Relationship between carbon stocks and tree species diversity in a humid Guinean savanna landscape in northern Sierra Leone

Global sustainable development goals include reducing greenhouse gas emissions from land-use change and maintaining biodiversity. Many studies have examined carbon stocks and tree species diversity, but few have studied the humid Guinean savanna ecosystem. This study focuses on a humid savanna landscape in northern Sierra Leone, aiming to assess carbon stocks and tree species diversity and compare their relationships in different vegetation types. We surveyed 160 sample plots (0.1 ha) in the field for tree species, aboveground carbon (AGC) and soil organic carbon (SOC). In total, 90 tree species were identified in the field. Gmelina arborea, an exotic tree species common in the foothills of the Kuru Hills Forest Reserve, and Combretum glutinosum, Pterocarpus erinaceous and Terminaria glaucescens, which are typical savanna trees, were the most common species. At landscape level, the mean AGC stock was 29.4 Mg C ha^?1 (SD 21.3) and mean topsoil (0–20 cm depth) SOC stock was 42.2 Mg C ha^?1 (SD 20.6). Mean tree species richness and Shannon index per plot were 7 (SD 4) and 1.6 (SD 0.6), respectively. Forests and woodlands had significantly higher mean AGC and tree species richness than bushland, wooded grassland or cropland (p < 0.05). In the forest and bushland, a small number of large diameter trees covered a large portion of the total AGC stocks. Furthermore, a moderate linear correlation was observed between AGC and tree species richness (r = 0.475, p < 0.001) and AGC and Shannon index (r = 0.375, p < 0.05). The correlation between AGC and SOC was weak (r = 0.17, p < 0.05). The results emphasise the role of forests and woodlands and large diameter trees in retaining AGC stocks and tree species diversity in the savanna ecosystem.     

Changes in forest cover and carbon stocks of the coastal scarp forests of the Wild Coast,South Africa

Land-use intensification and declines in vegetative cover are considered pervasive threats to forests and biodiversity globally. The small extent and high biodiversity of indigenous forests in South Africa make them particularly important. Yet, relatively little is known about their rates of use and change. From analysis of past aerial photos we quantified rates of forest cover change in the Matiwane forests of the Wild Coast, South Africa, between 1942 and 2007, as well as quantified above and belowground (to 0.5?m depth) carbon stocks based on a composite allometric equation derived for the area. Rates of forest conversion were spatially variable, with some areas showing no change and others more noticeable changes. Overall, the net reduction was 5.2% (0.08% p.a.) over the 65-year period. However, the rate of reduction has accelerated with time. Some of the reduction was balanced by natural reforestation into formerly cleared areas, but basal area, biomass and carbon stocks are still low in the reforested areas. The total carbon stock was highest in intact forests (311.7 ± 23.7 Mg C ha^?1), followed by degraded forests (73.5 ± 12.3 Mg C ha^?1) and least in regrowth forests (51.2 ± 6.2 Mg C ha^?1). The greatest contribution to total carbon stocks was soil carbon, contributing 54% in intact forests, and 78% and 68% in degraded and regrowth forests, respectively. The Matiwane forests store 4.78 Tg C, with 4.7 Tg C in intact forests, 0.06 Tg C in degraded forests and 0.02 Tg C in regrowth forests. The decrease in carbon stocks within the forests as a result of the conversion of the forest area to agricultural fields was 0.19 Tg C and approximately 0.0003 Tg C was released through harvesting of firewood and building timber.     

广东省森林资源及碳储量分布

利用2009年广东省森林资源监测数据,研究广东省森林资源和碳储量分布。结果表明,2009年广东省森林资源中2／3是商品林,并以一般用材林为主,速生林（含短轮伐期）的比例不到1／5,生态公益林的面积占林业用地面积1／3;各区域的森林资源中均以商品林为主,占64.7％～73.7％。商品林中除其他区域外均以一般用材林为主,占商品林面积的59.8％～81.3％,而其他区域以速生林为主。广东省的森林碳密度为32.2t／hm^2,其大小呈现粤北〉其他〉粤西〉珠三角〉粤东,森林碳储量为302.3TgC。     

Above and below ground organic carbon stocks in a sub-tropical Pinus roxburghii Sargent forest of the Garhwal Himalayas

