Concentrations and depositions of SO2, SO4 2− etc. in a Chongqing suburban forested area

During the period from 25 May 1991 to 30 May 1992 the atmospheric concentrations and depositions of oxides of sulfur were continuously measured in a suburban masson pine forest which is currently experiencing severe dieback, in Chongqing, China. The annual mean concentrations of SO₂ and particulate SO₄ ^2? were 220 μ g/m³ (77 ppbv) and 32 μ g/m³ respectively. The atmospheric concentrations of these sulfur compounds were high in late autumn and winter. The annual wet and dry depositions of sulfur to the forest as measured by throughfall and stemflow were 93.1 and 46.6 kgSha^?1a^?1 respectively. These depositions are among the highest level ever reported in the world. Althogh the cause of the dieback of the masson pine trees has not been unequivocally determined, it is probable that the direct impact of SO₂ is more likely the cause than acid deposition.     

中亚热带杉木人工林和米槠次生林树干茎流和穿透雨磷的动态特征

磷(P)伴随树干茎流和穿透雨输入到森林,成为补充亚热带森林生态系统P流失的一个重要途径,但其在不同类型生态系统中的动态特征缺乏必要的关注。以中亚热带杉木人工林和米槠次生林为研究对象,通过测定2015年6月至2018年8月间树干茎流和穿透雨中P浓度,探讨了2个林分树干茎流和穿透雨P浓度的差异、季节变化特征及影响因素。结果表明,杉木人工林树干茎流和穿透雨P浓度变化范围分别为0.002～0.026,0.003～0.024 mg/L,米槠次生林树干茎流和穿透雨P浓度变化范围分别为0.003～0.024,0.003～0.031 mg/L,2个林分树干茎流和穿透雨P浓度均在夏季表现出显著差异。2个林分的树干茎流P浓度均为夏季高于冬季,杉木人工林穿透雨P浓度在季节上无显著差异,而米槠次生林夏秋季较高,冬春季偏低,树干茎流P浓度略微高于穿透雨。2个林分的树干茎流量在4个季节均具有显著差异,米槠次生林均高于杉木人工林,而穿透雨量在季节上无差异。杉木人工林P浓度与树干茎流量和穿透雨量均呈负相关关系,而米槠次生林P浓度与树干茎流量和穿透雨量均呈正相关关系。表明不同林分林冠结构和形态学特征的差异能显著影响亚热带森林生态系统降水中P的再分配。研究结果为深入认识森林生态系统P随水文过程的动态特征提供基础数据。     

浑河上游典型水源涵养林降雨再分配过程

为明确浑河上游典型水源涵养林的降雨再分配过程,以浑河上游地区5种典型水源涵养林(红松人工林、落叶松人工林、红松混交林、落叶松混交林、阔叶混交林)为研究对象,应用自记式观测记录仪,分析不同林型林冠层对降水再分配过程(穿透雨、树干茎流、林冠截留)的影响。结果表明:各林型穿透雨量(率)、树干茎流量(率)、林冠截留量均随林外降雨量增加而增大;穿透雨量、树干茎流量、林冠截留量均与林外降雨量呈显著的线性正相关;各林型穿透雨率、树干茎流率与林外降雨量呈显著的对数函数关系;红松混交林、落叶松混交林的树干茎流率(32.12%,15.44%)均高于阔叶混交林与红松、落叶松人工林,红松、落叶松人工林的林冠截留能力(80.66%,77.47%)高于阔叶混交林、针阔混交林。该结果为浑河上游地区水源涵养林的最优空间结构配置与经营管理提供科学依据。     

Above-Ground Sulfur Cycling in Adjacent Coniferous and Deciduous Forests and Watershed Sulfur Retention in the Georgia Piedmont,U.S.A.

