Scientific American
Hannah Waters
The Environmental Nature
January 14, 2013
Environmental Science: City Trees Grow Faster,
But Seedlings Struggle to Take Root
Hannah Waters
The Environmental Nature
January 14, 2013
Environmental Science: City Trees Grow Faster,
But Seedlings Struggle to Take Root
Summary:
Urban areas are growing in size, and with them. The number of trees influenced by city life.City trees have to deal with very different growing conditions than trees in more rural areas or old forests. Raise summertime nighttime temperatures by 2-5°F on average–and as much as 22°F on clear nights–compared to the surrounding non-urban areas. Coniferous trees common in the U.S. Pacific Northwest, grow more quickly but produce fewer seedlings, potentially putting these urban forest ecosystems on an unpredictable long-term trajectory.m the Universities of California and Washington compared forest patches within urban Seattle (5,000 to 12,000 people per square mile), in rural areas outside the city (150 to 3,000 people per square mile), and old-growth forest in Mount Rainier National Park (people-free), measuring air temperature and soil nitrogen as a proxy for nutrients.The authors speculate that higher temperatures created longer growing seasons, allowing each tree a bit more time to stretch toward the sky, and the excess nitrogen may have acted as a fertilizer.Baby plants are very sensitive to soil moisture, which would be more prone to dehydration because of increased evaporation under warm climates.. Urban and rural forests receive more human foot traffic, so seedlings in these more disturbed forests may have been trampled to death. A fairly predictable list of species will colonize, thrive and become rare as a forest matures, a process known as succession. |
Reflection:
My thought in Scientific American is why urban and rural forests receive more human foot traffic? Urban and rural forests receive more human foot traffic, so seedlings in these more disturbed forests may have been trampled to death. It’s also possible that trees in urban and rural forests are just too young to produce a lot of seedlings. Old-growth forests have many more mature trees, which produce far more seed-laden cones. |