Construction of tree volume equations for Chinese fir plantations in Guizhou Province, southwestern China

Forest volume, the major component of forest biomass, is an important issue in forest resource monitoring.It is estimated from tree volume tables or equations. Based on tree volume data of 1840 sample trees from Chinese fir （Cunninghamia lanceolata） plantations in Guizhou Province in southwestern China, parallel one- and two-variable tree volume tables and tree height curves for central and other areas were constructed using an error-in-variable modeling method. The results show that, although the one-variable tree volume equations and height curves between the central and other areas were significantly different, the two-variable volume equations were sufficiently close, so that a generalized two-variable tree volume equation could be established for the entire province.     

杉木生态系统生物量与固碳能力的分析与评价

杉木(Cunninghamia lanceolata)是我国特有的优良速生针叶树种,分布地域广阔,在碳循环及维护生态系统平衡等方面发挥着非常重要的作用。本文通过分析大量文献,讨论了立地条件、分布区域和经营方式等因素对杉木林生态系统生物量和生产力的影响。根据文献资料对杉木林生态系统生物量和固碳能力进行了初步估测。结果表明:①中国杉木林生态系统平均生物量约为36.516 t.hm-2,平均生产力约为8.412 t.hm-2.a-1。杉木林生产力的最大值在杉木中心分布区的中亚热带,尤以中亚热带南部亚地带的最高,其生产力平均达13.50 t.hm-2.a-1;中亚热带北部亚地带平均为11.95 t.hm-2.a-1;南亚热带和北亚热带分别是8.83 t.hm-2.a-1和5.54 t.hm-2.a-1;北热带地区杉木林的生物生产力最低,平均为5.02t.hm-2.a-1。②1994年以前的统计数据,中国杉木林生态系统的总植物碳储量为:幼龄林9.98×106t,中龄林31.61×106t,近熟林11.73×106t,成熟林7.50×106t,过熟林2.87×106t,总计为63.69×106t。③目前,中国杉木林面积达1 239.1×104hm2,蓄积量为47 357.33×104m3,换算成生物量约为18 938.20×104t,总固碳量约为5 211.65×104t.a-1。目前,杉木林生态系统的碳储量的估算没有包括土壤以及凋落物层的碳含量,因此,所估算的杉木林固碳能力和总的碳储量可能偏低。     

Estimation of aboveground biomass in mangrove forests using high-resolution satellite data

Mangroves play important roles in providing a range of ecosystem services, mitigation of strong waves, protection of coastlines against erosion, maintenance of water quality, and carbon sink in the context of global warming. For trees in mangrove forests in southern Ranong Province, Thailand, we investigated the allometric relationship between crown area derived from high-resolution satellite data and stem diameter and used the resulting model to estimate aboveground biomass. We used QuickBird panchromatic and multispectral data acquired for the study area on 15 October 2006 as the high-resolution satellite data. Individual tree crowns were extracted from the satellite image of panchromatic data by using the watershed method, and the species were identified by using the maximum-likelihood method for the multispectral data. Overall classification accuracy for species identification was 88.5 %. The biomass derived from our field survey was plotted against aboveground biomass in the sample plots, estimated from the QuickBird data. The regression line through the origin between the satellite-estimated biomass and biomass based on the field data had a slope of 1.26 (R ² = 0.65). Stand aboveground biomass estimated from the high-resolution satellite data was underestimated because of a lack of data on the biomass of suppressed trees and inappropriate segmentation of crowns of large trees into two or more trees.     

Estimating aboveground biomass in forest and oil palm plantation in Sabah, Malaysian Borneo using ALOS PALSAR data

