Analytical model of carbon storage in the trees, soils, and wood products of managed forests

The carbon balance between managed forests and the atmosphere depends critically on the frequency and intensity of harvesting, and the lifetime of harvested products. To assess more quantitatively the nature of this dependence, a theoretical analysis, previously applied to carbon storage in trees and wood products only, is extended here to include the carbon in forest floor detritus and soil. A dimensionless combination of the parameters of the model, alpha, with critical value alpha(c), is identified such that for alpha < alpha(c), the conversion of old-growth forest to managed forest releases carbon to the atmosphere in the long term. Parameter alpha is given by the combination f(t)D/T(*), where f(t) is the fraction of old-growth forest carbon stored in trees, D is the residence time of harvested biomass (wood products and slash debris) within the system, and T(*) is the rotation period for maximum sustained yield (maximum mean annual increment). The critical value alpha(c), typically in the range 0.5-0.7, is derived for a variety of forest types. Parameter alpha determines the degree to which the carbon accumulated in harvested biomass offsets the loss of carbon in trees due to felling and in soils due to reduced litter input. When alpha > alpha(c), long-term carbon storage is optimized by harvesting for maximum sustained yield.     

南亚热带杉木人工林材种结构长期立地与密度效应

[目的]揭示南亚热带杉木人工林材种发育的长期立地和密度动态效应规律。[方法]以广西大青山A(1 667株·hm^-2)、B(3 333株·hm^-2)、C(5 000株·hm^-2)、D(6 667株·hm^-2)、E(10 000株·hm^-2)5种初植密度、36 a生杉木(Cunninghamia lanceolata)密度试验林为研究对象,分析密度和立地影响下材种株数与材种材积分布的动态变化规律。[结果]杉木林分小径材株数和材积比率在初期随林龄增长而递增,达峰值后随林龄增长而减少,初植密度越小、立地指数级越高,减少速度越快;中、大径材株数和材积比率随林龄增长而增加,初植密度越小、立地指数级越高,增速越快。18立地指数级D及以下密度林分28 a生前中径材材积比例约50%;36 a生时A密度林分大径材材积比例约50%。16立地指数级中低初植密度林分中径材材积比例均超过45%,且以C密度林分最高、约48%;36 a生时A密度林分大径材材积比例超过26%。14立地指数级,A密度林分中径材材...     

杨树工业用材林培育技术研究

本文通过对培育杨树工业用材林的立地条件,栽培品种选择,合理密度及最佳轮伐期的确定,以及栽植,林分抚育管理等关键技术措施的论述,为实现定向,速生,丰产,优质,稳定和高效的培育目标,建立了辽宁省的杨树工业用材林基地,提供了可靠的技术保障。     

Managing forests for wood yield and carbon storage: a theoretical study

Which forest management regimes best achieve the dual objectives of high sustained timber yield and high carbon storage, including the carbon stored in soil and wood products? A mechanistic forest ecosystem simulator, which couples carbon, nitrogen and water (Edinburgh Forest Model), was calibrated to mimic the growth of a pine plantation in a Scottish climate. The model was then run to equilibrium (1) as an undisturbed forest, (2) removing 2.5, 10, 20 or 40% of the woody biomass each year (3) removing 50% of the woody biomass every 20 years, and (4) clear-felling and replanting every 60 years as in conventional plantations in this climate. More carbon was stored in the undisturbed forest (35.2 kg C m(-2)) than in any regime in which wood was harvested. Plantation management gave moderate carbon storage (14.3 kg C m(-2)) and timber yield (15.6 m(3) ha(-1) year(-1)). Notably, annual removal of 10 or 20% of woody biomass per year gave both a high timber yield (25 m(3) ha(-1) year(-1)) and high carbon storage (20 to 24 kg C m(-2)). The efficiency of the latter regimes could be attributed (in the model) to high light interception and net primary productivity, but less evapotranspiration and summer water stress than in the undisturbed forest, high litter input to the soil giving high soil carbon and N(2) fixation, low maintenance respiration and low N leaching owing to soil mineral pool depletion. We conclude that there is no simple inverse relationship between the amount of timber harvested from a forest and the amount of carbon stored. Management regimes that maintain a continuous canopy cover and mimic, to some extent, regular natural forest disturbance are likely to achieve the best combination of high wood yield and carbon storage.     

