,下降较快;西面液流速率下降滞后于南面;在北与东面,2个方位液流速率变化不大.在此基础上,采用边材面积作为纯量,对胡杨近熟林耗水量进行了推算.胡杨林边材面积与胸径之间存在较高的相关性,两者之间的关系可以用幂模型很好地拟合.通过实测标准地的胸径分布,推算出林地边材面积的分布,利用热脉冲测定单木液流通量,推算出黑河下游胡杨近熟林年生长期(4-10月)耗水量为3 172 m3·hm-2.     

Spatial distribution pattern and dynamics of the primary population in a natural Populus euphratica forest in Tarim Basin, Xinjiang, China

One 50 m × 50 m standard plot was sampled in a natural forest of Populus euphratica in Awati County, situated at the edge of the Tarim Basin, Xinjiang Uygur Autonomous Region, China. The field investigation was conducted with a contiguous grid quadrate method. By means of a test of variance/mean value ratio, aggregation intensity index and theoretical distribution models, the spatial distribution pattern and the dynamics of primary populations in P. euphratica forest were studied. The results showed that the spatial distribution pattern of two dominant arbor populations conformed to clumped distribution. The aggregation intensity of the P. euphratica population was higher than that of P. pruinosa population. The spatial distribution pattern of two companion plant populations in the shrub layer also conformed to clump type, though the aggregation intensity of Tamarix chinensis was higher. In the herb layer, the distribution patterns of Glycyrrhiza uralensis and Asparagus persicus conformed respectively to a clumped pattern and a random pattern. The results of a Taylor power method test and Iwao’s regression model also verified that both P. euphratica and P. pruinosa populations belong to a clumped pattern. Although the distribution pattern of P. pruinosa population at different development stages all belonged to a clumped distribution pattern, the aggregation intensity dropped gradually along with age development. The distribution patterns of the P. euphratica population at different development stages changed from random type to clumped type, and further to random type. The differences in spatial distribution patterns of different populations at different development stages were related not only to ecological and biological characteristics of each species in the communities in the light of competitive exclusion principle among the populations, but were also closely related to the habitats in which the species lived in. __________ Translated from Journal of Southwest Forestry College, 2007, 27(2): 1–5 [译自: 西南林学院学报]     

Structural characteristics and eco-adaptability of heteromorphic leaves of <Emphasis Type="Italic">Populus euphratica</Emphasis>

The microstructural and ultrastructural traits of three kinds of typical leaves ofPopulus euphratica Olive, including lanceolate, broad-ovate and dentate broad-ovate leaves, were studied by using electron microscope and optical microscope. The resuits showed that with the leaves changing from lanceolate shape to dentate broad-ovate shape, their structure obviously tended to be xeromorph: developed palisade tissue, undeveloped spongy tissue, thick cutin layer and sunken stomas. The amount of mitochondria tended to be increased, and the shape of chloroplasts varied from regular spindle to irregular rotundity or oval. The leaves were covered with wax without cilium, and the stomas on the upper and lower epidermis of the leaves opened unevenly. The stomas on the lower epidermis were deeper than those on the upper epidermis under the scanning electron microscope. The results implied that the structural characteristics of the diversiform-leaves ofP euphratica are related to its eco-adaptability.     

Sap flow of Castanopsis jianfengensis and its relationship with environmental factors in a tropical montane rainforest

Using thermal dissipation and the ICT-2000TE equipment made in Australia, the sap flow of Castanopsis jianfengensis and various environmental factors were measured simultaneously in a mixed tropical montane rainforest at Jianfengling Nature Forest Reserve (18°369′N, 108°52′E, 860 m elevation) during the dry and rainy seasons of 2002. The results show that sap flow velocity of C. jianfengensis exhibited a monopeak pattern on clear days and a multi-peak pattern on cloudy or rainy days. Sap flow velocity had significant positive correlations with solar radiation, air temperature, vapor pressure deficit and wind speed and a negative correlation with air relative humidity. In the dry season, sap flow velocity had a significant positive correlation with soil temperature and poor correlation with soil moisture; it was the opposite in the rainy season, indicating that precipitation clearly affected sap flow. Linear regression models between sap flow and environmental factors were established and were significant at the 0.005 level of probability. The mean transpiration rates of C. jianfengensis were 103.5 and 41.3 kg/d in our single tree and 1.94 and 0.77 mm/d in stand level in the dry and rainy season, respectively. __________ Translated from the Chinese Journal of Applied Ecology, 2007, 18(4): 742–748 [译自:应用生态学报]     