Conversion of tropical forests to oil palm plantations in Malaysia and Indonesia has resulted in large-scale environmental degradation, loss of biodiversity and significant carbon emissions. For both countries to participate in the United Nation’s REDD (Reduced Emission from Deforestation and Degradation) mechanism, assessment of forest carbon stocks, including the estimated loss in carbon from conversion to plantation, is needed. In this study, we use a combination of field and remote sensing data to quantify both the magnitude and the geographical distribution of carbon stock in forests and timber plantations, in Sabah, Malaysia, which has been the site of significant expansion of oil palm cultivation over the last two decades. Forest structure data from 129 ha of research and inventory plots were used at different spatial scales to discriminate forest biomass across degradation levels. Field data was integrated with ALOS PALSAR (Advanced Land-Observing Satellite Phased Array L-band Synthetic Aperture Radar) imagery to both discriminate oil palm plantation from forest stands, with an accuracy of 97.0% (κ = 0.64) and predict AGB using regression analysis of HV-polarized PALSAR data (R² = 0.63, p < .001). Direct estimation of AGB from simple regression models was sensitive to both environmental conditions and forest structure. Precipitation effect on the backscatter data changed the HV prediction of AGB significantly (R² = 0.21, p < .001), and scattering from large leaves of mature palm trees significantly impeded the use of a single HV-based model for predicting AGB in palm oil plantations. Multi-temporal SAR data and algorithms based on forest types are suggested to improve the ability of a sensor similar to ALOS PALSAR for accurately mapping and monitoring forest biomass, now that the ALOS PALSAR sensor is no longer operational.     

Aboveground biomass of three conifers in the Qianyanzhou plantation, Jiangxi Province, China

Regressive models of the aboveground biomass for three conifers in subtropical China—slash pine (Pinus elliottii), Masson pine (P. massoniana) and Chinese fir (Cunninghamia lanceolata)—were established. Regression analysis of leaf biomass and total biomass of each branch against branch diameter (d), branch length (L), d ³ and d ² L was conducted with functions of linear, power and exponent. A power law equation with a single parameter (d) was proved to be better than the rest for Masson pine and Chinese fir, and a linear equation with parameter (d ³) is better for slash pine. The canopy biomass was derived by adopting the regression equations to all branches of each individual tree. These kinds of equations were also used to fit the relationship between total tree biomass, branch biomass, foliage biomass and tree diameter at breast height (D), tree height (H), D ³ and D ² H, respectively. D ² H was found to be the best parameter for estimating total biomass. However, for foliage biomass and branch biomass, both parameters and equation forms showed some differences among species. Correlations were highly significant (P<0.001) for foliage biomass, branch biomass and total biomass, among which the equation of the total biomass was the highest. With these equations, the aboveground biomass of Masson pine forest, slash pine forest and Chinese fir forest were estimated, in addition to the allocation of aboveground biomass. The above-ground biomass of Masson pine forest, slash pine forest and Chinese fir forest was 83.6, 72.1 and 59 t/hm² respectively, and the stem biomass was more than the foliage biomass and the branch biomass. The underground biomass of these three forests which estimated with others’ research were 10.44, 9.42 and 11.48 t/hm², and the amount of carbon-fixed were 47.94, 45.14 and 37.52 t/hm², respectively. __________ Translated from Chinese Journal of Applied Ecology, 2006, 17(8): 1382–1388 [译自: 应用生态学报]     

Acidity and chemistry of bulk precipitation,throughfall and stemflow in a Chinese fir plantation in Fujian,China

Acidity and chemistry of open and intercepted precipitation in a Chinese fir plantation in Fujian, China, were monitored at two sites located at varying distances from the SO₂ sources. Acidification and chemical enrichment were observed to be extremely significant for stemflow, but only slightly for throughfall. The pH values for rainfall showed some seasonal patterns. In contrast, the electric conductivity and chemical components showed a strong seasonal trend over the three-year period, which were supposed to be negatively correlated with the amount of rainfall. Differences in pH values between two sites suggested the acidifying effects of sulfur dioxide on precipitation.     

湖南杉木人工林近自然经营问题探讨

德国人工林在19世纪,与湖南杉木人工林有相似之处,采用单一树种营造大面积人工林,造成地力消耗很大,无法实现林木的可持续利用。本文从杉木经营历史,分析了现有栽培制度下的炼山、幼林抚育、轮伐期短、林分结构单一等现状所导致的杉木人工林生产力下降、林地地力衰退。本研究引进德国森林近自然经营理念及原则改造杉木人工林,分别对杉木幼林、中林、成林进行第1代目标树经营,为第2代目标树形成创造有利条件,使林地地力得到恢复,达到可持续经营的目的,同时获得较大经济效益。     

