Shrubby legumes for fallow improvement in northern Laos: establishment, fallow biomass, weeds, rice yield, and soil properties

An experiment was carried out in a slash-and-burn production system in northern Laos to evaluate legume establishment methods and effects of legume species on fallow vegetation, weeds, yield of upland rice, and soil parameters. Cajanus cajan, Calliandra calothyrsus, Crotalaria anagyroides, Flemingia congesta, Leucaena leucocephala, and Sesbania sesban were dibbled separately or mixed with rice. Legume and planting method had no effect on rice yield. Legume establishment was slightly improved and vigor after rice harvest was higher when planted in separate hills. Compared to control (no legume), the above ground fallow biomass observed 13 months after establishment, consisting mostly of Chromolaena odorata, was reduced by 68% with C. anagyroides and by 40% with L. leucocephala, while other species had no effect. Most of the C. cajan and S. sesban plants died. In March 1995, 22 months after planting, the biomass was 0.21, 0.25, 1.62 and 2.56 kg m^-2 for F. congesta, C. calothyrsus, C. anagyroides, and L. leucocephala, respectively. Legume species had no effect on rice yield or weed biomass in the rice crop. The species tested can influence fallow vegetation but do not allow for field preparation without burning. Compared to mulching, burning of residue reduced weed biomass by 42%, soil organic C by 9% and the C/N ratio by 6% but increased extractable P by 90% and pH by 8%. This revised version was published online in August 2006 with corrections to the Cover Date.     

Theories of swidden agriculture,and the political economy of ignorance

Swidden agriculture is today the focus of a great deal of debate in the context of agroforestry development in humid, tropical countries. This paper argues that much of this debate deals not with the empirical facts of swidden agriculture, however, but rather with widely-accepted myths, and that this explains the widespread failures of developmental schemes involving swidden agriculturalists. The paper examines three of these myths in some detail. One myth is that swidden agriculturalists own their land communally (or not at all), work it communally, and consume its yields communally. The truth is that their land (including land under secondary forest fallow) is typically owned by individual households, it is worked by individual household labor forces and/or by reciprocal but not communal work groups, and its yields are owned and consumed privately and individually by each household. A second myth is that swidden cultivation of forested land is destructive and wasteful, and in the worst cases results in barren, useless grassland successions. The truth is that swidden cultivation is a productive use of the forests, indeed more productive than commercial logging in terms of the size of the population supported, and forest-grassland successions are typically a function not of rapaciousness but of increasing population/land pressure and agricultural intensification — the grasses, including Imperata cylindrica, having value both as a fallow period soil-rebuilder and as cattle fodder. A third myth is that swidden agriculturalists have a totally subsistence economy, completely cut off from the rest of the world. The truth is that swidden agriculturalists, in addition to planting their subsistence food crops, typically plant market-oriented cash crops as well, and as a result they are actually more integrated into the world economy than many of the practitioners of more intensive forms of agriculture. In the conclusion to the paper, in a brief attempt to explain the genesis of these several myths, it is noted that they have generally facilitated the extension of external administration and exploitation into the territories of the swidden agriculturalists, and hence can perhaps best be explained as a reflection of the political economy of the greater societies in which they dwell.     

Recovery of floristic diversity,composition and structure of regrowth forests on fallow lands: implications for conservation and restoration of degraded forest lands in Laos

New Forests - In Laos, there are extensive shifting cultivation areas and regrowth forests spontaneously established on fallow lands. The aims of the study were to conduct a comparative study of...     

内蒙古红花尔基鸟类群落与植被类型相互关系研究

调查了内蒙北部红花尔基夏季鸟类群落,一共记录了28种鸟类。在每个实验地取5个10m×10m的样方进行植被调查。利用线性回归方程来确定植被郁闭度和鸟类数量和鸟类密度的关系。分析结果显示鸟类数量和鸟类密度的变化及鸟类群落的形成是随着森林类型和总植物量而变化。鸟类数量和密度都随总植物量的降低而减少。鸟类群落的相似性在繁殖时期非常低,在同一分类簇中,最大相似性不超过0.65。这表明鸟类群落间种类的构成存在着显著差异。鸟类的繁殖密度与森林的生长阶段具有密切的关系,一般情况下,从稀疏的草原生态系统到顶级生态系统鸟类的密度呈现逐渐增加的趋势。图3表4参21。     

Relationship between vegetation types,soil and topography in southern forests of Iran

