The changing Amazon forest

Long-term monitoring of distributed, multiple plots is the key to quantify macroecological patterns and changes. Here we examine the evidence for concerted changes in the structure, dynamics and composition of old-growth Amazonian forests in the late twentieth century. In the 1980s and 1990s, mature forests gained biomass and underwent accelerated growth and dynamics, all consistent with a widespread, long-acting stimulation of growth. Because growth on average exceeded mortality, intact Amazonian forests have been a carbon sink. In the late twentieth century, biomass of trees of more than 10cm diameter increased by 0.62+/-0.23tCha-1yr-1 averaged across the basin. This implies a carbon sink in Neotropical old-growth forest of at least 0.49+/-0.18PgCyr-1. If other biomass and necromass components are also increased proportionally, then the old-growth forest sink here has been 0.79+/-0.29PgCyr-1, even before allowing for any gains in soil carbon stocks. This is approximately equal to the carbon emissions to the atmosphere by Amazon deforestation. There is also evidence for recent changes in Amazon biodiversity. In the future, the growth response of remaining old-growth mature Amazon forests will saturate, and these ecosystems may switch from sink to source driven by higher respiration (temperature), higher mortality (as outputs equilibrate to the growth inputs and periodic drought) or compositional change (disturbances). Any switch from carbon sink to source would have profound implications for global climate, biodiversity and human welfare, while the documented acceleration of tree growth and mortality may already be affecting the interactions among millions of species.     

树轮分析用于森林干扰强度推测的实例研究

树木年轮生长释放一直广泛应用于重建森林干扰,但没有直接的研究证明利用树木年轮分析建立的干扰强度的可靠程度,本文试图通过一个取自青海省互助国家森林公园(1987年经历过择伐)的样方进行验证.在40m×50m的青扦林样方内取胸径≥5cm的树木(124株)树轮芯样并测定胸径、树高和择伐后山杨(PopulusdavilianaDode)树桩(55个)的基径以及树木与树桩的距离.分析结果表明1987和1988年树木生长释放百分率为38.7%,与该林分的准确干扰强度37.7%(树桩基部断面积与该断面积加树木胸高断面积之和的比值)相接近.1980～1989年10a间树木生长释放百分率为62.9%,该10a间的平均干扰强度为37.0%(生长释放百分率62.9%/生长释放平均次数1.7),也接近于该林分的准确干扰强度,因而用树轮资料重建森林干扰强度是可行和可靠的.     

Spatial analysis of density dependent pattern in coniferous forest stands

An investigation of spatial pattern in relatively sparse Pinus ponderosa-P. Jeffreyi stands showed that a simple Poisson model of random distribution described the pattern at 5 to 50 m scales in the denser stands examined when allowance is made for inhibition between nearest neighbors. There is evidence for a clumped distribution in large quadrats for the sparsest stands, which concurs with prior work where a mixed Poisson model was fit to the data. The technique used was innovative in that it involved digitally recording tree locations from high resolution aerial photos, which allowed for the automatic application of several statistical techniques in order to determine how pattern varies with plot density and scale. Point locations were recorded for six 11.3 ha plots in three density regions of a 340 ha study area in northeastern California, USA. The inter-event distance distribution, and one- and two-dimensional power spectra were calculated, and variable quadrat analysis was performed for the data sets. The second order and spectral analyses showed no evidence of a distinctive clumped pattern at any scale, and all analyses showed that the pattern was regular at the scale of the average inter-plant distance in the denser stands. For the sparser stands, the counts in large quadrats did not fit a Poisson distribution, but were better fit by a mixed Poisson model describing aggregated pattern.     

The international politics of national parks

National parks are the keystone institutions of environmental conservation. Because national parks make certain lands part of the state itself, international agencies and nongovernmental organizations that promote national parks propose, in effect, to alter the state, as well as the local economy and state relations with social groups. Has international political pressure caused states to create national parks? I consider whether countries highly involved in international politics have the largest proportions of land in national parks. I conclude that many states create minimal park systems as symbolic gestures to the international community. Field researchers may find it easier to explain the success or failure of parks if they identity why state officials decide that adopting international conservation norms will enhance state authority over people and state sovereignty over land.     

An analysis of density responses of forest and woodland birds to composite physiognomic variables

Habitat ordinations were performed on 37 sites in forests and woodlands along a latitudinal transect that spanned over 250 km in central Victoria. Australia. Multivariate analyses of these data by using nonmetric. multidimensional scaling (AIDS) were used to generate composite variables. The relationships of these composite variables and densities (by area) of 58 species of forest and woodland birds were assessed by using linear and polynomial regressions. Only seven of the 58 species of birds did not display a significant relationship to one or other of the five composite variables. Approximately 50% of the avian species showed significant relationships with each of the first two composite variables, but lower percentages were observed for the other three variables. About a third of all significant correlations were either of second or third order, ft appears that marked curvilinearities associated with the first composite variable can be interpreted as linear responses with respect to the secondary composite variable. These results suggest that, although composite variables derived from multivariate classifications are statistically independent, there often may be substantial biological dependence between the composite variables. Therefore, for biological interpretation, it would be appropriate to regard composite variables derived from multivariate classifications as suites of related variables. Some authors have traced sharp discontinuities in distributions of species with respect to habitat structure by using presence/absence data alone. This approach appears to be sensitive to sampling of habitat types, and densities should be used wherever possible.     