Atmospheric deposition and above-ground cycling of sulfur (S) were evaluated in adjacent deciduous and coniferous forests at the Panola Mountain Research Watershed (PMRW), Georgia, U.S.A. Total atmospheric S deposition (wet plus dry) was 12.9 and 12.7 kg ha-¹ yr-¹ for the deciduous and coniferous forests, respectively, from October 1987 through November 1989. Dry deposition contributes more than 40% to the total atmospheric S deposition, and SO₂ is the major source (～55%) of total dry S deposition. Dry deposition to these canopies is similar to regional estimates suggesting that 60-km proximity to emission sources does not noticeably impact dry deposition at PMRW. Below-canopy S fluxes (throughfall plus stemflow) in each forest are 37% higher annually in the deciduous forest than in the coniferous forest. An excess in below-canopy S flux in the deciduous forest is attributed to leaching and higher dry deposition than in the coniferous forest. Total S deposition to the forest floor by throughfall, stemflow and litterfall was 2.4 and 2.8 times higher in the deciduous and coniferous forests, respectively, than annual S growth requirement for foliage and wood. Although S deposition exceeds growth requirement, more than 95% of the total atmospheric S deposition was retained by the watershed in 1988 and 1989. The S retention at PMRW is primarily due to SO₄ ²- adsorption by iron oxides and hydroxides in watershed soils. The S content in white oak and loblolly pine boles have increased more than 200% in the last 20 yr, possibly reflecting increases in emissions.     

黄前水库上游生态修复区典型植被林冠层水文效应

利用森林水文与水量平衡原理,采用固定标准地方法,对山东省泰安市黄前水库上游水土保持生态修复区典型植被类型的林冠层水文效应进行了研究。结果表明:①在P=18 mm的降雨条件下,生态修复区内不同树种林冠对降雨截留量的排序为油松>赤松>侧柏>麻栎>刺槐,树干径流量和林内穿透雨量没有发现有类似的规律,针叶林比阔叶林的林冠截留量大。②不同造林密度对林冠截留量的影响总体趋势为造林密度越大林冠截留量越多,反之林冠截留量就越少;林内穿透雨量与林冠截留量的变化规律相反。③不同郁闭度林分与不同造林密度的林分对降雨的再分配规律相同。④不同混交方式的林分对降雨的截留量排序为松刺栎混交>油松>松栎混交>松刺混交>麻栎>刺槐;树干径流量和林内穿透雨量的规律不明显。⑤生态修复区内典型植被林冠截留量在降雨量较小时(P=4.50 mm)截留作用很明显,林冠截留率较大;但随着雨量增加,树干径流量逐渐增大,林冠截留率呈减小趋势。     

Long-Term Monitoring Study on Rain, Throughfall, and Stemflow Chemistry in Evergreen Coniforous Forests in Hokkaido, Northern Japan

Long-term study on acid precipitation monitoring at suburban forests in Sapporo city showed that bulk precipitation pH were below 4.8 in recent years. Throughfall and stemflow chemistry for two main coniferous species (Abies sachalinensis and Picea jezoensis) showed different regime for pH and element deposition. The mean annual pH values of throughfall and stemflow in Picea stand were 1.0 to 1.3 units higher than that of rain collected outside the forest. In contrast, mean annual pH of throughfall and stemflow in Abies stand were 0.3 to 0.5 units higher than that of rain. Mean annual inorganic nitrogen input via throughfall and stemflow were estimated 0.41±0.11 gN/m²/yr in Abies stand, 0.44±0.13 gN/m²/yr in Picea stand. Cation input via throughfall, especially for K, in Picea stand was 1.4 times as large as that in Abies stand. Mean annual input of S in both stands was the same level. The possible effects on surface soil properties and nutrient cycling in northern evergreen conifers was discussed.     