农户生产效率及测度研究--以安徽省金寨县为案例

引言森林资源和林业发展在中国南方集体林区中发挥着重要作用。中国南方集体林区林地面积和森林蓄积占全国的比重分别为38.40%和17.79%,人工林面积和蓄积占全国的比重分别为54.40%和52.02%(国家林业局,2000)。1978年以来,实行了家庭联产承包责任制以后,重新恢复家庭作为农村生产与生活的基本单位,由集体化向以家庭为基本生产单位的转变视为制度创新。这个制度安排是否导致经济效率和总要素生产率发生了变化?如果发生了变化,是如何变化的?变化程度有多大?与此同时,森林资源丰富的中国南方集体林区的经济效率是否发生了变化,变化程度如何?生产…     

Simulating age-related changes in carbon storage and allocation in a Chinese fir plantation growing in southern China using the 3-PG model

Chinese fir [(Cunninghamia lanceolata (Lamb.) Hook (Taxodiaceae)] plantations are helping to meet China's increasing demands for timber, while, at the same time, sequestering carbon (C) above and belowground. The latter function is important as a means of slowing the rate that CO₂ is increasing in the atmosphere. Available data are limited, however, and even if extensive, would necessitate consideration of future changes in climatic conditions and management practices. To evaluate the contribution of Chinese fir plantations under a range of changing conditions a dynamic model is required. In this paper, we report successful outcome in parameterizing a process-based model (3-PG) and validating its predictions with recent and long-term field measurements acquired from different ages of Chinese fir plantations at the Huitong National Forest Ecosystem Research Station. Once parameterized, the model performed well when simulating leaf area index (LAI), net primary productivity (NPP), biomass of stems (W_S), foliage (W_F) and roots (W_R), litterfall, and shifts in allocation over a period of time. Although the model does not specifically include heterotrophic respiration, we made some attempts to estimate changes in root C storage and decomposition rates in the litterfall pool as well as in the total soil respiration. Total C stored in biomass increased rapidly, peaking at age 21 years in unthinned stands. The predicted averaged above and belowground NNP (13.81 t ha⁻¹ a⁻¹) of the Chinese fir plantations between the modeling period (from 4 to 21-year-old) is much higher than that of Chinese forests (4.8–6.22 t ha⁻¹ a⁻¹), indicating that Chinese fir is a suitable tree species to grow for timber while processing the potential to act as a C sequestration sink. Taking into account that maximum LAI occurs at the age of 15 years, intermediate thinning and nutrient supplements should, according to model predictions, further increase growth and C storage in Chinese fir stands. Predicted future increases (approximately 0–2 °C) in temperature due to global warming may increase plantation growth and reduce the time required to complete a rotation, but further increases (approximately 2–6 °C) may reduce the growth rate and prolong the rotational age.     

Estimation of the fine root biomass in a Japanese cedar (Cryptomeria japonica) plantation using minirhizotrons

We estimated fine root biomass in a Japanese cedar (Cryptomeria japonica) plantation using a min-irhizotron technique. Since data obtained from minirhizo-trons are limited to the length and diameter of fine roots observed on minirhizotron tubes, data conversion is necessary to determine the fine root biomass per unit soil volume or unit stand area. We first examined the regression between diameter squared and weight per unit length of fine roots in soil core samples, and calculated the fine root biomass on minirhizotron tubes from their length and diameter. Then we determined conversion factors based on the ratio of the fine root biomass in soil core samples to that on minirhizotron tubes. We examined calculation methods, using a single conversion factor for total fine root biomass in the soil for depths of 0–40cm (Cal1), or using four conversion factors for fine roots in the soil at 10-cm intervals (Cal2). Cal1 overestimated fine root biomass in the lower soil or underestimated that in the upper soil, while fine root biomass calculated using Cal2 better matched that in soil core samples. These results suggest that minirhizotron data should be converted separately for different soil depths to better estimate fine root biomass.     

