Mar 2007, Volume 2 Issue 1
    

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  • Soil NH4+/NO3? nitrogen characteristics in primary forests andthe adaptability of some coniferous species
    CUI Xiaoyang, SONG Jinfeng
    2007, 2(1): 1-10. https://doi.org/10.1007/s11461-007-0001-8
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    In terrestrial ecosystems, soil nutrient regimes at a plant s living site generally represent the plant s nutrition habitat . Plant species frequently well adapt to their original nutrition habitat  during a long process of evolution, and the apparent preference for ammonium or nitrate nitrogen source (NH4+ or NO3?) might be an important aspect of the adaptation. Plants typically favor the nitrogen form most abundant in their natural habitats. Nitrate has been recognized as the dominant mineral nitrogen form in most agricultural soils and the main nitrogen source for crops, but it is not usually the case in forest ecosystems. A large number of studies show that the nutrition habitats  associated with primary forest soils are typically dominated by NH4+ rather than NO3?, generally with NO3? content much lower than NH4+. Low levels of NO3?in these forest soils generally correspond to low net rates of nitrification. The probable reasons for this phenomenon include: 1) nitrification limitations and/or inhibitions caused by lower pH, lower NH4+ availability (autotrophic nitrifiers cannot successfully compete for NH4+ with heterotrophic organisms and plants), or allelopathic inhibitors (tannins or higher-molecular-weight proanthocyanidins) in the soil; or 2) substantial microbial acquisition of nitrate in the soils, which makes net nitrification rates substantially less than gross nitrification rates even though the latter are relatively high. Many coniferous species (especially such late successional tree species as Tsuga heterophylla, Pinus banksiana, Picea glauca, Pseudotsuga meziesii, Picea abies, etc.) fully adapt to their original NH4+-dominated nutrition habitats  so that their capacities of absorbing and using non-reduced forms of nitrogen (e.g., NO3?) substantially decrease. These conifers typically show distinct preference to NH4+ and reduced growth due to nitrogen-metabolism disorder when NO3? is the main nitrogen source. The physiological and biochemical mechanisms that account for the adaptation to NH4+-dominated systems (or limited ability to use NO3?) for the coniferous species include: i) distribution and activity of enzymes for catalyzing nitrogen reduction and assimilation, generally characterized by lower nitrate reductase (NR); ii) greater tolerance to NH4+ or rapid detoxification of ammonium nitrogen in the roots; iii) lower capacity of absorption to NO3? by roots that might be controlled by feedback regulations of certain N-transport compounds, such as glutamine; iv) relations and balance between nitrogen and other elements (such as Ca2+, Mg2+, and Zn2+ etc.). Some NH4+-preferred conifers might be more adapted (tolerant) to lower base cation conditions; v) NO3?2+ nutrition, rather than NH4+, that may lead to the loss of considerable quantities of organic and inorganic carbon to the surrounding media and mycorrhizal symbiont and probably contribute to slower growth; and vi) the metabolic cost of reducing NO3? to NH4+2+ that may make shade-tolerant conifers favor the uptake of reduced nitrogen (NH4+). The adaptation of late successional conifers to NH4+-dominated habitats has profound ecological implications. First, it might be an important prerequisite for the climax forest communities dominated by these conifers to maintain long-term stability. Second, primary coniferous or coniferous-broadleaved forests have been widely perturbed because of commercial exploitation, where the soil ammonium nitrogen pool tends to be largely transformed to nitrate after disturbance. In such a situation, the coniferous species that were dominant in undisturbed ecosystems may become poor competitors for nitrogen, and the site will be occupied by early successional (pioneer) plants better adapted to nitrate utilization. In other words, the implicit adaptation of many conifers dominant in undisturbed communities to ammonium nitrogen will cause difficulties in their regeneration on disturbed sites, which must be taken into account in the practical restoration of degraded temperate forest ecosystems.
