Changes in fineroot growth dynamics in response to phosphorus application in an Acacia mangium plantation in Vietnam

Fineroots (≤ 2 mm diameter) are dynamic components of the forest ecosystems and play important role in water and nutrient acquisition in forests. These roots are sensitive to forest fertilization and therefore, the response of fineroots to nutrient application would provide better understanding of the forest carbon and nutrient dynamics that will be helpful in sustainable forest management plans. Two fertilization treatments, including (1) F400: 400 g P₂O₅ (16.5%)/tree and (2) F600: 600 g P₂O₅ /tree, and F0: control (without fertilization), were applied in an Acacia mangium plantation with a planting density of 1100 trees/ha (3 m?×?3 m). The evaluation of fineroot growth across seasons showed that fertilization significantly increased production and subsequent mortality and decomposition. The total decomposition associated with F600 application was 7.95 tons ha^?1 year^?1, equaling 121% of F400 and 160% of the control. Mortality in F600 was 8.75 tons ha^?1 year^?1, equaling 111% of F400 and 198% of F0, while production in F600 was 10.40 tons ha^?1 year^?1, equaling 127% of F400 and 143% of F0. Fineroot production, mortality, and decomposition are seasonally dependent, with higher values measured in the rainy season than in the dry season. Stand basal area increment was significantly correlated with fineroot production (R²?=?0.75), mortality (R²?=?0.44), and decomposition (R²?=?0.48). This study showed that fertilization could facilitate fineroot production, which can then lead to a higher turnover of carbon and nutrients through the decomposition of the greater mass of the fineroots.

     

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]     

深圳凤凰山马占相思林下植物多样性分析

通过对深圳市宝安区已列入2007年生态风景林改造工程的马占相思林分进行样地调查,运用丰富度、多样性、均匀度等指标,研究了马占相思林下植物的多样性.结果表明,林下已出现众多的乡土植物种类,其物种构成主要包括桃金娘科、铁线蕨科、菊科、禾本科、蔷薇科、梧桐科、茜草科、樟科、冬青科的植物,样方中出现最多的物种为桃金娘、扇叶铁线蕨、假臭草、芒、春花、山芝麻、九节、鸡眼藤、豺皮樟、梅叶冬青等;但各样方的丰富度和物种多样性并不高,且分布不均匀,表明马占相思人工林对乡土物种多样性有一定的影响,但并不会造成根本的破坏.建议在生态风景林改造时对部分地段进行林下植物的改造,以提高物种多样性.     

马占相思与厚荚相思树皮抽提物的比较研究

对马占相思树皮和厚荚相思树皮单宁进行定性和定量分析，模拟栲胶生产小试并对制取的栲胶进行质量分析。结果表明：两种树皮所含单宁均属缩合类单宁；绝干马占相思树皮含单宁高达36.75％，纯度为85．9％．单宁与非单宁之比为6．10，约2．34t气干树皮可生产1t栲胶，制得的栲胶不仅单宁含量高，颜色浅．而且鞣革渗透速度快,富有弹性．皮质好．证明马占相思树皮是一种优良的栲胶原料；绝干厚荚相思树皮含单宁仅9.56％．生产1t栲胶约需气干树皮4．96t，制得的栲胶含单宁53．32％．含非单宁46.47％．测得栲胶中多酚含量接近70％，可代替部分酚类物质用于制取高分子材料，可见大量的厚荚相思树皮也有生产栲胶的价值。     

桉树、厚荚相思和马占相思树种热值比较分析

充分利用木质能源对于缓解我国能源危机,减轻生态负荷有很大作用。为此,对广西省北海市合浦县内桉树、厚荚相思和马占相思三种速生树种的热值进行试验研究。结果表明,桉树的热值为19.782kJ/g,马占相思的热值为20.640kJ/g,厚荚相思的的热值为20.978kJ/g;桉树、厚荚相思和马占相思三树种的各器官中,热值由高到低的顺序大致为树叶和树枝、树干边材、树干心材和树皮,其中,马占相思树皮的发热量界于树叶与树枝之间。     

