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11.
MORAIS PAULO AMORIM ANTÓNIO VIEIRA DA SILVA CLÁUDIA RIBEIRO TERESA COSTA SANTOS JORGE AFONSO COSTA HELOÍSA 《Journal of genetics》2015,94(3):509-512
Journal of Genetics - 相似文献
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Semiempirical modeling of abiotic and biotic factors controlling ecosystem respiration across eddy covariance sites 总被引:1,自引:0,他引:1
MIRCO MIGLIAVACCA MARKUS REICHSTEIN ANDREW D. RICHARDSON ROBERTO COLOMBO MARK A. SUTTON GITTA LASSLOP ENRICO TOMELLERI GEORG WOHLFAHRT NUNO CARVALHAIS ALESSANDRO CESCATTI MIGUEL D. MAHECHA LEONARDO MONTAGNANI DARIO PAPALE SÖNKE ZAEHLE ALTAF ARAIN ALMUT ARNETH T. ANDREW BLACK ARNAUD CARRARA SABINA DORE DAMIANO GIANELLE CAROLE HELFTER DAVID HOLLINGER WERNER L. KUTSCH PETER M. LAFLEUR YANN NOUVELLON CORINNA REBMANN HUMBERTO R.
Da ROCHA MIRCO RODEGHIERO OLIVIER ROUPSARD MARIA‐TERESA SEBASTIÀ GUENTHER SEUFERT JEAN‐FRANCOISE SOUSSANA MICHIEL K.
Van Der MOLEN 《Global Change Biology》2011,17(1):390-409
In this study we examined ecosystem respiration (RECO) data from 104 sites belonging to FLUXNET, the global network of eddy covariance flux measurements. The goal was to identify the main factors involved in the variability of RECO: temporally and between sites as affected by climate, vegetation structure and plant functional type (PFT) (evergreen needleleaf, grasslands, etc.). We demonstrated that a model using only climate drivers as predictors of RECO failed to describe part of the temporal variability in the data and that the dependency on gross primary production (GPP) needed to be included as an additional driver of RECO. The maximum seasonal leaf area index (LAIMAX) had an additional effect that explained the spatial variability of reference respiration (the respiration at reference temperature Tref=15 °C, without stimulation introduced by photosynthetic activity and without water limitations), with a statistically significant linear relationship (r2=0.52, P<0.001, n=104) even within each PFT. Besides LAIMAX, we found that reference respiration may be explained partially by total soil carbon content (SoilC). For undisturbed temperate and boreal forests a negative control of total nitrogen deposition (Ndepo) on reference respiration was also identified. We developed a new semiempirical model incorporating abiotic factors (climate), recent productivity (daily GPP), general site productivity and canopy structure (LAIMAX) which performed well in predicting the spatio‐temporal variability of RECO, explaining >70% of the variance for most vegetation types. Exceptions include tropical and Mediterranean broadleaf forests and deciduous broadleaf forests. Part of the variability in respiration that could not be described by our model may be attributed to a series of factors, including phenology in deciduous broadleaf forests and management practices in grasslands and croplands. 相似文献
13.