  • Comparison of fractal characteristics of species richness patterns among different plant taxonomic groups along an altitudinal gradient
    REN Haibao, MA Keping, ZHANG Linyan
    2007, 2(1): 11-17. https://doi.org/10.1007/s11461-007-0002-7
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    This study was done using the non brown fractal model to quantify and compare the variations in the species richness of trees, shrubs, herbs and all plants along an altitudinal gradient and to characterize the dominating ecological processes that determine the variations. Two transects were sampled far away from any anthropogenic disturbances along the shady slopes of the Dongling mountains in Beijing, China. Both transects were continuous and 2 m wide, and every individual tree and shrub was recorded in each of them. Discrete quadrats of 1 m?1 m were located along the transects A and B for estimation of the herb species richness along the altitudinal gradients. The level interval between the quadrats was 10 m and 25 m respectively. In this study, transects A and B were combined into one transect AB, and 40 m was selected as the optimal quadrat length along the altitudinal gradients for measuring the plant species richness patterns. Species richness in each quadrat was calculated using a program written in Matlab 6.0. Direct gradient analysis was used to describe the overall trends in the species richness of trees, shrubs, herbs and other plants with change in altitude, while the non-brown fractal model was used to detect more accurately their variations at various scales along the gradient. The model assumed that each class of ecological processes affecting the distribution of a variable could be represented by an independent spatial random function. Generally, ecological phenomena are determined not by a single ecological process but by multiple ones. These processes act on ecological patterns within their own spatial scales. In the non-brown fractal model, the spatial random functions are nested within a larger range of spatial scales. The relative contribution of the spatial random functions to the spatial variation of a variable is indicated by a weighting parameter that has to be greater than or equal to zero. In this paper, we reached the following results and conclusions. Firstly, the direct gradient method describes the general trends of trees, shrubs, herbs and all plants along the altitudinal gradient but is unable to provide further details on the altitudinal variations in the species richness. The non-brown fractal model brought out the altitudinal variations in the species richness of trees, shrubs and herbs at various scales and related them to the ecological processes. The sharp changes in the double-log variograms suggest that the non-brown fractal model is suitable for characterizing the altitudinal patterns in the species richness of trees, shrubs and herbs at various scales but is not appropriate for explaining the variations in the plant species richness, since no significant changes were found in the double-log variograms in this case. Secondly, for the trees, the double-log variogram was divided into two scale ranges (0 245 m and 245 570 m), with a fractal dimension of 1.83 and 1.10, respectively, implying that changes in the tree species richness were random at small scales (0 245 m) and almost linear at large scales (245 570 m) along the altitudinal gradients. This suggests that altitudinal variations in the tree species richness are dominated by short-range processes at small scales and by long-range processes at large scales. Thirdly, for shrubs and herbs, the double-log variograms exhibited three ranges (0 101 m, 125 298 m and 325 570 m), and the fractal dimensions were 1.78 and 1.97, 1.56 and 1.43, and 1.08 and 1.25, respectively. The results indicate that, as in the case of trees, species richness of shrubs and herbs are distributed randomly at small scales and change in a linear manner at large scales although variations in the herb species richness is less heterogeneous than shrub species richness at large scales. Theses results also indicate that species richness of shrubs and herbs change approximately like brown movement at middle scales. The results also suggest that altitudinal variations in the specie richness of shrubs and herbs are dominated by three ecological processes, short-range ecological processes at small scales, long-range ecological processes at large scales, and brown fractal processes at middle scales. Interestingly, comparisons of the variations in the species richness of shrubs and herbs reveal that shrubs and herbs present the same scale range in spatial variation in species richness but display different trends in species richness along the altitudinal gradient, i.e. the shrub species richness decreased with increasing elevation whereas the herb species richness peaked at the mid-high elevation. These patterns suggest that although the scales at which the main processes affect patterns in species richness are the same, the processes are completely different, or the processes are similar but the responses of the shrubs and herbs to the ecological processes are different. Finally, the plant species richness did not show any obvious pattern along the altitude gradient and maintained a constant fractal dimension across all scales, this is perhaps because the processes defining the patterns of plant species richness had similar weights and acted over closely related scales.
