English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Open

Presents the pdf analysis as premium feature

PDF Analysis

Insights

Presents the summarisation as premium feature

Summarisation

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Ontogenetic changes in gas exchange parameters provide both insight into mechanisms underlying tree growth patterns, and data necessary to scale environmental impacts on young trees to predict responses of older trees. We present a quantitative review and meta-analysis of field measurements of gas exchange parameters in saplings and mature trees of 35 tree species (seven conifers, seven temperate deciduous trees, and 21 tropical evergreen trees). Data for saplings were obtained in both understory environments and open areas or large gaps. We also present data on ontogenetic changes in photosynthesis for  Pseudotsuga menziesii  (Mirb.) Franco and  Tsuga heterophylla  (Raf.) Sarg., species of particular interest because of their large maximal heights and long life-spans. Among tree species, there is evidence for both ontogenetic increases and ontogenetic decreases in photosynthetic capacity on a leaf area basis ( A  area ). Overall,  A  area  is generally higher for upper-canopy leaves of adult trees than for saplings, especially in temperate deciduous trees. However, the pattern for photosynthetic capacity on a leaf mass basis ( A  mass ) is the reverse of that observed for  A  area . Saplings of both conifers and broad-leaved trees, even when acclimated to low-light conditions, characteristically have a higher  A  mass  than adult trees. This pattern is driven largely by an ontogenetic increase in leaf mass per unit area (LMA), as found in 100% of studies reviewed. Data for Pacific Northwest conifers, although including measurements on some of the tallest trees studied, did not differ greatly from patterns found in other tree species. We conclude that ontogenetic changes in LMA are the single most consistent difference between saplings and adult trees, and that changes in LMA and related aspects of leaf morphology may be critical to understanding both variation in gas exchange during tree growth, and stage-dependent responses of trees to environmental change.

Photosynthetic differences between saplings and adult trees: an integration of field results by meta-analysis