基于买方市场的森林碳汇价格形成机制分析——以北京市化工行业为例

为了探究买方市场中森林碳汇价格的形成机制,本文首先构建森林碳汇经营主体的收益方程,求解出市场碳汇价格的最低价格;其次,利用能源生态足迹法测算企业碳汇影子价格;最后计算三种买方市场结构下的碳汇价格,并对企业影子价格和市场价格进行对比。本文以北京市化工行业为例进行实证研究,结果表明:(1)在完全竞争市场中,企业影子价格等于市场价格。(2)在完全垄断市场和寡头垄断市场中,除完全垄断市场的石油加工、炼焦和核燃料加工业及寡头垄断市场的非金属矿物制造业外,企业影子价格均小于市场价格。本文结果对政府稳定碳交易市场优化森林碳汇价格具有一定的参考价值。     

湖南省碳排放强度与森林碳汇地域差异分析

碳排放强度与森林碳汇是评价区域碳减排工作的两项重要指标。对湖南省的碳排放强度与森林碳汇的地域差异进行研究,有利于促进该省的区域碳减排工作。通过对湖南省14个地州市在2010—20145年的年均碳排放强度和森林碳汇进行核算,并基于湖南省各地区碳排放强度与森林碳汇的差异,对14个地州市进行了二维聚类分析。结果表明:(1)湖南省各地区碳排放强度存在明显的地域差异。(2)湖南省森林碳汇的地域分布格局为湘西湘南湘北湘中。(3)按照湖南省碳排放强度与森林碳汇的地域差异可以将全省14个地州市分为四个区域类型。张家界、湘西州、永州属于低碳排放强度-高森林碳汇地区;株洲和长沙、常德属于低碳排放强度-低森林碳汇地区;湖南省中部主要是高碳排放强度-低森林碳汇地区;怀化、邵阳、衡阳、郴州属于高碳排放强度-高森林碳汇地区。最后依照结论对促进湖南省区域碳减排工作提出了建议。     

森林碳汇环境库兹涅茨曲线特征及其影响因素分析

文中基于2004-2020年中国省际面板数据，运用环境库兹涅茨模型实证分析森林碳汇与经济发展水平之间的关系，通过面板数据灰色关联模型测算森林碳汇与各影响因素之间的关联度。研究发现：森林碳汇与经济发展水平之间的关系呈“N”型曲线；从整体上看，各影响因素与森林碳汇的灰色关联度都较高，从大到小依次为劳动要素投入、造林面积、森林采伐、林业产业发展水平、营林固定资产投资、森林受灾程度；具体来看，全国4大林区森林碳汇与各影响因素的灰色关联度具有差异性。建议提高森林资源经营管理水平，完善森林碳汇市场，促进林业产业结构升级，以助力林业经济高质量发展。     

京津冀地区基于森林碳汇量的碳汇市场建设研究

指出了森林碳汇市场不是自发形成的,需要政策制度的引导,但森林碳汇服务这种商品的质量和数量难以确定,价值发现的过程不同于一般商品。针对森林碳汇物理量和价值量的计算,通过构建模型,计算出了京津冀地区森林碳汇量,以此作为森林碳汇市场建设的基础,并在分析当前市场的基本情况与存在问题基础上,提出了推进京津冀森林碳汇市场建设的对策建议。     

中国南方杉木森林碳汇供给的经济分析

以我国南方杉木主产区的典型林场为案例点,基于3种不同立地条件和经营强度的土地类型上进行裸地造林的假设,运用改进的杉木生长模型和修正的Faustman-Hartman模型分析增加碳汇收益对杉木人工林经营的影响.研究发现:考虑碳汇收益将明显增加林地作为资产的价值,林地作为资产的价值增加可能使其他用途的土地转化为林业用地,最优轮伐期也随着碳汇价格的增加而呈延长趋势,但对不同类型林地的影响存在差异.中等和劣等林地的碳汇供给量对碳汇价格的反应更加敏感,为通过市场和价格手段来改变现有林地经营方式进而增加林地的森林碳汇供给提供了可能.杉木林地的碳汇供给量与利率和木材价格呈负相关关系,但是利率和木材价格变化对不同类型林地的影响又各不相同.利率和木材价格变化对优等林地的碳汇供给量影响整体不显著,但在一个较低利率水平下或者木材价格下降的情景下,中等和劣等林地杉木碳汇的供给量大幅度提高.碳汇供给量与利率的变化关系也为采用金融手段来刺激增加森林碳汇提供可能.     