  • Relationship and its ecological significance between plant species diversity and ecosystem function of soil conservation in semi-humid evergreen forests, Yunnan Province, China
    WANG Zhenhong, YANG Chengbo, YANG Limei, ZHOU Zizong, RAO Jing, YUAN Li, LI Ju
    2007, 2(1): 18-27. https://doi.org/10.1007/s11461-007-0003-6
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    In recent years, the relationship between biodiversity and ecosystem stability, productivity, and other ecosystem functions has been extensively studied by using theoretical approaches, experimental investigations, and observations in natural ecosystems; however, results are controversial. For example, simple systems were more stable than complex systems in theoretical studies, and higher productivity was observed in human-made ecosystems with poorer species composition, etc. The role of biodiversity in the ecosystem, such as its influence on sustainability, stability,and productivity, is still not understood. Because acceleratedsoil-erosion in various ecosystems has caused a decreaseof primary productivity, a logical way used in the study of the relationship between biodiversity and ecosystem function can be used to study the relationship between plant species diversity and soil conservation. In addition, biodiversity is a product of evolutionary history, and soil erosion is a key factor controlling the evolution of modern environment on the surface of the Earth. A study on the relationship between bio diversity and soil-erosion processes could help us understand the environmental evolution of Earth. Fifteen 10 m·40 m standard runoff plots were established to measure surface runoff, soil erosion, and total P loss in different secondary communities of semi-humid evergreen broad-leaved forests that varied in composition, diversity, and level of disturbance and soil erosion. The following five communities were studied: AEI (Ass. Elsholtzia fruticosa+Imperata cylindrical), APMO (Ass. Pinus yunnanensis+Myrsine africana+Oplismenus compsitus), APLO (Ass. Pinus yunnanensis+Lithocarpus confines+Oplismenus compsitus), AEME (Ass. Eucalyptus smith+Myrsine africana+Eupatorium adenophorum), and ACKV (Ass. Cyclobalanopsis glaucoides+Keteleeria evelyniana+Viola duelouxii). Tree density, the diameter of the tree at breast height, and the hygroscopic volume of plant leaves were determined in each plot. Results indicated that surface runoff, soil erosion, and total P loss decreased as a power function with increase in plant species diversity. Their average values for three years were 960.20 m3/(hm2 · year), 11.4 t/(hm2 · year), and 127.69 kg/(hm2 · year) in the plot with the lowest species diversity, and 75.55 m3/(hm2 · year), 0.28 t/(hm2 · year), and 4.71 kg/(hm2 · year) in the plot with the highest species diversity, 12, 50, and 25 times respectively lower compared with the lowest species diversity plots. The coefficients of variation of surface runoff, soil erosion, and total P loss also followed a power function with the increase of plant species diversity, and were 287.6, 534.21, and 315.47 respectively in the lowest species diversity plot and 57.93, 187.94, and 59.2 in the highest species diversity plot. Enhanced soil conservation maintained greater stability with increased plant species diversity. Plant individual density increased linearly and the canopy density and cross section at breast height increased logarithmically with the increase of plant species diversity. The hydrological function enhanced as the plant species diversity increased. There were obviously relationships between plant species diversity and rainfall interception, coverage, and plant individual density, which was related to soil conservation functions in the five forest communities. The complex relationships between plant species diversity and the above-mentioned ecological processes indicated that plant species diversity was an important factor influencing the interception of rainfall, reducing soil erosion and enhancing the stability of soil conservation, but its mechanism is not known. This experiment showed that plant species diversity promoted soil and nutrient conservation and ultimately lead to the increase of the primary productivity of the ecosystem, and was thus a good way to study the relationship between biodiversity and ecosystem stability. Rainfall interception could be assessed easily using the hygroscopic volume of plant leaves. Because there were strong correlations between plant species diversity and soil conservation functions, the patterns of plant species diversity will show a certain level of predictability on the interactions of life systems with surface processes of the Earth.
  • Effects of different forest practices on Pinus tabulaeformis population dynamics and species diversity in the Huanglongshan forest region
    WU Tao, ZHANG Wenhui, LU Yuanchang, FAN Shaohui
    2007, 2(1): 28-33. https://doi.org/10.1007/s11461-007-0004-5
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    Three Pinus tabulaeformis populations which experienced tending, shelterwood cutting, and closed tending were separately investigated to study the effects of these three forest practices on the age structures, static life tables, survivorship curves, and species diversities of P. tabulaeformis populations in Huanglongshan Mountain. Time sequence model was adopted to predict the dynamic population numbers of different P. tabulaeformis populations with different forest practices. The results revealed that the three populations are essentially identical in population structure, their young and old individuals make up a small proportion and their mid-aged individuals make up a large proportion and consequentially P. tabulaeformis populations generally stand stable. In the P. tabulaeformis communities with three tending practices, the highest species abundance index appears with tending and shelterwood cutting and the highest evenness index and species diversity appears with closed tending. The P. tabulaeformis populations with tending and shelterwood cutting practices belong to one developmental type and the P. tabulaeformis populations with closed tending practices belong to a stable type. It indicated that in the future, closed tending as the major practice and tending and shelterwood cutting as the supporting practices should be applied for P. tabulaeformis populations in Huanglongshan Mountain so that the communities will develop continuously.