Estimation of drought-related limitations to mid-rotation aged plantation grown Eucalyptus globulus by phloem sap analysis

Previous research has shown that carbon isotope signatures (Δ¹³C) may correlate well with water status in 1–2 years old, plantation grown Eucalyptus globulus. Here we investigate this relationship for mid-rotation aged (5 years) trees and whether a simple field determination of phloem sugar concentrations is a reliable surrogate for Δ¹³C. We sampled six plantations covering much of the climatic range of E. globulus plantations in Australia (average annual rainfall 618–1094 mm). We found significant correlations between phloem Δ¹³C and phloem sugar concentrations across and within plantations. Both parameters were also correlated with a climate wetness index. We thus conclude that phloem sugar concentration is a useful surrogate for Δ¹³C and hence water status of mid-rotation E. globulus. We also observed strong correlations of phloem Δ¹³C and phloem sugar concentrations with growth across all plantations, providing some confirmation that water limits growth of E. globulus at a larger scale. This relationship was much weaker or absent within plantations, suggesting that factors other than water supply contribute significantly to growth limitations at smaller (within-plantation) scales.     

Interrelationships between leaf heat conductivity and tissue structures of different varieties of Populus tomentosa Carr.

Plant heat conductivity largely depends on tissue structure. Different structures lead to different heat conductivity. As well, water transfer also plays a very important role in heat transfer in plants. We have studied leaf heat conductivity and tissue structure of 3- and 30-year-old Populus tomentosa Carr. trees using infrared thermal imaging, steady state heat conductivity surveys and paraffin section and investigated the relationship between leaf heat conductivity, tissue structure and water content of leaves. The results show that the temperature on leaf surfaces among the various varieties of trees was almost the same. Leaf heat conductivity, temperature and water content of leaves are positively correlated. The thicker the leaf tissue structures, the larger the heat resistance. That is, the tighter the cells and the smaller the interspaces, the smaller the heat conductivity, which is not conducive for heat transfer.     

Stand-scale transpiration estimates in a Moso bamboo forest: (I) Applicability of sap flux measurements

The applicability of sap flux (F_d) measurements to bamboo forests has not been studied. This study was undertaken to establish an optimal and effective design for stand-scale transpiration (E) estimates in a Moso bamboo forest. To this aim, we validated F_d measurements in Moso bamboos in a cut bamboo experiment. In addition, we analyzed how sample sizes affect the reliability of E estimates calculated from F_d and conducting culm area (A_{S_b}). In the cut bamboo experiments, we found that F_d measurement using a 10 mm probe was a valid means of determining the water-use behavior of a Moso bamboo, although a specific correction was needed. Furthermore, we calculated E from stand A_{S_b} (A_{S_stand}) and mean stand F_d (J_S). Employing Monte Carlo analysis, we examined potential errors associated with sample size in E, A_{S_stand}, and J_S using an original dataset with A_{S_b} and F_d measured for 40 and 16 individuals, respectively. Consequently, we determined the optimal sample size for both A_{S_stand} and J_S estimates as 11. The optimal sample sizes for J_S were almost the same under different vapor pressure deficit and soil moisture conditions. The optimal sample size for J_S at the study site was less than that of a coniferous plantation in the same region probably owing to small individual-to-individual variations in sap flux in the Moso bamboo forest. Our study concludes that sap flux measurements are an applicable technique for assessing water use in Moso bamboo forests.     

Agrobacterium-mediated transformation of lombardy poplar (Populus nigra L. var.italica Koehne) using stem segments

Genetically transformed lombardy poplar (Populus nigra L. var.italica Koehne) plants were regenerated by co-cultivation of stem segments withAgrobacterium tumefaciens strain LBA4404 that harbored a binary vector (pBI121) which included genes for β-glucuronidase (GUS) and neomycin phosphotransferase. Successful transformation was confirmed by the ability of stem segments to produce calli in the presence of kanamycin, histochemical and fluorometric assays of GUS activity in plant tissues, and Southern blot analysis.     

