Drought in California turns deadly for the trees in the state

Greg Asner
This image shows progressive water stress on California's forests.

The lakes in California have been drained due to drought, causing the land to subside and forcing the state to enforce draconian water rules.

A new study has found that several years of no rain or little rain is taking a significant toll on the forests in the state.

Researchers from the Carnegie Institution for Science at Stanford University concluded from the study that about 58 million large trees around California experienced loss of water that could threaten their existence. The phenomenon has been active since 2011 on account of historic drought faced by the State. Insect outbreaks that include the destructive dark beetle and higher temperatures are adding to the impact of the drought and enhancing the risk to the trees dying out and ushering in large-scale changes to the ecosystems.

Gregory Asner, the lead author of the study from Carnegie, stated that California is dependent on her forests for carbon storage, water provisioning, and timber products, apart from recreation, and tourism.  Therefore, the trees have tremendous importance culturally, economically and ecologically. The drought has brought the state’s forest to significant peril, and the situation could cause long-term changes to the ecosystems impacting biodiversity and animal habitats.

Advanced tools employed by the research team show that some 41,000 square miles of forest with about 888 million large trees have experienced a noticeable change in the quantum of water stored in the canopies of the trees during the period 2011-2015. Of this, some 58 million large trees spread across 3,861 square miles have reached thresholds of water loss which the scientists deem extremely dangerous for the long-term health of the forests.

Laser guided imaging spectrometer was used by Asner and his colleagues to obtain an accurate picture on the health of the trees. With this tool, they could measure the water mass in the canopy.

A substantial decrease in the level of canopy water has been documented by the study. Tree mortality rate has also gone up substantially due to the ongoing drought in California, and the trend is more likely to continue in the coming years too. The forests in the state will come under increased stress from higher temperatures. It is important therefore to have the ability to monitor the forest conditions periodically over large spatial scales.  The information gained will be extremely useful for private as well as public forest land managers and their process of decision making.