  • Variations of fine root diameter with root order in Manchurian ash and Dahurian larch plantations
    WANG Xiangrong, WANG Zhengquan, GU Jiacun, MEI Li, HAN Youzhi, GUO Dali
    2007, 2(1): 34-39. https://doi.org/10.1007/s11461-007-0005-4
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    Fine root lifespan and turnover play an important role in carbon allocation and nutrient cycling in forest ecosystems. Fine roots are typically defined as less than 1 or 2 mm in diameter. However, when categorizing roots by this diameter size, the position of an individual root on the complex lateral branching pattern has often been ignored, and our knowledge about relationships between branching order and root function thus remains limited. More recently, studies on root survivals found that longevity was remarkably different in the same branching level due to diameter variations. The objectives of this study were: (1) To examine variations of fine root diameter from the first- to fifth-orders in Fraxinus mandshurica Rupr and Larix gmelinii Rupr roots; and (2) To reveal how the season, soil nutrient, and water availability affect root diameter in different branch order in two species. This study was conducted at Maoershan Forest Research Station (45?21´ 45?25´ N, 127?30´ 127?34´ E) owned by Northeast Forestry University in Harbin, northeast China. Both F. mandshurica and L. gmelinii were planted in 1986. In each plantation, fine roots of two species by sampling up to five fine root branch orders three times during the 2003 growing season from two soil depths (i.e., 0 10 and 10 20 cm) were obtained. The results showed that average diameters of fine roots were significantly different among the five branch orders. The first-order had the thinner roots and the fifth order had the thickest roots, the diameter increasing regularly with the ascending branch orders in both species. If the diameter of fine roots was defined as being smaller than 0.5 mm, the first three orders of F. mandshurica roots and the first two orders of L. gmelinii roots would be included in the fine root population. The diameter ranges of the fine roots from first-order to fifth-order were 0.15 0.58, 0.18 0.70, 0.26 1.05, 0.36 1.43, and 0.71 2.96 mm for F. mandshurica, and 0.17 0.76, 0.23 1.02, 0.26 1.10, 0.38 1.77, and 0.84 2.80 mm for L. gmelinii. The average coefficient of variation in first-order roots was less than 10%, second- and third-order was 10 20%, and fourth- and fifth-order was 20 30%. Thus, variation in root diameter also increased with the ascending root order. These results suggest that fine roots , which are traditionally defined as an arbitrary diameter class (i.e., <2 mm in diameter) may be too large a size class when compared with the finest roots. The finest roots have much shorter lifespan than larger diameter roots; however, the larger roots are still considered a component of the fine root system. Differences in the lifespan between root diameter and root order affect estimates of root turnover. Therefore, based on this study, it has been concluded that both diameter and branch order should be considered in the estimation of root lifespan and turnover.
  • Altitudinal patterns of the flora of seed plants of Dawei Mountain in Yunnan Province, south China
    WANG Juan, DU Fan, YANG Yuming, MA Qinyan
    2007, 2(1): 40-46. https://doi.org/10.1007/s11461-007-0006-3
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    Altitudinal gradient incorporates multiple resource gradients, which vary continuously in different fashions. It is important to study the mountain floristic patterns along altitudinal gradients, which reveal the regular pattern of the flora along the environmental gradients, the changing trend of biodiversity patterns along the altitudinal gradient, and relevance of biological fitness. To explore the compositional characteristics and ecological significance of floristic patterns along altitudinal gradient in China National Nature Reserve of Dawei Mountain in the southeast of Yunnan Province, field investigations have been made to the flora along the two routes of the southwest slope and the northeast slope of the said reserve, including a vertical vegetation transect. Meanwhile, further investigations have also been made to the flora of Dawei Mountain, which has been accounted for in the literature, as Flora Yunnan, The Seed Plant in Yunnan, and so on. The structural characteristics of the flora and the altitudinal distribution pattern of its floristic components were analyzed. By applying systematic cluster analysis, the altitudinal position of the dividing line of floristic changes along altitudinal gradient was detected, and the effects of the montane climate on the vertical variation of floristic composition were studied. Conclusions were put forward. This paper can be summarized as follows: (1) The obvious boundary that differentiates tropical floristic elements is located at the altitude of approximately 1,500 m; it is reasonable to stipulate the boundary line between tropical rain forests and the evergreen broad-leaved forests. (2) The vertical vegetation spectrum made by cluster analysis shows that humid rain forests are below 700 m a.s.l, montane rain forests are between 700 and 1,500 m, monsoon evergreen broad-leaved forests are between 1,300 and 1,800 m, and montane mossy evergreen broad-leaved forests are above 1,800 m a.s.l. Nonrepresentative montane mossy dwarf forests (above 2,100 m) in the area are distributed in windward sides and in barren land on the mountain slopes.
