Seasonal Dynamics of Litterfall in a Sub-Alpine Spruce-Fir Forest on the Eastern Tibetan Plateau: Allometric Scaling Relationships Based on One Year of Observations

Abstract

Abstract:Litterfall is the primary source of carbon and nutrients that determine soil fertility in forest ecosystems. Most current studies have focused on foliar litter, but the seasonal dynamics and allometric scaling relationships among different litter components (e.g., foliar litter, woody litter, reproductive litter, and epiphytic litter) are poorly understood. Here, we investigated the litter production of various litter components in a sub-alpine spruce-fir forest on the eastern Tibetan Plateau based on one year of observations (from August 2015 to July 2016). Our results showed that total litter production (L T ) was 2380 kg·ha −1 ·year −1 (3% of the aboveground forest biomass), of which 73.6% was foliar litter (L F ), 15.6% was woody litter (L W ), 3.0% was reproductive litter (L R ), 1.3% was epiphytic litter (L E ), and 6.5% was miscellaneous material (L M ). The total litterfall was bimodal (with peaks occurring in April and October) and was dominated by tree species (85.4% of L T , whereas shrubs accounted for 6.8% of L T ). The litter production of evergreen species (68.4% of L T ) was higher than that of deciduous species (23.8% of L T ). Isometric relationships were observed between litter components and the total litter (i.e., L F ∝L T 0.99≈1 and L R ∝L T 0.98≈1 ), and allometric relationships were also found (i.e., L W ∝L T 1.40>1 and L M ∝L T 0.82<1 ). However, because some components did not exhibit obvious seasonal dynamics (i.e., L E ), some relationships could not be expressed using allometricand L E versus L M ). Thus, the different litter components showed different seasonal dynamics, and the total litter dynamics were primarily determined by the variation in foliar litter. In addition, the allometric relationships of the forest litterfall varied with the litter components, functional types (evergreen versus deciduous) and vertical structures (tree versus shrub). This study provides basic data and a new insight for future plant litter studies.

Newly shed litters contain an abundance of extractable humus carbon in a subalpine forest on the eastern Tibetan Plateau

“…), which were consistent with the study results obtained for subalpine forest (Appendix : Table S1; Fu et al. ), indicating that the litterfall input was the main driver of the carbon stocks. This finding could have occurred because the climatic factors indirectly affected the HC stocks by influencing litterfall amount.…”

“…The peak stock in the foliar litter was related to the litterfall amount of foliar litter and agreed with that of the total stock (Fu et al. ). In addition, a large HC stock in twig litter occurred in June (Fig.…”

“…A), likely due to the increase in twig litter production caused by snow (Fu et al. ). Moreover, the HC stock in the foliar litter of deciduous tree species (522.18 kg/hm 2 ) remains larger than that of evergreen tree species (512.36 kg/hm 2 ) due to their higher litterfall amount (Fig.…”

“…The annual mean precipitation is approximately 850 mm (Fu et al. ). The winter normally extends from late October to late April of the following year, and the growing season is from April to November (Wu et al.…”

“…Representative shrubs include Salix cupularis , Salix paraplesia , Rosa omeiensis , and Berberis silva‐taroucana among many others (Fu et al. ).…”