A unique approach was used to evaluate stomatal and nonstomatal constraints to photosynthesis in 19 naturally occurring, deciduous tree species on xeric, mesic and wetmesic sites in central Pennsylvania, USA, during relatively wet (1990) and dry (1991) growing seasons. All species exhibited significantly decreased stomatal conductance to CO2 (gc) in 1991 compared to 1990. The mesic species had drought related decreases in photosynthesis (A) attributed primarily to increased absolute stomatal limitation to A (Lg), whereas in the wet‐mesic species, the absolute mesophyll limitation (Lm) was at least as important as Lg in limiting A during drought. The xeric species maintained relatively high A during drought despite decreased gc. In the xeric and mesic species, Lm decreased and Lg increased during drought due to stomatal closure. From xeric to mesic to wet‐mesic, the relative stomatal limitation (Ig) generally decreased faster, and relative mesophyll limitations to A increased faster, with increasing gc suggesting greater photosynthetic capacity (i.e. greater potential maximum A) with increasing drought tolerance rank of species. Few species exhibited a significant drought‐related decrease in photosynthetic capacity. The results of this landscape‐based study indicate that the interaction of stomatal and nonstomatal limitations of A vary in a manner consistent with species' drought tolerance and site conditions, and that nonstomatal constraints to A in field plants during a moderate, season‐long drought were generally not as severe as reported in controlled studies.
|Original language||English (US)|
|Number of pages||7|
|Journal||Plant, Cell & Environment|
|State||Published - Dec 1993|
All Science Journal Classification (ASJC) codes
- Plant Science