Leaf Fresh Weight Versus Dry Weight: Which is Better for Describing the Scaling Relationship between Leaf Biomass and Leaf Area for Broad-Leaved Plants?

Abstract

Leaf dry mass per unit area (LMA) is considered to represent the photosynthetic capacity, which actually implies a hypothesis that foliar water mass (leaf fresh weight minus leaf dry weight) is proportional to leaf dry weight during leaf growth. However, relevant studies demonstrated that foliar water mass disproportionately increases with increasing leaf dry weight. Although scaling relationships of leaf dry weight vs. leaf area for many plants were investigated, few studies compared the scaling relationship based on leaf dry weight with that based on leaf fresh weight. In this study, we used the data of three families (Lauraceae, Oleaceae, and Poaceae, subfamily Bambusoideae) with five broad-leaved species for each family to examine whether using different measures for leaf biomass (i.e., dry weight and fresh weight) can result in different fitted results for the scaling relationship between leaf biomass and area. Reduced major axis regression was used to fit the log-transformed data of leaf biomass and area, and the bootstrap percentile method was used to test the significance of the difference between the estimate of the scaling exponent of leaf dry weight vs. area and that of leaf fresh weight vs. area. We found that there were five species across three families (Phoebe sheareri (Hemsl.) Gamble, Forsythia viridissima Lindl., Osmanthus fragrans Lour., Chimonobambusa sichuanensis (T.P. Yi) T.H. Wen, and Hibanobambusa tranquillans f. shiroshima H. Okamura) whose estimates of the scaling exponent of leaf dry weight to area and that of leaf fresh weight to area were not significantly different, whereas, for the remaining ten species, both estimates were significantly different. For the species in the same family whose leaf shape is narrow (i.e., a low ratio of leaf width to length) the estimates of two scaling exponents are prone to having a significant difference. There is also an allometric relationship between leaf dry weight and fresh weight, which means that foliar water mass disproportionately increases with increased leaf dry weight. In addition, the goodness of fit for the scaling relationship of leaf fresh weight vs. area is better than that for leaf dry weight vs. area, which suggests that leaf fresh mass might be more able to reflect the physiological functions of leaves associated with photosynthesis and respiration than leaf dry mass. The above conclusions are based on 15 broad-leaved species, although we believe that those conclusions may be potentially extended to other plants with broad and flat leaves.

Leaf shape influences the scaling of leaf dry mass vs. area: a test case using bamboos

“…Leaf shape appears to be an important factor even when data from different species are pooled. For example, a previous study shows that the scaling exponent of leaf fresh mass vs. area is 1.147 for the pooled data of 11 bamboo species (r 2 = 0.99, Lin et al 2018; see also Huang et al 2019). This finding can be explained by the fact that all bamboo plants have a similar leaf shape regardless of the differences in the quotients of leaf width and length (Shi et al 2018(Shi et al , 2019b.…”

“…If the increase in surface area is proportional to that of dry mass (which means that the scaling exponent of leaf dry mass vs. area is equal to unity), LMA is a constant. However, numerous data sets have demonstrated that leaf area, on average, fails to keep pace with leaf mass for many broad-leaved species (Milla and Reich 2007;Niklas et al 2007;Huang et al 2019), i.e., the scaling exponent for leaf surface area vs. dry mass is less than 1.0. This phenomenon has been referred to as "diminishing returns" (Niklas et al 2007).…”

Increased soil moisture aggravated the competitive effects of the invasive tree Rhus typhina on the native tree Cotinus coggygria

“…Drier soils have been demonstrated to significantly increase the total biomass of invasive species, whereas, the native species are unaffected by the soil water status [31]. Invasive plant can adjust the resource allocation to leaf, which can decrease leaf are to reduce transpiration loss [32]. However, the relative growth rate of invasive Lantana camara decreased under drought condition; thus, limiting its invasion into arid and sub-arid environments [33].…”

Detection and characterization of resistance to acetolactate synthase inhibiting herbicides in Anisantha and Bromus species in the United Kingdom

“…Fresh biomass was used as proxy for measuring herbicide resistance because the fresh biomass was able to reflect the physiological functions of leaves associated with photosynthesis and respiration better than dry biomass . ALS‐inhibitor herbicides showed variable control in efficacy for all four brome species tested particularly in A. sterilis (Fig.…”