For sustainable forest management, understanding the ecological factors that determine vegetation composition are important. Here, the relation between the vegetation composition and environmental factors(elevation, aspect, slope, CaCO_3, K, P, C, N, C/N, bulk density,soil porosity, saturation moisture content, EC, pH, sand, silt and clay) was investigated in the Khonj forests, Fars Province, Iran. Characteristic land units, each 200 m2, were chosen for sampling to analyze species composition, soil characteristics and topographic factors. The floristic data were classified using a two-way indicator species analysis(TWINSPAN). Means were then compared using an ANOVA and Duncan multiple range test to detect any variations between groups. Also, the Kaiser–Meyer–Olkin index and Bartlett test were used to measure sampling adequacy. The four vegetation groups identified comprised the species Achillea wilhelmsii, Tanacetum parthenium,Convolvulus spinosus, Capparis spinosa. A detrended canonical correspondence analysis(DCCA) ordination diagram clearly illustrated the relationship between vegetation and environmental factors. According to the results,group 1 with A. wilhelmsii as the indicator species has a positive relation with slope and elevation. T. parthenium was the indicator species of group 2, that appears in areas with high silt and low bulk density and sand. The results showed that group 3 with Convolvulus spinosus as the indicator species was distributed in soils with high bulk density, low silt and pH as well. Group 4 with C. spinosa as the indicator species occurs in sandy soils and low slopes.Using DCCA, we determined the relationship between species and environmental factors more accurately. Results of this study can be used to restore vegetation or maintain species composition in ecological sensitive areas.     

黑河地区火烧与森林虫害关系的初步研究

文章通过对黑河地区过火林地的虫害发生数量和种类的调查研究，表明樟子松和落叶松人工林在火烧后极易受到小蠹类和天牛类蛀干害虫的攻击。利用逻辑斯蒂回归分析表明，树干熏黑高度和胸径对虫害发生数量有一定影响但不是很显著。分别利用树干熏黑高度及其转换后的火强度与虫害发生数量进行一元线性回归分析，结果表明二者与虫害发生数量间的线性关系比较显著，火强度与虫害发生数量的线性关系更显著些。该结论可为火灾之后虫害发生量的预测提供依据。     

汪清林区天然林食叶害虫危害与林分的关系

为探讨汪清林区天然林中食叶害虫危害与林分特征的关系,在林区选取了针叶林、针阔混交林以及阔叶混交林3种类型林分共36块临时样地,比较了不同类型林分的食叶害虫为害率,分析了食叶害虫危害与立地条件、林分特征的关系.结果表明:不同林分间的食叶害虫为害率存在显著的差异,多重比较显示,食叶害虫为害率在林分间差异非常明显,即阔叶混交林＞针阔混交林＞针叶林;食叶害虫为害率与针叶树比例呈极显著的负相关,与林木Simpson指数呈极显著的正相关,与林木Shannon-Wiener指数呈极显著的正相关,同时食叶害虫为害率与林分郁闭度的关系显著.汪清林区天然林中食叶害虫危害格局符合“联合易感性”假说.     

森林文化与现代森林可持续经营关系的探讨

森林文化与森林可持续经营密不可分,本文阐述了森林文化与森林可持续经营的内涵,并对这二者关系进行了探讨,指出森林文化与森林可持续经营之间是唇齿相依、一脉相承、和谐发展、相互促进的关系。森林文化是现代林业建设中实现森林可持续经营管理的重要动力,是实现生态文明的必然要求。     

Relationships between floristic diversity and vegetation indices,forest structure and landscape metrics of fragments in Brazilian Cerrado

Favorable characteristics for development of agricultural activities were crucial factors in the fast substitution of the physiognomy of the Cerrado by agricultural crops and pastures. During this occupation process, the remaining natural vegetation became extremely fragmented and a little is known about the structural and functional integrity even about the species diversity of these ecosystems. The use of vegetation indices as indicators of the forest integrity has been shown to be a useful tool for environmental planning and also for conservation strategies. In this study, we analyzed the correlations between floristic diversity of 22 forests fragments, from diversity indices of Shannon and the equability of Pielou; and the structural parameters of communities represented by basal area and cylindrical volume. Correlations between the diversity and patch metric: AREA, PERIM, GYRATE, PARA, SHAPE, FRAC, CIRCLE, CONTIG, CORE, CAI, PROX and ENN obtained for fragments and among the indices NDVI, SAVI, EVI, MVI5 and MVI7 derived from TM/Landsat images acquired in two seasons were also evaluated. The index which presented strongest correlation with floristic diversity was EVI and the one that showed strongest correlation with the equability was MVI5. The structural parameters basal area and cylindrical volume did not present correlations with diversity and equability. The diversity and equability indices showed correlations with the fragment shape.     