  • Leaf and twig litter decomposition of main species in different forests along the north slope of Changbai Mountain, northeast China
    GUO Zhongling, ZHENG Jinping, LIU Wande, FAN Chunnan, LI Qingkang, YU Guirui, MA Yuandan, HAN Shijie
    2007, 2(1): 47-54. https://doi.org/10.1007/s11461-007-0007-2
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    From 2001 to 2003, the litter decomposition dynamics of dominant tree species were conducted using a litterbag burying method in the broadleaf-Korean pine forest, spruce fir forest and Ermans birch forest, which represents three altitudinal belts in Changbai Mountain, northeast China. The spatial and temporal dynamics of litter decomposition and the effects of litter properties were examined. Furthermore, the decomposition trend of different species was simulated by the Olson model, and results showed that annual mass loss rates increased over time, but was not significantly correlated. Leaf decomposition rates increased after decomposing for 638 days (1.75 years), and the order of dry weight remaining rates of leaf litter for different species is: Asian white birch (Betula platyphylla) (24.56%)Tilia amurensis) (24.81%)Pinus koraiensis) (38.48%)Picea jezoensis var. microsperma) (41.15%)Betula ermanii) (41.53%)Abies nephrolepis) (42.62%). The dry weight remaining rates of twig litter was smaller than that of leaf litter, and followed the order of Amur linden (44.98%)Asian white birch (0.624)>Korean pine (0.441)>spruce (0.406)>fir (0.397)>Ermans birch (0.385); in twig, it ranged from 7.8 to 29.3 years, and k follows the order: Amur linden (0.391)>fir (0.204)>Korean pine (0.176)>spruce (0.157)>Asian white birch (0.148)>Ermans birch (0.102). In general, the differences of decomposition rate are evident between leaf and twig litter and among species, and were higher in broad-leaved species compared with coniferous species at the same elevation, and decreased with the ascending of elevation.
  • Spatial distribution pattern, scale and gap characteristics of Pinus armandii population in Qinling Mountains, China
    LAN Guoyu, CHEN Wei, LEI Ruide
    2007, 2(1): 55-59. https://doi.org/10.1007/s11461-007-0008-1
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    Based on the data collected from 27 plots of the Pinus armandii community in Qinling Mountains, we studied the spatial distribution pattern, scale, and gap characteristics of the P. armandii population. The results showed that the population had a clumped distribution before age 50. At the age range from 15 to 25, though the population tended to be distributed randomly, the distribution was still clumped. The population distribution at the age range from 40 to 50 was at the transitional stage from clumped to random. After age 50, the population started to be senesced, the distribution pattern turning from clumped to random. The distribution pattern scale of P. armandii always changes with the development stage of the population, being 100 m2 in general. The gap size of P. armandii population was similar to its distribution pattern scale, and the gaps of 80 130 m2 occupied 59% of the total. Because of the better light and nutrient condition in the gap, P. armandii seedlings grew well, which helped the population keep its stability through mobile mosaic circling .
