Computer Simulation of Fiber Length and Width Distribution for Two Poplar Woods

1 INTRODUCTIONPoplar is the major afforestation species in China, andhas been used for pulping since 1960s (Xu Weiying,1988). Fiber morphology makes remarkable effectson quality of paper, and attract great attention (KurtH M, Lynch D L, 2001).The quantification, via modeling, of the variation inwood properties is usually accomplished usingstatistical techniques. Fundamental of theseapplications is a variety of probability distributions(Melo, et al, 2000). Due to considerable degree of…     

Forest plant and macrofungal differences in the Greater and Lesser Khingan Mountains in Northeast China: A regional?historical comparison and its implications

Forests in Northeast China in the Greater and Lesser Khingan Mountains (GKM and LKM) account for nearly 1/3 of the total state-owned forests in the country. Reg...     

Influence of volcanic ash deposits on the radial growth of trees in Central Mexico: the case of Parícutin volcano

The impact of volcanic eruptions on humans and infrastructure has been significant and widely documented. However, the impact on forests covered by ash or tephra has not been as widely known or documented. This research evaluated the ashfall effects of the 1943–1952 Parícutin eruption on the radial growth of trees located near the top and flanks of the Tancítaro stratovolcano, ca.10 km southwest of the Parícutin volcano. We carried a dendrochronological sampling out in a temperate forest dominated by Pinus hartwegii and Abies religiosa trees. A ring-width chronology was built with 68 increment cores from 47 trees showed two statistically significant suppression events. The first event occurred from 1943 to 1946; it was caused by falling ash of the eruptive columns from Parícutin during the first 6 months of its eruption (February–June 1943). The second event occurred from 1818 to 1823, and it is attributed to the 1818 eruption of Volcán de Colima. The 1943–1946 suppression event observed in the tree rings demonstrates that trees are useful as palaeoenvironmental archives to evaluate the influence of volcanic eruptions in recent centuries in the Trans-Mexican Volcanic Belt. Our results indicate that falling ash immediately impacted the growth of trees in intertropical mountain zones of the Michoacan state located in the Michoacán-Guanajuato Volcanic Field. Such impact means that future eruptions may cause damage to crops and trees at the local and regional levels. Our findings contribute to evaluating volcanic hazards and risks in areas with active volcanoes and monogenetic volcanic fields.

     

Wood Use and Forest Management for Carbon Sequestration in Community Forestry in Sierra Juárez,Mexico

Forest managers and policy-makers are being encouraged to incorporate carbon sequestration as a criterion for decision-making. This is a great challenge for small-scale forestry where the conspicuous lack of practical knowledge available for managers prevents the implementation of criteria to promote carbon sequestration. The carbon simulation model CO2FIX combined with local data could provide valuable information for C sequestration in these small-scale forestry systems. The research reported here focuses on community forestry located in the Juarez Mountain Range (Oaxaca State, Mexico), and analyzes the influences of forest management and wood-use (20 scenarios based on five forest management plans and four wood-use strategies) on the changes of C stock (biomass C, soil organic C, products C and fuelwood C) over time. The comparison of the whole stocks to reference results show that group-selection, based on an uneven-aged forest management system involving small patches, has only about half the C benefit relative to clear-cutting harvesting. A forest management strategy focused on oak logwood has a lower C benefit (70 %), and a forest management strategy focused on oak fuelwood has a higher C benefit (120 %) relative to the average of the studied wood-use strategies. Thus, in the study area forest managers and policy-makers who wish to mitigate climate change should increase the rotation period from 40 to 50 years in clear-cutting areas, continue with 40 years in group-selection areas, and promote the use of oak for bioenergy.     

Spatio-temporal distribution of Hylobius abietis in Scots pine stands – implications for pest monitoring

Journal of Pest Science - The protection of reforested areas against the large pine weevil Hylobius abietis is one of the greatest forest management challenges in many European countries. No...     