Factors affecting transpiration of Pinus tabulaeformis in a semi-arid region of the Loess Plateau

The effects of soil water and meteorological factors affecting transpiration of Pinus tabulaeformis were studied under different levels of soil water content to offer a scientific basis for increasing efforts in afforestation survival and management of soil water in forested land. Under artificial control methods for soil water and potting experiments, the transpiration rate (T _r) of P. tabulaeformis and environmental factors were measured using a portable steady porometer (Li-1600) and a speedy weight method (BP-3400) during a representative fine day in the growing season of 2004. The results indicated that the diurnal course of T _r and R _st of P. tabulaeformis displayed a double-peaked curve and a “W” curve under different levels of soil water content. Given a representative fine day, the T _r could be represented as a cubic relation with soil water content (SWC). The SWC which caused maximum T _r values of P. tabulaeformis was 17.7%, 19.8%, and 17.5% in July, August and October respectively. T _r was affected not only by physiological characteristics, but also by SWC and meteorological factors. T _r was significantly correlated with meteorological factors when the soil water was sufficient, but this correlation would decrease under conditions of serious water stress. Under such stress conditions, air temperature was the primary factor to affect T _r in July and August and photosynthetically active radiation (PAR) was the primary factor in October. When soil water is sufficient, the main factors affecting T _r were relative humidity (RH), air temperature (T _a) and leaf temperature (T _l) in July, August and October respectively. __________ Translated from Science of Soil and Water Conservation, 2007, 5(1): 49–54 [译自: 中国水土保持科学]     

Efficiency of extracting microarthropods from the canopy litter in a Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis> D. Don) plantation: a comparison between the washing and Tullgren methods

We compared the efficiency of washing versus the Tullgren method for extracting microarthropods from dead leaves and branches in the canopy of Cryptomeria japonica trees. Oribatida and Collembola were consistently the numerically dominant taxa of microarthropods, but the relative abundance differed between the two extraction methods. Oribatida accounted for more than 70% of all the microarthropods collected by the washing method but less than 30% by the Tullgren method. Collembola accounted for less than 10% collected by the washing method but about 60% by the Tullgren method. The density of Oribatida was higher when collected by the washing method than by the Tullgren method, and vice versa for the density of Collembola. Our results suggest that the washing method is appropriate for collecting Oribatida and other microarthropods, whereas the Tullgren method is better for collecting Collembola from the canopy litter of C. japonica trees.     

The influence of Desert False Indigo, <Emphasis Type="Italic">Amorpha fruticosa</Emphasis>, and three arbuscular mycorrhizae fungi on the growth of <Emphasis Type="Italic">Populus ussuriensis</Emphasis> seedlings

The influence of Desert False Indigo, Amorpha fruticosa, on the growth of Populus ussuriensis seedlings inoculated with three arbuscular mycorrhizae (AM) fungi (Glomus mosseae, Glomus intraradices, Glomus sinuosa) was studied using the nylon net method. The results showed that all three AM fungi infected P. ussuriensis seedlings and G. intraradices and also G. mosseae infected A. fruticosa. The AM fungi promoted growth of P. ussuriensis and Desert False indigo seedlings. Moreover, under co-cultivation with A. fruticosa, the biomass of P. ussuriensis increased significantly. The concentration of nitrogen in P. ussuriensis grown with A. fruticosa and the concentration of soluble nitrogen in the rhizosphere were also higher than when grown alone. Hypha were found on the two plant seedlings inoculated with G. mosseae and G. intraradices, suggesting that AM fungi may transport nutrients from seedlings of A. fruticosa to the rhizosphere of P. ussuriensis seedlings, which may have promoted the growth of P. ussuriensis. The AM fungi played a critical role on the effect of A. fruticosa on growth of P. ussuriensis.     

Recovery of canopy trees and root collar sprout growth in response to changes in the condition of the parent tree after a fire in a cool-temperate forest

The relationship between the recovery of canopy trees after fire and root collar sprout dynamics was investigated during 1998–2000 in a secondary cool-temperate broad-leaved forest consisting of Quercus mongolica var. grosseserrata and Betula platyphylla var. japonica trees, in northern Hokkaido, Japan, which burned in April 1998. All of the Betula trees that were severely damaged, two-thirds of those slightly damaged, and half of those intact in 1998, died within three growing seasons after the fire. By contrast, half of the Quercus trees that were slightly damaged and half of those severely damaged recovered their foliage, and no slightly damaged or intact trees died during the three growing seasons after the fire. Many Betula trees developed several fruiting bodies of wood-destroying fungi on their stems, irrespective of damage severity. Fungi also infected some of the surviving Quercus, although the crowns tended to recover. Although many sprouting Betula were observed in 1998, the number of sprouts declined rapidly over the study period. Multiple regression analyses showed that the survival and growth of Betula sprouts were positively influenced by the number of sprouts in 1998, damage severity in 1998, and the degree of recover or decline during the study period, and were negatively influenced by parent tree size. On the other hand, a few sprouts of Quercus remained alive. Quercus remained dominant and the dominance of Betula was rapidly reduced after the fire. However, many Betula sprouts remained alive. Stand structure will change drastically for the time being.