Background
The authors introduce the subject of their study by saying "most models predict that climate warming will increase the release of carbon dioxide from the terrestrial biosphere into the atmosphere, thus triggering positive climate-terrestrial carbon feedback which leads to a warmer climate." However, they state that the "stimulation of biomass accumulation and net primary productivity of terrestrial ecosystems under rising temperature (Rustad et al., 2001; Melillo et al., 2002; Luo et al., 2009) may enhance carbon sequestration and attenuate the positive feedback between climate warming and the terrestrial biosphere." So which view is correct?

What was done
Lin et al. conducted a meta-analysis of pertinent data they obtained from 127 individual studies that were published prior to June 2009, in order to determine if the overall impact of a substantial increase in the air's CO2 concentration on terrestrial biomass production would likely be positive or negative.

What was learned
The three scientists report that for the totality of terrestrial plants included in their analysis, "warming significantly increased biomass by 12.3%," while noting there was a "significantly greater stimulation of woody (+26.7%) than herbaceous species (+5.2%)." They also found that the warming effects on plant biomass production "did not change with mean annual precipitation or experimental duration," and that "other treatments, including CO2 enrichment, nitrogen addition, drought and water addition, did not alter warming responses of plant biomass."

What it means
The Chinese researchers conclude, in their words, that "results in this and previous meta-analyses (Arft et al., 1999; Rustad et al., 2001; Dormann and Woodin, 2001; Walker et al., 2006) have revealed that warming generally increases terrestrial plant biomass, indicating enhanced terrestrial carbon uptake via plant growth and net primary productivity." Thus, we can logically expect that (1) the ongoing rise in the air's CO2 content will soften its own tendency to increase global temperatures, while at the same time (2) blessing earth's terrestrial vegetation with greater growth rates and biomass production, both in the agricultural arena and throughout the planet's many natural ecosystems.

References
Arft, A.M., Walker, M.D., Gurevitch, J., Alatalo, J.M., Bret-Harte, M.S., Dale, M., Diemer, M., Gugerli, F., Henry, G.H.R., Jones, M.H., Hollister, R.D., Jonsdottir, I.S., Laine, K., Levesque, E., Marion, G.M., Molau, U., Molgaard, P., Nordenhall, U., Raszhivin, V., Robinson, C.H., Starr, G., Stenstrom, A., Stenstrom, M., Totland, O., Turner, P.L., Walker, L.J., Webber, P.J., Welker, J.M. and Wookey, P.A. 1999. Responses of tundra plants to experimental warming: meta-analysis of the international tundra experiment. Ecological Monographs 69: 491-511.

Dormann, C.F. and Woodin, S.J. 2002. Climate change in the arctic: using plant functional types in a meta-analysis of field experiments. Functional Ecology 16: 4-17.

Luo, Y.Q., Sherry, R., Zhou, X.H. and Wan, S.Q. 2009. Terrestrial carbon-cycle feedback to climate warming: experimental evidence on plant regulation and impacts of biofuel feedstock harvest. Global Change Biology Bioenergy 1: 62-74.

Melillo, J.M., Steudler, P.A., Aber, J.D., Newkirk, K., Lux, H., Bowles, F.P., Catricala, C., Magill, A., Ahrens, T. and Morrisseau, S. 2002. Soil warming and carbon-cycle feedbacks to the climate system. Science 298: 2173-2176.

Rustad, L.E., Campbell, J.L., Marion, G.M., Norby, R.J., Mitchell, M.J., Hartley, A.E., Cornelissen, J.H.C., Gurevitch, J. and GCTE-NEWS. 2001. A meta-analysis of the response of soil respiration, net nitrogen mineralization, and aboveground plant growth to experimental ecosystem warming. Oecologia 126: 543-562.

Walker, M.D., Wahren, C.H., Hollister, R.D., Henry, G.H.R., Ahlquist, L.E., Alatalo, J.M., Bret-Harte, M.S., Calef, M.P., Callaghan, T.V., Carroll, A.B., Epstein, H.E., Jonsdottir, I.S., Klein, J.A., Magnusson, B., Molaug, U., Oberbauer, S.F., Rewan, S.P., Robinson, C.H., Shaver, G.R., suding, K.N., Thompson, C.C., Tolvanen, A., Totland, O., Turner, P.L., Tweedie, C.E., Webber, P.J. and Wookey, P.A. 2006. Plant community responses to experimental warming across the tundra biome. Proceedings of the National Academy of Sciences USA 103: 1342-1346.