Dissecting amazonian biodiversity

Biogeographical and biodiversity studies in Iowland Amazonian rain forests typically refer to observed or postulated distribution barriers such as past unfavorable climates, mountains, rivers, and river floodplains that divide the uniform tierra firme (noninundated) forest. Present-day ecological heterogeneity within tierra firme has hardly been discussed in this context, although edaphic differences are known to affect species distribution patterns in both inundated areas and tierra firme. Quantification of landscape heterogeneity in Peruvian Iowland Amazonia (500,000 kilometers squared), based on field studies and satellite image analysis, shows that Peruvian Amazonia is considerably more heterogeneous than previously reported. These observations have implications for the research, management, and conservation of Amazonian biodiversity.     

海南中部山区天然林物种组成与群落特征变化

为了揭示受20世纪50年代砍伐影响的热带天然林在自然恢复过程中物种组成与群落特征变化趋势,以海南中部山区山地雨林原始林、低地雨林次生林、山地雨林次生林、云雾林次生林4个森林动态样地为对象,基于2012—2020年2次植被调查,从物种组成、区系组成、群落外貌特征等方面分析群落动态特点。结果表明：2012—2020年,（1）山地雨林原始林S?rensen群落相似度为0.960,物种组成最稳定;低地雨林次生林为0.921;山地雨林次生林为0.889;云雾林次生林为0.794,物种更替最明显。随着短期演替进行,各群落间S?rensen群落相似度升高,多年来有更多相同的物种。（2）各群落排名第1的优势种重要值均降低,云雾林次生林优势种重要值下降明显,向更为混合的多优势种群落发展。（3）随着短期演替进行,群落郁闭度增加,喜阳的前中期树种逐渐被耐荫的演替中后期种替代,分布区窄的海南特有种作为补员树种进入群落。（4）各群落均以热带区分布为绝对优势,并以热带亚洲（印度-马来西亚）分布为主。随海拔升高,温度降低,呈现出热带性减弱、温带性加强的特点。8年间,植物区系地理成分更加复杂。（5）叶性质呈现出以中型...     

Formation of secondary organic aerosols through photooxidation of isoprene

Detailed organic analysis of natural aerosols from the Amazonian rain forest showed considerable quantities of previously unobserved polar organic compounds, which were identified as a mixture of two diastereoisomeric 2-methyltetrols: 2-methylthreitol and 2-methylerythritol. These polyols, which have the isoprene skeleton, can be explained by OH radical-initiated photooxidation of isoprene. They have low vapor pressure, allowing them to condense onto preexisting particles. It is estimated that photooxidation of isoprene results in an annual global production of about 2 teragrams of the polyols, a substantial fraction of the Intergovernmental Panel on Climate Change estimate of between 8 and 40 teragrams per year of secondary organic aerosol from biogenic sources.     

Amazonia 1492: pristine forest or cultural parkland?

Archaeology and indigenous history of Native Amazonian peoples in the Upper Xingu region of Brazil reveal unexpectedly complex regional settlement patterns and large-scale transformations of local landscapes over the past millennium. Mapping and excavation of archaeological structures document pronounced human-induced alteration of the forest cover, particularly in relation to large, dense late-prehistoric settlements (circa 1200 to 1600 A.D.). The findings contribute to debates on human carrying capacity, population size and settlement patterns, anthropogenic impacts on the environment, and the importance of indigenous knowledge, as well as contributing to the pride of place of the native peoples in this part of the Amazon.     

江西省宜春市樟树地区冻雨天气总结

利用基层台站常规气象资料分析江西省宜春市樟树地区过去5年冻雨天气过程,从冻雨形成机制入手,剖析总结形成冻雨的天气形势特征,从中寻找归纳冻雨天气预报着眼点,对提高冻雨天气预报准确率具有比较实用的指导意义.     