Dynamics of pine forest state at changing emission loads

The dynamics of pine stands (Pinus sylvestris L.) polluted by fluorine-containing emissions has been studied for several decades—from the moment of emission source appearance to present. Condition of the pine stands was estimated on the complex of parameters: accumulation of toxicants in the needle and changing physiological, biochemical and morphometrical parameters of trees. On the basis of the available data several scenarios of situation development were predicted for the following years.     

基于森林清查资料的江西和浙江森林植被固碳潜力

以我国江西、浙江两省的森林植被为研究对象,基于1999-2003年间第六次全国森林清查数据及收集的1030个亚热带森林样地文献资料,依据林分生长的经验方程,估算了两个地区森林2004-2013年的固碳潜力,并基于455个样点的调查数据研究了不同森林管理措施(纯林间种、间伐、施肥)对森林未来固碳潜力的影响.结果表明:第六次森林清查以来的10年(2004-2013)间,江西森林植被年均自然固碳潜力约11.37 Tg C·a-1(1Tg=1012g),而浙江省森林植被年均自然固碳潜力约4.34 Tg C·a-1.纯林间种对江西、浙江两省森林植被固碳潜力影响最大,其次为间伐抚育,施肥的影响最小,纯林间种、间伐和施肥3种森林管理措施使江西省森林植被固碳潜力分别提高(6.54±3.9)、(3.81±2.02)和(2.35±0.6) Tg C·a-1,浙江省森林植被固碳潜力分别提高(2.64±1.28)、(1.42±0.69)和(1.15±0.29) Tg C·a-1.     

Accelerating the domestication of forest trees in a changing world

In light of impending water and arable land shortages, population growth and climate change, it is more important than ever to examine how forest tree domestication can be accelerated to sustainably meet future demands for wood, biomass, paper, fuel and biomaterials. Because of long breeding cycles, tree domestication cannot be rapidly achieved through traditional genetic improvement methods alone. Integrating modern genetic and genomic techniques with conventional breeding will expedite tree domestication. Breeders will only embrace these technologies if they are cost-effective and readily accessible, and forest landowners will only adopt end-products that meet with regulatory approval and public acceptance. All parties involved must work together to achieve these objectives for the benefit of society.     

Downscaling indicators of forest habitat structure from national assessments

Downscaling is an important problem because consistent large-area assessments of forest habitat structure, while feasible, are only feasible when using relatively coarse data and indicators. Techniques are needed to enable more detailed and local interpretations of the national statistics. Using the results of national assessments from land-cover maps, this paper demonstrates downscaling in the spatial domain, and in the domain of the habitat model. A moving window device was used to measure structure (habitat amount and connectivity), and those indicators were then analyzed and combined with other information in various ways to illustrate downscaling.     

The changing landscape of European and international regulation on embryonic stem cell research

Legislation in individual member states of the European Union on human embryonic stem cell (hESC) research is as divergent as the different cultural, ethical, and religious views on the issue. On the occasion of the public launch of the European Human Embryonic Stem Cell Registry (hESCreg: www.hescreg.eu), a two-day symposium was held on 18 and 19 January 2008 in Berlin to offer participants an overview of state-of-the-art hESC research and legislation throughout Europe and in selected regions of the world. Thirty leading scientists from Europe as well as from the United States, Japan, and Australia reported on a range of aspects related to research on hESC and reviewed the key elements of the newly established hESCreg database of hESC lines. In this article we summarize and complete the information on the current status of international hESC regulation.     

Five centuries of changing forest vegetation in the Northeastern United States

Maps of physiognomic classes of vegetation in the northeastern UnitedStates before European human impact and for the late 20th century, based onpollen data, closely resemble each other, indicating a robust pattern in theface of the novel and extensive disturbances of the last 500 years. On the otherhand, species abundances have changed considerably, with today's vegetationhaving less Fagus L. and TsugaCarrière and more Betula L.,Picea A. Dietr., and Abies Miller.Picea and Castanea Miller increasedfrom 1700 to 1900, but have decreased in this century. The difference betweenthe main physiognomic classes has remained strong, however, with continuouslymore Picea, Abies andBetula in the north and more QuercusL. and Carya Nutt. in the south, indicating the dominanceof climate in regulating the relative abundances of these genera. Thevegetational patterning within these broad classes has changed in some placesand remained stable in others, suggesting differences in local factors thatdetermine relative species abundances. The influence of slight altitudinalgradients, for example, may influence forest composition only after severalgenerations of trees, while substrate differences may be apparent in the firstforest that regenerates after agricultural abandonment or logging. Forests oftoday, therefore, reflect complex interactions of disturbance and environment,and may be in equilibrium with some but not all features of their currentenvironments.     

