மேற்கு நோக்கி நகரும் மரங்கள்

மரங்கள் இயற்கையில் நிகழும் மாற்றங்களுக்கு ஏற்ப தங்களை தகவமைத்துக்கொள்ளும். இதன்படி, பழக்கமான வெப்பநிலைக்காக மரங்கள் வட, தென் துருவங்களை நோக்கியே நகரும் என தாவரவியலாளர்கள் கணித்திருந்தனர். ஆனால், அமெரிக்காவில், கடந்த 30 ஆண்டுகளாக, 86 வகை மரங்களை ஆராய்ந்த தாவரவியல் விஞ்ஞானிகள், அவை எதிர்பாராதவிதமாக மேற்கு பகுதியை நோக்கி நகர ஆரம்பித்திருப்பது தெரியவந்துள்ளது.

trees-moving

பருவநிலை மாற்றம், குறிப்பாக, மழைப் பொழிவில் ஏற்பட்டுள்ள மாற்றம் இந்த மரப் பெயர்வுகளுக்கு காரணமாக இருக்கலாம் என பர்டியூ பல்கலைக்கழக (Purdue University) விஞ்ஞானிகள் கருதுகின்றனர்.

4

Trees in eastern US head west as climate changes

Ecologists have long predicted that climate change will send plants and animals uphill and towards the poles in search of familiar temperatures. Such movements have increasingly been documented around the world. But a study now shows that changing rainfall patterns may be driving some tree species in the eastern United States west, not north.

Songlin Fei, a forest ecologist at Purdue University in West Lafayette, Indiana, and his colleagues tracked the shifting distributions of 86 types of trees using data collected by the US Forest Service’s Forest Inventory and Analysis Program during two periods: from 1980 to 1995 and between 2013 and 2015 for all states. They found more species heading west than north, probably partly because of changing precipitation patterns.

This study suggests that, in the near-term, trees are responding to changes in water availability more than to temperature changes, he says.

Most of the trees that shifted west were angiosperms, or flowering trees. Northbound trees were usually gymnosperms, which are mostly conifers in North America.

Increased precipitation in the central United States could be one explanation for the angiosperms’ westward movement, says Fei. The increase in moisture is still subtle enough that only the more drought-tolerant and faster-growing flowering trees, which have more-efficient and robust vascular systems, can take advantage for now.

What is certain is that the forests of today will look different 10, 20 or 30 years from now. “If you think of these species as members of a family, the question is, will some families break apart, or will they travel together?” says Fei. “We might be talking about these families breaking apart.”

Source Dinamalar and Nature

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