Stem growth of multipurpose tree species: net effect of micrometeorological variability assessed by principal component regression

Abstract

In a typical year in the central Amazon, there is a mild dry season, but its effect on stem growth of multipurpose forest tree species is not yet well known. This study aimed to determine the individual effect of microclimatic parameters on stem growth after removing the influence of intercorrelation among microclimatic variables. Monthly stem diameter increment was measured in six species (46 trees) from January 2018 to December 2020. Microclimatic variables recorded were irradiance, air temperature, rainfall, and vapor pressure deficit. Principal component regression was used to assess the effect of micrometeorological variability on stem growth. On average, stem growth increased with an increase in rainfall and soil water content, but decreased with rise in maximum temperature and maximum vapor pressure deficit. These findings indicate that, when removing the effect of intercorrelation between microclimatic parameters, vapor pressure deficit may, in fact, affect stem growth. We demonstrate that the reduction in stem growth during the dry season can also be related to an increase in maximum temperature and maximum vapor pressure deficit, and not only to a decline in soil water content.

Stem growth of Amazonian species is driven by intra-annual variability in rainfall, vapor pressure and evapotranspiration

“…For instance, Silva et al (2003) and Dias et al (2022) found no effect of precipitation on stem growth in the central Amazon, while Yang et al (2018) found that photosynthesis, over the entire Amazon region, can decline in the dry season. Likewise, Méndez (2018) and Souza & Marenco (2022) reported a decline in stem growth during the dry season in a terra-firme rainforest of the central Amazon.…”

“…There are also shown stem growth in diameter (SG mm month -1 ± standard error), number of tree per species (n), mean diameter at breast height (DBH, in cm), height (H, in m), and wood density (WD, in g cm-3). Tree height (H) was computed using the equation of Souza & Marenco (2022), being H (m) .…”

“…It is known that climatic variables are often correlated (e.g. Clark et al 2003;Antezana-Vera & Marenco 2021;Souza & Marenco 2022), which makes it rather difficult to assess the individual effects of microclimatic factors on tree growth.…”