Distinct Responses of Leaf Traits to Environment and Phylogeny Between Herbaceous and Woody Angiosperm Species in China

Abstract

Leaf traits play key roles in plant resource acquisition and ecosystem processes; however, whether the effects of environment and phylogeny on leaf traits differ between herbaceous and woody species remains unclear. To address this, in this study, we collected data for five key leaf traits from 1,819 angiosperm species across 530 sites in China. The leaf traits included specific leaf area, leaf dry matter content, leaf area, leaf N concentration, and leaf P concentration, all of which are closely related to trade-offs between resource uptake and leaf construction. We quantified the relative contributions of environment variables and phylogeny to leaf trait variation for all species, as well as for herbaceous and woody species separately. We found that environmental factors explained most of the variation (44.4-65.5%) in leaf traits (compared with 3.9-23.3% for phylogeny). Climate variability and seasonality variables, in particular, mean temperature of the warmest and coldest seasons of a year (MTWM/MTWQ and MTCM/MTCQ) and mean precipitation in the wettest and driest seasons of a year (MPWM/MPWQ and MPDM/MPDQ), were more important drivers of leaf trait variation than mean annual temperature (MAT) and mean annual precipitation (MAP). Furthermore, the responses of leaf traits to environment variables and phylogeny differed between herbaceous and woody species. Our study demonstrated the different effects of environment variables and phylogeny on leaf traits among different plant growth forms, which is expected to advance the understanding of plant adaptive strategies and trait evolution under different environmental conditions.

Keywords: angiosperm species; climate variability and seasonality; functional biogeography; leaf traits; phylogeny; plant growth form.

FIGURE 1

Geographical distribution of sampling sites in China. The size of the green dots on the map indicates the relative number of species measurements.

FIGURE 2

Boxplots of leaf traits for all species (All), herbaceous species (H), and woody species (W). The number above each box indicates the total number of species per group. The bottom and top of the boxplots indicate the first and third quartile, the two whiskers correspond to the 1.5 times of the outliers, and the solid dots within the boxes are the mean values. Different lowercase letters indicate significant differences between herbaceous and woody species (p < 0.05). (A) SLA, specific leaf area; (B) LDMC, leaf dry matter content; (C) LA, leaf area; (D) LNC, leaf N concentration; (E) LPC, leaf P concentration.

FIGURE 3

Correlations of leaf traits with climate variables based on a phylogenetic linear mixed model (PLMM). Significant correlations between leaf traits and climate variables are shown (p < 0.05). Positive values represent positive correlations between leaf traits and climate variables, while negative values represent negative correlations between them. (A) All species; (B) herbaceous species; (C) woody species. SLA, specific leaf area; LDMC, leaf dry matter content; LA, leaf area; LNC, leaf N concentration; LPC, leaf P concentration; MASL, mean annual sunlight; MAT, mean annual temperature; GST, mean growing season temperature; MDR, mean diurnal range; MTAR, mean annual range of temperature; MTWM, mean temperature of the warmest month of a year; MTCM, mean temperature of the coldest month of a year; MTWQ, mean temperature of the warmest quarter of a year; MTCQ, mean temperature of the coldest quarter of a year; AA0, active accumulated temperature above 0°C; MAP, mean annual precipitation; GSP, mean growing season precipitation; MPAR, mean annual range of precipitation; MPWM, mean precipitation of the wettest month of a year; MPDM, mean precipitation of the driest month of a year; MPWQ, mean precipitation of the wettest quarter of a year; MPDQ, mean precipitation of the driest quarter of a year; AET, actual evapotranspiration; AI, aridity index; PET, potential evapotranspiration.

FIGURE 4

Correlations of leaf traits with soil variables based on a phylogenetic linear mixed model (PLMM). Significant correlations between leaf traits and soil variables are shown (p < 0.05). Positive values represent positive correlations between leaf traits and soil variables, while negative values represent negative correlations between them. (A) All species; (B) herbaceous species; (C) woody species. SLA, specific leaf area; LDMC, leaf dry matter content; LA, leaf area; LNC, leaf N concentration; LPC, leaf P concentration; SAND, percentage of sand fraction; SILT, percentage of silt fraction; CLAY, percentage of clay fraction; BD, bulk density; SOM, soil organic matter; SOC, soil organic carbon; STN, soil total N; STP, soil total P; STK, soil total K; CCEC, clay cation exchange capacity; SCEC, soil cation exchange capacity; BS, base saturation; TEB, total exchangeable bases; CaCO₃, calcium carbonate content; ESP, exchangeable sodium percentage; EC, electrical conductivity.

FIGURE 5

Variance partitioning for leaf traits using a phylogenetic linear mixed model (PLMM) for (A) all species, (B) herbaceous species, and (C) woody species. SLA, specific leaf area; LDMC, leaf dry matter content; LA, leaf area; LNC, leaf N concentration; LPC, leaf P concentration.