A forestry expert says the 2011 Texas drought weakened trees but dehydration was likely not why millions of trees died.
Eric Taylor is a forestry specialist with the Texas AgriLife Extension Service.
Taylor said in most cases trees that died likely were already stressed from environmental factors, such as overcrowding, age and compacted soil. Taylor also said inappropriate use of herbicides could have contributed to tree deaths.
Taylor said lack of water may be the trigger, but many trees likely died from excessive heat, insect damage and diseases.
The Texas Forest Service last December announced a preliminary estimate of up to 500 million trees killed by the drought. Crews have spent the last two months doing ground surveys for a more specific drought count.
Taylor's findings were announced Friday.