Earlier springs are causing reduced nitrogen availability in North American eastern deciduous forests

Area of Science:

• Forest Ecology
• Climate Change Science
• Biogeochemistry

Background:

• Anthropogenic climate warming impacts forest phenology, altering growing seasons.
• Extended growing seasons can enhance photosynthesis but may increase demand for soil resources.
• Potential for increased nitrogen limitation due to higher plant demand or ecosystem losses.

Discussion:

• This study investigated the link between earlier spring phenology and nitrogen availability in Eastern North American forests.
• Data from 222 trees across three species were analyzed over the past 30 years.
• Earlier spring phenology was found to decrease nitrogen availability by increasing demand relative to supply.

Key Insights:

• Earlier spring phenology in Eastern North American forests has led to reduced nitrogen availability for trees.
• Observed declines in nitrogen availability did not correlate with reduced wood production.
• Increased atmospheric CO2 and water availability may be mitigating nitrogen limitation's impact on productivity.

Outlook:

• Nitrogen limitation is projected to increase in these forests under current environmental change trajectories.
• This increasing limitation may further restrict the carbon sequestration potential of forests.
• Understanding these dynamics is crucial for predicting future forest ecosystem responses to climate change.