土壤含水量对浅层滑坡区土体抗剪强度影响

通过对重庆缙云山一浅层滑坡区杉木和马尾松林地上土壤剖面原状土、过2mm筛后土壤的剪切试验,研究了土壤含水量对浅层滑坡区土体抗剪强度的影响。结果表明：原状土土壤断面抗剪强度随土壤天然含水量增大而减小,随土层加深而增大。土层越深,土壤含水量对土壤抗剪强度的影响越小。同一土壤在不同的含水量的条件下,随着含水量的增大,粘聚力C值和内摩擦角φ值均减小,并且土壤含水量对土壤粘聚力C值的影响程度大于对土壤内摩擦角φ值的影响程度。     

上犹县长防林不同森林植被类型土壤蓄水能力初探

通过2004和2009年两次对江西上犹长防林不同森林植被类型土壤持水特性的测定分析,结果表明:同一植被类型随着其生长发育,其土壤蓄水能力相应提高;各植被类型的土壤蓄水能力均明显高于荒山地;土壤容重、毛管孔隙度及非毛管孔隙度三者的综合特征对土壤蓄水能力有着重要影响;不同植被类型的土壤蓄水能力存在差异,针阔混交林的土壤蓄水能力优于杉木纯林、针叶混交林、湿地松纯林和马尾松纯林;2004、2009年各植被类型土壤蓄水能力分别在25200~40320 t hm-2和30240~63360 t hm-2之间,若蓄存1×108 m3的水则所需的相应森林面积分别在2480.2~3968.3 hm2和1578.3~3206.9 hm2之间,而荒山地则分别为7142.9 hm2和7440.5 hm2。     

原始红松林和次生白桦林降雨截留分配效应研究

 以小兴安岭原始红松林为研究对象,通过97场的降雨测定,对原始红松林的降雨截留分配效应进行系统研究。结果表明:原始红松林在生长季内的林冠截留量为98.68 mm,占同期降雨量的19.61%,是次生白桦林的1.3倍。与全国其他森林类型的平均林冠截留率（11.4%～36.5%）相比,原始红松林的林冠截留率处于中等水平。原始红松林在生长季内的穿透雨量和树干径流量分别为395.77和8.78mm,分别占同期降雨量的78.65%和1.74%。与次生白桦林相比,其穿透雨量减少,而树干径流量增加。统计分析表明,原始红松林的林冠截留量、林内穿透雨量和树干径流量与林外降雨量之间均呈现紧密的三次多项式函数关系（p<0.01）,而次生白桦林的林内穿透雨量与林外降雨量之间却呈现良好的直线关系（p<0.01）。最后,对影响林内穿透雨和树干径流的因子进行筛选和分析,为研究针阔混交林的降雨分配效应提供重要参考。     

丘陵陡坡荒山灌木草丛及其造林地生态系统碳库的分配格局

植被恢复往往有利于提高生态系统的碳储量,但对南方丘陵陡坡荒山灌木草丛造林后如何影响生态系统碳库及其分配格局仍知之甚少。选取江西泰和典型丘陵陡坡(>25°)荒山灌木草丛和马尾松(Pinusmassoniana)造林19年后的林地为对象,开展上、中、下坡0～75cm土壤层和植物体碳储量的对比研究。结果表明,造林地土壤容重低于灌木草丛,土壤石砾含量与土壤碳含量和碳密度呈显著负相关,表明造林有利于改善土壤物理结构;石砾含量影响土壤碳积累。荒山灌木草丛和马尾松林土壤碳含量和碳密度均表现为随土壤加深呈下降的趋势(P<0.05),但上、中、下坡的变异规律不一致,且2种生态系统之间差异不显著。荒山灌木草丛和马尾松生态系统碳储量分别为52.85,111.31t/hm2,均表现为自上、中坡至下坡呈增加的趋势;灌木草丛和马尾松林中的植物体分别占生态系统碳储量的11.2%和59.5%。灌木草丛马尾松造林碳年均增汇3.08t/(hm2.a),林分生物量的积累是造林增汇的直接原因;推断种植耐瘠速生树种是提高困难立地造林碳增汇的有效途径。     

Transfer of dissolved Al, Fe and Si in two Amazonian forest environments in Brazil

