Latitudinal gradient

Carboniferous 345 Myr Climate cools, marked latitudinal gradients. Extensive forests of early vascular plants, especially club mosses, horsetails, ferns. Coal beds form. Amphibians diversify first reptiles appear. Radiation of early insect orders... 

Denning, A. S., Fung, I. Y. and Randall, D. A. (1995). Latitudinal gradient of atmospheric CO2 due to seasonal exchange with land biota. Nature 376, 240-243. 

Bird MI, Chivas AR, Head J (1996) A latitudinal gradient in carbon turnover times in forest soils. Nature 381 143-146... 

Hellstrom et al (2004)] were used as a surrogate for atmospheric concentrations. They serve to evaluate the latitudinal gradients of the model results. The biomass DDT concentrations are compared to mixing ratios of DDT in the lowest atmospheric model layer. Ratios of observational data were calculated for pine needles from the same growth year. 

Table 3.4 Latitudinal gradients of DDT in pine needles [Jensen et al (1992), Hellstrom et al (2004)] compared to ratios of atmospheric concentrations in the model.

The comparison of model results with observations reveals significant discrepancies, especially in the Arctic, where concentrations are overestimated by the model in ocean and atmosphere. The model does not reproduce the observed latitudinal gradient of DDT in the ocean, i.e. the modelled and observed gradients have a different sign. Observations show, that the contamination of the ocean by DDT is decreasing towards the Arctic, whereas in the model simulation contaminations are increasing. 

Pemberton, P. W. (1998). The occurrence and abundance of plants with extrafloral nectaries, the basis for antiherbivore defensive mutualisms, along a latitudinal gradient in east Asia. Journal of Biogeography 25 661-668. 

S and 20°S DMS concentrations, in the same depth range, as mentioned above varied between 1 and 5 nM. DMS levels were lower in 1998 with strong latitudinal gradients. 

Figure 7 Latitudinal gradients of termite generic richness north and south of the equator (source Eggleton, 2000).

Wieder R. K. and Yavitt J. B. (1994) Peatlands and global climate change insights from comparative studies of sites situated along a latitudinal gradient. Wetlands 14, 229-238. 

Nybakken, L., Aubert, S., Bilger, W. 2004. Epidermal UV screening of arctic and alpine plants along a latitudinal gradient in Europe. Polar Biol. 27 391-398. 

Robberecht, R., Caldwell, M. M., Billings, W. D. 1980. Leaf ultraviolet optical properties along a latitudinal gradient in the arctic-alpine life zone. Ecology 61 612-619. 

Figure 5.9. Density of radiata pine shows no latitudinal gradient in Chile the average age of the stands is 22 (Delmastro et ah, 1982).

X 10 M in polar regions) [99,111]. This trend can largely be explained in terms of latitudinal gradients in temperature and UVR, both of which decrease with increasing latitude. Temperature inversely affects rates, in part, because apparent quantum yields for the photoproduction of H2O2 decrease nearly two-fold per 10°C decrease in temperature [99,112]. This temperature depend-... 

Ozone observations near 90 km available from the Solar Mesosphere Explorer are characterized by strong latitudinal gradients and large local variations. Barth et al. (1983) suggested that this may result from downward transport of oxygen from the thermosphere because of the long Ox lifetime at these altitudes, as shown in Figure 5.3. 

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