Distribution of cranes in Hulunber Grassland and Daxing’an mountains forest region in inner Mongolia

The Daxing’an Mountains and Hulunber Grassland are located in the northeastern border area of China. This region covers a large area of rich biodiversity. The natural environment here is well protected because of low pressure of human activity. There are 5 species of cranes here. They are Red-crowned crane (Grus japonensis), White-napped crane (Grus vipio), Siberian White crane (Grus leucogeranus), Grey crane (Grus lifordi) and Demoiselle crane (Anthropoides virgo). Red-crowned crane is a breeding species that is widely distributed in this area. The main breeding population of this species is in Heilongjiang Province. They migrate to the south of China in winter. White-napped crane, Grey crane, Demoiselle crane are also summer birds. It remains unknown if Siberian White crane breeds here. Since the population of Red-crowned crane, White-napped crane, Siberian White crane in China are at the edge of endangering, so they are listed in the namelist of national protected species. But Grey crane, Demoiselle crane have a larger population, and are widely distributed. (Responsible Editor: Zhu Hong)     

Degraded Ecosystem and its Rehabilitating Measures in Sandy Areas of North China

Ecosystem degradation occurs in parallel with desertification process in sandy areas of North China. The vast sandy areas in North China are characterized with flexible environments and fragile ecosystems as well as intensive human activities. Due to the annual precipitation gradient decreases from east to west in North China, the whole sandy region falls into 3 main climatic zones: arid, semi-arid and dry sub-humid zones.The ecosystems in each type of climatic zones are different in climatic conditions, human activities, cultural dimensions, vegetation covers, landscapes, and causes and processes of ecosystem degradation. Therefore, the most effective rehabilitation measures of degraded ecosystems in different types of the climatic zones are also different. For the arid sandy areas, vegetation rehabilitation of degraded ecosystems needs to be completely closed, assisting with artificial measures, such as plantation, irrigation or others. For semi-arid sandy areas, the effective measures of vegetation re     

Carbon storage in harvested wood products: implications of different methodological procedures and input data—a case study for Portugal

This study aims to quantify the contribution of the harvested wood products (HWP) to the carbon removals/emissions by the agriculture, forestry and land-use sector (hereafter referred to as HWP contribution) using the tier 1 method proposed by the Intergovernmental Panel on Climate Change (IPCC) in the 2006 Guidelines (hereafter referred to as GL tier 1 method) and to compare it with the results obtained with the tier 2 method proposed by the IPCC in the Good Practice Guidance for Land Use, Land-Use Change and Forestry (hereafter referred to as GPG tier 2 method). The HWP contribution was calculated for three approaches: stock change, production and atmospheric flow. Another objective was to perform a sensitivity analysis in order to identify the calculation procedures and the input data that have the largest impact on the HWP contribution estimates. An uncertainty analysis was also carried out with Monte Carlo simulation. The case study of Portugal was analysed in this study. The HWP contribution obtained with the GL tier 1 method ranged from 150 to 1,240 Gg C year⁻¹, for the period from 1990 to 2004. These results are similar to those obtained with the GPG tier 2 method, except for the production approach, since the GL tier 1 method underestimated carbon accumulation in solid waste disposal sites (SWDS) under this approach. The most influential calculation procedures and input data were the algorithm used to calculate the change in carbon stocks for the pools that follow a first-order decay, the procedure to estimate the input of carbon to the pool of HWP in SWDS, the procedure to determine the change in carbon stocks of HWP in SWDS for the production approach, the type of carbon stocks considered in SWDS and the conversion factor for wood-based panels.     

Farmers’ objectives toward their woodlands in the upper Midwest of the United States: implications for woodland volumes and diversity