Optimal management of Korean pine plantations in multifunctional forestry

Korean pine is one of the most important plantation species in northeast China.Besides timber,it produces edible nuts and plantations sequester carbon dioxide from the atmosphere.This study optimized the management of Korean pine plantations for timber production,seed production,carbon sequestration and for the joint production of multiple benefits.As the first step,models were developed for stand dynamics and seed production.These models were used in a simulation–optimization system to find optimal timing and type of thinning treatments and optimal rotation lengths.It was found that three thinnings during the rotation period were optimal.When the amount or profitability of timber production is maximized,suitable rotation lengths are 65–70 years and wood production is 5.5–6.0 m~3 ha~(-1) a~(-1).The optimal thinning regime is thinning from above.In seed production,optimal rotation lengths are over 100 years.When carbon sequestration in living biomass is maximized,stands should not be clear-cut until trees start to die due to senescence.In the joint production of multiple benefits,the optimal rotation length is 86 years if all benefits(wood,economic profits,seed,carbon sequestration) are equally important.In this management schedule,mean annual wood production is 5.5 m~2 ha~(-1) and mean annual seed yield 141 kg ha~(-1).It was concluded that it is better to produce timber and seeds in the same stands rather than assign stands to either timber production or seed production.     

Do multipurpose companion trees affect high value timber trees in a silvopastoral plantation system?

Establishment of native timber trees on deforested land may contribute to the livelihood of farmers, to improved ecosystem services and to increased greenhouse gas uptake. Here, we present a new silvopastoral planting design to assess species performance and interspecific competition or facilitation effects among native timber and multipurpose trees in Central America. Two timber species, Tabebuia rosea and Cedrela odorata, were established in three low-density planting regimes allowing combined tree and future livestock production: (1) solitary planting, (2) companion planting with Guazuma ulmifolia, and (3) companion planting with the nitrogen-fixing Gliricidia sepium. We quantified survival, growth and reforestation potential of the two timber species subjected to the different planting regimes for the first 2 years after establishment. Nitrogen concentration as well as stable nitrogen and carbon isotope composition (δ¹⁵N, δ¹³C) of leaves of the timber saplings were determined. T. rosea showed higher survival and better growth than C. odorata under varying environmental conditions (soil, concomitant vegetation). Performance of the timber saplings was unaffected by either companion species. Planting regimes had no effect on foliar nitrogen concentration and δ¹⁵N of the two timber species, although δ¹⁵N values indicated nitrogen fixation activity in G. sepium trees. Planting regimes affected foliar δ¹³C values in T. rosea. δ¹³C values were significantly higher in solitarily growing individuals, suggesting lower exposition to water stress conditions in saplings surrounded by companion species. As we found positively correlated growth traits among timber and multipurpose trees, a combined planting may benefit farmers by providing additional goods and services.     

杉木人工林材种结构的立地及密度效应研究

采用30年生未间伐的杉木人工林连续观测数据,研究了不同林龄立地质量、林分密度对林分材种结构的影响。结果表明:初植密度相同时,立地质量越好各材种出现时间及达到最大出材率的时间越早,22立地指数初植密度1 667株·hm^-2的小径材最大出材率出现时间较16立地指数初植密度1 667株·hm^-2早4 a,中径材最大出材率出现的时间早6 a;立地指数相同时,随初植密度增加小径材出材率的峰度及峰值均减小,20立地指数样地中,初植密度为1 667株·hm^-2的小径材出材率峰值较初植密度为10 000株·hm^-2的高17%,而初植密度对中径材、大径材影响不大;在林分发展的不同时期,林分密度对材种出材率的影响不同,30年生时林分蓄积相近的但初植密度不同的样地,初植密度越大小径材出材率越高,大径材出材率越低。     

