Plant biomass of grasses in active restoration grasslands shows stronger
association with its eco-physiological properties than native grasslands
alongside degradation
Abstract
Grassland degradation can affect plant eco-physiological properties and
thus influence ecosystem productivity and ecosystem function. However,
how land degradation affects the relationship between plant biomass and
eco-physiological properties of active restoration grasslands and native
grasslands in alpine meadow is less understood. A series of degraded
grasslands (non-degraded, slightly degraded, moderately degraded,
heavily degraded and extremely degraded grasslands) and a series of
active restoration grasslands (active restored grasslands with different
growth time, 5 years, 9 years, 11 years, 14 years and 17 years) were
selected to investigate the relationship between eco-physiological
properties and aboveground biomass (AGB) of grasses alongside
degradation. Results showed that the AGB, net photosynthetic rate (Pn)
and plant nitrogen (N) concentration decreased significantly with
increased levels of degradation in native grasslands. Plant
photosynthetic capacity, plant N and phosphorus (P) concentration
significantly decreased at 9th year or longer than 9 years of replanting
time in active restoration grasslands. Plant eco-physiological
properties in active restoration grasslands shows stronger association
with its AGB than native grasslands. In native grasslands, degradation
affect AGB directly and through Pn indirectly. In active restoration
grasslands, degradation affect AGB directly and through Pn, plant N and
P indirectly. Our results indicated that through improving plant
nutrients to restore degraded active grasslands may be more effective
than to restore degraded native grasslands.