The balance of Si, Fe and Al in the soil solution determines more or less the course of soil formation in the tropics. We have tried to improve understanding of the processes by studying fluxes of dissolved Si, Fe and Al from the atmosphere, through the canopy and the soil, and to the groundwater, in two distinct Amazonian ecosystems, one a typical rainforest, developed on a Ferralsol, the other a so-called ‘Campinarana’ forest, developed on a Podzol. The Si, Fe and Al in the rain and the throughfall and the stemflow were measured throughout a year, and the leaching of Si, Fe and Al through the upper soil and at the groundwater level were estimated. The annual balance showed that stemflow inputs were negigible compared with the contributions from throughfall and rain. The inputs of Fe, Al and Si to the topsoil from the rain and from dust and biological release in the canopy were small but not negligible. These sources contributed more aluminium in the Campinarana than in the rainforest. The rainfall constituted the main input of dissolved Fe and Al to the topsoil in both ecosystems. The element balances in the soil horizons confirmed that the present functioning of the Ferralsol results in aluminization and desilicification. We also found that the elements are transported in micropore flow and on translocated particles, as well as in freely percolating water.     

The role of organic horizons and canopy to modify the chemistry of acidic deposition in some forest ecosystems

To clarify the mechanisms of pH buffering in forest ecosystems, field observations of pH and ionic concentrations in precipitation (R), throughfall (Tf), stemflow (Sf), and leachates from organ c horizons (Lo) were conducted for three years at three stands in Tomakomai (TK) and Teshio (TS) in Hokkaido, northern Japan. Weighted mean rates of H⁺ input as wet deposition at TK and TS were estimated in the range from 0.3 to 1.0 and 0.4–0.6 kmol_c ha^?1 y^?, respectively. While the net H⁺ flux was reduced significantly by the forest canopy, net fluxes of other ions by throughfall, especially for Na⁺, Cl^?, and SO₄ ^2?, were apparently greater than those by precipitation. The canopy modification of the H⁺ flux was more remarkable under deciduous stands than under coniferous stands, suggesting that the efficiency of conifers as the collectors of dry deposition is greater than that of deciduous ones. More than 50% of H⁺ flux due to throughfall was absorbed by the organic horizons and the weighted mean pH of Lo at TK and TS was in the range from 4.9 to 5.5 and 5.0–5.5, respectively. Results from field observation and field leaching experiments, showed that the major H⁺ sinks of the organic horizons are exchange reaction of Ca²⁺, Mg²⁺ and K⁺. Organic acids or organo-metallic complexes of lower pK(=5.0–5.5) played a significant role as counter anions in O horizons leachate in coniferous forests. Our results indicate the importance of biogeochemical modifications in the canopy and organic horizon in acid buffering mechanisms of forest ecosystems.     

Effects of forest plantations on rainfall redistribution and erosion in the red soil region of Southern China

To evaluate the effects of different forest plantations on rainfall redistribution, we measured throughfall, stemflow, interception loss, surface runoff and soil loss from July 2004 to September 2005 in the three types of forest plantations Eucommia ulmoides, Vernicia fordii and Pinus massoniana. The results showed that differences in throughfall and stemflow between the three forest plantations were significant (p < 0·05). Throughfall was highest in the V.fordii plantation and stemflow was highest in the E.ulmoides plantation. Throughfall plus stemflow below the E.ulmoides canopy was greater than that underneath the other forest types. Moreover, significant spatial variation in throughfall was observed. Throughfall in P.massoniana was 28·0–39·7% higher at a stem distance < 60 cm or 11·5% lower at a stem distance > 120 cm than in the other forests, but the difference was not significant between E.ulmoides and V.fordii. Moreover, the difference in throughfall at stem distances 60–120 cm was not significant between the different forest plantations. For E.ulmoides, throughfall under the peripheral crown part was 16·1% higher than that close to the stem. In contrast to E.ulmoides, P.massoniana had 26·8% lower throughfall under the peripheral crown part than close to the stem. No significant difference was found in throughfall for the various stem distances underneath V.fordii. Stemflow in E.ulmoides was 2–3 times higher than in the other forests (p < 0·01). Interception loss accounted for 19·9% of gross rainfall for E.ulmoides, 20·8% for V.fordii and 27·2% for P.massoniana. Surface runoff and soil loss differed considerably among the three types of forest plantations. Annual runoff and total soil loss were lowest in the P.massoniana forest and highest in the V.fordii forest. This study indicated that P.massoniana, as a reforestation tree species, had the most positive effect on soil and water conservation among the three forest plantations. Copyright © 2008 John Wiley & Sons, Ltd.     