Distributional Ecology of New Guinea Birds: Recent ecological and biogeographical theories can be tested on the bird communities of New Guinea

The concepts by which MacArthur and Wilson have transformed the science of ecology in the past decade, and the results of ecological studies such as mine on New Guinea bird communities, have implications for conservation policies. For example, primary tropical rain forest, the most species-rich and ecologically complex habitat on earth, has for millions of years served as the ultimate evolutionary source of the world's dominant plant and animal groups. Throughout the tropics today, the rain forests are being destroyed at a rate such that little will be left in a few decades. When the rain forests have been reduced to isolated tracts separated by open country, the distribution of obligate rain forest species will come to resemble bird distributions on New Guinea land-bridge islands after severing of the land bridges. The smaller the tract, the more rapidly will forest species tend to disappear and be replaced by the widespread second-growth species that least need protection (13). This ominous process is illustrated by Barro Colorado Island, a former hill in Panama that became an island when construction of the Panama Canal flooded surrounding valleys to create Gatun Lake. In the succeeding 60 years several forest bird species have already disappeared from Barro Colorado and been unable to recolonize across the short intervening water gap from the forest on the nearby shore of Gatun Lake. The consequences of the species-area relation (Fig. 1) should be taken into consideration during the planning of tropical rain forest parks (13). In a geographical area that is relatively homogeneous with regard to the fauna, one large park would be preferable to an equivalent area in the form of several smaller parks. Continuous nonforest strips through the park (for example, wide highway swaths) would convert one rain forest "island" into two half-size islands and should be avoided. If other considerations require that an area be divided into several small parks, connecting them by forest corridors might significantly improve their conservation function at little further cost in land withdrawn from development. Modern ecological studies may also be relevant to the understanding of human populations. For instance, during a long period of human evolution there appear to have been not one but two coexistent hominid lines in Africa, the Australopithecus robustus-A. boisei ("Zinjanthropus") line, which became extinct, and the Australopithecus africanus-A. habilis line, which led to Homo sapiens (27). The need to maintain niche differences between these lines must have provided one of the most important selective pressures on the ancestors of modern man in the late Pliocene and early Pleistocene. Thus, any attempt to understand human evolution must confront the problem of what these ecological segregating mechanisms were. To what extent were contemporaneous species of the two lines separated by habitat, by diet, by size difference, or by foraging technique, and were their local spatial distributions broadly overlapping or else sharpened by behavioral interactions as in the case of the Crateroscelis warblers of Fig. 6? To take another example, there are striking parallels between the present distributions of human populations and of bird populations on the islands of Vitiaz and Dampier straits between New Guinea and New Britain. Some of these islands were sterilized by cataclysmic volcanic explosions within the last several centuries. The birds that recolonized these islands have been characterized as coastal and small-island specialists of high reproductive potential, high dispersal powers, and low competitive ability, unlike the geographically closer, competitively superior, slowly dispersing, and breeding birds of mainland New Guinea (10, 11, 13). It remains to be seen whether the people of the Vitiaz-Dampier islands, the Polynesians, and other human populations that colonize insular or unstable habitats also have distinctive population ecologies.     

新会古兜山阔叶林主要群落类型及其结构特征

本文利用古兜山阔叶林的标准地调查资料,对其进行主要群落类型的划分和结构特征的分析。古兜山阔叶林是属于半热带沿海湿润季风区域的热带雨林性常绿季雨林,正处于旺盛生长的中幼龄阶段,植物种类繁多和森林资源丰富,但次生性较强,结构复杂,群落类型较多,共有八个主要群落类型。     

海南甘什岭热带低地雨林不同演替阶段根系的生物量特征

热带地区植物根系生物量的研究对预测气候变化条件下土壤碳库的变化和热带雨林次生演替地下生态学过程的认识具有重要意义。在海南三亚市甘什岭自然保护区内,选取4个植被恢复阶段（草本群落、灌木群落、40 年次生林和60 年次生林）,利用平均标准木机械布点法采集0～100 cm根系样品,研究根系生物量、不同根系径级组成结构以及地下垂直分布规律。研究结果表明:（1）甘什岭热带低地雨林不同演替阶段根系生物总量在5.23～28.98 t·hm?2,植被恢复演替（正向）显著地增加了根系生物量,其中草本至灌木阶段不显著;（2）木本植物群落根系生物量以粗根（>2 mm）为主,最高占其总生物量的89.76%,草本则以细根（≤2 mm）为主,占其总生物量的53.53%以上;随着甘什岭植被的恢复,粗根占根系生物量的比例逐渐增加,细根占根系生物量的比例逐渐减小。（3）甘什岭热带低地雨林近80%的根系生物量集中分布在 0～20 cm 土层中,随着土壤剖面深度的增加,根系生物量大幅度减少,草本群落生物量在土壤剖面中的垂直变化规律呈指数回归,其余各恢复演替阶段呈幂函数回归。（4）根系生物量模型中,树高、D2H（胸径的平方与树高的乘积）与根系生物量拟合最好,在实践应用中,可根据林木的树高和D2H估测甘什岭地区植被根系生物量。本研究结果为进一步研究甘什岭热带低地雨林植物群落地下碳素分配及土壤碳库变化奠定基础,还可为估算我国热带低地雨林地区植被根系生物量和生产力提供参考。     

