Biophysical Characteristics of the Uplands

BIOPHYSICAL CHARACTERISTICS OF THE UPLANDS

by Antonio C. Antonio

December 31, 2014

The standard criterion in classifying areas as “upland” is the slope… land areas with a slope greater than 18% is considered uplands.  Other than this criterion, it is generally hard to describe uplands since their biophysical characteristics are quite varied in terms of climate, topography, soils and vegetation.

CLIMATE – It is very important to know the climactic condition in a particular upland area in the archipelago.  This will be an indispensable tool and knowledge in upland management.  Based on the distribution of rainfall, there are four climate types in the Philippine uplands. Climactic Type I has two pronounced seasons; the dry season (November to April) and the wet season (May to October).  Climactic Type II has no pronounced dry season but has a very pronounced wet season (November to January). Climactic Type III where either dry or wet seasons are not pronounced although it’s relatively dry from November to April and wet the rest of the year.  Climactic Type IV is characterised by evenly distributed rainfall throughout the year.

TOPOGRAPHY AND SOIL – Areas with elevation greater than 60 meters and lands with slopes greater than 50% are considered uplands which include mild, moderate and steep slopes and even plateaus.  32% or roughly 9.6 million hectares of the total land area in the Philippines have acidic soil (phosphorous, potassium, calcium and magnesium) as well as toxic levels of exchangeable aluminium and manganese… therefore, have severe nutrient limitations that radically diminishes their productivity.  The main contributory factor to the low fertility of upland soil is high erosion rate.

HYDROLOGY – About 54% to 95% of the upland areas in the Philippines are rain-fed.  Western and Eastern Visayas, Northern and Western Mindanao, Ilocos, Southern Tagalog and Bicol Region have the highest proportions of these rain-fed areas.  However, we also have several upland areas which are considered hydrologically impaired which are caused primarily by reforestation.  When the soil has low infiltration capacity, soil erosion becomes a big problem.  In general, the water supply in the Philippine upland has deteriorated in terms of quality and quantity.  It is also largely believed that lowland flooding can be attributed to deforestation and the low absorption capacity of the uplands.

FLORA AND FAUNA – The Philippines is considered a megadiversity where a lot of endemic plant and animal species can be found.  This, however, has been threatened by human activities and intervention in the uplands.  Poorly planned land use conversions wiped-out tree and plant species and numerous species of birds, mammals, amphibians and reptiles are considered rare but threatened and endangered.

In a nutshell, these are the biophysical characteristics of the uplands.

Just my little thoughts…

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