  • Soil properties in forest gaps and under canopy in broad-leaved Pinus koraiensis forests in Changbai Mountainous Region, China
    ZHANG Chunyu, ZHAO Xiuhai
    2007, 2(1): 60-65. https://doi.org/10.1007/s11461-007-0009-0
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    The species composition and diversities, and soil properties under canopy gaps in broad-leaved Pinus koraiensis forests were studied in the Changbai Mountains. The results indicated that the species composition and diversities in gap were different from those under canopy. The Shannon-Wiener index, evenness index, and abundance index in gap were higher than those under canopy in the seedling layer, while the community dominance in the seedling layer increased in closed canopy. The physicochemical properties of soil changed with the change of space and resource availability in gaps. The thickness, standing crop, and water holding capacity of the litter layer under canopy were significantly (p<0.01) higher than those in gap. The content of total nitrogen and total potassium of litter in gap were 10.47% and 20.73% higher than those under canopy, however, the content of total phosphorus and organic carbon under canopy were 15.23% and 12.66% more than those under canopy. The water content of 0 10 cm and 10 20 cm of soil layer in gap were 17.65% and 16.17% more than those under canopy. The soil buck density of 0 10 cm were slightly higher under canopy than that in gaps, but there was no significant difference in the soil buck density of the 10 20 cm soil layer. The soil pH values were 5.80 and 5.85 in gap and under canopy, respectively, and were not significantly different. The content of soil organic matter, total nitrogen, and total potassium in gap were 12.85%, 7.67%, and 2.38% higher than those under canopy. The content of NH4+2+-N, available phosphorus, available potassium, and total phosphorus in soil under canopy were 13.33%, 20.04%, 16.52%, and 4.30% higher than those in gap.
  • Influence of floods on natural riparian forests along the Ergis River, west China
    CHENG Kewu, ZANG Runguo, ZHANG Weiyin, ZHOU Xiaofang, BAI Zhiqiang
    2007, 2(1): 66-71. https://doi.org/10.1007/s11461-007-0010-7
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    The riparian forests along the Ergis River, west China, composed mainly of Salicaceae species, play an important role in eco-environment protection and sustainable development of local agriculture, stockbreeding, and social economy of the northern desert region of Xinjiang Uygur Autonomous Region. The study of the influence of floods on the natural riparian forests is imperative for the understanding of the successional process and the acceleration of conservation and restoration of forests. By investigating the relationship between floods and dispersal of seeds, sprouting, natural regeneration, the structure of the forests, and their current distribution, we conclude that: 1) the ripening and dispersal periods of Salicaceae species seeds overlap largely with flood occurrence periods, and the sprouting and natural regeneration of seeds depend greatly on flood events; 2) floods supply soil water and increase groundwater level of riparian land through flood irrigation and horizontal infiltration to maintain the normal growth of the riparian forests; 3) floods have a decisive influence on the structure, composition, and distribution pattern of riparian forests, and any disturbance in the water flow has a profound effect on these characteristics. Given these facts, some management measures for conservation and restoration of the riparian forests are proposed, including the establishment of riparian forest buffer belt, bank stabilization measures, and maintenance of flood protection.
  • Impacts of fractal features of soil on moisture infiltration capacity of typical stands in Jinyun mountain of Chongqing city
    WANG Yujie, WANG Yunqi
    2007, 2(1): 72-77. https://doi.org/10.1007/s11461-007-0011-6
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    The soil structure was expressed with fractal dimensions of particle size distribution (PSD), aggregate size distribution (ASD), and soil pore size distribution (SPD). The effect of soil fractal features on soil infiltration velocity and process was studied. The result of the fractal feature shows that fractal dimensions of PSD are obviously greater than those of ASD and SPD, and in different soil genetic horizons, the fractal dimension of ASD has the greatest variability, and shows a downtrend on the top-to-bottom genetic horizon. According to the soil infiltration process curve, the infiltration process was divided into three phases: (1) the initial phase (0 5 min), (2) the transition phase (5 30 min), and (3) the stable phase (30 180 min). In the initial phase of infiltration, the soil structure of soil genetic horizon A was the major influencing factor; in the transition phase of infiltration, the pore distribution of soil horizon AB and soil structure of horizon B were the major influencing factors; in the stable phase of infiltration, the soil structure of horizon C was the major influencing factor to the infiltration velocity. Soil infiltration process is influenced comprehensively by soil PSD, ASD, and SPD. In the overall soil water infiltration, the infiltration in shrub forest land was much faster than that in other land uses, and in the initial infiltration phase, arable land soil infiltration was much faster than that in forest land, and in the stable infiltration phase, the infiltration velocity in forest land was faster than that in arable land.
