# Knowledge Quality Diagnosis of Spatial Graph Representations

In aboveground biomass estimation on the southeastern Tibetan Plateau, a spatial graph built from geographic nearest neighbors links valley forest to adjacent alpine meadow, because horizontal closeness does not imply ecological similarity. The study first quantifies these misconnections, then rebuilds the graph by keeping only edges whose endpoint elevation difference falls below a threshold, raising local-interpolation R² from 0.362 to 0.409 across 6,638 samples and ten seeds. Under a strict 30 km buffer holdout the same construction scores 0.054 lower than the ungated graph, so the gain depends on training neighbors remaining near the test points.

In aboveground biomass estimation on the southeastern Tibetan Plateau, a spatial graph built from geographic nearest neighbors links valley forest to adjacent alpine meadow, because horizontal closeness does not imply ecological similarity. The study first quantifies these misconnections, then rebuilds the graph by keeping only edges whose endpoint elevation difference falls below a threshold, raising local-interpolation R² from 0.362 to 0.409 across 6,638 samples and ten seeds. Under a strict 30 km buffer holdout the same construction scores 0.054 lower than the ungated graph, so the gain depends on training neighbors remaining near the test points.