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1.
Rev. biol. trop ; 57(supl.1): 111-118, nov. 2009. graf, mapas
Article in Spanish | LILACS, SaludCR | ID: lil-637927

ABSTRACT

Natural regeneration of woody species in a Costa Rican plantation of Vochysia guatemalensis (Vochysiaceae) and the effect of P and NPK fertilization. Forest plantation management strategies, including the selection of species, may have positive or negative effects over plant regeneration in the tropics. in this case, understory woody plants density and richness were studied in Tabarcia de Mora, Costa Rica, in a monoculture of Vochysia guatemalensis (ten year old plantation). Nineteen 80 m²plots, with several fertilization treatments (0-0; 0-50; 50-0, 50-50 g/plant of P, and NPK, during the first years, P placed once at the hole) in a completely randomized factorial design, were analyzed. Afterwards, the NPK fertilizer was increased from 150 to 200 g/ plant/year until the plantation was six year old. The plots, established after the coffee plantation was eliminated, had a minimum management schedule, basically the elimination of herbaceous vegetation once or twice a year during the first three years, and a tree thinning when the plantation was four year old, to increase spacing from 2x2 to 4x4 m. All woody vegetation taller than 0.5 m was tallied. A total of circa 10 000 ind/ha, distributed in 90 species, were found, mostly native of the region, some identified for forestry use, others important for the fauna. The majority of the species had low relative densities and frequencies. Sixteen percent of the plants reached heights greater than 2.5 m. Several factors seem to explain this regeneration pattern: a canopy with an intermediate openness, a low intensity forestry management, the nearness of the plantation to a mature forest fragment, and that the Vochysia plantation substituted a coffee plantation where soil conservation strategies and an annual fertilization management plan were applied. Finally, plots with only P had significantly higher species richness and abundance (χ2=15.364, gl=3, p=0.002) probably because the trees in this treatment were less developed (when compared with the others). Rev. Biol. Trop. 57 (Suppl. 1): 111-118. Epub 2009 November 30.


Las estrategias de manejo y las especies seleccionadas en plantaciones forestales pueden tener efectos positivos o negativos sobre la regeneración vegetal en los trópicos. Esta investigación estudió la abundancia y riqueza de plantas leñosas bajo el dosel de un monocultivo de Vochysia guatemalensis de diez años. Se evaluaron 19 parcelas de 80 m²en Tabarcia de Mora, con varios tratamientos de fertilización (0-0; 0-50; 50-0, 50-50 g/ planta de P, y NPK, respectivamente, este ultimó se aumentó de 150 a 200 g hasta que la plantación alcanzó los seis años), en un diseño factorial totalmente al azar. Se contaron e identificaron todas las especies leñosas con más de 0.5 m de altura, con un total de aproximadamente 10 000 ind/ha en 90 especies, siendo éstas principalmente nativas de la zona (varias maderables, otras importantes para la fauna), la mayoría con bajos índices de importancia (suma de la densidad y frecuencias relativas). Un 16% alcanzaron alturas superiores a 2.5 m. Se considera que varios factores pudieron favorecer dicha regeneración, como un dosel con una apertura inter-media, un manejo forestal de bajo impacto, la cercanía de un fragmento boscoso maduro, y el establecimiento de la plantación en sustitución de un cafetal donde se aplicaban estrategias de conservación de suelos y se fertilizaba anualmente. Finalmente, se determinó una mayor abundancia y riqueza en las parcelas con solo P (χ²=15.364, gl=3, p=0.002), probablemente porque los árboles de Vochysia tendieron a ser menos desarrollados en comparación con los otros tratamientos.


Subject(s)
Regeneration/physiology , Trees/classification , Forestry , Forestry/methods , Costa Rica
2.
Rev Biol Trop ; 54(3): 927-34, 2006 Sep.
Article in Spanish | MEDLINE | ID: mdl-18491634

ABSTRACT

Germination tests on Garcinia intermedia (Clusiaceae) seeds showed the growth of two types of roots: additionally to the primary root, a secondary root crosses the seed lengthwise. To determine its possible role on the survival and growth of this species, 90 seedlings at least six months old (collected in Central Costa Rica) were planted in plastic bags with organic soil, and placed in a greenhouse. The seedlings were treated as follows: treatments in which the primary or secondary root was cut off, and a control group with both roots intact (30 replicates each). After three months 10 seedlings/month/treatment were extracted to measure their height, basal diameter, root length (main and secondary root), and biomass of the stem, roots and seed (without its coat). Control seedlings had the highest growth, followed by those without secondary roots. Nonetheless, more than 90% of the seedlings whose primary roots were cut off, survived after five months of the excision treatment, in part due to the capacity of this species to regenerate its radical system through the seed reserves, sprouting of a primary-like root, and/or the growth stimulus of the secondary root (60% of the total: 20% with sprouts from the primary root stump, 13.3% with a growth stimulus of the secondary root, and 26.7% with both conditions). The length of the sprouted roots was significantly different only on those plants that were extracted during the first two monthly measurements, when compared with the control (F6 = 18.6, F7 = 16.0, p < 0.01).


Subject(s)
Garcinia/growth & development , Germination/physiology , Plant Roots/growth & development , Seedlings/physiology , Seeds/growth & development , Garcinia/physiology , Plant Roots/physiology , Seeds/physiology , Time Factors
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