  • RAPD analysis of genetic relationships among Sphaeropsis sapinea isolates
    WU Xiaoqin, WANG Yu, XIONG Dabin
    2007, 2(1): 78-81. https://doi.org/10.1007/s11461-007-0012-5
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    Genetic relationships were studied among 23 isolates of Sphaeropsis sapinea collected from China, the United States, England, South Africa and Chile by using a random amplification of a polymorphic DNA (RAPD) analytical method. One hundred and 35 DNA fragments were amplified with 12 random primers by a polymerase chain reaction PCR technique and 96.3% were polymorphic. The genetic dendrogram based on RAPD analysis showed that the S. sapinea isolates could be divided into three types. Isolate CWS41 from Chile was separated genetically as the first type that was different from other isolates and isolates F2 and J2 from China comprised the second group. The third RAPD group accommodated other isolates including the B morphotype isolate CWS43 from the United States.
  • Discrimination of Bursaphelenchus xylophilus and Bursaphelencus mucronatus by PCR-RFLP technique
    CHEN Fengmao, YE Jianren, WU Xiaoqin, TANG Jian
    2007, 2(1): 82-86. https://doi.org/10.1007/s11461-007-0013-4
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    A polymerase chain reaction restriction fragment length polymorphism analysis was used to discriminate isolates of Bursaphelenchus xylophilus and B. mucronatus. The amplifications of B. xylophilus isolates yielded one fragment of approximately 890 bp and that of B. mucronatus was about 930 bp. Digestion of amplified products of each nematode isolate with five restriction endonucleases revealed the following results: 1) Dra I digestion of the internal transcribed spacer (ITS) products of B. xylophilus populations yielded two fragments of 510 and 380 bp. Dra I could not digest the ITS products of B. mucronatus populations; 2) Sal I could not digest the ITS products of all B. xylophilus populations, but it could digest those of B. mucronatus populations into two fragments, which were 720 and 220 bp; 3) digested products of four B. xylophilus populations by Msp I yielded two fragments of 530 and 360 bp, except GZ02, which could not be digested. B. mucronatus populations yielded three fragments: 340, 290, and 180 bp; 4) all populations of B. xylophilus and B. mucronatus could not be digested by Apa I; 5) digestion of the ITS products of B. xylophilus and B. mucronatus yielded two fragments of 520 and 370 bp, and 530 and 400 bp respectively. The restriction endonucleases Dra I and Sal I could be used to identify B. xylophilus and B. mucronatus. Because the results of digestion of B. xylophilus and B. mucronatus were markedly different, they were very easy to be identified and applied; Msp I and Xho I were not suitable for identification of B. xylophilus and B. mucronatus and Apa I could not identify and distinguish between B. xylophilus and B. mucronatus.
  • Comparison of stomatal characteristics and photosynthesis of polymorphic Populus euphratica leaves
    ZHENG Caixia, QIU Jian, JIANG Chunning, YUE Ning, WANG Xiuqin, WANG Wanfu
    2007, 2(1): 87-93. https://doi.org/10.1007/s11461-007-0014-3
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    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.
  • Selection, propagation and cultivation of Pinus massoniana clones for pulp use
    JI Kongshu, GONG Jia, WANG Zhangrong, QIU Jinqing, CHEN Yabin, LIN Wenjiang
    2007, 2(1): 94-98. https://doi.org/10.1007/s11461-007-0015-2
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    Based on the growth, wood property of the ortets, and rooting abilities of cuttings, 32 Pinus massoniana clones for pulp use were selected from forests of superior provenance, mixed families, and progeny test of seed orchard by two-step selection. The average height and DBH growth of three-year-old clones were 28.6% and 16.7%, respectively, higher than those from seedlings, and average gain of wood density reached 8.7%. Rooting rate of all these clones was over 80%, 28% higher than the clones selected by a single step. A cutting orchard of 0.33 hm2 on the hillside was constructed to intensively produce cuttings according to the tests on construction methods, pruning, and fertilization. A total of 50,000 grade!`, 37,500 grade !a, and 62,500 grade !b cuttings were collected per hectare of this cutting orchard each time, and were cut three times each year. With all the above techniques, 48 hm2 of clonal forests for pulp use of those clones had been planted in five places in Fujian Province. Container stecklings are more likely to increase the planting survival rate.