The effects of organic carbon on acid rain in a temperate forest in Japan

From recent studies, we noticed that stemflow had an acidity that differed from that of precipitation or throughfall. Organic substances, supplied from the tree surface, would be one of the factors that modifies the acidity of rain. The objectives of this study were to determine the DOC concentration and to clarify the influence of dissolved organic carbon (DOC) on acidity in precipitation, throughfall and stemflow. Throughfall and stemflow were measured in sugi [Cryptomeria japonica D. Don], hinoki [Chamaecyparis obutusa Endl.] and kojii [Castanopsis cuspidata (Thumb.) Schottky.] stands. All samples were analyzed for their pH, electric conductivity (EC), major inorganic anions and cations and DOC concentration.The annual average of DOC was highest in stemflow, and that of throughfall and precipitation were one-third and one-tenth of stemflow, respectively. The averages of DOC in stemflow in two coniferous, sugi and hinoki stands, were higher than that of broadleaved kojii stand. DOC concentration was low in summer and high in winter in all stands. In Stemflow, pH and DOC were negatively correlated, while EC and DOC in stemflow were positively correlated in all stands. However in throughfall, there was no evident relationship between pH, DOC and EC. This relationship was not explained by the cause of organic acid.     

Impacts of forests on water chemistry

Forest canopies and soil organic horizons have been identified as two major components of forest ecosystems interacting with and altering the chemistry of rainwater. Data, collected over a 13-yr period from different softwood and hardwood stands located in central New Brunswick, are presented to demonstrate differences among stands in their ability to alter the chemistry of rainwater. In both the canopies and the soil organic horizons, retention and exchange processes are effective in altering the chemistry of rainwater. Significant species effects are recognized in the partitioning of rainwater into throughfall, stemflow, and interception, and in altering of its chemistry. Stemflow components generally contribute to acidity, while throughfall reduces acidity of rainwater. Some of the chemical characteristics of rainwater reaching the forest floor are shown to be similar to those of streams associated with the forest stands. The data show significant species effects on the moisture retention characteristics of the organic materials accumulated under each stand, which in turn affect the residence time of the acid components of rain. Admittedly, before entering streams and lakes associated the composition of the liquid leaving the organic horizons is further altered by mineral soils.     

亚热带米槠次生林和杉木人工林林冠截留特征比较

通过对福建三明地区米槠次生林和杉木人工林林内穿透雨和树干茎流进行对比分析,研究2种林分类型对降雨再分配规律的影响及其关键影响因素。在研究区2种林分内分别选取了3个20m×20m标准样地,同时设置了穿透雨和树干茎流收集装置,每场降雨后测定相应的水量。结果表明:研究期内年降雨量为1 706.6mm,米槠次生林和杉木人工林林内穿透雨量没有显著差异,总穿透雨量分别为1 204.0mm和1 289.9mm,分别占年降雨的70.6%和75.6%;米槠次生林树干茎流量显著高于杉木人工林(p0.05),两者的树干茎流率分别为4.8%和2.7%;米槠次生林和杉木人工林的林冠截留率分别为24.7%和21.8%。林内穿透雨量与林冠郁闭度和叶面积指数呈负相关关系,说明林分郁闭度越高则穿透雨量越少。米槠次生林和杉木人工林林冠截留的差异主要受林冠开阔度和树皮结构的影响,因此树种差异显著改变了森林生态系统降水再分配模式。     

