2006/01/01 by Achim Häger · 1 citation
Agricultural and Biological Sciences · Biochemistry, Genetics and Molecular Biology · Environmental Science · #Altitude (triangle) #Atmospheric sciences #Biology #Botany and Geology in Latin America and Caribbean #Canopy #Cloud forest #Ecology #Environmental science #Forest ecology and management #Forestry #Geography #Geology #Hydrology (agriculture) #Montane ecology #Oceanography #Plant and Fungal Interactions Research #Ridge #Throughfall #Transect
paper · pdf · doi:10.53846/goediss-2265
openalex publication_date 2006/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
Climatic variability and soil properties were investigated for different tropical montane cloud forest types in the Monteverde Reserve in north western Costa Rica during 2003 and 2004. Eight plots (500 m2 each) were established along a 2.5 km transect across the continental divide in the Tilarán mountains, covering an altitude range from 1200 m asl (above sea level) to 1500 m asl on both, the windward (Atlantic) and the leeward (Pacific) slope. Rainfall, horizontal precipitation (clouds, fog and wind driven rain), throughfall and temperature were measured at seven meteorological field stations in corresponding altitudes on both slopes. Wind speed, relative humidity and photosynthetic active radiation were recorded on the ridge and at the lowest field stations. Volumetric soil water content was observed at monthly intervals. Physical and chemical soil properties were analysed. Forest structure and composition were analysed, taking into account all woody plants with a diameter at breast height (dbh) > 5 cm. Epiphytic biomass and composition were compared on the ridge and at the lowest plots by representative sampling. Forest dynamics were observed by recording fallen canopy and subcanopy trees on a 12.5 ha strip along the transect in intervals of two weeks. The growth of 60 trees was measured on the ridge and at the lowest points of the transect during one year. Annual mean temperature on the ridge was 16.2 °C. It declined at an average of 0.6 °C/100 m increasing elevation on the windward slope, compared to 0.8 °C/100 m on the side facing west. Temperatures and relative humidity showed the strongest oscillations on the leeside at 1200 m asl during the dry season. Annual rainfall ranged from 6390 mm at 1200 m asl on the Atlantic slope to 3690 mm at the same altitude on the leeward side. The highest annual input of horizontal precipitation occurred on the ridge (3560 mm). On the lowest windward site 330 mm were measured. At the same altitude on the Pacific slope the value was only 28 mm. The annual throug hfall amount on the ridge was 118 % in relation to rainfall. At the lowest climate stations on both sides of the mountain range throughfall was about 70 % of rainfall, due to less cloud interception and higher interception loss. Spatial throughfall variation depends on precipitation and canopy properties. Volumetric soil water content ranged close to 80 % in the ridge area for most of the year. On the lower Pacific slope the soil water content decreased clearly during the dry season: it ranged between 16 % and 60 % over the year. Soil acidity, cation exchange capacity and base saturation are most favourable for plant growth at the lower lee sites. On the ridge soil conditions are less favourable, highest humus accumulations were also observed in this area. The upper canopy layer is above 30 m and basal area can exceed 70 m2 ha-1 at the lower elevations on both slopes. On the Atlantic slope tree heights decrease strongly with elevation while stem density increases. At the windward sites above 1400 m asl the canopy height lies below 15 m. Canopy density and the relation between tree height and diameter increases clearly at the lower elevations of the transect. Wind stress, soil chemistry, partial water logging and the inclination of the terrain control tree growth. At 1200 m asl on the leeward side the highest α diversity of woody plants was measured. It was lowest close to the ridge. There is almost a complete species turnover from the ridge area to the lower leeward plots within an altitude range of only 300 m. Calculated epiphytic biomass (including humus and ground rooted lianas and hemiepihytes) was highest at 1450 m asl on the Pacific slope, where it reached 39 t ha-1. At the drier leeward slope epiphytic biomass was also very high (32 t ha-1). Especially bryophytes decline clearly at the lower elevations. The number of vascular species related to the sampled tree surface declined about 50 % at the lower site, compared to the plot at 1450 m asl. The recording of fallen canopy and subcanopy trees resulted in 5.2 trees ha-1 a-1 along the transect. The maximum (9.4 collapsed trees ha-1 a-1) was observed between 1400 m asl on the Atlantic slope and the flat ridge area at 1500 m asl. A turnover rate of less than 100 years is calculated for this exposed forest type. For the lower sites a turnover time of less than 200 years is estimated. The annual growth of the stand volume was 9.5 m3 ha-1 a-1 on the ridge top. At 1200 m asl values ranged between 11.9 and 12.8 m3 ha-1 a-1.