No abstract

Epiphytic bryophytes (EB) are some of the most commonly found plant species in tropical montane cloud forests, and they play a disproportionate role in influencing the terrestrial hydrological and nutrient cycles. However, it is difficult to estimate the abundance of EB due to the nature of their “epiphytic” habitat. This study proposes an allometric scaling approach implemented in twenty-one 30 × 30 m plots across an elevation range in 16,773 ha tropical montane cloud forests of northeastern Taiwan to measure EB biomass, a primary metric for indicating plant abundance and productivity. A general allometry was developed to estimate EB biomass of 100 cm2 circular-shaped mats (n = 131) with their central depths. We developed a new point-intercept instrument to rapidly measure the depths of EB along tree trunks below 300 cm from the ground level (sampled stem surface area (SSA)) (n = 210). Biomass of EB of each point measure was derived using the general allometry and was aggregated across each SSA, and its performance was evaluated. Total EB biomass of a tree was estimated by referring to an in-situ conversion model and was interpolated for all trees in the plots (n = 1451). Finally, we assessed EB biomass density at the plot scale of the study region. The general EB biomass-depth allometry showed that the depth of an EB mat was a salient variable for biomass estimation (R2 = 0.72, p < 0.001). The performance of upscaling from mats to SSA was satisfactory, which allowed us to further estimate mean (±standard deviation) EB biomass of the 21 plots (272 ± 104 kg ha−1). Since a significant relationship between tree size and EB abundance is commonly found, regional EB biomass may be mapped by integrating our method and three-dimensional remotely sensed airborne data.

10Epiphytic bryophytes (EB) are some of the most commonly found plant species in tropical 11 montane cloud forests, and they play a disproportionate role in influencing the terrestrial 12 hydrological and nutrient cycles. However, it is difficult to estimate the abundance of EB due to 13 the nature of their "epiphytic" habitat. This study proposes an allometric scaling approach to 14 measure EB biomass, implemented in 16,773 ha tropical montane cloud forests of northeastern 15Taiwan. A general allometry was developed to estimate EB biomass of 100 cm 2 circular-shaped 16 mats (n = 131) and their central depths. A point-intercept instrument was invented to measure 17 the depths of EB along tree trunks (n = 210) below 3-m from the ground level (sampled stem 18 surface area [SSA]) in twenty-one 30  30 m plots. Biomass of EB of each point measure was 19 derived using the general allometry and was aggregated across each SSA, and its performance 20 was evaluated. Total EB biomass of a tree was estimated by referring to an in-situ conversion 21 model and was interpolated for all trees in the plots (n = 1451). Finally, we assessed EB 22 biomass density at the plot scale and preliminarily estimated EB biomass of the study region. 23The general EB biomass-depth allometry showed that the depth of an EB mat was a salient 24 variable for biomass estimation (R 2 = 0.72, p < 0.001). The performance of upscaling from mats 25 to SSA was satisfactory, which allowed us to further estimate mean ( standard deviation) EB 26 biomass of the 21 plots (272  104 kg ha -1 ) and to provide preliminary estimation of the total 27 EB biomass of 4562 Mg for the study region. Since a significant relationship between tree size 28 and EB abundance is commonly found, regional EB biomass may be mapped by integrating our 29 method and three-dimensional airborne data. 30