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Range Expansion (Plants - Europe) -- Summary
When the atmosphere's CO2 concentration is experimentally increased, the vast majority of earth's plants lose less water to the atmosphere via transpiration while producing more biomass, the latter of which phenomena is generally more strongly expressed in woody perennial species than in annual herbaceous plants. Consequently, in concert with future increases in the air's CO2 concentration, earth's bushes, shrubs and trees will likely grow better and expand their ranges more than non-woody species will. Simultaneously, the increase in atmospheric CO2 content will make many plants of all types actually prefer warmer temperatures (Idso and Idso, 1994), which suggests that if air temperatures continue to rise in the future, that phenomenon will also spur both woody and non-woody plants to expand their ranges and grow more vigorously. In this summary, therefore, we review some of the evidence for this two-pronged phenomenon as it has operated in the past, focusing on what has been learned in Europe.

Allen et al. (1999) analyzed sediment cores extracted from a lake in southern Italy and from the Mediterranean Sea, developing a high-resolution 100,000-year climate and vegetation data set for this region. Their work revealed that rapid changes in vegetation were correlated with rapid changes in climate, such that complete shifts in natural ecosystems sometimes occurred over periods of less than 200 years.

Over the warmest portion of the record (the current interglacial), when the atmosphere's CO2 content was also at its highest, the total organic carbon content of the vegetation reached its highest level as well, more than doubling values experienced over the prior part of the record (the last great ice age). Other proxy indicators revealed that during the more productive woody-plant period of the current interglacial, the increased vegetative cover also led to less soil erosion.

The results of this study demonstrate that the biosphere can - and does! - respond to rapid changes in climate. In fact, the group of 15 scientists states that "the biosphere was a full participant in these rapid fluctuations, contrary to widely held views that vegetation is unable to change with such rapidity." Furthermore, warmer was always found to be better in terms of vegetative vitality. Consequently, future warming in this region, especially with continued increases in the air's CO2 concentration, will likely return it to a more favorable environmental state than that of the present.

Olsson et al. (2000) studied two mountain valleys in Norway typical of the Norwegian summer farming mountain ecosystem, which they say is shaped by human activities rooted in pre-history. More specifically, they quantified changes in land use and landscape patterns in the two areas over the period 1960-1993. In doing so, they learned that the grasslands and heathlands that had dominated the mountain slopes of the two areas in prior centuries are, in their words, "today decreasing due to forest invasion" characterized by "the spread of subalpine woodlands, and a raised treeline."

The researchers feel that the expansion of the subalpine woodlands "is primarily related to changes in the human use of those areas," which latter changes, in their estimation, are "much more influential than possible effects of climate change." However, it is possible that rising temperatures, together with the help provided by the ongoing rise in the air's CO2 concentration, may also be playing a role in the forests' comeback. In any event, the increasing presence of forests on the mountains of Norway is but one more manifestation of the spreading dominance of woody plants over the face of the planet, which is actually invigorating the biosphere and helping to slow the rate of rise of the atmosphere's CO2 concentration.

In another mountainous part of Europe, Walther et al. (2005) resurveyed (in July/August 2003) the floristic composition of the uppermost ten meters of ten mountain summits in the Swiss Alps, applying the same methodology used in earlier surveys of the same mountain tops by Rubel (1912), whose survey was conducted in 1905, and Hofer (1992), whose survey was conducted in 1985. Hence, their analysis covered the bulk of the Little Ice Age-to-Current Warm Period transition (1905-2003), the last portion of which (1985-2003) is claimed by climate alarmists to have experienced a warming that was unprecedented over the past two millennia in terms of both the rate of temperature rise and the level to which the temperature rose.

In conducting their research, Walther et al. found that whereas the mean increase in species numbers recorded by Hofer (1992) for the time interval 1905 to 1985 was 86%, their data indicated that "species numbers recorded in 2003 were generally more than double (138%) compared to the results by Rubel (1912) and 26% higher than those reported by Hofer (1992)." Expressed another way, they say "the rate of change in species richness (3.7 species/decade) was significantly greater in the later period compared to the Hofer resurvey (1.3 species/decade)." Most important of all, they found that "the observed increase in species numbers does not entail the replacement of high alpine specialists by species from lower altitudes [our italics], but rather has led to an enrichment [our italics] of the overall summit plant diversity."

This finding is incredibly important, for in spite of the apparent reasonableness of the global warming extinction hypothesis, whereby high-altitude species are predicted by climate alarmists to be "squeezed out of existence" by other species migrating upwards from lower mountain levels to escape the stress of increasing temperatures, Walther et al. find no sign of this dire consequence over an entire century of warming in the Swiss Alps, in harmony with the similar findings of other researchers that we describe in more detail in our major report The Specter of Species Extinction: Will Global Warming Decimate Earth's Biosphere?

Last of all, and most recently, Jump et al. (2006) "combined population genomic and correlative approaches to identify adaptive genetic differentiation linked to temperature within a natural population of the tree species Fagus sylvatica L. [European beech] in the Montseny Mountains of Catalonia, northeastern Spain," concentrating on three areas: the upper treeline (high Fagus limit, HFL), the lower limit of F. sylvatica forest (low Fagus limit, LFL), and an area of the forest interior.