Estimation of aboveground tree carbon stock using SPOT-HRG data (a case study: Darabkola forests)

Forests are among the most important carbon sinks on earth. However, their complex structure and vast areas preclude accurate estimation of forest carbon stocks. Data sets from forest monitoring using advanced satellite imagery are now used in international policy agreements. Data sets enable tracking of emissions of CO₂ into the atmosphere caused by deforestation and other types of land-use changes. The aim of this study is to determine the capability of SPOT-HRG Satellite data to estimate aboveground carbon stock in a district of Darabkola research and training forest, Iran. Preprocessing to eliminate or reduce geometric error and atmospheric error were performed on the images. Using cluster sampling, 165 sample plots were taken. Of 165 plots, 81 were in natural habitats, and 84 were in forest plantations. Following the collection of ground data, biomass and carbon stocks were quantified for the sample plots on a per hectare basis. Nonparametric regression models such as support vector regression were used for modeling purposes with different kernels including linear, sigmoid, polynomial, and radial basis function. The results showed that a third-degree polynomial was the best model for the entire studied areas having an root mean square error, bias and accuracy, respectively, of 38.41, 5.31, and 62.2; 42.77, 16.58, and 57.3% for the best polynomial for natural forest; and 44.71, 2.31, and 64.3% for afforestation. Overall, these results indicate that SPOT-HRG satellite data and support vector machines are useful for estimating aboveground carbon stock.     

Integrating regional climate change into allometric equations for estimating tree aboveground biomass of Masson pine in China

Key message

A climate-sensitive aboveground biomass (AGB) equation, in combination with nonlinear mixed-effects modeling and dummy variable approach, was developed to examine how climate change may affect the allometric relationships between tree diameter and biomass. We showed that such changes in allometry need to be taken into account for estimating tree AGB in Masson pine.

Context

As a native species and being widely distributed in subtropical China, Masson pine (Pinus massoniana Lamb.) forests play a pivotal role in maintaining forest ecosystem functions and mitigation of carbon concentration increase at the atmosphere. Traditional biomass allometric equations do not account for a potential effect of climate on the diameter–biomass relationships. The amplitude of such an effect remains poorly documented.

Aims

We presented a novel method for detecting the long-term (2041–2080) effects of climate change on the diameter–biomass relationships and the potential consequences for long-term changes of biomass accumulation for Masson pine.

Methods

Our approach was based on a climate-sensitive AGB model developed using a combined nonlinear mixed-effects model and dummy variable approach. Various climate-related variables were evaluated for their contributions to model improvement. Heteroscedasticity was accounted for by three residual variance functions: exponential function, power function, and constant plus function.

Results

The results showed that diameter at breast height, together with the long-term average of growing season temperature, total growing season precipitation, mean temperature of wettest quarter, and precipitation of wettest quarter, had significant effects on values of AGB. Excessive rain during the growing season and high mean temperature in the wettest quarter reduced the AGB, while a warm growing season and abundant precipitation in the wettest quarter increased the AGB.

Conclusion

Climate change significantly affected the allometric scale of biomass equation. The new climate-sensitive allometric model developed in this study may improve biomass predictions compared with the traditional model without climate effects. Our findings suggested that the AGB of Masson pine trees with the same diameter at breast height under three climate scenarios including representative concentration pathway (RCP) 2.6, RCP 4.5, and RCP 8.5 in the future period 2041–2080 would increase by 24.8 ± 32.7% (mean ± standard deviation), 27.0 ± 33.4%, and 27.7 ± 33.8% compared with the constant climate (1950–2000), respectively. As a consequence, we may expect a significant regional variability and uncertainty in biomass estimates under climate change.

     

皖南丘岗地区火炬松人工林伴生树种的选择与配置

简要介绍了试验林地的概况,选择了25个树种进行试验,并按各树种林分平均胸径、平均树高、平均单株材积和平均单位面积蓄积的年平均生长量进行排序。对主要伴生树种的生长发育过程作了说明,指出伴生树种选择应遵循的原则以及混交形式,同时提出把建立林道和营造生态防火林带相结合。为皖南丘岗地区火炬松人工林提出可供选择的主要伴生树种。     

Effects of canopy interception on energy conversion processes in a Chinese fir plantation ecosystem

