Our goal was to assess the potential of two exotic and five native tree species in reestablishing trees to degraded land in the
15
humid tropics of southern Costa Rica. Our study site was deforested in the 1950s. Steep topography and high rainfall led
16
subsequently to severe erosion, which exposed nutrient-poor, acid, unproductive subsoil. Our site is typical of many tropical
17
overgrazed pastures that have been established in high rainfall areas on ultisols worldwide. Restoration of useful trees to such
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lands is difficult when erosion is severe.
19
We established 30 experimental blocks in 1994 across our study site that varied in topography and degree of erosion. We
20
analyzed survival over 7 years and height after 3 and 7 years.
Pinus tecunumanii
, non-native to Costa Rica but native to Central
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America, was the outstanding performer with best growth and survival among all blocks. Several of the Costa Rican natives, all
22
considered valuable for timber, survived and grew moderately well (
Vochysia guatemalensis
,
Terminalia amazonia
,
Calo-
23
phyllum brasiliense
).
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We assessed the effect of erosion on survival and growth. Survival and/or growth negatively correlated with degree of erosion
25
in five of the seven species.
P. tecunumanii
, a