Patterns of local species richness and their associations with functional traits in a 60‐ha tropical forest dynamics plot

Abstract

Understanding the underlying mechanisms of diversity maintenance in tropics remains a challenge for ecologists. To reveal the underlying mechanism from a plant‐eye‐view perspective, we examined the patterns of local species richness which was defined as the number of species around individuals of a target species within circles of different radii and their correlations with major plant functional traits in a tropical montane rainforest. In 2012, we established a 60‐ha forest dynamics plot (FDP) in tropical montane rainforest on Hainan Island, China. In 2013, we measured eight functional traits (specific leaf area [SLA], leaf dry matter content [LDMC], wood density, potential maximum height, leaf carbon content [LCC], leaf nitrogen content [LNC], leaf phosphorus content [LPC], and leaf potassium content) of all the species in the FDP. Based on all the mapped individuals that had a diameter at breast height ≥10 cm, we utilized individual species–area relationships function (ISARs(r)) combined with the heterogeneous Poisson null model to quantify the patterns of local species richness at scales from 1 to 50 m. Regression analysis was used to determine which functional traits could influence the local diversity pattern. Results showed that the 123 ISARs(r) curves were relatively similar and no species seemed to be extremely higher or lower than the average of all the ISARs(r) curves. The percentage of species that behaved predominantly as accumulators or repellers or neutrally was 42.23%, 13.82%, and 43.9% at scale of <30 m, respectively. But at scales ≥30 m, more than 70% of all species behaved neutrally suggesting that facilitative interactions probably occurred when neighborhoods were <30 m apart. Among the eight measured traits, the SLA, LNC, and LPC were negatively associated with local species richness. Our results indicated that (1) the spatial community structure was not controlled by key species; (2) facilitative interactions played an important role in local diversity maintenance; (3) species with conservative functional trait syndromes were more likely to have relatively high local species richness in the tropical montane rainforest on Hainan Island, China.

Ecological uniqueness of species assemblages and their determinants in forest communities

“…The Hnjfl FDP is located in the Jianfengling National Nature Reserve (18°23′–18°50′N, 108°36′–109°05′E) in the south‐western region of Hainan Island, China. A 60‐ha (1,000 × 600 m) FDP within a vast area of continuous old‐growth tropical montane rainforest (TMRF) in the core area of the reserve was established from March 2009 to November 2012 (Xu et al., 2015; Zang et al., 2019). In the present study, we used data collected from a continuous 6‐ha (300 × 200 m) area (i.e.…”

Assessing the functional vulnerability of woody plant communities within a large scale tropical rainforest dynamics plot

“…A 60-ha FDP has been established in the core area of the Nature Reserve, serving as a typical seasonal moist tropical rainforest landscape ( Figure 1 ; Supplementary Table S1 ). In the study area (60-ha FDP), the elevation ranges from 866m to 1016m, the annual average temperature is 24.5°C and the monthly average ranges from 19.4°C to 27.3°C, with a wet season from May to October and a dry season from November to April ( Zang et al., 2019 ). The FDP was divided into 1,500 0.04-ha (20m×20m) subplots, which served as the basic units for investigation and monitoring.…”

Conspecific negative density dependence of trees varies with plant functional traits and environmental conditions across scales in a 60‐ha tropical rainforest dynamics plot

“…The altitude of the FDP varies from 866.3 m to 1,016.7 m, which is well within the tropical montane rainforest range. The 1,000 m × 600 m FDP was established according to the standard for FDP establishment (Condit, 1998; details in Zang et al., 2019). All woody stems with diameter at 1.3 m above ground (DBH) ≥1 cm in the plot were mapped, measured, identified to species, and tagged.…”

“…Each functional trait was measured on 10 individuals per species, according to standard protocols (Pérez-Harguindeguy et al, 2013). Details of plant functional traits measurements can be found in Zang et al (2019).…”