Dynamic spatial patterns of leaf traits affect total respiration on the crown scale

Temporal and spatial variations of leaf traits caused conflicting conclusions and great estimating errors of total carbon budget on crown scales. However, there is no effective method to quantitatively describe and study heterogeneous patterns of crowns yet. In this study, dynamic spatial patterns of typical ecological factors on crown scales were investigated during two sky conditions, and CEZs (crown ecological zones) method was developed for spatial crown zoning, within which leaf traits were statistically unchanged. The influencing factors on hourly and spatial variations of leaf dark respiration (R(d)) were analysed, and total crown respiration (R(t)) was estimated based on patterns of CEZs. The results showed that dynamic spatial patterns of air temperature and light intensity changed significantly by CEZs in special periods and positions, but not continuously. The contributions of influencing factors on variations of R(d) changed with crown depth and sky conditions, and total contributions of leaf structural and chemical traits were higher during sunny days than ecological factors, but lower during cloudy days. The estimated errors of R(t) may be obviously reduced with CEZs. These results provided some references for scaling from leaves to crown, and technical foundations for expanding lab-control experiments to open field ones.