17 research outputs found
Neighbour identity hardly affects litter-mixture effects on decomposition rates of New Zealand forest species.
The mass loss of litter mixtures is often different than expected based on the mass loss of the component species. We investigated if the identity of neighbour species affects these litter-mixing effects. To achieve this, we compared decomposition rates in monoculture and in all possible two-species combinations of eight tree species, widely differing in litter chemistry, set out in two contrasting New Zealand forest types. Litter from the mixed-species litter bags was separated into its component species, which allowed us to quantify the importance of litter-mixing effects and neighbour identity, relative to the effects of species identity, litter chemistry and litter incubation environment. Controlling factors on litter decomposition rate decreased in importance in the order: species identity (litter quality) >> forest type >> neighbour species. Species identity had the strongest influence on decomposition rate. Interspecific differences in initial litter lignin concentration explained a large proportion of the interspecific differences in litter decomposition rate. Litter mass loss was higher and litter-mixture effects were stronger on the younger, more fertile alluvial soils than on the older, less-fertile marine terrace soils. Litter-mixture effects only shifted percentage mass loss within the range of 1.5%. There was no evidence that certain litter mixtures consistently showed interactive effects. Contrary to common theory, adding a relatively fast-decomposing species generally slowed down the decomposition of the slower decomposing species in the mixture. This study shows that: (1) species identity, litter chemistry and forest type are quantitatively the most important drivers of litter decomposition in a New Zealand rain forest; (2) litter-mixture effects—although statistically significant—are far less important and hardly depend on the identity and the chemical characteristics of the neighbour species; (3) additive effects predominate in this ecosystem, so that mass dynamics of the mixtures can be predicted from the monocultures
Litter mass loss rates in pine forests of Europe and Eastern United States: some relationships with climate and litter quality
The purpose of this study was to relate regional variation in litter mass-loss rates (first year) in pine forests to climate across a large, continental-scale area. The variation in mass-loss rate was analyzed using 39 experimental sites spanning climatic regions from the subarctic to subtropical and Mediterranean: the latitudinal gradient ranged from 31 °N to 70 °N and may represent the the largest geographical area that has ever been sampled and observed for the purpose of studying biogeochemical processes. Because of unified site design and uniform laboratory procedures, data from all sites were directly comparable and permitted a determination of the relative influence of climate versus substrate quality viewed from the perspective of broad regional scales. Simple correlation applied to the entire data set indicated that annual actual evapotranspiration (AET) should be the leading climatic constraint on mass-loss rates (Radj2 = 0.496). The combination of AET, average July temp. and average annual temp. could explain about 70% of the sites' variability on litter mass-loss. In an analysis of 23 Scots pine sites north of the Alps and Carpatians AET alone could account for about 65% of the variation and the addition of a substrate-quality variable was sufficiently significant to be used in a model. The influence of litter quality was introduced into a model, using data from 11 sites at which litter of different quality had been incubated. These sites are found in Germany, the Netherlands, Sweden and Finland. At any one site most ( ≫ 90%) of the variation in mass-loss rates could be explained by one of the litter-quality variables giving concentration of nitrogen, phosphorus or water solubles. However, even when these models included nitrogen or phosphorus even small changes in potential evapotranspiration resulted in large changes in early-phase decay rates. Further regional subdivision of the data set, resulted in a range of strength in the relationship between loss rate and climatic variables, from very weak in Central Europe to strong for the Scandinavian and Atlantic coast sites (Radj2 = 0.912; AET versus litter mass loss). Much of the variation in observed loss rates could be related to continental versus marine/Atlantic influences. Inland locations had mass-loss rates lower than should be expected on the basis of for example AET alone. Attempts to include seasonality variables were not successful. It is clear that either unknown errors and biases, or, unknown variables are causing these regional differences in response to climatic variables. Nevertheless these results show the powerful influence of climate as a control of the broad-scale geography of mass-loss rates and substrate quality at the stand level. Some of these relationships between mass-loss rate and climatic variables are among the highest ever reported, probably because of the care taken to select uniform sites and experimental methods. This suggest that superior, base line maps of predicted mass-loss rates could be produced using climatic data. These models should be useful to predict the changing equilibrium litter dynamics resulting from climatic change
Global surveillance of cancer survival 1995–2009: analysis of individual data for 25 676 887 patients from 279 population-based registries in 67 countries (CONCORD-2)
Background: Worldwide data for cancer survival are scarce. We aimed to initiate worldwide surveillance of cancer survival by central analysis of population-based registry data, as a metric of the effectiveness of health systems, and to inform global policy on cancer control.
Methods: Individual tumour records were submitted by 279 population-based cancer registries in 67 countries for 25·7 million adults (age 15–99 years) and 75 000 children (age 0–14 years) diagnosed with cancer during 1995–2009 and followed up to Dec 31, 2009, or later. We looked at cancers of the stomach, colon, rectum, liver, lung, breast (women), cervix, ovary, and prostate in adults, and adult and childhood leukaemia. Standardised quality control procedures were applied; errors were corrected by the registry concerned. We estimated 5-year net survival, adjusted for background mortality in every country or region by age (single year), sex, and calendar year, and by race or ethnic origin in some countries. Estimates were age-standardised with the International Cancer Survival Standard weights.
Findings: 5-year survival from colon, rectal, and breast cancers has increased steadily in most developed countries. For patients diagnosed during 2005–09, survival for colon and rectal cancer reached 60% or more in 22 countries around the world; for breast cancer, 5-year survival rose to 85% or higher in 17 countries worldwide. Liver and lung cancer remain lethal in all nations: for both cancers, 5-year survival is below 20% everywhere in Europe, in the range 15–19% in North America, and as low as 7–9% in Mongolia and Thailand. Striking rises in 5-year survival from prostate cancer have occurred in many countries: survival rose by 10–20% between 1995–99 and 2005–09 in 22 countries in South America, Asia, and Europe, but survival still varies widely around the world, from less than 60% in Bulgaria and Thailand to 95% or more in Brazil, Puerto Rico, and the USA. For cervical cancer, national estimates of 5-year survival range from less than 50% to more than 70%; regional variations are much wider, and improvements between 1995–99 and 2005–09 have generally been slight. For women diagnosed with ovarian cancer in 2005–09, 5-year survival was 40% or higher only in Ecuador, the USA, and 17 countries in Asia and Europe. 5-year survival for stomach cancer in 2005–09 was high (54–58%) in Japan and South Korea, compared with less than 40% in other countries. By contrast, 5-year survival from adult leukaemia in Japan and South Korea (18–23%) is lower than in most other countries. 5-year survival from childhood acute lymphoblastic leukaemia is less than 60% in several countries, but as high as 90% in Canada and four European countries, which suggests major deficiencies in the management of a largely curable disease.
Interpretation: International comparison of survival trends reveals very wide differences that are likely to be attributable to differences in access to early diagnosis and optimum treatment. Continuous worldwide surveillance of cancer survival should become an indispensable source of information for cancer patients and researchers and a stimulus for politicians to improve health policy and health-care systems