Data from: Applied paleoecology for macrophyte restoration: Defining Anthropocene baselines in Lake Liangzi

The global degradation of freshwater lakes threatens biodiversity and
critical ecosystem services. Restoring aquatic macrophytes is essential
for reversing this decline, yet a fundamental challenge persists: the
debate between aiming for historical baseline conditions or accepting
novel ecosystems in the Anthropocene. This dilemma is exacerbated by a
lack of long-term data about pre-degradation states. Current assessments
are based mainly on short-term in situ observations, providing limited
insights into historical reference conditions and hindering the
development of effective restoration targets. Here, we develop an
evolutionary restoration methodological approach that integrates
sedimentary ancient DNA (sedaDNA), pollen, macrofossils, satellite remote
sensing, and contemporary surveys to determine the centennial-scale
trajectory of macrophyte communities and inform their restoration targets.
Taking Lake Liangzi (eastern China) as a case study, our results show that
submerged taxa (e.g., Potamogeton crispus, Najas minor, and Chara spp.)
dominated under oligotrophic conditions until the 1960, after which
nutrient pollution drove a shift to floating-leaved and emergent taxa
(e.g., Nelumbo nucifera, Nymphaea macrosperma, and Pontederia crassipes),
and eventually to an algal-dominated regime. Ecological Quality Ratio
(EQR) assessments reveal a clear degradation trajectory in Lake Liangzi;
macrophytes ecological quality declined from Good (pre-2010) to Poor
(present). The results indicate that restoration to pre-1960 baseline
conditions is unlikely to be directly achievable. Instead, we propose a
phased restoration pathway that first targets re-establishment of the
ecologically functional Anthropocene baseline represented by the 1960–2010
coexistence state, with the longer-term aspiration of recovering submerged
macrophyte-dominated communities. Synthesis and applications: Findings
move beyond the polarized historical vs. novel ecosystem debate by
advancing a dynamic restoration pathway and targets for macrophytes. This
pathway presents the Anthropocene baseline as a pragmatic stepping stone
toward long-term recovery and offers managers phased, realistic targets
that sustain ecosystem services while keeping the operational historical
reference as an aspirational goal. The method established offers a
practical basis for developing effective restoration strategies and can be
applied to Lake Liangzi and similar shallow lakes. It directly informs
global freshwater restoration under the UN Decade on Ecosystem
Restoration.