  • Surface energy of preservative-treated southern yellow pine (Pinus spp.) by contact angle measurement
    CAO Jinzhen, Pascal D. Kamdem
    2007, 2(1): 99-103. https://doi.org/10.1007/s11461-007-0016-1
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    In this study, the contact angles of four different reference liquids (including distilled water, diiodomethane, formadide and glycerol) formed on the surfaces of wood, treated with chromated copper arsenate (CCA) and two other emerging copper-based water-borne systems (commercial names: NW and NS) were measured with sessile drop method. Based on the contact angle data, the surface energy was obtained from the acid-base approach. The total surface energy consisted of Lifshiz-van der Waals parameter and acid-base parameter. Results showed that the NW and CCA treatments made the wood surface more hydrophobic while the NS treatment had the reverse effect on the wood surface mainly owing to the increased penetration of earlywood. By using three liquids, diiodomethane, formamide and distilled water, the total surface energy obtained for untreated earlywood, untreated latewood, CCA-treated earlywood, CCA-treated latewood, NW-treated earlywood, NW-treated latewood, NS-treated earlywood and NS-treated latewood were 43.1, 44.5, 43.4, 45.1, 49.4, 40.6, 46.0 and 40.9 mJ/m2, respectively. The surface energy of CCA-treated wood was almost the same as untreated wood. After NW and NS treatments, the surface energy of both earlywood and latewood changed a little. However, the change was not so obvious as to draw any further conclusion concerning the influence of NW and NS treatments on the surface energy of wood.
  • Improvement of wood properties by urea-formaldehyde resin and nano-SiO2
    SHI Jinshu, LI Jianzhang, ZHOU Wenrui, ZHANG Derong
    2007, 2(1): 104-109. https://doi.org/10.1007/s11461-007-0017-0
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    In order to improve wood properties of triploid clones of Populus tomentosa, urea-formaldehyde (UF) resin was compounded with nano-SiO2, coupling agents and flame retardants in different ways to prepare five kinds of modifiers. The poplar wood samples were impregnated with the modifiers and heated to prepare UF-SiO2-wood composites. The antiswelling efficiency, resistance of water absorption, oxygen index and hardness of the composites were measured. Results show that all of the modifiers reduced water absorption of poplar wood and enhanced flame resistance and hardness. Nano-SiO2 showed a marked effect in improving the hardness of wood. In addition, all of the modifiers, except UF-C-SiO2-polymer, improved the dimensional stability of poplar wood. The UF resin and nano-SiO2 compound improved general properties of poplar wood.
  • Effects of solid water and foliar fertilizer on survival and growth of seedlings in sand prevention and control
    WANG Yutao, LI Jiyue, LIU Ping
    2007, 2(1): 110-114. https://doi.org/10.1007/s11461-007-0018-z
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    To promote afforestation in sandy lands and increase the effects of prevention and control of desertification, the application of a new drought-resistant product solid water and foliar fertilizer Shifengle  was studied. A comparison of three treatments (solid water, foliar fertilizer, and control) showed that both solid water and foliar fertilizer increased plant survival rate by 10% and 18.2%, respectively. Afforestation survival rates of Salix psammophila and Hedysarum mongolicum reached over 90%. In addition, height and crown growth as well as biomass of seedlings were improved by the treatments.
  • Effects of forest on precipitation chemistry and total suspended particles of stem-flow in Jiufeng National Forest Park, Beijing
    WANG Dengzhi, NIE Lishui, LI Jiyue
    2007, 2(1): 115-118. https://doi.org/10.1007/s11461-007-0019-y
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    Precipitation chemistry was monitored in two different types of forests (mixed Pinus tabulaeformis and Quercus variabilis forest and pure Q. variabilis forest) in Jiufeng National Forest Park, in western Beijing. Results showed that the pH value of precipitation ranged between 6.13 and 6.97 and no acid rain appeared; the mean electrical conductivity (EC) was 0.18 mS/cm and mean total suspended particles (TSP) was 44.02 mg/L, but these values changed significantly with different amounts of stem-flow. Acidification occurred in the stem-flow to different extents: that of P. tabulaeformis > Q. variabilis. The mean EC value of stem-flow in P. tabulaeformis in the mixed forest was 1.00 mS/cm, which was 5.88 times as high as that of precipitation outside the forest. EC values of Q. variabilis in pure and mixed forests show little difference, 0.34 and 0.30 mS/cm, respectively and were 2.00 and 1.76 times higher than that of precipitation. During the summer, EC values of stem-flow of P. tabulaeformis decreased over time and with an increase in the amount of precipitation. The mean TSP of stem-flow in mixed forest was 116.95 mg/L, but 87.14 mg/L in the pure forest, which were 72.93 and 43.12 mg/L higher than that of precipitation.