title: Effects of topography on simulated net primary productivity at landscape scale.
abstract: Local topography significantly affects spatial variations of climatic variables and soil water movement in complex terrain. Therefore, the distribution and productivity of ecosystems are closely linked to topography. Using a coupled terrestrial carbon and hydrological model (BEPS-TerrainLab model), the topographic effects on the net primary productivity (NPP) are analyzed through four modelling experiments for a 5700 km(2) area in Baohe River basin, Shaanxi Province, northwest of China. The model was able to capture 81% of the variability in NPP estimated from tree rings, with a mean relative error of 3.1%. The average NPP in 2003 for the study area was 741 gCm(-2)yr(-1) from a model run including topographic effects on the distributions of climate variables and lateral flow of ground water. Topography has considerable effect on NPP, which peaks near 1350 m above the sea level. An elevation increase of 100 m above this level reduces the average annual NPP by about 25 gCm(-2). The terrain aspect gives rise to a NPP change of 5% for forests located below 1900 m as a result of its influence on incident solar radiation. For the whole study area, a simulation totally excluding topographic effects on the distributions of climatic variables and ground water movement overestimated the average NPP by 5%.
authors.affiliation: International Institute of Earth System Science, Nanjing University, Nanjing 210093, China.
authors.forename: X F
authors.initials: XF
authors.lastname: Chen
authors.forename: J M
authors.initials: JM
authors.lastname: Chen
authors.forename: S Q
authors.initials: SQ
authors.lastname: An
authors.forename: W M
authors.initials: WM
authors.lastname: Ju
mesh_terms: D018533:Biomass; D002244:Carbon / Q000378:metabolism; D002681:China; D002980:Climate; D003198:Computer Simulation; D003247:Conservation of Natural Resources; D017753:Ecosystem; D005618:Fresh Water / Q000737:chemistry; D040362:Geographic Information Systems; D005843:Geography; D008954:Models, Biological; D013472:Sunlight; D013997:Time Factors; D014197:Trees / Q000254:growth & development*; D014872:Water Movements
chemical_list: D002244:Carbon