Divergent response and adaptation of specific leaf area to environmental change at different spatio-temporal scales jointly improve plant survival

Specific leaf area (SLA) is one of the most important plant functional
traits. It integrates multiple functions and reflects strategies of plants
to obtain resources. How plants employ different strategies (e.g., through
SLA) to respond to dynamic environmental conditions remains poorly
understood.This study aimed to explore the spatial variation in SLA and
divergent adaptation of plants by changing SLA through the lens of
biogeographic patterns, evolutionary history, and short-term responses.
SLA data for 5424 plant species from 76 natural communities in China were
systematically measured and integrated with meta-analysis of field
experiments (i.e., global warming, drought, and nitrogen addition). The
mean value of SLA across all species was 21.8 m2 kg–1, ranging from 0.9 to
110.2 m2 kg–1. SLA differed among different ecosystems, temperature zones,
vegetation types, and functional groups. Phylogeny had a weak effect on
SLA, but plant species evolved toward higher SLA. Furthermore, plants
responded nonlinearly to environmental change by changing SLA.
Unexpectedly, radiation was one of the main factors determining the
spatial variation in SLA on a large scale. Conversely, short-term
manipulative experiments showed that SLA increased with increased resource
availability and tended to stabilize with treatment duration. However,
different species exhibited varying response patterns. Overall, long-term
adaptation of plants to environmental gradients and its short-term
response to resource pulses through variation in SLA jointly improve plant
adaptability to a changing environment. Overall SLA-environment
relationships should be emphasized as a multidimensional strategy for
elucidating environmental change in future research.