纸浆材人工林复合轮伐期的讨论

针对我国纸浆材人工林的经营现状和存在的问题,本文提出了复合轮伐期的概念。纸浆材人工林实行复合轮伐期经营的材积收获量,将比单一轮伐期经营高出20%,再加上复合轮伐期生产的大径锯材市场价格高的因素,相应的经济收益将高出更多。复合轮伐期充分利用了地力和林木生长的潜力,它不仅是纸浆材轮伐期和大径锯材轮伐期的复合,也是经营目的的复合,体现了现代林业多目标培育林木的经营原则。     

Effects of using certain tree species in forest regeneration on volume growth,timber yield,and carbon stock of boreal forests in Finland under different CMIP5 projections

We studied how the use of certain tree species in forest regeneration affected the volume growth, timber yield, and carbon stock of boreal forests in Finland under the current climate (1981–2010) and recent-generation global climate model (GCM) predictions (i.e., multi-model means and individual GCMs of CMIP5), using the representative concentration pathways RCP4.5 and RCP8.5 over the period 2010–2099. Forest ecosystem model simulations were conducted on upland national forest inventory plots throughout Finland. In a baseline management regime, forest regeneration was performed by planting the same tree species that was dominant before the final cut. In alternative management regimes, either Scots pine, Norway spruce, or silver birch were planted on medium-fertility sites. Other management actions over rotation were done as in a baseline management. Compared to baseline management, an increased planting of birch resulted in relative sense highest increase in the volume growth, timber yield, and carbon stock in forests in the south, especially under severe climate projections (e.g., multi-model mean RCP8.5, and GCMs such as HadGEM2-ES RCP8.5 and GFDL-CM3 RCP8.5). This situation was opposite for Norway spruce. In the north, the volume growth, timber yield, and carbon stock of forests increased the most under severe climate projections (e.g., multi-model mean RCP8.5 and CNRM-CM5 RCP8.5), regardless of tree species preference. The magnitude of the climate change impacts depended largely on the geographical region and the severity of the climate projection. Increasing the cultivation of birch and Scots pine, as opposed to Norway spruce, could be recommended for the south. In the north, all three species could be cultivated, regardless of the severity of climate change.     

Optimal forest rotation periods: integrating timber production and carbon sequestration benefits in Pinus tabulaeformis plantations on the Loess Plateau,P.R. China

Determining the optimal rotation period was a crucial component of forest sustainable management strategies, especially under climate change. This paper had two objectives: (1) to determine the economic benefits and optimal rotation periods for timber production when coupled to carbon sequestration, as predicted by time series prediction models for Pinus tabulaeformis plantations in China; and (2) to evaluate how different carbon prices and interest rates affected optimal rotation periods using the forest land expectation value. The results suggested that time series prediction models were valuable for estimating timber volumes and carbon sequestrations based on surveys of different-aged stands. Importantly, since integrating carbon sequestrations into timber production benefits did not increase optimal rotation periods, this should promote P. tabulaeformis plantation management. In the sensitivity analysis, a higher carbon price increased the profitability of carbon sequestration and timber production, but not optimal rotation periods, though they were reduced under higher interest rates. In conclusion, incorporating both timber production and carbon sequestration benefits would sharply increase forest-based revenues, while realizing the carbon sequestration potential of P. tabulaeformis plantations. This approach was clearly useful to the development of reforestation/afforestation projects trying to mitigate climate change and also provided a theoretical basis for sustainable forest management.     

西双版纳天然林保护与林业可持续发展

西双版纳天然林保护工程的实施对制止区内的环境退化和资源危机,协调人与自然的关系具有重要的作用.在天然林保护工程的实施过程中,对区域的经济、社会和文化造成了一定的影响.为保障社区林业的可持续发展,针对天然林保护给社区带来的影响,提出了发展非木材产品,加强经济林果的发展以及营造速生丰产林和薪炭林的对策,以实现西双版纳的天然林保护和林业可持续发展.     