我国森林碳汇市场构建初探

在研究森林碳汇服务物理关系的基础上, 提出应该建立与之相应的市场化机制, 并从供求双方、价格机制、交易成本和政府的作用等几个方面对森林碳汇市场的构建进行了初步探讨。     

不同经营目标下的芦头林场杉木人工林经济效益分析

国有林场在森林经营中发挥重要的作用，通过考虑森林生态系统的多目标功能，研究不同经营目标对林场的森林碳汇价值的影响因素，能够充分发挥森林的多种功能和多重价值，有助于完善森林的精准经营理论，体现森林的生态、经济和社会效益。本文以湖南省芦头国有林场杉木人工林为研究对象，基于林地期望价值法、杉木生长模型及木材价格数据，分别以理想核算模式与年核算模式两种碳汇效益核算模式，估算单一木材经营目标、碳汇与木材复合经营目标下的杉木人工林的最佳轮伐期、碳汇成本以及林地期望价值，并分析不同碳价格和贴现率变动的敏感性变化。结果显示：针对芦头林场的杉木人工林的营林条件，在碳汇与木材复合经营目标下，杉木人工林的最佳轮伐期为21 a。仅估算木材收益，年林地期望价值为139 690.04元·hm^-2;复合收益的理想核算模式期望值为143 034.33元·hm^-2,年核算模式的期望值为155 937.80元·hm^-2。与单一木材经营相比，考虑碳汇收益后林地期望价值显著提升，两种核算模式下的最优轮伐期随着碳汇价格的增加而呈延长趋势，与贴现率呈负相关；两种碳...     

从市场主体角度探析森林碳汇市场发展

森林碳汇市场的主体包括需求者、供给者和第三方独立认证机构.文章从目前全球变暖的大背景下森林碳汇市场的主体构成状况,即较高的交易成本,缺乏流动性,不合理的市场竞争3个方面阐述了森林碳汇市场主体对森林碳汇市场的影响.提出了建立适合市场状况的交易体系,培育国内需求市场,积极发挥政府的监管和引导作用等对我国发展碳汇市场的建议.     

林业碳汇项目类型及开发策略分析

以项目为载体的林业碳汇作为重要交易标的,已经在国内外主要的碳交易市场体系中频繁出现。但是,由于不同碳市场产生的背景、主要目标及交易规则的差异,对参与交易的林业碳汇项目开发标准与具体要求不尽相同。合格的可交易林业碳汇在全球林业碳汇市场中所占份额依然很小,林业碳汇尚未发挥其应有的作用与潜力。文中在对国内外林业碳汇市场发展概况进行简要梳理并对目前主要林业碳汇项目类型及其特征进行比较分析的基础上,结合我国碳市场发展与森林经营特点,提出了我国林业碳汇的未来发展策略:一是立足国内,建立多元化林业碳汇市场;二是立足资源优势,重点发展森林经营碳汇项目;三是加强林业基础数据与信息化建设,降低林业碳汇项目交易成本;四是加强不同碳市场衔接与协同,并积极参与国际市场交易。     

基于层次分析法的湖南省森林碳汇发展潜力评价

为了对湖南省各县森林碳汇发展潜力进行定量评价,运用层次分析法选取森林现有和潜在发展面积、森林结构、林木生长率、生物多样性和社会经济5个指标来构建森林碳汇发展潜力指数计算模型,确定权重值分别为0.35、0.25、0.20、0.10、0.10。基于森林碳汇发展潜力指数计算模型,将森林碳汇发展潜力等级分为高、中、一般、低,所对应的指数区间分别为(0.60,1.00]、(0.40,0.60]、(0.30,0.40]、[0,0.30]。结果表明:在湖南省124个县(区)范围内,森林碳汇发展潜力高的县(区)为沅陵县与安化县。     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.     

qPCR quantification of Ophiognomonia clavigignenti‐juglandacearum from infected butternut trees under different release treatments

