High-altitude Polylepis woodlands are distributed throughout the Andes and in the past
were regarded as a rare and special kind of vegetation found in ravines, rocky slopes
and block fields in the highlands. However there is now increasing evidence to suggest
that this unique and localised occurrence is in fact fragments of a past far greater
woodland that has, over time whittled down to the woodland patches that characterise it
today. It is to a greater extent human activity that is to blame (cutting for firewood and
building materials together with over grazing). Consequently, these woodlands are now
considered to represent one of the most vulnerable habitats in the high Andes. The
principle cause of such threats to mountain environments are in many cases the product
between poverty-driven land conversion as these woodlands constitute the only wood
resource at higher elevations, as well as oasis of fertile soil within an otherwise bleak
and harsh environment. One of the major difficulties in the elaboration of conservation
and regeneration strategies for such an ecosystem are the large gaps of information
existing today, particularly concerning the age, growth rate and age-related yield of
Polylepis trees. This study, using dendroecological techniques, aims to contribute basic
information on the aforementioned parameters, thereby attempting to extend the
horizons of knowledge and understanding of the ecology and growth dynamics of highaltitude
Polylepis racemosa woodlands in South America. The study focuses on an area
situated in the Cusco region of Peru, where two Polylepis woodland patches are found
on either side of a steep valley, where the slopes are west and east facing. The
objectives of the study are to (1) determine the relationship between age and heights of
sampled trees, and age and diameters of sampled trees (2) determine the relationship
between the rate of growth of individual trees and their position along the transect (edge
effect) as well as their position in reference to surrounding individuals (density) (3)examine growth ring variability among individual trees (4) investigate the potential for
developing a model of sustainable woodland management for Polylepis racemosa.
Results show that ofthe two woodland patches the trees in the west facing woodland are
larger, older and exhibits faster rates of growth than the east facing woodland. This is
thought to be a product of the lesser density exhibited in the west facing stand than the
east facing. Results showed that a significant relationship between mean growth rates
and density exists where growth rate decreases as density increases. Growth variability
among individuals and between sites is high, suggesting again that individual trees are
responding in terms of ring width development to local micro site factors such as
density. From the resultant data a preliminary protocol of sustaining harvesting was
devised.
Key words: Polylepis racemosa, Peru, high altitude, dendroecology, tree rings, age,
growth rate, conservation, regeneration.Faculty of Scienc