不同栽植代数29年实生杉木生长规律的研究

通过对南平溪后２９年实生杉木不同连栽代数生长过程的分析,结果表明：１代和２代杉木在１０年生前树高、胸径和材积的生长量相近,此后,２代的生长迅速下降（早衰）,２９年生的平均单株材积比１代的下降４１４６％。３代杉木树高、胸径和材积生长一开始就比２代的差,但未出现大幅度的衰退现象,２９年生的单株材积比２代的下降１７７０％。杉木栽植代数越少,生长高峰出现时间越早,峰值越大,速生期持续时间亦越长。     

Optimum stand density of Chinese pine forests in Taihang limestone mountains, Shanxi Province

lntroductionChinesepine(Pinust8blaeformNisoneofthemostimportanttreespeciesforafforestationandwidelyspreadinTaihanglimestonemountains,ShanxiProvince.Ittakes85%ofthetotaIareaofpIantations.ChinespineplantationsplantedaremainIyforpurposeofsoiIandwaterconservationandtimber.TheinvestigationofChinesepinepIantationsmadelastdecadeshowedthat,accordingtotheirsitecondition,theexistingstandsdidnotmeettheappro-priatedensity.Standsstructureisuniform.Waterlossandsoilerosionareserious,andsoiffertilitygetd…     

A statistical analysis of spatiotemporal variations and determinant factors of forest carbon storage under China’s Natural Forest Protection Program

The Natural Forest Protection Program (NFPP) is one of the key ecological forestry programs in China. It not only facilitates the improvement of forest ecological quality in NFPP areas, but also plays a significant role in increasing the carbon storage of forest ecosystems. The program covers 17 provinces, autonomous regions, and municipalities with correspondingly diverse forest resources and environments, ecological features, engineering measures and forest management regimes, all of which affect regional carbon storage. In this study, volume of timber harvest, tending area, pest-infested forest, fire-damaged forest, reforestation, and average annual precipitation, and temperature were evaluated as factors that influence carbon storage. We developed a vector autoregression model for these seven indicators and we studied the dominant factors of carbon storage in the areas covered by NFPP. Timber harvest was the dominant factor influencing carbon storage in the Yellow and Yangtze River basins. Reforestation contributed most to carbon storage in the state-owned forest region in Xinjiang. In state-owned forest regions of Heilongjiang and Jilin Provinces, the dominant factors were forest fires and forest cultivation, respectively. For the enhancement of carbon sequestration capacity, a longer rotation period and a smaller timber harvest are recommended for the Yellow and Yangtze River basins. Trees should be planted in state-owned forests in Xinjiang. Forest fires should be prevented in state-owned forests in Heilongjiang, and greater forest tending efforts should be made in the state-owned forests in Jilin.     

Financial feasibility of increasing carbon sequestration in harvested wood products in Mississippi

Longer forest rotation ages can potentially increase accumulation of carbon in harvested wood products due to a larger proportion of sawlogs that can be used for manufacturing durable wood products such as lumber and plywood. This study quantified amounts of carbon accumulated in wood products harvested from loblolly pine (Pinus taeda L.) stands grown in Mississippi by extending rotation ages traditionally used to manage these stands for timber. The financial viability of this approach was examined based on carbon payments received by landowners for sequestering carbon in standing trees and harvested wood products. Results indicated a potential to increase carbon accumulated in wood products by 16.11 metric tons (t) of carbon dioxide equivalent (CO₂e) per hectare (ha) for a rotation increase of 5 years and 67.07 tCO₂e/ha for a rotation increase of 65 years. Carbon prices of $50/tCO₂e and $110/tCO₂e would be required to provide a sufficient incentive to forest landowners to extend rotations by 5 and 10 years, respectively. With 2.8 million ha of loblolly pine stands in Mississippi, this translates to a possible increase in wood products carbon of 45 million tCO₂e and 80 million tCO₂e for harvest ages increased by 5 and 10 years, respectively. Higher carbon prices lengthened rotation ages modestly due to low present values of carbon accumulated with long rotations.     

Initial Responses to Fertilizing Eucalyptus grandis at Planting are Sustained until Harvesting

The results of six fertilizer experiments with Eucalyptus grandis are discussed and the development of various tree parameters with age are studied. It is shown that in the initial years of growth mean height and breast height diameter are increased as a result of fertilizing at the time of planting, but the absolute differences between fertilized and unfertilized trees remain more or less constant with increasing age. Fertilizing increases total basal area also, and consequently timber yield, but this increase becomes greater up to at least nine years of age or final felling. These increases in timber yield economically justify fertilizing at planting. Brief recommendations are given of how best to conduct field experiments designed to study fertilizer application.     