南宁马占相思人工林生态系统碳素密度与贮量

对南宁市马占相思人工林3个不同年龄阶段(4,7和11年生)生态系统的碳素密度、贮量及其空间分布特征进行研究.结果表明:马占相思不同器官中碳素密度为455.4～494.5 g·kg-1,各器官碳素密度表现为:皮＞干或叶＞枝＞根;同一林分中各层次碳素密度表现为乔木层＞灌木层＞草本层;0～80 cm土层中碳素密度随林龄增加而增大,且随土层深度增加而下降;3个年龄阶段马占相思人工林生态系统总碳贮量分别为117.63,176.70和202.08 t·hm-2,其中乔木层分别占25.67%,46,10%和50.91%,灌木和草本层分别占1.82%,1.65%和1.62%,土壤层分别占69.84%,49.62%和44.59%,凋落物层分别占2.68%,2.34%和2.88%;3个年龄阶段林分碳素年净固定量分别为10.66,15.70和12.55 t·hm-2a-1,其中乔木层碳素年净固定量分别为7.54,12.14和9.36 t·hm-2a-1,占林分总量的70.17%,74.14%和74.58%;凋落物层碳素年固定量分别为312,3.56和3.191 t·hm-2a-1,占林分总量的70.17%.74.14%和74.58%.     

Actual and potential transpiration and carbon assimilation in an irrigated poplar plantation

We examined the tradeoffs between stand-level water use and carbon uptake that result when biomass production of trees in plantations is maximized by removing nutrient and water limitations. A Populus trichocarpa Torr. x P. deltoides Bartr. & Marsh. plantation was irrigated and received frequent additions of nutrients to optimize biomass production. Sap flux density was measured continuously over four of the six growing-season months, supplemented with periodic measurements of leaf gas exchange and water potential. Measurements of tree diameter and height were used to estimate leaf area and biomass production based on allometric relationships. Sap flux was converted to canopy conductance and analyzed with an empirical model to isolate the effects of water limitation. Actual and soil-water-unlimited potential CO(2) uptakes were estimated with a canopy conductance constrained carbon assimilation (4C-A) scheme, which couples actual or potential canopy conductance with vertical gradients of light distribution, leaf-level conductance, maximum Rubisco capacity and maximum electron transport. Net primary production (NPP) was about 43% of gross primary production (GPP); when estimated for individual trees, this ratio was independent of tree size. Based on the NPP/GPP ratio, we found that current irrigation reduced growth by about 18% compared with growth with no water limitation. To achieve maximum growth, however, would require 70% more water for transpiration, and would reduce water-use efficiency by 27%, from 1.57 to 1.15 g stem wood C kg(-1) water. Given the economic and social values of water, plantation managers appear to have optimized water use.     

Diurnal and seasonal variability in radial distribution of sap flux density: Implications for estimating stand transpiration

Daily and seasonal patterns in radial distribution of sap flux density were monitored in six trees differing in social position in a mixed coniferous stand dominated by silver fir (Abies alba Miller) and Norway spruce (Picea abies (L.) Karst) in the Alps of northeastern Italy. Radial distribution of sap flux was measured with arrays of 1-cm-long Granier probes. The radial profiles were either Gaussian or decreased monotonically toward the tree center, and seemed to be related to social position and crown distribution of the trees. The ratio between sap flux estimated with the most external sensor and the mean flux, weighted with the corresponding annulus areas, was used as a correction factor (CF) to express diurnal and seasonal radial variation in sap flow. During sunny days, the diurnal radial profile of sap flux changed with time and accumulated photosynthetic active radiation (PAR), with an increasing contribution of sap flux in the inner sapwood during the day. Seasonally, the contribution of sap flux in the inner xylem increased with daily cumulative PAR and the variation of CF was proportional to the tree diameter, ranging from 29% for suppressed trees up to 300% for dominant trees. Two models were developed, relating CF with PAR and tree diameter at breast height (DBH), to correct daily and seasonal estimates of whole-tree and stand sap flow obtained by assuming uniform sap flux density over the sapwood. If the variability in the radial profile of sap flux density was not accounted for, total stand transpiration would be overestimated by 32% during sunny days and 40% for the entire season.     

Effect of pruning Acacia mangium on growth,form and heart rot

Small volumes of timber are now being produced from Acacia mangium plantations in Indonesia. These trees require pruning and thinning to increase the strength and appearance of the wood. However, cut surfaces from pruning are potential infection courts for the entry of decay-causing fungi like heart rot. This study investigated the effects of pruning on stem form and the incidence of heart rot in an 18-month-old plantation of Acacia mangium in South Sumatra. The objectives were to assess whether pruning is associated with an increase in the incidence of heart rot and whether form pruning compared to lift pruning reduced the incidence of heart rot and improved stem form. Form pruning removed 25% of leaf area by removing large branches and those subtending a narrow angle with the stem up to 3 m height, and lift pruning removed 25% of crown length from below. Trees in these treatments were singled before pruning. The third treatment, a control, was not singled and was used to assess base levels of heart rot.No significant difference in diameter increment between the two pruning treatments was found. There was strong evidence that form pruning was associated with better form 18 months after treatment. Trees in this treatment had a reduced number of branches >30 mm diameter and improved stem straightness (reduced kink). Lift pruning reduced average branch size but did not improve stem straightness. No heart rot was detected in any treatment.The results showed that form pruning is likely to have positive benefits on stem straightness and is likely to be effective to any selected pruning height. However a subsequent lift pruning is still considered a requirement. While wounds created from pruning and singling are assumed to have a large impact on the incidence of heart rot, this may not be an issue unless there is a sufficient source of fungi present in the environment to invade the wounds.     