The functions of canopy interception on energy conversion processes in a Chinese fir plantation ecosystem were studied with the aid of long-term observation data in Huitong. The results showed that the absorbed, penetrated and reflected amounts of solar radiation were, respectively, 2.5543 × 10⁹ J/(m²·year) (absorption rate of 0.827), 2.5306 × 10⁸ J/(m²·year) (penetration rate of 0.082), and 2.7432 × 10⁸ J/(m²·year) (reflection rate of 0.091) by the canopy. The conversion of net solar radiation to latent heat in the process of evaporation from canopy interception amounted to 6.3695 × 10⁸ J/(m²·year) (accounting for 22.9% of total ecosystem net radiation and 30.4% of ecosystem evaporation), which was an important part of the budget of the energy system. Canopy interception consumed kinetic energy of raindrops in overcoming resistance of branches and leaves, which collected raindrops, followed with the conversion of potential energy in raindrops to kinetic energy with falling raindrops. In general, the diameter of raindrops from the canopy is larger than that of the raindrops above the canopy as a result of the collection effort by the canopy. The kinetic energy of raindrops from the canopy, therefore, was higher than that of raindrops in the atmosphere. The drop-size distribution from the canopy was affected by the structure of the canopy layer rather than the amount of precipitation and precipitation intensity. The canopy had no important nor efficient effects on decreasing the kinetic energy of raindrops in our case study with a first branch height of 7 m and precipitation amounts over 3 mm. However, the canopy would play a key role in decreasing kinetic energy of raindrops in two cases, that of a small amount of precipitation and one of heavy precipitation intensity, in which the canopy could intercept the largest amount of precipitation in the former condition and the canopy could scatter bigger raindrops to smaller raindrops with striking leaves in the case of heavy precipitation. __________ Translated from Scientia Silvae Sinicae, 2007, 43(2): 15–20 [译自: 林业科学]     

农户生产效率及测度研究(续)--以安徽省金寨县为案例

2.联合生产效应分析根据随机前沿生产函数回归结果计算农户生产要素对林业生产弹性计算结果见表5。表5中计算结果分为包含制度因素和不包含制度因素两个方案,两个方案中农牧业产值对林业产值的弹性均为正值,也就是说,农牧业产值的增长能够带来林业产值的增长,二者之间的弹性系数大于1,农牧业产值增长1个百分点,则林业增长超过一个百分点,具有相互推动作用表明金寨县并不存在林牧矛盾。两个方案比较,包括制度因素方案的弹性系数小于不包括制度因素的弹性系数,1978年、1980年、1985年、1990年1995年、1996年和1997年,不包含制度因素方案与包括…     

Measurement and Analysis of Production Performance of Rural Households in Jinzhai County, Anhui Province

Using a multi-input multi-output production technology and survey data from Jinzhai County, western Anhui Province, China, the author first measured the production performance of rural households -- their efficiency, economy of scale, and productivity during 1978-1997, and then related the measured production performance with institutional change, market access, and other factors. Preliminary results show that: 1) performance differs a great deal across households and over time; 2) institutional changes and market accessibility have played a major role in improving performance; 3) depending on the specific resources, their effects are variable.     

短周期杉木人工林不同林龄土壤肥力综合评价

为探讨不同生长发育阶段林地土壤肥力状况及地力衰退趋势,分析影响地力衰退的主要影响因子,以不同林龄(2、4、6、8和11 a)杉木短周期小径材培育人工林的土壤样本为研究对象,检测土壤有机质、全氮、全钾、全磷、水解性氮、速效钾、有效磷、有效铁、交换性钙、交换性镁含量和pH值共11个土壤肥力指标,分析不同林龄土壤养分差异及其变化趋势。结果表明:除土壤pH值外,土壤主要肥力指标的变化幅度较大,有机质、全氮、水解性氮、速效钾、有效磷含量在不同土层和不同林龄间均存在极显著差异(P<0.01);随着林龄的增长,林地土壤有机质和氮磷肥消耗较大,其中,表土层(0~20 cm)有机质、水解性氮、有效磷含量到11 a主伐时的降幅均超过30%,但不同林龄间各肥力指标差异不显著;采用改进后的Nemerow法计算的土壤肥力综合指数为0.412~0.530,土壤肥力等级为Ⅲ级(P_综<0.9),土壤肥力较低,相比较而言,土壤中有机质和氮肥含量较充足,而交换性阳离子极为贫乏;有机质、速效钾、水解性氮、有效磷含量与综合肥力指数呈显著或极显著正相关(R_偏~2>0.8),是影响土壤肥力的主要因子;土壤肥力综合指数随林龄增大而降低,11 a主伐期比造林初期(2 a)下降22.26%,但不同林龄间各单项肥力指数及综合肥力指数均不存在显著差异(P>0.08)。在该栽培模式的超短经营周期内,随着林龄增大及林木生长对土壤养分的消耗,林地土壤肥力出现一定程度的退化现象,但并未达到显著水平,有必要通过提高整地质量、改良土壤、林粮间作、增施有机肥及氮磷钾肥等措施适度增加土壤肥力,维持林地长期生产力。     