Evidence from paleosols for the geological antiquity of rain forest

Kaolinitic claystones in Paleozoic paleokarst underlying the Middle Pennsylvanian Fort Scott Limestone near Drake, Missouri, contain abundant fossil root traces. These include a surficial root mat as well as stout, woody, deeply penetrating root traces: a rooting pattern similar to that under rain forest. Also similar to soils of rain forest is the deeply weathered clay of the paleosol, in which minimal amounts of nutrient bases remain. Forest communities adapted to oligotrophic clayey substrates in humid climates existed at least 305 million years ago.     

Coadapted competitors: the flowering seasons of hummingbird-pollinated plants in a tropical forest

A system of compensating phenological responses of different species to unusual rainfall conditions may play a major role in maintaining an orderly, staggered sequence of flowering peaks among the hummingbird-pollinated plants of a Costa Rican rain forest. Quantitative phenological studies over several years may be essential to understanding the temporal organization of many tropical communities.     

酸雨与森林衰退关系研究综述

酸雨对森林的危害已成为全球性的重要环境问题之一.文中论述了酸雨与森林衰退关系及其不确定性因素,氮素沉降对森林生态系统的影响,以及我国酸雨对森林的危害情况与发展趋势.最后,讨论了酸化生态系统的恢复及其存在的主要问题.     

Functional traits and niche-based tree community assembly in an Amazonian forest

It is debated whether species-level differences in ecological strategy, which play a key role in much of coexistence theory, are important in structuring highly diverse communities. We examined the co-occurrence patterns of over 1100 tree species in a 25-hectare Amazonian forest plot in relation to field-measured functional traits. Using a null model approach, we show that co-occurring trees are often less ecologically similar than a niche-free (neutral) model predicts. Furthermore, we find evidence for processes that simultaneously drive convergence and divergence in key aspects of plant strategy, suggesting that at least two distinct niche-based processes are occurring. Our results show that strategy differentiation among species contributes to the maintenance of diversity in one of the most diverse tropical forests in the world.     

秦岭锐齿栎林和油松林林冠层对大气降雨水质的影响

在秦岭火地塘林区选择了锐齿栎林(Quercus aliena var. acuteserrata)和油松林(Pinus tabulaeformis)两种主要林型,采用对比分析的方法,就其林冠层对大气降雨水质的影响进行了探讨.结果表明:锐齿栎林、油松林林冠层均有降低雨水酸性的作用,油松林降低雨水酸性的能力相对较强;两种林...     

吉林地区春季第一场透雨前期高空环流形势浅析

通过对历年吉林地区第一场透雨出现时大气环流的形势演变进行研究,客观总结预报着眼点,为吉林地区做好第一场透雨的预报提供依据。     

酸沉降影响下春季庐山森林生态系统水溶态氮的分布及其动态

对1998 年春季庐山森林生态系统中降水、透冠水、茎流水、土壤渗漏水和沟水的水溶态氮(NH 4 -N、NO-3 -N、NO-2 -N) 进行了观测和分析研究。结果表明, 庐山酸雨pH值较1993年升高, 总氮亦有所增加; 系统中氮流通量加大, 输入量大于输出量。土壤尚能有效缓冲大气氮沉降; 氮的输出量中, 以灯台树(Cornusccontroversa)和山胡椒(L.glauca)为主的阔叶林系统多于以日本柳杉(Cryptom eria japonicum ) 为主的针叶林系统; 阔叶林较针叶林更有效地抵抗酸沉降。氮的分布及其动态表明阔叶林生态系统对酸沉降具有较强的缓冲能力。     