舟曲林区森林苗圃灾害类型与主要气象因子的关系

介绍了舟曲林区森林苗圃灾害类型和主要危害形式,经分析该林区森林苗圃灾害与主要气象因子的关系后认为,该林区每年3~9月是森林苗圃灾害多发期,其中5月是灾害发生高峰期。同时,提出了该林区森林苗圃灾害控制措施。     

Upland agriculture,the land frontier and forest decline in the Philippines

Population pressure, expansion of small-scale agriculture and shifting cultivation are commonly cited as the causes of tropical deforestation. A close examination of deforestation and agriculture in the Philippine uplands reveals, however, that the vast majority of agriculturists must be sedentary farmers. In addition, the importance of population pressure as a cause of deforestation in the Philippines cannot be supported by the available evidence. Lastly, the concept of arable land is shown to be of limited value in discussing upland agriculture in the Philippines.     

三峡库区森林和土壤侵蚀关系研究

以三峡库区秭归县为对象,研究了森林植被特点和土壤侵蚀状况,结果表明,森林覆盖率与土壤侵蚀之间表现出较强的相关性,森林覆盖率上升,土壤侵蚀面积减少,侵蚀强度降低,在秭归境内森林覆盖率每上升一个百分点,土壤侵蚀面积减少16 km2,侵蚀模数下降91.2.tkm-2.a-1。在三峡库区秭归县内土壤侵蚀量要小于土壤允许流失量500 t.km-2.a-1,林分覆盖度需达到90%     

Relationship between vegetation carbon storage and urbanization: A case study of Xiamen, China

Rapid growth of the Chinese urban population and the expansion of urban areas have led to changes in urban forest structure and composition, and consequently changes in vegetation carbon storage. The purpose of this study is to quantify the effects of urbanization on vegetation carbon storage in Xiamen, a city located in southern China. Data used for this study were collected from 39,723 sample plots managed according to the forest management planning inventory program. Data from these plots were collected in 4 non-consecutive years: 1972, 1988, 1996 and 2006. The study area was divided into three zones, which were defined according to their level of urbanization: the urban core, the suburban zone, and the exurban zone. Total vegetation carbon storage and the vegetation carbon density for each study period were calculated for each zone. Our results show that urban vegetation carbon storage has increased by 865,589.71 t during the period from 1972 to 2006 (34 years) in Xiamen, with a rapid increase between 1972 and 1996, then relatively little change between 1996 and 2006. The increase in vegetation carbon storage is mainly due to the large percentages of the suburban and exurban areas which exist in Xiamen city, and the implementation of reforestation programs in these two zones. The percentage of total regional carbon storage in the city center (urban core), suburbs and exurbs was 5%, 23% and 72%, respectively. This demonstrates that the exurbs store the majority of vegetation carbon, and thus play a critical role in the vegetation carbon storage of the study area. The intensification of urbanization in the future will likely expand the urban core and reduce the area of the suburbs and exurbs, and thus potentially decrease total vegetation carbon storage. This article concludes with a discussion of the implications of these results for vegetation carbon management and urban landscape planning.     

Accumulation of airborne fluorides in forest trees and vegetation

The accumulation of fluoride in natural vegetation exposed to emissions from five aluminium smelter plants in Norway was studied during the years 1990–93. About 2000 leaf, bark and twig samples of 60 plant species, collected mostly during the growing season, were analysed. Rowan (Sorbus aucuparia) was widespread and common in the areas studied, and was used as a reference species. Fluoride concentrations in monthly samples of rowan leaves were linearly related to fluoride exposure (average fluoride concentration in ambient air × days since leaf emergence). The accumulation coefficient for rowan was estimated to be 1.7 m³/g dry wt. day. Most other species had values between 0.3 and 1.5; the median for all species was 0.8. The fern Dryopteris filix-mas was exceptional, containing on average three times greater fluoride concentrations man rowan. High background levels indicated that soil uptake contributed significantly to the fluoride accumulation in this species. The fluoride concentrations in bark and shoots of trees were mostly low compared with leaves, but the bark of Betula pendula and B. pubescens had very high concentrations.     

Estimation of the carbon storage of forest vegetation and carbon emission from forest fires in Heilongjiang Province,China