A projected increase in stand volume of introduced provenances of Acacia mangium in seedling seed orchards in South Sumatra, Indonesia

 Increases in stand volume with some currently introduced provenances of Acacia mangium: Papua New Guinea (PNG) and Far North Queensland (FNQ), were projected based on their superiorities in 3-year height growth in seedling seed orchards using the growth model developed for unthinned plantation for pulp and paper production in South Sumatra, Indonesia. The height growth of these provenances was better than that of the local selections from Subanjeriji by 10%–15% at 3 years old and these percentage superiorities would be expected to remain at around 9%–14% until the 8-year rotation. This amount of increase would result in a 7%–10% increase in basal area and hence it would produce a 17%–26% increase in stand volume at rotation age when compared with the Subanjeriji seed source that was being widely used for the plantation establishment of A. mangium in Indonesia. Received: July 24, 2002 / Accepted: December 3, 2002 Acknowledgments The authors thank Mr. Hardjono, the director of plantation establishment at PT Musi Hutan Persada for his permission to use data of permanent plots for the growth modeling of A. mangium. The authors are grateful to the staff at PT Musi Hutan Persada, Research and Development Center for Biotechnology and Forest Tree Improvement, Japan International Cooperation Agency for their implementations of the study. Our thanks are also due to Dr. Yoshida, associate professor at Kyushu University, for his advice on developing the growth modeling work. Correspondence to:S. Kurinobu     

Removal of Acacia mangium overstorey increased growth of underplanted Anisoptera marginata (Dipterocarpaceae) on an Imperata cylindrica grassland site in South Kalimantan,Indonesia

Effect of removing Acacia mangium overstorey on the growth of underplanted Anisoptera marginata saplings was studied in a mixed tree plantation established on an Imperata cylindrica dominated grassland site in South-Kalimantan, Indonesia. At the time of overstorey removal the Acacia mangium trees were 80 months old (average height 21 m and DBH 20 cm) and the underplanted Anisoptera marginata saplings 68 months old (average height 4.2 m and DBH 3.1~cm), and the spacing of both species was 2 m × 4 m with such an arrangement that the saplings were located within the same lines as the nurse trees. Eight plots of 192 m² in size were randomly designated to overstorey removal (canopy gap) and no removal (closed canopy) treatments. Removal of Acacia mangium overstorey was carried out by girdling and later cutting down the dead trees. The Imperata grass did not show regrowth in canopy gaps. The mean annual increment for height and DBH of Anisoptera marginata within 22 months after the treatment were higher in canopy gaps (1.3 m a^-1 and 1.4 cm a^-1) than under closed canopy (0.7 m a^-1 and 0.7 cm a^-1). Results indicate good prospects for diversifying the composition of fast-growing forest plantations on grasslands and integrating slow-growing valuable species in plantation programs. Studies on other establishment methods, such as planting in gaps or lines, and further management practices as well as their effect on available light, moisture and nutrients are needed.     

尾叶桉树、马占相思新造林地白蚁、蟋蟀的防治

掌握害虫发生发展规律,做好虫情监测,采取正确的虫害防治措施、可有效控制尾叶桉、马占相思大面积造林时白蚁、蟋蟀的危害。     

Early development of three planted indigenous tree species and natural understorey vegetation in artificial gaps in an Acacia mangium stand on an Imperata cylindrica grassland site in South Kalimantan,Indonesia