Accurate estimates of tree carbon,forest floor carbon and organic carbon in forest soils (SOC) are important in order to determine their contribution to global carbon (C) stocks.However,information about these carbon stocks is lacking.Some studies have investigated regional and continental scale patterns of carbon stocks in forest ecosystems;however,the changes in C storage in different components (vegetation,forest floor and soil) as a function of elevation in forest ecosystems remain poorly understood.In this study,we estimate C stocks of vegetation,forest floor and soils of a Pinus roxburghii Sargent forest in the Garhwal Himalayas along a gradient to quantify changes in carbon stock due to differences in elevation at three sites.The biomass of the vegetation changes drastically with increasing elevation among the three sites.The above-ground biomass (AGB) and below-ground biomass (BGB) were highest at site Ⅰ (184.46 and 46.386 t·ha-1 respectively) at an elevation of 1300 m followed by siteⅡ (173.99 and 44.057 t·ha-1 AGB and BGB respectively) at 1400 m and the lowest AGB and BGB were estimated at site Ⅲ(161.72 and 41.301 t·ha-1) at 1500 m.The trend for SOC stock was similar to that of biomass.Our results suggest that carbon storage (in both soil and biomass) is negatively correlated with elevation.     

燕山北部华北落叶松人工林与杨桦天然次生林土壤碳密度的比较

为了了解人工造林过程对土壤碳储量的影响,对燕山西部山地常见的华北落叶松人工林和杨桦天然次生林土壤有机碳含量进行了研究。结果表明,华北落叶松人工林和杨桦天然次生林的土壤剖面平均有机碳含量分别为30.45g/kg和28.45g/kg,二者没有明显差异;2种林分的土壤有机碳含量均随着土层深度的增加而降低,下降幅度则随深度的增加逐渐减缓,表层土壤对土壤的碳存储贡献更大。总的来看,土壤有机碳含量在深层(30cm以下)相邻土层之间差异不显著,说明深层土壤中,有机碳含量变化较小。由以上结果可以得出结论,在造林措施适当、人为干扰较少的条件下,人工林同样可以维持与天然林相近的较高的土壤碳储量。     

A review of carbon dynamics and assessment methods in the miombo woodlands

Provision of accurate carbon (C) measurements and analysis are critical components in quantification of C stocks. The objectives of this review were to (1) compile and synthesise current knowledge of available methods for C stock estimation, (2) examine socio-economic drivers of land-use and land-cover change and their influence on woodland C stocks and (3) identify gaps of knowledge and methodological inadequacies in understanding factors affecting C stocks of major C pools for miombo woodlands of southern Africa. The review shows that quantification of forest C is a challenging task, mainly associated with knowledge gaps and methodological challenges. This has brought about a high level of uncertainty and inconsistencies, mainly due to the accounting methods applied. Furthermore, it is necessary to consider the inherent spatial heterogeneity of the landscape and stand density in order to ensure development of accurate C estimation methodologies when developing C models. Ultimately, developing widely applicable biomass models for southern Africa will require detailed assessments, including different aspects of wood C fractions. It is evident from the review that a comprehensive understanding of socio-economic drivers of land-use and land-cover change is necessary to ensure better-informed sustainable forest management policy direction, strategy and practice to deliver C and livelihood options.     

Estimated stocks of organic carbon in mangrove roots and sediments in Hinchinbrook Channel,Australia

Aboveground and belowground root biomasses (Babove and Broot) were measured for young, isolated Rhizophorastylosa on Iriomote Island, Japan. The relationship between these two parameters was significant and given as the equation, Broot(g dry weight) = 0.394 × Babove(g dry weight) – 485 (r = 0.986). Multiple regression analyses also revealed good correlation between diameter and biomass of prop roots (Dprop and Bprop) and between prop root and root biomasses. Consequently, root biomass could be estimated from the measurements of diameter and biomass of prop roots using the multiple regression equation, Broot(g dry weight) = 80.0 ×Dprop(cm) + 0.86 ×Bprop (g dry weight) – 251. The relationship between DBH (diameter at breast height) and prop root biomass was also adequately described using an allometric equation.In Hinchinbrook Channel, Australia, redox potential (measured as Eh) and organic carbon stocks in the top 5cm of mangrove sediments were measured along a 600m transect from the frequently inundated, Rhizophora dominated zone on the creek edge, towards higher grounds, where Ceriops spp. became increasingly dominant. Eh values were about –60mV near the creek edge and increased to 260mV on higher grounds. Organic carbon stocks showed an opposite trend to Eh, with the values decreasing from about 360tCha–1 to 160tCha–1. At 18 sites, representing six different habitats, organic carbon stocks were also measured along with the DBH of mangrove trees. DBH was converted into aboveground biomass and then into root biomass using the equations obtained in the study on Iriomote Island. The average organic carbon stocks in the top 50 cm of sediments, aboveground biomass and root biomass were 296tCha–1, 123 tCha–1 and 52 tCha–1, respectively, and accounted for 64%, 25% and 11% of the total organic carbon stock.     

