The Impact of forest use and reforestation on soil hydraulic conductivity in the Western Ghats of India: Implications for surface and sub-surface hydrology

摘要: Summary There is comparatively limited information in the humid tropics on surface and sub-surface permeability of: (i) forests which have been impacted by multi-decades of human occupancy (ii) forestation land various states degradation. Even less known about dominant stormflow pathways for these respective scenarios. We sampled field saturated hydraulic conductivity, K∗ at 23 sites four depths (0 m, n = 166), (0.10 m, n = 139), 0.45–0.60 m, n = 117, (1.35–1.50 m, n = 117) under disturbed forest (Forest), production local species (Degraded Forest) tree-plantations (Acacia auriculiformes, 7–10 years old, Tectona grandis, ∼25–30 years Casuarina equisetifolia, 12 years old) Uttar Kannada district, Karnataka, India, Western Ghats. The sampling strategy was also undertaken across three physiographic blocks main soil types. Subsequently determined were then linked with rainfall intensity–duration–frequency (IDF) characteristics to infer pathways. Degraded Forest shows an order magnitude decline as result impacts decadal century time scales. lowest associated Forests over Laterite (Eutric Nitosols Acrisols) Red soils Nitosols) infiltration-excess overland flow, IOF probably occurs. Further there a progressive depth supporting Forests. A. auriculiformes plantations Lateritic are progressively restoring near-surface K∗, but their still remain quite low when compared permeability. Consequently retain ‘memory’ from previous degraded state. In contrast Black (Vertisols) relatively insensitive T. grandis this group has very irrespective cover, so that likely prevails. Overall, Laterites most variable other groups. Thus studies, more prevalent region. More especially so, taking into account marked reduction during wet season dry measurements. addition, we demonstrated potential ‘infiltration – trade-off’ hypothesis be realized landscape certain conditions degradation restoration. It relevant combination or using baseline. intensity use effects monoculture ecology (relative native, mixed forests) critical factor affecting time. Predicted changes rain events future enhance flow all soils, restoration efforts stake-holders, preferably native non-invasive species, needed address concern.