This paper reports the results of a study that explores the relationship between farm woodland owners’ stated intentions for owning woodland, and the structure and composition of these woodlands in the states of Illinois, Indiana and Iowa in the upper Midwest of the United States. Data from two sample-based inventories conducted by the USDA Forest Service, Forest Inventory and Analysis (FIA) program were combined for this analysis—the FIA forest resources inventory and the National Woodland Owner Survey (NWOS). We looked for relationships between product value and investment in woodlands, as reflected in volumes and tree quality. We also examined whether measures of diversity reflected specific management focus. Our results partially supported our hypotheses. Woodland-focused ownership reasons were found to have larger volumes and individual tree sizes. We found that a passive woodland ownership reason—that woods were “part of the farm”—generally had lower volumes per hectare. Although we were not able to differentiate between different forest product classes and measures of volume, we did find that those landowners who harvested veneer had more volume than those who harvested for firewood. Woodland owners who salvage-harvested their woodlands—a harvesting reason that is more reactive than proactive—exhibited lower volumes per hectare than those who harvested for more proactive, product-focused reasons. Biodiversity was also found to be related to the ownership focus and harvest intent. Generally, there was lower diversity in overstory species when the woodland was viewed merely as “part of the farm,” when the product harvested was fence posts and when timber was harvested for salvage or land clearing. The small sample size limits our analysis, but we can conclude that focusing the woodland owners on management of their woodlands—regardless of what the specific management goals might be—should increase productivity and biodiversity of those woodlands.

Parallel Study on Potential and Existing Geographical Distribution of Haloxylon Dominated Desert Vegetation in China

Potential vegetation or natural vegetation refers to the vegetation developed when vegetation and climatic condition have reached a balance under modern climatic conditions (Qin Dahe 2002). Existing vegetation or actual vegetation refers to the mosaic of existing vegetation observed currently(Mueller-Dombois et al. 1986). The definition of potential vegetation implies that the potential vegetation is built on the basis of the relationship between existing vegetation and modern climate, contai…     

Analysis on the Spatial Distribution and Evolutionary Trends of Farmers’ Forestry Income in China

With regard to the implementation of the Collective Forestry Tenure Reform in China, the proportion of forestry income in farmers’ total family income has gradually increased with rapid increases observed in some provinces. Due to these regional disparities, it is important to analyze the spatial distribution and evolutionary trends of farmers’ forestry income to uncover the underlying factors for the existing distribution and note gradual changes from the perspective of economic geography. When spatial distribution and evolutionary trends of farmers’ forestry income data from 31 provinces from 2000 to 2012 were analyzed, we found that farmers’ forestry income during the 13-yr period grew quickly, but the disparities between the highest and lowest income rates gradually widened as large increases in income within a few provinces constituted the bulk of the overall increase across China. We attribute the observed spatial distribution and evolutionary trends to an imbalanced distribution of forestry resources, varying forest species, complicated forestry ownership, multiple forestry policies, differences of labor, and forestry investment.     

A New Function for Modelling Diameter Frequency Distribution in the Tropical Rain Forest of Xishuangbanna, Southwest of China

Permanent plots in the montane tropical rain forests in Xishuangbanna, southwest China, were established, and different empirical models, based on observation data of these plots in 1992, were built to model diameter frequency distributions.The focus of this study is on predicting accuracy of stem number in the larger diameter classes, which is much more important than that of the smallcr trees, from the view of forest management, and must be adequately considered in the modelling and estimate.There exist 3 traditional ways of modelling the diameter frequency distribution: the negative exponential function model, limiting line function model, and Weibull distribution model. In this study, a new model, named as the logarithmic J-shape function, together with the others, was experimented and was found as a more suitable model for modelling works in the tropical forests.     

Distribution and development strategy for Jatropha curcas L. in Yunnan Province, Southwest China

Yunnan Province is the main distributing area of Jatropha curcas L. This plant is abundant in several drainage areas of the dry-hot, dry-warm and sub-humid valleys in the south subtropical area of Yunnan Province. The seeds that were picked from trees blossoming between April and May and fructifying between September and October will have large seed yield and fine quality. For developing bio-diesel stock forest of J. curcas in areas with adaptive climate, seeding measures for afforestation should be taken and techniques on breeding, fast-growing, and high-yielding plantation cultivation are very important.     