Changes of carbon stocks in bamboo stands in China during 100 years

Bamboo stands are one of the most important forest types in China, covering an area of about 4.99 million hectares, and estimation of their carbon stocks is vital for China's national carbon accounting. Bamboo biomass and carbon fraction, as well as soil bulk density and soil organic matter content, data were collated from 40 publications describing conditions at 35 sites in 10 Chinese provinces where most bamboo stands are distributed. Carbon stocks and its changes in the living biomass and soil organic matter in bamboo stands in China in the past five decades were estimated based on these collated data together with the area of bamboo stands and number of bamboo culms derived from the National Forestry Inventory (NFI). Our estimates indicate that the carbon stocks in bamboo stands in China have been increasing since the 1950s with estimated values of 318.55 Tg  C (1950–1962), 427.37 Tg C (1977–1981), 463.80 Tg C (1984–1988), 493.00 Tg C (1989–1993), 548.79 Tg C (1994–1998) and 631.58 Tg C (1999–2003) accompanying the increase of bamboo stand area. Based on correlation between forest area and bamboo area, as well as the trends of forest area predicted in government strategy documents for forest development over the next five decades, the carbon stocks in bamboo stands for 2010, 2020, 2030, 2040 and 2050 are estimated to be 727.08 Tg C, 839.16 Tg C, 914.43 Tg C, 966.803 Tg C and 1017.64 Tg C, respectively.     

Effect of tree species on carbon stocks in forest floor and mineral soil and implications for soil carbon inventories

Forest soil organic carbon (SOC) and forest floor carbon (FFC) stocks are highly variable. The sampling effort required to assess SOC and FFC stocks is therefore large, resulting in limited sampling and poor estimates of the size, spatial distribution, and changes in SOC and FFC stocks in many countries. Forest SOC and FFC stocks are influenced by tree species. Therefore, quantification of the effect of tree species on carbon stocks combined with spatial information on tree species distribution could improve insight into the spatial distribution of forest carbon stocks.We present a study on the effect of tree species on FFC and SOC stock for a forest in the Netherlands and evaluate how this information could be used for inventory improvement. We assessed FFC and SOC stocks in stands of beech (Fagus sylvatica), Douglas fir (Pseudotsuga menziesii), Scots pine (Pinus sylvestris), oak (Quercus robur) and larch (Larix kaempferi).FFC and SOC stocks differed between a number of species. FFC stocks varied between 11.1 Mg C ha⁻¹ (beech) and 29.6 Mg C ha⁻¹ (larch). SOC stocks varied between 53.3 Mg C ha⁻¹ (beech) and 97.1 Mg C ha⁻¹ (larch). At managed locations, carbon stocks were lower than at unmanaged locations. The Dutch carbon inventory currently overestimates FFC stocks. Differences in carbon stocks between conifer and broadleaf forests were significant enough to consider them relevant for the Dutch system for carbon inventory.     

The environmental characteristics of forest land and the techniques of reforestation in fired land in Daxing’an mountains

Analysis of nature environmental condition and evaluation of selection and integration of techniques have been carried out in Daxing’an mountains from 1987. The character of soil generation in this area is influenced by the frigid, coniferous forest vegetation, weather, glacier and late soil formation process. Synthesis techniques for high yield plantation include high seedling quality, suitable site preparation and effective protection measures for young trees.     