Growth and yield of some indigenous trees in an Amazonian agroforestry system: a rural-history-based analysis

Over the years farmers of Japanese descent in the Brazilian Amazon have planted indigenous trees that yield various products and services: fruit, seeds,bark, latex, oil, and shade and wind breaks for understory crop plants. Production of timber is often the intended end use of such planted trees. Long-term growth performance of these trees nevertheless has not been well documented. The authors constructed 65-year growth curves for nine indigenous tree species based on measurements of diameter at breast height (dbh), height, and tree age data provided by farmers in the Brazilian State of Pará. An index of wood prices used to calculate state stumpage taxes was then applied to mean stem wood growth curves to produce price curves. These price curves estimate both present value of standing timber, and the value added from annual growth of standing timber in the agroforestry systems studied. The results of this study provide local farmers with a tool to estimate potential annual income from the growth of their trees, and a basis for planning timber harvest rotations. This study's approach may be applicable in other parts of the tropics, where growth information about indigenous trees commonly used in agroforestry is lacking.This revised version was published online in November 2005 with corrections to the Cover Date.     

Growth, herbivore distribution, and herbivore damage of timber trees in a tropical silvopastoral reforestation system

Context

The reforestation of degraded tropical pastures requires innovative tree planting systems that consider land user needs.

Aim

We established a silvopastoral reforestation system and assessed the effects of companion trees on the native timber tree Tabebuia rosea in Panama. Timber tree individuals were established in (1) solitary plantings (TSol) or in companion plantings with (2) Guazuma ulmifolia (TGua) or (3) the nitrogen-fixing Gliricidia sepium (TGli).

Methods

We quantified growth characteristics and herbivory of T. rosea, and analyzed leaf chemistry (including the stable isotopes ??¹⁵N and ??¹³C) and structure (leaf mass per area).

Results

Companion trees significantly affected stem diameter growth of T. rosea. Stem diameter growth was as high in TGli trees as in TSol trees but was reduced in TGua trees. Furthermore, TGua trees had higher leaf water content, and lower ??¹³C and lower leaf mass-to-area ratio than TGli trees, suggesting there were effects of shading by G. ulmifolia on T. rosea. Herbivory was high but not affected by planting regimes. Leafing phenology did not differ between planting regimes and G. sepium did not increase nitrogen content in T. rosea leaves.

Conclusion

Companion tree planting can support timber tree growth in silvopastoral reforestations, but adequate species selection is crucial for successful implementation of this planting system. Tree?Ctree interactions seem to be more relevant for timber tree growth than herbivory in the studied system.     

目标规划与轮伐公式确定森林收获的比较分析

利用中国林科院热带林业实验研究中心2009年森林资源二类调查数据,分别利用目标线性规划与传统森林轮伐公式计算热林中心马尾松纯林和杉木纯林用材林年采伐量,比较分析同一个经理期（2009—2019年）两种计算方法的不同;结果表明：轮伐公式计算的采伐量一般偏大,且目标规划单位面积年经济收益是轮伐公式获得经济效益的10 20倍。利用目标规划法在同时实现材积收获量最大、出材量最大、净现值收益最大的目标前提下,对森林结构进行调整,使资源分布满足可持续经营的要求,即尽可能达到法正状态。     

广东郁南51年生灰木莲生长研究

研究以广东省郁南林场大东坑工区内 51 年生灰木莲 Manglietia conifera 为研究对象，对灰木莲树高、胸径、材积、树干通直度、侧枝生长习性等指标进行调查和分析。结果表明：51 年生灰木莲生长良好，胸径平均为 44.28 cm，最大为 79.60 cm，树高平均为 20.79 m，最高为 27.00 m，单株材积平均为 1.48 m3，最高为 3.65 m3。可见，灰木莲引种在广东郁南适应性强，能够生长良好，具有生长速度快，树干通直，自然整枝好等特点，是该地区可以推广种植和培育大径材的优良树种。