Early performance of two dipterocarp species Anisoptera marginata and Shorea parvifolia, and a long-living pioneer species Peronema canescens (Verbenaceae) planted in artificial gaps (size 260 m²) and surrounding untreated stands was studied in a fast-growing plantation of Acacia mangium on an Imperata cylindrica grassland site in South Kalimantan, Indonesia. Forty seedlings of each species were planted at one-meter intervals in lines across each of the five gaps, starting and ending under closed stand. Survival, height and diameter (d_0.05) increments were measured, and the effect of gap opening on the composition and abundance of understorey vegetation (grass, shrub and native tree seedlings and saplings) was studied. 19 months after planting, average survival rates were 97% for A. marginata, 94% for P. canescens and 71% for S. parvifolia, with no statistical differences between gap and closed stand. Substantial mortality and damage of dipterocarps were caused by wild boars; minor damage by dieback (for S. parvifolia) and insect pests (for A. marginata). Early growth was clearly influenced by distance from gap centre and light conditions; the growth of seedlings was greater the nearer the seedlings were situated to centre and the higher the level of daily photosynthetic photon flux density (PPFD) was. Gap opening increased the growth of shrub species Chromolaena odorata, but not that of Imperata grass. It also increased the density and height growth of saplings of native pioneer and secondary tree species. Seedling density increased both in closed stand and actual gaps, but was higher inside gaps.Results indicate good prospects for diversifying the composition of fast-growing forest plantations on severely degraded former forest lands and integrating slow-growing valuable species in plantation programs. Both in-depth ecophysiological studies on species-specific growth requirements, and practical oriented research on silvicultural options and economics need further studies.     

海南省桉树、木麻黄、马占相思削度方程研建

建立削度方程是编制材种出材率表的首选方法和基础。本文以海南省桉树、木麻黄、马占相思为研究对象,利用Ormerod(1971)提出的削度方程为基本削度方程,并在此基础上构建了可变参数削度方程进行模型研建。通过比较分析,结果表明:所建立的海南省桉树、木麻黄和马占相思3个树种的削度方程拟合效果均好,复相关系数基本上在0.96以上,预估精度在99.0%以上,无系统偏差,具有较好的适用性;且可变参数削度方程明显优于基本削度方程,是生产上的首选模型。     

Function and value of water conservation in different age classes of Acacia mangium plantations

For this paper, we studied the water-holding capacity of canopy, vegetation layer under canopy and litter layer, the water-holding capacity and permeability of soil as well as their changes with growth of stands in Acacia mangium plantations of three different age classes (four-, seven-and 11-year-old). Results show that total water-holding above ground in the order of 11-year stand age (52.86 t/hm²)>seven-year stand age (41.90 t/hm²)>seven-year stand age (25.78 t/hm²), the increment tendency increased with stand age. Similar sequence also obtained on the water-holding capacity and permeation capacity of soil (0–40 cm). The total water-storage capacity both above ground and soil in four-year-old, seven-year-old and 11-year-old of A. mangium plantations were 2,023.0, 2,158.4 and 2,260.4 t/hm², respectively, and the all value of water conservation were 1,372.70, 1,474.42 and 1,549.91 yuan (RMB)/hm², respectively. Therefore, A. mangium plantation had a good ability to modify soil structure and good water conservation function. __________ Translated from Journal of Soil and Water Conservation, 2006, 20(5): 5–8, 27 [译自: 水土保持学报]     

Carbon isotope discrimination in leaf juice of Acacia mangium and its relationship to water-use efficiency

Using the PMS pressure chamber and isotope mass spectrometer (MAT-252), the leaf juice of Acacia mangium was obtained, and the carbon isotope discrimination (D) representing the most recently fixed carbon in the juice was determined. At the same time, the water-use efficiency of A. mangium was estimated. The results indicated that the carbon isotope ratio in the air of forest canopy (δ _a), 10 m high a bove ground averaged − 7.57 ± 1.41 ‰ in cloudy days, and − 8.54±0.67‰ in sunny days, respectively. The diurnal change of the carbon isotope ratio in the photosynthetic products of the leaf juice (δ _p) was of saddle type in cloudy days, but dropped down from morning to later afternoon in sunny days. A strong negative correlation between δ _p and leaf-to-air vapor pressure deficit (D) was observed in sunny days, but a slight change in δ _p was found in cloudy days. The δ _p also decreased with decreasing leaf water potential (Ψ), reflecting that water stress could cause the decrease of δ _p. The carbon isotope discrimination of the leaf juice was positively correlated with the ratio between intercellular (P _i) and atmospheric (P _a) partial pressure of CO₂. For A. mangium, the isotope effect on diffusion of atmospheric CO₂ via stomata was denoted by a = 4.6‰, and that in net C₃ diffusion with respect to P _i was indicated by b = 28.2‰. The results were in reasonable accord with the theoretically diffusive and biochemical fractionation of carbon isotope. It was defined that carbon isotope discrimination of photosynthetic products in A. mangium leaf juice was in proportion to that from photosynthetic products in dry material. The water-use efficiency estimated by the carbon isotope discrimination in leaf juice, fit well with that measured by gas exchange system (R ² = 0.86, p < 0.0001). The application of leaf juice in measuring the stable carbon isotope discrimination would reduce the effects of fluctuating environmental factors during the synthesis of dry matter, and improve the ecophysiological studies on carbon and water balance when scaling from the plant to canopy in the fields. __________ Translated from Chinese Journal of Ecology, 2008, 27(4): 497–503 [译自: 生态学杂志]     