With respect to the temperature differential between the HFL and LFL locations, the researchers note that the 648-m altitudinal difference that separates them "equates to a mean temperature difference of 3C ... based on the altitudinal lapse rate of 0.51C per 100 m reported by Penuelas and Boada (2003) for Montseny." Likewise, with respect to the region's manifestation of 20th-century global warming, they report that "by 2003, temperatures had increased by approximately 1.65C when compared with the 1952-1975 mean," which temperature change, as they see it, "is likely to represent a strong selection pressure."

Numerous tests conducted by Jump et al. on the data they collected revealed that the frequency of a particular F. sylvatica allele showed a predictable response to both altitudinal and temporal variations in temperature, with a declining frequency and probability of presence at the HFL site that the Spanish research team determined to be "in parallel with rising temperatures in the region over the last half-century." As a result, they say their work "demonstrates that adaptive climatic differentiation occurs between individuals within populations, not just between populations throughout a species geographic range," which further suggests, in their words, that "some genotypes in a population may be 'pre-adapted' to warmer temperatures (Davis and Shaw, 2001)."

The researchers also went on to contend that "the increase in frequency of these genotypes," which occurred in their study in parallel with rising temperatures, "shows that current climatic changes are now imposing directional selection pressure on the population," and that "the change in allele frequency that has occurred in response to this selection pressure also demonstrates that a significant evolutionary response can occur on the same timescale as current changes in climate (Davis et al., 2005; Jump and Penuelas, 2005; Thomas, 2005)."

In concluding, Jump et al. suggest that an evolutionary response to global warming of the type they describe is likely already underway, which further suggests that many species of plants likely will not be forced to migrate either poleward in latitude or upward in altitude in response to global warming, as climate alarmists adamantly claim they will be forced to do. Rather, plants will have the opportunity to so shift their ranges (i.e., expand them) at the cold-limited boundaries of their ranges, but they need not be forced to make any major changes at the heat-limited boundaries of their ranges, due in part to the phenomenon elucidated by Jump et al., as well as the tendency for optimum plant temperatures to rise in response to increasing atmospheric CO2 concentrations, as is also described in our major report The Specter of Species Extinction: Will Global Warming Decimate Earth's Biosphere?

In light of these several observations made throughout various parts of Europe, it would appear that indigenous plants of all types - but especially bushes, shrubs and trees - will continue to expand their ranges as the air's CO2 content, and possibly its temperature, continue to rise in the years and decades ahead.

References
Allen, J.R.M., Brandt, U., Brauer, A., Hubberten, H.-W., Huntley, B., Keller, J., Kraml, M., Mackensen, A., Mingram, J., Negendank, J.F.W., Nowaczyk, N.R., Oberhansli, H., Watts, W.A., Wulf, S. and Zolitschka, B. 1999. Rapid environmental changes in southern Europe during the last glacial period. Nature 400: 740-743.

Davis, M.B. and Shaw, R.G. 2001. Range shifts and adaptive responses to Quaternary climate change. Science 292: 673-679.

Davis, M.B., Shaw, R.G. and Etterson, J.R. 2005. Evolutionary responses to changing climate. Ecology 86: 1704-1714.

Hofer, H.R. 1992. Veranderungen in der Vegetation von 14 Gipfeln des Berninagebietes zwischen 1905 und 1985. Ber. Geobot. Inst. Eidgenoss. Tech. Hochsch. Stift. Rubel Zur 58: 39-54.

Idso, K.E. and Idso, S.B. 1994. Plant responses to atmospheric CO2 enrichment in the face of environmental constraints: a review of the past 10 years' research. Agricultural and Forest Meteorology 69: 153-203.

Jump, A.S., Hunt, J.M., Martinez-Izquierdo, J.A. and Penuelas, J. 2006. Natural selection and climate change: temperature-linked spatial and temporal trends in gene frequency in Fagus sylvatica. Molecular Ecology 15: 3469-3480.

Jump, A.S. and Penuelas, J. 2005. Running to stand still: adaptation and the response of plants to rapid climate change. Ecology Letters 8: 1010-1020.

Olsson, E.G.A., Austrheim, G. and Grenne, S.N. 2000. Landscape change patterns in mountains, land use and environmental diversity, Mid-Norway 1960-1993. Landscape Ecology 15: 155-170.

Penuelas, J. and Boada, M. 2003. A global change-induced biome shift in the Montseny Mountains (NE Spain). Global Change Biology 9: 131-140.

Rubel, E. 1912. Pflanzengeographische Monographie des Berninagebietes. Engelmann, Leipzig, DE.

Thomas, C.D. 2005. Recent evolutionary effects of climate change. In: Lovejoy, T.E. and Hannah, L. (Eds.), Climate Change and Biodiversity, Yale University Press, New Haven, Connecticut, USA, pp. 75-88.

Walther, G.-R., Beissner, S. and Burga, C.A. 2005. Trends in the upward shift of alpine plants. Journal of Vegetation Science 16: 541-548.

Last updated 4 April 2007