Soil carbon stock assessment in the tropical dry deciduous forest of the Sathanur reserve forest of Eastern Ghats,India

Climate change and carbon mitigation through forest ecosystems are some of the important topics in global perspective. Tropical dry forests are one of the most widely distributed ecosystems in tropics, which remain neglected in research. The soil organic carbon (SOC) stock was quantified on a large scale (30 1-ha plots) in the dry deciduous forest of the Sathanur reserve forest of Eastern Ghats. The SOC stock ranged from 16.92 to 44.65 Mg/ha with a mean value of 28.26 ± 1.35 Mg/ha. SOC exhibited a negative trend with an increase in soil depth. A significant positive correlation was obtained between SOC stocks and vegetation characteristics viz. tree density, shrub basal area, and herb species richness, while a significant negative correlation was observed with bulk density. The variation in SOC stock among the plots obtained in the present study could be due to differences in tree abundance, herb species richness, shrub basal area, soil pH, soil bulk density, soil texture etc. The present study generates a large-scale baseline data of dry deciduous forest SOC stock, which would facilitate SOC stock assessment at the national level as well as to understand its contribution on a global scale.     

Active organic carbon pool of coniferous and broad-leaved forest soils in the mountainous areas of Beijing

In order to explore the effects of different forest types on active soil carbon pool, the amounts and density of soil organic carbon (SOC) were studied at different soil horizons under typical coniferous and broad-leaved forests in the mountainous area of Beijing. The results showed that the amount of total SOC, readily oxidizable carbon and particulate organic carbon decreased with increasing depths of soil horizons and the amounts at depths of 0–10 cm and 10–20 cm in broad-leaved forest was clearly higher than that in coniferous forests. The trend of a decrease in SOC density with increasing depth of the soil horizon was similar to that of the amount of SOC. However, no regular trend was found for SOC density at different depths between coniferous forest and broad-leaved forests. The ratio of readily oxidizable carbon to total amount of SOC ranged from 0.36–0.45 and the ratio of particulate organic carbon to total amount of SOC from 0.28–0.73; the ratios decreased with increasing depths of soil horizons. Active SOC was significantly correlated with total SOC; the relationship between readily oxidizable carbon and particulate organic carbon was significant. A broad-leaved forest may produce more SOC than a coniferous forest.     

实验室不同温度下添加细根(草根)对土壤活性有机碳的影响

研究不同温度(10,20和30℃)条件下分别向土壤中添加光皮桦细根(直径<2 mm)与扁穗牛鞭草草根混合物(处理1)、光皮桦细根(处理2)、扁穗牛鞭草草根(处理3)和柳杉细根(处理4)这4种处理对土壤活性有机碳的影响。结果表明:添加细根的种类、培养温度和培养时间均对土壤微生物量碳、水溶性有机碳、易氧化有机碳和总有机碳含量产生影响;120天后各处理的土壤微生物量碳、水溶性有机碳、易氧化有机碳和总有机碳含量都显著大于对照(P<0.05);在60和120天后,处理1的土壤微生物量碳、水溶性有机碳、易氧化有机碳和总有机碳含量都显著大于其他处理(P<0.05);温度对土壤微生物量碳和水溶性有机碳含量的影响表现为30℃>20℃>10℃,对易氧化有机碳和总有机碳含量的影响表现为10℃>20℃>30℃(P<0.05)。     

异速模型评估森林植被生物量有机碳储量

在孟加拉的吉大港南部森林地区,利用异速模型评估森林植被的有机碳的储量.异速模型被分别应用测试树木(被划分两个胸高直径级)、灌木和草本植物.采用基部面积估算胸高直径级为从> 5 cm 到 ≤ 15 cm 和> 15 cm树木的生物量有机碳储量模型最好,分别有很高的决定系数(胸高直径级> 5 cm 到 ≤ 15 cm 的r2 为0.73697,胸高直径级> 15 cm 的r2为0.87703),且回归系数(P = 0.000)显著.其它模型(包括采用树高,胸高直径,树高和胸高直径,以及综合树高、胸高直径和木材密度)的线性和对数关系都表现出很低的决定系数.分别建立了20种优势树种的异速模型,采用树木基部面积的模型都得到很高的决定系数值.单独采用灌木和草本植物总生物量的异速模型有较高的决定系数(灌木的r2 为0.87948,草本植物的r2 为0.87325),且回归(系数)性显著(P = 0.000).生物量有机碳的评估是复杂的和耗时的研究,本研究所建立的异速模型可以应用于孟加拉和其它热带(地区)国家的森林植被的有机碳储量的测算.     