Diurnal and seasonal variations in carbon fluxes in bamboo forests during the growing season in Zhejiang province,China

Bamboo forest is an important forest type in subtropical China and is characterized by fast growth and high carbon sequestration capacity. However, the dynamics of carbon fluxes during the fast growing period of bamboo shoots and their correlation with environment factors are poorly understood. We measured carbon dioxide exchange and climate variables using open-path eddy covariance methods during the 2011 growing season in a Moso bamboo forest(MB, Phyllostchys edulis) and a Lei bamboo forest(LB, Phyllostachys violascens) in Zhejiang province,China. The bamboo forests were carbon sinks during the growing season. The minimum diurnal net ecosystem exchange(NEE) at MB and LB sites were-0.64 and-0.66 mg C m^-2 s^-1, respectively. The minimum monthly NEE, ecosystem respiration(RE), and gross ecosystem exchange(GEE) were-99.3 ± 4.03, 76.2 ±2.46, and^-191.5 ± 4.98 g C m^-2 month^-1, respectively,at MB site, compared with-31.8 ± 3.44, 70.4 ± 1.41,and^-157.9 ± 4.86 g C m^-2 month^-1, respectively, at LB site. Maximum RE was 92.1 ± 1.32 g C m^-2 month^-1 at MB site and 151.0 ± 2.38 g C m^-2 month^-1 at LB site.Key control factors varied by month during the growing season, but across the whole growing season, NEE and GEE at both sites showed similar trends in sensitivities to photosynthetic active radiation and vapor pressure deficit,and air temperature had the strongest correlation with RE at both sites. Carbon fluxes at LB site were more sensitive to soil water content compared to those at MB site. Both onyear(years when many new shoots are produced) and offyear(years when none or few new shoots are produced)should be studied in bamboo forests to better understand their role in global carbon cycling.     

Productivity of successive rotations of Acacia mangium plantations in Sumatra,Indonesia: impacts of harvest and inter-rotation site management

The impacts of wood harvest, biomass removal and inter-rotation site management practices on productivity of Acacia mangium in South Sumatra were studied over 12 years across successive rotations. The productivity measured as MAI increased from 29.4 m³ ha^?1 year^?1 in the first to 48.0 m³ ha^?1 year^?1 in the second rotation. Whole tree harvesting (total stem, branches and leaves) caused a 21 % reduction in volume compared to harvesting merchantable wood alone in the next rotation. The rates of nutrients accumulation in trees were highest during the first year of growth, and declined from age 2 years. Significant amounts of nutrients were recycled through litter fall from 1 year after planting. Results highlight the importance of management which promotes nutrient supply on stand growth. Removal of slash and litter lowered soil pH, by about 0.1 unit. A small reduction was also found in soil organic carbon and nitrogen in the top soil during the first 3–4 years but values returned to pre-harvest levels by the end of the rotation. Extractable soil phosphorus and exchangeable cations decreased by the end of second rotation but these measures underestimate the nutrient pools available for A. mangium. These findings along with results from other studies have helped to implement operations which promote conservation of site resources for sustainable production in the region.     

The flammability of shrubs and trees in anAcacia mangium plantation based on silica-free ash content

Preliminary research to understand the flammability of 14 species of shrubs and 8 species of trees based on silica-free ash content was done in order to recognize which shrubs or trees are more flammable. The results show that the silica-free ash content of shrubs and trees leaves was greater than the stems ranging between 1.7% and 11.4% for leaf and 0.4% and 7.8% for the stems. The shrubsDicranopteris linearis, Imperata cylindrica, Eupatorium pubescens, Lantana camara, Eugenia sp.,Cliforia laurifolia, Pterospermum sp.,Hibiscus similis, Clidemia hirta andTrema orientalis must be considered when fire invades the plantation as well as the treeParaserianthes falcataria, Eucalyptus urophylla, Calliandra callothyrsus, andPeronema canescens.