Community forestry for poverty alleviation in China with reference to Huoshan County,Anhui Province

Increasing attention has been paid to the question of whether and how community forestry links with poverty reduction in the mountainous regions in developing countries. Household-based community forestry was first implemented in Yunnan and spread over other parts of China in the 1980s. In this forestry management system, rural households are the main actors. Household forestry is a form of small-scale community forestry and suits the rural areas of China, where social overhead capital and skilled human resources are lacking. Community forestry has played a remarkable role in guiding and facilitating rural poverty alleviation in Huoshan County, Anhui Province. This paper describes how the community forestry project in Huoshan County has helped the farmers improve their livelihoods through the creation of a forestry model involving science and technology demonstration households and independent farmers’ organisations. The sustainable poverty alleviation model developed in Huoshan has proved to be effective in poverty alleviation and environmental protection, featuring the participatory forestry components of the project, namely household forestry, science and technology demonstration households, and independent farmers’ organisations. With technological and financial aid from government, the local farmers were able and willing to establish this small-scale forestry management system, planting fast-growing multiple-use tree species with substantial economic benefits.     

Relationship between species diversity and biomass of eucalyptus plantation in Guangxi, south China

To reveal the relationship between species diversity and biomass in a eucalyptus (Eucalyptus urophylla × E. grandis) plantation located in the Dongmen State Forestry Farm of Guangxi, south China, 18 sample plots were established and the total biomass, arbor layer biomass and undergrowth biomass of communities were subsequently harvested. The results were as follows: 1) Species richness in eucalypt plantation had remarkable positive correlation with biomass of arbor layer, undergrowth and community (α = 0.001), its correlation coefficients were 0.6935, 0.7028 and 0.7106 respectively. 2) Leaf area index (LAI) had remarkable positive correlation with species richness and undergrowth biomass (α = 0.001). Its correlation coefficients were 0.7310 and 0.6856, respectively. 3) Arbor layer biomass had remarkable correlation with soil organic matter and hydrolysable N, its correlation coefficients was 0.6416 and 0.6203 respectively. Species richness had remarkable correlation with soil organic matter and correlation coefficient was 0.6359. Among them, the correlation was significant at the 0.1 level. Undergrowth biomass had little correlation with nine soil nutrients and correlation coefficients were under 0.4. To sum up, species diversity was advantageous to the promotion of the biomass of the eucalyptus plantation, and the variation of LAI and soil nutrient in small-scales could result in the difference of species diversity and biomass in different sample plots. Translater from Scientia Silvae Sinicae, 2008, 44(4): 14–19 [译自: 林业科学]     

Allometric equations based on a fractal branching model for estimating aboveground biomass of four native tree species in the Philippines

Fractal branching models can provide a non-destructive and generic tool for estimating tree shoot and root length and biomass, but field validation is rarely described in the literature. We compared estimates of above ground tree biomass for four indigenous tree used on farm in the Philippines based on the WanFBA model tree architecture with data from destructive sampling. Allometric equations for the four species varied in the constant (biomass at virtual stem diameter 1) and power of the scaling rule (b in Y = aD ^b ), deviating from the value of 8/3 that is claimed to be universal. Allometric equations for aboveground biomass were 0.035 D ^2.87 for Shorea contorta, 0.133 D ^2.36 for Vitex parviflora, 0.063 D ^2.54 for Pterocarpus indicus and 0.065 D ^2.28 for Artocarpus heterophyllus, respectively. Allometric equations for branch biomass had a higher b factor than those for total biomass (except in Artocarpus); allometric equations for the leave + twig fraction a lower b. The performance of the WanFBA model was significantly improved by introduction of a tapering factor “τ“ for decrease of branch diameter within a single link. All statistical tests performed on measured biomass versus biomass predicted from the WanFBA results confirm the viability of the WanFBA model as a non-destructive tool for predicting above-ground biomass equations for total biomass, branch biomass and the leaf + twig fraction.