Sung-Hyun Min

Gridded rainfall products interpolated from gauge networks underpin landslide early warning, and a common view holds that their main deficiency in mountains is the omission of orographic enhancement. This study tests that view using an independent network: 464 mountain stations operated by the Korea Forest Service that do not enter the operational grid of the Korea Meteorological Administration. Over five summers (2020–2024, 92,663 wet station-days after quality control), daily rainfall interpolated from the 615 meteorological-agency stations alone was compared with measurements from the mountain stations. Three findings follow. First, summer daily rainfall showed no systematic dependence on elevation: the median elevation gradient within the mountain network ranged from −0.05 to +0.10 mm per 100 m across the five years, and interpolation from the lowland network reproduced the day-to-day gradient in both sign and magnitude. Second, interpolation attenuated extremes in proportion to their intensity, capturing 112% of 1–10 mm days but 75% of days above 200 mm; the operational configuration classified only 26% of 200-mm days as exceeding 200 mm. Third, this loss was not recoverable: terrain-weighted regression, a PRISM-type local regression and ordinary kriging performed no better than inverse-distance weighting, and quadrupling gauge density raised exceedance detection from 0.25 to 0.37. Forty-four percent of the mountain extremes had no gauge within 10 km that recorded a comparable total. Radar reflectivity confirmed that these extremes were spatially real. At 9,656 landslide sites the operational field placed 25% above 200 mm; adding the mountain network raised this to 49%. The deficiency of the gauge-interpolated field for landslide forecasting is the attenuation of extremes between gauges, which denser networks and better interpolators do not cure and which the inclusion of mountain observations partly does. Keywords: rainfall interpolation; gauge network density; extreme precipitation; orographic enhancement; landslide early warning; independent validation; Korea

Pollination is the rate-limiting reproductive step in dioecious fruit crops. However, the developmental pathway through which pollination interventions translate into fruit weight remains unclear. Here, we tested whether seed set was the dominant pathway linking three pollination methods, namely, artificial pollination (AP), pollen dispenser-assisted bee pollination (BTD), and bee-only pollination (BT), to fruit weight and soluble solids content (SSC) in gold kiwifruit (Actinidia chinensis cv. ‘Haegeum’). A total of 2940 individually measured fruits were collected across two orchards in southern Korea (2018–2025), comprising 2022 main experiment (n = 1800), supporting trials (2018–2020, N = 540, including a six-treatment factorial design in 2020), and a 2025 replication of 600 fruits. Across the calibration range (seed number 100–700), each additional seed contributed 0.063–0.072 g of fruit weight (R² = 0.68–0.72). The slopes were statistically indistinguishable among AP, BTD, and BT. Mediation analysis was triangulated through three estimators: partial correlation (49.8–63.1% mediation), product-of-coefficients with 10,000 bootstrap resamples (70.3–77.4% indirect-effect mediation), and model-free stratification that converged on the same conclusion. When seed number was matched (500–700 range), treatment differences in fruit weight collapsed to non-significance (F = 0.34, p = 0.714). The two mediation percentages reflect different denominators, that is, standardised association vs. unstandardised total effect, and both estimators agree qualitatively. SSC was not mediated by the seed number (2 = 95.1%), with two years in which BTD significantly exceeded AP. In 2025, BTD achieved the Ferguson (1984) ≥1000-seed commercial standard in 79% of fruits. These findings identify the seed set as a method-independent reproductive bottleneck, reframing pollination system evaluation around pollen deposition-to-seed set conversion rather than around the delivery mechanism and support an efficiency-focused approach to orchard pollination management.