Terpenes and forest decline

Convincing evidence of tropical forest decline.

In a recent issue of PNAS, Grainger (1) claimed that the evidence for decline of global tropical forests is ‘‘unclear’’ and that it is difficult to demonstrate that it is happening ‘‘convincingly using available tropical forest area data.’’ We agree with most of the article, yet we feel these statements overstate the uncertainty about tropical deforestation. His assessment is based only on the ...

Restoring Soil Calcium Reverses Forest Decline

Forest decline in the northeastern United States has been linked to the effects of acid deposition on soil nutrients. To test this link, we added a calcium silicate mineral to a paired watershed at the Hubbard Brook Experimental Forest, New Hampshire, in an amount designed to gradually replace the estimated amount of calcium lost as a result of human activity in the 20th Century (primarily beca...

Forest fragmentation and the decline of migratory songbirds

Drought-induced forest decline: causes, scope and implications.

A large number of episodes of forest mortality associated with drought and heat stress have been detected worldwide in recent decades, suggesting that some of the world's forested ecosystems may be already responding to climate change. Here, we summarize a special session titled 'Drought-induced forest decline: causes, scope and implications' within the 12th European Ecological Federation Congr...

Ecosystem properties and forest decline in contrasting long-term chronosequences.

During succession, ecosystem development occurs; but in the long-term absence of catastrophic disturbance, a decline phase eventually follows. We studied six long-term chronosequences, in Australia, Sweden, Alaska, Hawaii, and New Zealand; for each, the decline phase was associated with a reduction in tree basal area and an increase in the substrate nitrogen-to-phosphorus ratio, indicating incr...