C and N stocks under three plantation forest ecosystems of Chinese fir, Michelia macclurei and their mixture

Chinese fir (Cunninghamia lanceolata), a type of subtropical fast-growing conifer tree, is widely distributed in South China. Its plantation area covers more than 7 × 10⁶ hm², accounting for 24% of the total area of plantation forests in the country. In recent decades, the system of successive plantation of Chinese fir has been widely used in southern China due to anticipated high economic return. However, recent studies have documented that the practice of this system has led to dramatic decreases in soil fertility and forest environment as well as in productivity. Some forest ecologists and managers recognize the ecological role performed by broadleaf trees growing in mixtures with conifers, and a great deal of studies on mixture effects have been conducted, particularly on mixture species of temperate and boreal forests, but these research results were not completely consistent. Possibilities include dependence of the mixture effects in large part to specific site conditions, the interactions among species in mixtures and biological characteristics of species. Although some researchers also studied the effects of mixtures of Chinese fir and broadleaf tree species on soil fertility, forest environment and tree growth status, little information is available about the effects of Chinese fir and its mixtures with broadleaves on carbon and nitrogen stocks. The experimental site is situated at the Huitong Experimental Station of Forest Ecology, Chinese Academy of Sciences, Hunan Province (26°40′–27°09′ N, 109°26′–110°08′ E). It is located at the transition zone from the Yunnan-Guizhou Plateau to the low mountains and hills of the southern bank of the Yangtze River at an altitude of 300–1,100 m above mean sea level. At the same time, the site is also a member of the Chinese Ecosystem Research Network (CERN), sponsored by the Chinese Academy of Sciences (CAS). This region has a humid mid-subtropical monsoon climate with a mean annual precipitation of 1,200–1,400 mm, most of the rain falling between April and August, and a mean temperature of 16.5°C with a mean minimum of 4.9°C in January and a mean maximum of 26.6°C in July. The experimental field has red-yellow soil. After a clear-cutting of the first generation Chinese fir (Cunninghamia lanceolata) plantation forest in 1982, three different plantation forest ecosystems, viz. mixture of Michelia macclurei and Chinese fir (MCM), pure Michelia macclurei stand (PMS) and pure Chinese fir stand (PCS), were established in the spring of 1983. A comparative study on C and N stocks under these three plantation forest ecosystems was conducted in 2004. Results showed that carbon stocks were greater under the mixtures than under the pure Chinese fir forest and the pure broad-leaved forest, and the broadleaves and the mixtures showed higher values in nitrogen stocks compared with the pure Chinese fir forest. The spatial distribution of carbon and nitrogen stocks was basically consistent, the value being greater in soil layer, followed by tree layer, roots, understory and litter layer. The carbon and nitrogen stocks in soil layer were both highly correlated with the biomass in understory and litter layer, indicating that understory and forest litterfall exerted a profound effect on soil carbon and nitrogen stocks under plantation ecosystems. However, correlations among soil carbon, nitrogen stocks and below ground biomass of stand have not been observed in this study. Translated from Acta Ecologica Sinica, 2005, 25(12): 3,146–3,154 [译自: 生态学报]     

江西安福不同类型毛竹林地土壤微生物量碳特征研究

为了掌握毛竹林地土壤微生物量碳的动态变化特征,以江西省安福林区的毛竹纯林、竹阔混交林、竹杉混交林这3种不同类型毛竹林地作为研究对象,同时以中亚热带阔叶林和杉木纯林林地为对照,对其土壤微生物量碳(SMBC)含量的季节变化情况及其在各土层的剖面分布情况进行了研究。结果表明:不同类型毛竹林地的SMBC含量间差异较大,不同类型林地0~60 cm土层的SMBC含量平均值的大小顺序为竹阔混交林(157.62 mg·kg~(-1))毛竹纯林(143.17 mg·kg~(-1))竹杉混交林(110.19 mg·kg~(-1))阔叶林(101.07 mg·kg~(-1))杉木林(86.56 mg·kg~(-1));各林分类型的SMBC含量均表现出明显的季节差异,春季的SMBC含量均极显著高于其他季节;各林分类型其SMBC含量的平均值均随土层的加深而降低,其分布在各土层的含量间的差异均达到显著水平,说明土壤表层的积聚作用明显;毛竹林地的SMBC占土壤总有机碳(TOC)的比率为1.01%~1.11%,高于阔叶林地的0.67%和杉木林的0.79%;毛竹纯林、竹阔混交林和竹杉混交林的SMBC与TOC的相关系数分别为0.71、0.55和0.47。     