The forest resource of Heilongjiang province has important position in china. On the basis of the six times of national forest inventory data （1973-1976, 1977-1981, 1985-1988, 1989-1993, 1994-1998, 1999-2003） surveyed by the Forestry Ministry of P. R. China from 1973 to 2003, the carbon storage of forests in Heilongjiang Province are estimated by using the method of linear relationship of each tree species between biomass and volume. The results show that the carbon storage of Heilongjiang forests in the six periods （1973-1976, 1977-1981, 1985-1988, 1989-1993, 1994-1998, 1999-2003） are 7.164×10^8 t, 4.871×10^8 t, 5.094×10^8 t, 5.292×10^8 t, 5.594×10^8 t and 5.410×10^8 t, respectively., which showed a trend of decreasing in early time and then increasing. It indicated that Heilongjiang forests play an important role as a sink of atmospheric carbon dioxide during past 30 years. Based on the data of forest fires from 1980 to 1999 and ground biomass estimation for some forest types in Heilongjiang Province, it is estimated that the amount of mean annual consumed biomass of forests is 391758.65t-522344.95t, accounting for 6.4%-8.4% of total national consummation from forest fires, and the amount of carbon emission is 176 291.39t-235 055.23t, about 8% of total national emission from forest fires. The emission of CO2, CO, CH4 and NMHC from forest fires in Heilongjiang Province are estimated at 581761.6-775682.25 t, 34892.275-46523.04 t, 14091.11-18788.15 t and 6500-9000 t, respectively, every year.     

西部大开发与农林人力资源

实施西部大开发,再造祖国秀美山川,是以江泽民同志为核心的党的第三代领导集体高举邓小平理论伟大旗帜,把握历史,面向未来,高瞻远瞩,审时度势,总揽全局,站在跨世纪我国经济发展的战略高度作出的决策,是加快西部地区经济发展,逐步缩小东西部地区差距,确保国家长治久安,人民安居乐业,促进共同繁荣,实现中华民族伟大复兴的重要举措。在实施西部大开发中,人力资源的开发与利用至关重要。     

The forest vegetation and its differentiation under disturbance in a temperate mountain, China

Composition and structure of the main forest types, as well as the species changes under disturbance, were described as the representation of the forest vegetation in the north slope of Changbai mountain, northeast China. There were 3 forest zones from 600 m to 2,000 m asl, (1) broad-leaved-conifer mixed forest zone, 600–1,100 m asl, dominated byPinus koraiensis, Tilia amurensis, Acer mono, Ulmus japonica, (2) coniferous forest zone, 1,100–1,700 m asl, dominated byPicea jezoensis var.komarovii, P. koraiensis, Abies nephrolepis, and (3)Betula ermanii forest zone, 1,700–2,000 m asl, dominated byBetula ermanii, except for the east slope which was occupied byLarix olgensis. The evergreen component increased with elevation up to the upper limit of the coniferous forest zone (1,700 m), but disappeared in theB. ermanii zone. Species richness was significantly related to elevation. Towards higher elevation, the lapse rate of species-number was 1.6 species per 100 m, and it was only one species near the timberline. Species richness was reduced sharply under intensive disturbance, such as clear cutting, windfalletc. The species diversity was very low in the early stage of succession, and high in the later.     

靖远哈思山森林植被水文效应调查与分析

对靖远哈思山的天然油松林、云杉林、阳坡灌木林、阴坡灌木林４个主要植被类型的林冠截留、枯落物、枯落物水容量、土壤渗透、土壤物理性质等因子进行了调查测定和分析。结果表明,该区植被类型的林冠对降水截留效果较好,截持率为２０％－３２％,枯落物的吸水量是它自身重的２－３倍;每公顷森林土壤的贮水功益效能为１３２３．８４－２０８５．６７ｔ,具有较好的水源涵养功能。     

<Emphasis Type="Italic">Broussonetia papyrifera</Emphasis> (paper mulberry): its growth,yield and potential as a fallow crop in slash-and-burn upland rice system of northern Laos

In northern Laos, shortened fallows in the slash-and-burn upland rice system are not sustainable either from a production or economic standpoint. This paper evaluates the potential for using the indigenous fast-growing tree, Broussonetia papyrifera L. Vent. (paper mulberry) as an economic fallow crop. The objectives of this study are to assess the inner bark yield of paper mulberry, and to evaluate rice productivity following paper mulberry cultivation. In addition, allometric models for estimating the inner bark yield of paper mulberry are developed. Inner bark yield of paper mulberry stands ranging in age from 9 to 48 months ranged from 10 to 208 g m⁻², and increased with age. The models using diameter at breast height and stem height, or diameter at breast height only as independent variables explained well the variation in inner bark yield. When paper mulberry was completely removed during the rice growing season, rice yields in these areas were similar to those following weedy bush fallow. When paper mulberry was allowed to grow, rice yields were negatively correlated to paper mulberry stem density. When paper mulberry lateral branches were pruned back, rice yields could be maintained if the paper mulberry stem density was <0.22 stems m⁻², suggesting that if paper mulberry is managed properly, rice yields can be maintained at current levels. The paper mulberry-upland rice rotation system improves the productivity of a traditional slash-and-burn system through harvesting paper mulberry inner bark; however the long-term sustainability of such a system remains unclear and warrants further investigation.