“Diminishing returns” in the scaling of leaf area vs. dry mass in Wuyi Mountain bamboos, Southeast China

Abstract

The data collected for all five bamboo species are consistent with the "diminishing returns" hypothesis, i.e., the scaling exponents governing the leaf area vs. dry mass scaling relationship are less than one within and across species and are insensitive to light conditions or elevation.

Increase in light interception cost and metabolic mass component of leaves are coupled for efficient resource use in the high altitude vegetation

“…We used standardized major axis regression (SMA, also called reduced major axis regression) (Warton et al 2012) to analyze the scaling relationship between various traits. SMA is the recommended (Warton et al 2006(Warton et al , 2012 and most commonly used method for analyzing trait scaling relationships (Milla and Reich 2007, Niklas et al 2007, Sun et al 2017. SMA is appropriate when none of the variables (x or y) is independent, errors on x and y are in same order of magnitude and when our interest is in estimating line of best fit rather than predicting one variable from another (Warton et al 2012).…”

“…Solar radiation intensity increases with altitude, and during daytime in high altitudes, it remains well above the saturation levels for photosynthesis (Gale ) and is an advantage for plants growing there (Terashima et al 2011). However, high light environments at high altitudes may also cause photo damage (Taiz and Zeiger ) and therefore plants may invest towards appropriate adaptation for protection and utilization of high solar radiations. Atmospheric humidity decreases with increasing elevation, so water demand for transpiration also increases.…”

“…Since SLA is derived from A and M, studying A-M scaling relationship along with SLA becomes important and meaningful as this relationship tells us about 'how SLA changes' with change in leaf area across species and habitats. For example, when SLA decreases with increasing leaf area, the light interception cost increases (also called "diminishing returns") (Milla and Reich 2007, Niklas et al 2007, Pan et al 2013, Sun et al 2017. Similarly, other scaling relationships such as between leaf water mass (W) and M represents changes in W per unit change in leaf dry mass and, relationship between W and A represents changes in W per unit increase in leaf area.…”

“…Studies have been conducted in the past to analyze variation in α for A-M scaling relationship, across species (Milla and Reich 2007), species groups (Niklas et al 2007) and abiotic gradients (Pan et al 2013, Sun et al 2017), but such analyses for high altitude vegetation are lacking. In the high altitude region, such as in Himalaya, several gradients (presence of opposite slope aspects and elevational gradients) are present in a relatively small spatial scale making them as one of the most powerful 'natural laboratories' for studying ecological responses of plants (Körner 2007, Jump et al 2009, Dvorský et al 2016, Heggie 2016, Enquist et al 2017.…”

“Diminishing Returns” in the Scaling between Leaf Area and Twig Size in Three Forest Communities Along an Elevation Gradient of Wuyi Mountain, China

“…Lamina area and lamina mass are crucial leaf traits underpinning the metabolic performance of plants [11]. The "diminishing returns" economic principle provides one explanation for why the scaling of total plant growth as a function of total mass is governed by a scaling exponent with a value significantly less than one [12].…”