黄土高原地区学林（草）的基本思路

分析了我国黄土高原地区坡耕地存在的主要问题,根据黄土高原生态环境脆弱的具体情况,提出了退耕还林(草)的对策思路。     

The impact of land afforestation on carbon stocks surrounding Tehran,Iran

The city of Tehran,like many polluted metropolises of the world,has higher emissions of greenhouse gases than other cities in Iran,due to heavy consumption of fossil fuel and landuse changes.To estimate carbon sequestration in two 40 year-old stands of planted Cupressus arizonica and Fraxinus rotundifolia in degraded lands surrounding Tehran,sampling of above-and below-ground biomass,soil(at two depths of 0-15 and 15-30 cm),and leaf litter was done by systematic random sampling.The total carbon stocks of C.arizonica and F.rotundifolia stands were respectively 328.20 and 150.69 Mg·ha-1.The aboveground biomass with 233.16(71%)Mg·ha-1 in C.arizonica and88.16(58.50%)Mg·ha-1 in F.rotundifolia contributed the most shares to carbon sequestration.The diameter at breast height,total height,basal area,total volume,and biomass of C.arizonica were significantly(p0.01)higher than those of F.rotundifolia.Also the depth of 0-30 cm of soil contributed between 18.29%and 32.15%of total ecosystem carbon,respectively.The economic value of carbon sequestration in the two stands in 2011 was calculated at 3.5 and 2.5 million dollars,respectively.Our results indicate that afforestation of the degraded land surrounding Tehran would sequester more carbon than would continuously degraded land,the current status quo.These stands can absorb atmospheric CO2 at different rates,thus tree species selection and stand development should be considered in planning future afforestation projects.     

Bird communities and seedling recruitment in restoring seasonally dry forest using the framework species method in Northern Thailand

This study examined the effects of framework trees, planted in 1998, and bird community on the natural recruitment of tree seedling species in a forest restoration experiment designed to test the framework species method of forest restoration established by Chiang Mai University’s Forest Restoration Research Unit (FORRU-CMU). Tree seedlings establishing beneath five framework tree species: Erythrina subumbrans (Hassk.) Merr., Hovenia dulcis Thunb., Melia toosendan Sieb. & Zucc., Prunus cerasoides D.Don and Spondias axillaries Roxb., were surveyed. Five trees of each species were selected in the 8-year-old trial plots. Birds visiting each tree were observed to determine possible seed dispersal activities. Thirty-six tree seedling species were found beneath the selected trees, of which 11 were wind-dispersed and 25 were animal-dispersed. The population density of animal-dispersed tree seedlings was higher than the wind-dispersed seedlings beneath all selected framework trees. The sample plots beneath P. cerasoides supported the highest population density of tree seedlings. Forty-nine bird species were recorded visiting the framework trees between July 2006 and June 2007. Non-frugivorous birds were recorded more frequently than the frugivorous birds. The effects of birds on seedling recruitment were different among each of the selected framework tree. Bigger trees, which attracted high number of birds by providing food resources, roosting and nesting sites may increase the seed deposition more than smaller trees with fewer attractants.     

亚热带日本落叶松中、幼龄林土壤有机碳密度和分配特征

本文基于32块样地土壤数据,对亚热带日本落叶松中、幼龄林的土壤有机碳密度及其分配特征进行了分析,结果发现:(1)中龄林的有机碳含量、有机碳密度明显高于幼龄林;(2)混交林的有机碳含量、有机碳密度明显高于纯林;(3)0~80 cm的土壤有机碳密度为172.25 t/hm2。有机碳主要集中在表土层0~20 cm处,此表土层有机碳密度分别是土层20~40 cm、40~80 cm的175.21%、129.52%。在土层相同的情况下,随着土壤深度的增加,其土壤有机碳密度呈下降趋势;(4)与适宜亚热带地区生长的造林树种——杉木相比,日本落叶松林的土壤有机碳含量、土壤有机碳密度均明显高于20年生杉木人工林,说明日本落叶松林土壤的固碳能力大于杉木人工林,从侧面也反映了同样作为亚热带地区的造林树种,日本落叶松林要优于杉木人工林。