Canopy disturbance and intertree competition: implications for tree growth and recruitment in two yellow birch–conifer stands in Quebec, Canada

Composition, structure, and species-specific patterns of recruitment and growth were characterized in two yellow birch (Betula alleghaniensis Britt.)–conifer stands in Quebec, Canada, to improve our understanding of the dynamics of these complex ecosystems. The mixture of mid- and shade-tolerant species in the canopy, the inverse J-shape stem diameter distribution, and the age distribution were indicative that the two stands were in a late-successional stage. Recruitment of mid-tolerant species above 1.3 m in height appeared to be periodic and synchronized with historical spruce budworm (Choristoneura fumiferana Clem.) outbreaks, while the coniferous component of these mixedwood stands recruited continuously. Results suggest that recruitment of yellow birch and red maple (Acer rubrum L.) requires disturbances of a certain intensity that affect at least 25 % of the forest cover. In contrast, balsam fir (Abies balsamea (L.) Mill.) and red spruce (Picea rubens Sarg.) can recruit under the canopy without relying on moderate or large canopy disturbances. Results suggest that the historical disturbance regime, and differences in shade tolerance between species, largely govern the contemporary composition of these stands. This study improves the comprehension of mechanisms that regulate the dynamics of yellow birch-conifer stands and will be useful for the subsequent elaboration of forest management strategies.     

Stream water quality and its influencing factor in lower order streams in upriver sections of Ashihe River

For understanding the reasons that caused the degradation of water quality in lower order streams, systematic sampling was conducted at different spatial locations aiong the low order streams （1 st-5th） of Ashihe River continuum in Maoershan Experimental Forest of Northeast Forestry University, Sharlgzhi City, Heilongjiang Province, China. The indexes of stream water quality, i.e., the pH, dissolved oxygen（DO）, turbidity, temperature, PO43-P, NO3-N and NH4^＋-N concentrations, total dissolved inorganic nitrogen （TDIN-N, including concentrations of NO3^＋-N and NH4^＋-N）, and total phosphorus （inorganic and organic phosphorous, TP） were measured and analyzed. The stream order, related environmental settings and land-use type were recorded for each sampling location. The indexes of stream water quality at different locations with different stream orders and land use types were compared by ANOVA analysis. The indexes of stream water quality at different sampling locations were analyzed by Hierarchical cluster analysis. Result showed that water quality had significant difference in different stream orders and land use types; some locations with different stream features （stream order and land use type） were grouped into same clusters, indicating that random disturbances produced the variations in water quality, which made the spatial variances of stream water quality inconsistent with the general rules.     

The Property of Soil Loss and the Time Distribution on Forest Stand in Granite Region of the Three-gorges of the Yangtze River

本文研究了长江三峡花岗岩地区林地土壤流失特性．结果表明由鳞片状面蚀导致的土壤流失量月分布与月降雨量的分布趋势基本一致，二者呈现出较为明显的线性相关关系．植物盖度≥０．７０的林地土壤流失多集中发生在６～９月份，土壤流失量在５０００ｔ·ｋｍ－２·ａ－１以下．盖度＜０．７的林地土壤流失年内分布时间多在３～１０月份，土壤流失量为５００～６０００ｔ·ｋｍ－２·ａ－１．     

Response of Somatal Characteristics and its Plasticity to Different Light Intensities in Leaves of Seven Tropical Woody Seedlings

1 INTRODUCTIONAs an important structure in the leaves of terrestrialplants, stomata play a key role in the gas exchangebetween plants and atmosphere, and provide the mainchannels of water dissipation for plants. They also playa significant part in the regulation of photosynthesisand evaporation process. Researches have long beenconducted on stomata, and one of the most importantfields in plant physiological and ecological research isconcerned with the physiological and ecologicalcharacteri…     

Interpolating Topographic and Climatic Data for Spatial Analysis of Environment in China

Climate is a dominant environmental factor in building ecosystem structure and driving biotic dynamics with topographic dependence on spatial distribution. This paper demonstrates the application of interpolation technique to describe spatial climate distribution. A digital elevation model (DEM) in resolution of 0.01 degree of latitude and longitude has been developed because the incorporation of spatial dependence on topography is crucial to accuracy of interpolation. Climate data from sparse and discrete network stations were used to fit thin plate smoothing spline surfaces for monthly temperature and precipitation, which enable the regular gridded climate data set to be produced by coupling spline surfaces with underlying DEM. The summary statistics show the interpolation errors of monthly temperature varying between 0.4-0.9 ℃ and monthly precipitation, within 6%~ 11%, much better than the results of other methods. The fine resolution DEM and spatial climate data can be used as baseline of climate c