The standing waters of Coll and Tiree in a national and international context

Summary

The aquatic vascular plants and charophytes were surveyed in a total of 200 standing waters on the Inner Hebridean islands of Coll and Tiree. A TWINSPAN classification of the sites is used to divide them into seven groups. The groups demonstrate the range of variation in the standing waters of the two islands, which in turn reflects the presence of a range of substrates from acidic peat to calcareous sand. The lake types and the rare species recorded from Coll and Tiree suggest that these standing waters are of outstanding national and international nature conservation value.     

湖北省主要森林类型生态系统生物量与碳密度比较

利用野外调查数据对湖北省封山育林下的次生林、次生林、人工林森林生态系统碳密度进行了分析,结果表明:封山育林下的次生林、次生林和人工林生态系统乔木层平均碳密度分别为133.87、73.42和111.62t·hm-2,灌木层平均碳密度分别为1.65、1.40和1.52t·hm-2,草本层平均碳密度分别为0.13、0.09和0.13t·hm-2,枯落物层平均碳密度分别为0.47、1.34和0.93t·hm-2,乔木层碳密度作为生态系统碳储量的主要贡献者占总生物碳密度的98.35%、96.29%和97.74%,林下植被(灌木层和草本层)碳密度分别占1.31%、1.95%和1.44%,凋落物层碳密度分别占0.34%、1.76%和0.82%。土壤(0～100cm)碳密度平均值分别为57.04、66.92和54.12t·hm-2,土壤碳密度的60%储存在0～40cm土壤中,并随土层深度增加,各层次土壤碳密度逐渐减少。森林生态系统的乔木层、灌木层、草本层、凋落物层生物量和土壤层碳密度均表现出:封山育林下的次生林、次生林大于人工林。封山育林下的次生林、次生林和人工林碳密度分布序列为土壤(0～100cm)>乔木层>灌木层>草本层>枯落物层。可见,封山育林下的次生林更有助于提高森林碳汇,实施近自然林经营是提升该区域森林碳汇能力的重要途径。     

林火干扰对广东省桉树林生态系统碳密度的影响

林火作为森林非连续的生态因子,引起森林生态系统碳库碳储量与碳分配的变化,影响森林演替进程及固碳能力。以桉树林不同林火干扰强度的火烧迹地为对象,采用相邻样地比较法,以野外调查采样与室内试验分析相结合为主要手段,研究不同林火干扰强度对森林生态系统各碳库及生态系统碳密度变化和空间分布格局的影响,探讨林火干扰对生态系统碳密度与碳分布格局的影响机制。结果表明:林火干扰降低了植被碳密度(P<0.05),轻度、中度和重度林火干扰样地植被碳密度依次为67.88、35.68和15.50 t·hm^-2,相比对照分别下降了15.86%、55.78%和80.79%;在轻度、中度和重度林火干扰样地中,凋落物碳密度分别为1.43、0.94和0.81 t·hm^-2,相比对照分别降低了28.14%、52.76%和59.30%;不同林火干扰强度样地土壤有机碳密度均低于对照,且减少幅度随土壤剖面深度增加而逐渐变小,轻度、中度和重度林火干扰样地土壤有机碳密度分别为103.30、84.33和70.04 t·hm^-2,相比对照分别下降了11.67%、27....     

Wild brown trout Salmo trutta: an important national and international resource

SUMMARY. 1. Brown trout were once given a variety of latin and common names, but are now regarded as belonging to only one polymorphic species, Salmo trutta L. A review of their geographical distribution shows that this species was originally native to Europe but has been successfully introduced in at least twenty-four countries outside Europe.
2. Brown trout provide valuable commercial and sports fisheries, e.g. commercial and rod catches of sea-trout in England and Wales averaged 110,547 fish per year from 1983 to 1986 and the minimum value of these fisheries is estimated to be £55M.
3. It is concluded from this brief review that the major objectives of scientific research on wild brown trout should be: (a) an assessment of the current status of stocks; (b) the maintenance of existing populations; (c) the development and improvement of mathematical models that can be used as tools for the conservation and management of this important national and international resource.     

城市森林概念探析

在讨论、揭示有关城市森林和森林概念的基础上,对城市森林进行定义,认为城市森林是指在城市及其周边范围内以乔木为主体,达到一定的规模和覆盖度,能对周围的环境产生重要影响,并具有明显的生态价值和人文景观价值等的各种生物和非生物的综合体。进一步探讨城市森林的范围,对城市森林与园林以及城市绿地进行比较,并对城市森林的发展提出几点看法和建议。