温带森林磷沉降-水系统输出-迁移动态特征及对土壤磷影响

采用对比和分析的方法,研究了黑龙江省带岭凉水国家级自然保护区温带森林生态系统磷沉降、溪流、河流和渗透水输出磷含量动态特征,以及磷沉降和水系统磷输出对红松人工林、落叶松人工林、椴树红松混交林、枫桦红松混交林和白桦次生林5种林型土壤全磷和有效磷的影响。结果表明,研究区域通过降雨产生的年磷沉降量约为0.888 kg hm-2,7月除红松人工林外,其他4个林型穿透雨磷浓度均高于大气降雨的磷浓度。7月枫桦红松林、8月白桦次生林和红松人工林A层土壤渗透水磷浓度低于林内雨磷浓度,表层土壤对穿透雨中磷有固定作用。在凉水自然保护区森林生态系统内,森林系统内小溪流、凉水河和凉水森林系统外永翠河水磷浓度均较林外降雨及穿透降雨磷浓度高,表现为永翠河水>土壤A层渗透水>凉水河>小溪>穿透雨>大气降雨。表明土壤中部分磷素通过地表径流和壤中流流出森林生态系统,并汇集于林中小溪,最后进入河流,造成磷在小溪和河流中的富集。大气磷沉降、森林水系统磷输出均与椴树红松林A0层土壤全磷含量呈显著负相关,与红松人工林B层土壤全磷含量呈极显著正相关,与落叶松人工林A0层土壤有效磷含量呈极显著正相关。     

祁连山青海云杉林冠降雨再分配特征及影响因素

以祁连山排露沟小流域青海云杉林为研究对象,2015年5—9月观测了34场降雨的林外降雨量、穿透雨量和树干茎流量,并同步观测了相关的林外气象因子,分析了青海云杉林冠降雨再分配特征及影响因素。结果表明:(1)青海云杉林的总穿透雨量、树干茎流量和截留量分别为275.9,1.8,90.0mm,分别占总降雨量的75.04%,0.48%和24.48%,并在不同降雨量等级之间存在差异。(2)冠层降雨再分配各组成要素(穿透雨、树干茎流、林冠截留)与降雨量、降雨历时、10min最大雨强、空气相对湿度呈极显著的相关性。随着降雨量和降雨历时的增大,穿透雨量和树干茎流量均不断增大,而穿透雨率、树干茎流率和截留量(率)均逐渐趋于稳定。(3)青海云杉林内产生穿透雨和树干茎流的临界降雨量分别为0.8mm和9.6mm。因此,气象因素是影响冠层降雨再分配的重要因素之一。     

湖北宜昌风化花岗岩区林草植被改良土壤作用的定量化分析

为确定适宜湖北宜昌风化花岗岩地区的林草植被类型，利用主分量分析方法对该地区林草植被的土壤改良作用进行了数量化分析和评价。结果表明：松栎混交林对土壤的改良效果最好，草地次之，马尾松纯林则较差。     

Rainfall,Stemflow, and Throughfall Chemistry at Urban- and Mountain-facing Sites at Mt. Gokurakuji,Hiroshima, Western Japan

Rainfall, stemflow, and throughfall were collected from 1996 to 1999 at two types of forest sites: (1) forests near the traffic roads and urban areas and (2) forests away from the urban areas at Mt. Gokurakuji, Hiroshima, western Japan in order to estimatethe effects of anthropogenic activities on atmospheric deposition. Rainfall deposition for major ions showed small differences between the sites. The NO₃ ^- and SO₄ ^2-concentrations in stemflow were higher at the urban-facing slope than at the mountain-facing slope. Throughfall deposition of NO₃ ^- and SO₄ ^2- was also higher at urban-facing slopes. Net throughfall (NTF) deposition (throughfall minus rainfall) of NO₃ ^- and SO₄ ^2- accounted for 77 and50% of the total throughfall deposition on urban-facing slopes, respectively, while it accounted for 44 and 23% on themountain-facing slopes, respectively. These results indicated a higher contribution from dry deposition on urban-facing slopes compared to mountain-facing slopes. Atmospheric N (NO₃ ^- +NH₄ ⁺) deposition from throughfall was estimated to be around 17–26 kg N ha^-1 yr^-1 on urban-facing slopes, which was greater than the threshold of N deposition that could cause nitrogen leaching in Europe and the United States. The highload of atmospheric N deposition may be one of the factors bringing about the decline of pine forests on urban-facing slopesof Mt. Gokurakuji.