TERESA SCHWARZKOPF SUSAN J. RIHA TIMOTHY J. FAHEY STEPHEN DEGLORIA 《Austral ecology》2011,36(3):280-289
Cloud forest vegetation structure and composition were studied in the Venezuelan Andes at three sites in Mérida State. Although the sites are within 10 to 30 km of each other, climatic, geologic and topographic differences are remarkable. The main purpose of the study was to determine the relationship of specific environmental variables to forest vegetation characteristics, including basal area, tree height, density and diversity, and leaf area index (LAI). At 51 plots, all trees' diameter at breast height >10 cm were recorded and identified. Although the environment at the three sites is distinctive, the tree species composition of the most abundant species was very similar. None of the measured environment variables were significantly correlated with the measured vegetation structure variables, except LAI, which was correlated with slope orientation; LAI showed higher values at south‐facing plots. Tree height was relatively uniform, while basal area was highly variable and reached very high values. Stem densities were in the range reported elsewhere in cloud forests. Multivariate analysis using structure or composition data shows segregation of the plots by site. Principal component analyses by site indicate a minor impact of environmental factors on forest variables. At each site, a particular group of species are correlated with the ordination axes. We conclude that species pools and forest dynamics add to the complexity of the structure of the studied cloud forests. 相似文献
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Unexpected biodiversity loss under global warming in the neotropical Guayana Highlands: a preliminary appraisal 总被引:1,自引:1,他引:0
The fully vegetated summits of the table mountains that form the Guayana Highlands (GH), in northern South America, hold amazing biodiversity and endemism levels, and unique vegetation types. In spite of their present‐day healthy appearance, their biota is seriously threatened of habitat loss by upward displacement, because of the projected warming for the end of this century. Available data are still insufficient for a definite assessment, but preliminary estimations based on representative endemic vascular plant species show that roughly one‐tenth to one‐third of them would loss their habitat with the 2–4°C temperature increase predicted for the region by AD 2100. Given the underlying endemism, the eventual loss of biodiversity will be of global nature. Other mountain ranges around the world with similar characteristics of the GH, namely topographical isolation, high endemism and absence of nival stage because of the lower altitude, would be under similar unexpected risk, and should be urgently considered for conservation purposes. 相似文献
19.
SÒNIA GARCIA MIGUEL Á. CANELA TERESA GARNATJE E. DURANT MCARTHUR JAUME PELLICER STEWART C. SANDERSON JOAN VALLÈS 《Biological journal of the Linnean Society. Linnean Society of London》2008,94(3):631-649
The genome size of 51 populations of 20 species of the North American endemic sagebrushes (subgenus Tridentatae ), related species, and some hybrid taxa were assessed by flow cytometry, and were analysed in a phylogenetic framework. Results were similar for most Tridentatae species, with the exception of three taxonomically conflictive species: Artemisia bigelovii Gray, Artemisia pygmaea Gray, and Artemisia rigida Gray. Genome size homogeneity (together with the high morphological, chemical, and karyological affinities, as well as low DNA sequence divergence) could support a recent diversification process in this geographically restricted group, thought to be built upon a reticulate evolutionary framework. The Tridentatae and the other North American endemic Artemisia show a significantly higher genome size compared with the other subgenera. Our comparative analyses including genome size results, together with different kinds of ecological and morphological traits, suggest an evolutionary change in lifestyle strategy linked to genome expansion, in which junk or selfish DNA accumulation might be involved. Conversely, weed or invasive behaviour in Artemisia is coupled with lower genome sizes. Data for both homoploid and polyploid hybrids were also assessed. Genome sizes are close to the expected mean of parental species for homoploid hybrids, but are lower than expected in the allopolyploids, a phenomenon previously documented to be related with polyploidy. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 631–649. 相似文献
20.
ALFONSO SUSANNA NÚRIA GARCIA-JACAS ROSER VILATERSANA TERESA GARNATJE JOAN VALLÈS SEYED MAHMOOD GHAFFARI 《Botanical journal of the Linnean Society. Linnean Society of London》2003,143(4):411-418
Twenty chromosome counts are reported in the genus Cousinia and the monotypic genus Schmalhausenia , which are part of the Arctium group, from Armenia, Iran, Kazakhstan and Uzbekistan. Twelve are new and eight provide confirmation of scarce or disputable previous data. The correlation between karyological data, pollen type and molecular phylogeny is very close, and on this basis two main groups can be defined. One is the arctioid group, which comprises the genera Arctium and Schmalhausenia , and a small part of the genus Cousinia , with x = 18. The other is the genus Cousinia s.s. , with a dysploid series ranging from x = 13–11. Some considerations on the chromosomal evolution in the group are made. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Socety , 2003, 143 , 411–418. 相似文献