菜阳河自然保护区天然植被物种多样性研究

采用植物群落学的原理和方法,对菜阳河自然保护区内的3种主要天然植被物种多样性进行研究 结果表明:植被型相同的群落间物种相似性程度较高,植被型不同的群落间物种相似性系数为山地雨林和季节雨林>山地雨林和季风常绿阔叶林>季节雨林和季风常绿阔叶林 季节雨林群落优势种明显,重要值集中在少数优势种上;山地雨林群落优势种不明显,重要值分布均匀;季风常绿阔叶林群落优势种明显,重要值分布不均匀 山地雨林群落物种丰富,多样性指数明显高于季节雨林群落和季风常绿阔叶林群落 季节雨林在物种多样性上表现最低     

The duration of forest stages in southern Europe and interglacial climate variability

Foraminiferal oxygen isotope and pollen analyses from a deep-sea sequence off southwest Portugal show that the duration of temperate stages on land over the past 350,000 years varied considerably. The record shows forest contractions during intervals of low ice volume, coeval with declines in atmospheric methane, after which tree populations did not always recover. What emerges is that, although the broad timing of interglacials is consistent with orbital theory, their specific duration may be dictated by millennial variability. This complicates the prediction of the natural duration of interglacials, at least until the origin of this climate variability is understood.     

海南尖峰岭热带雨林区降雨和径流特征研究

[目的]研究海南尖峰岭热带雨林区降雨和径流特征。[方法]根据2007～2008年在海南尖峰岭热带雨林定位观测的降雨和径流数据,分析原始热带山地雨林、次生热带山地雨林和低地雨林等集水区的径流特征。[结果]林区在雨季能够有效削减洪峰,在旱季能够有效调节径流,表明具有较好的调洪补枯功能。林区雨季每公顷蓄水11 660～18 031 m3,从高到低分别为热带山地雨林次生林原始山地雨林低地雨林。旱季,热带山地雨林次生林和原始山地雨林每公顷补枯量分别为976.6和946.8 m3,低地雨林补枯功能不明显。[结论]该研究验证了热带雨林具有调洪补枯的功能假说。     

近30a安吉县毛竹林动态遥感监测及碳储量变化

通过最大似然分类法从不同时期陆地资源卫星Landsat-5 TM影像中提取毛竹Phyllostachys pubescens林信息,利用变化幅度和动态度2个指标对浙江省安吉县近30 a毛竹林面积时空动态特征进行了监测、评价与分析,并初步估算了各时期竹林地上总碳储量变化情况。结果表明：①各个时期影像分类总体精度和毛竹林信息提取的精度比较好,其中总体分类精度都在85%以上,而毛竹林Kappa系数为0.80~0.95。遥感估算的毛竹林面积与森林资源清查结果相吻合,两者决定系数（R2）达到0.981;②1986-2008年期间,除昆铜乡毛竹林面积呈负增长外（变化幅度为-8.49%）,其他各乡镇的毛竹林面积呈上升趋势,变化幅度为14%~86%,以孝丰镇增长幅度最大,天荒坪镇增长幅度最小;③针叶林、阔叶林以及农业用地的变化对毛竹林总面积增加的贡献最大;④根据毛竹林动态监测结果和毛竹林地上碳密度（20.297 Mg.hm-2）估算得到1986,1991,1998,2004和2008年5个时期安吉县竹林地上碳储总量分别为1.106,1.213,1.327,1.413和1.466 Tg,呈逐渐增加趋势。图2表4参31     

Reconstruction of the Amazon Basin effective moisture availability over the past 14,000 years

Quantifying the moisture history of the Amazon Basin is essential for understanding the cause of rain forest diversity and its potential as a methane source. We reconstructed the Amazon River outflow history for the past 14,000 years to provide a moisture budget for the river drainage basin. The oxygen isotopic composition of planktonic foraminifera recovered from a marine sediment core in a region of Amazon River discharge shows that the Amazon Basin was extremely dry during the Younger Dryas, with the discharge reduced by at least 40% as compared with that of today. After the Younger Dryas, a meltwater-driven discharge event was followed by a steady increase in the Amazon Basin effective moisture throughout the Holocene.