The use of a molecular assay for quantifying conidia of Ophiognomonia clavigignenti‐juglandacearum, the fungal pathogen responsible of butternut canker, was investigated. Purified DNA from conidia collected on glass fibre filters of a passive rain collectors was quantified using a TaqMan real‐time quantitative polymerase chain reaction (qPCR) assay. The qPCR assay could specifically discriminate the target species from all other North American known species of Ophiognomonia, and it was sensitive enough to repeatedly detect one conidium. A linear relationship between numbers of conidia and qPCR C_t values was determined, and used to assess the sporulation of the pathogen under trees that were released to promote their vigour. In total, 977 samples of field‐captured conidia from 49 trees, at two locations, and from two successive growing seasons were analysed. No significant difference of sporulation was observed under control and release treatments. However, our results demonstrated that qPCR assay was reliable for detecting and quantifying O. clavigignenti‐juglandacearum from environmental samples, which will be useful to assess further control methods for this disease.     

The potential of alley cropping in improvement of cultivation systems in the high rainfall areas of Zambia I. Chitemene and Fundikila

Three trials investigating the potential of alley cropping to improve the traditional systems of cultivation, chitemene and fundikila, in the Northern Province of Zambia are described. Flemingia congesta, Tephrosia vogelii, and Sesbania sesban, were grown in association with finger millet, groundnut, cowpea, and maize in various traditional cropping sequences. The indigenous species Tephrosia vogelii and Sesbania sesban were not able to withstand repeated pruning and the long following dry season, and were replaced with Calliandra calothyrsus, and Cassia spectabilis.Over a four year period, there was no benefit by alley cropping with any of the tree species on crop yields, and yields in alley crop treatments even dropped significantly below the control treatments in the fourth year, casting doubt on the potential of alley cropping for sustainable production. There was also no consistent effect on soil chemical characteristics in any of the trials. It was suggested that this lack of beneficial response to alley cropping was due to low tree biomass production low quality of prunings, and an inappropriate cropping sequence. There was no evidence that alley cropping contributed to enhanced nutrient recycling, despite substantial localised pools of soil nutrients, particularly in the chitemene, with which recycling could potentially occur.     

Toxicity of biocide GCSC-BtA on arthropod pests under different temperature conditions

The present research dealt with the toxicity of GCSC-BtA (Germany–China Scientific Cooperation-Bacillus thuringiensis-Abamectin), a new type biocide developed by conjugating a toxin from Bacillus thuringiensis (B.t.) with Abamectin from Streptomyces avermitilis, on arthropod pests under different temperature conditions. The results showed that GCSC-BtA possessed higher toxicity than B.t. crystal, Abamectin or Cypermethrin, with pest mortalities of 97.9, 93.7, 96.4, 82.3 and 96.7% for Tetranychus cinnabarinus (Boisd.) (Acari, Tetranychidae), Frankliniella occidentalis Pergande (Thys., Thripidae), Aphis fabae Scopoli (Hom., Aphididae), Plutella xylostella (L.) (Lep., Plutellidae) and Cameraria ohridella Deschka et Dimić (Lep., Gracillariidae), respectively. Toxicities of GCSC-BtA to T. cinnabarinus and P. xylostella decreased significantly at the older developmental stage with an exception that egg stage had the highest tolerance, in which LC₅₀s of GCSC-BtA were 0.0001, 0.0019 and 0.0708 mg/ml for nymph, adult and egg of T. cinnabarinus, and that 0.0399, 0.2035 and 0.9033 mg/ml for the 2nd instar larvae, 4th instar larvae and egg of P. xylostella, respectively. Also, the biocide was more effective to the lower stage of A. fabae than the higher one with LC₅₀s of 0.0023, 0.0086 and 0.0171 mg/ml against 1st instar nymph, 3rd instar nymph and adult, respectively. In general, toxicity of the new type of biocide was positively related to temperature against all the tested pests, except against T. cinnabarinus, where it was almost similar at the three temperature conditions. GCSC-BtA displayed significantly lower toxicities at 15/20°C than 20/25°C or 25/30°C against F. occidentalis, A. fabae, P. xylostella and C. ohridella. However, no significant difference was found in the toxicities against F. occidentalis, A. fabae and C. ohridella above 20°C, whereas toxicity against P. xylostella increased as temperature raised. Therefore, to achieve higher efficacy in the field, application rate and time should be devised according to these factors.