Differences In Basal Area Research Articles

Forest recovery in the karst region of Puerto Rico

Widespread deforestation has led to an increase in secondary forest in the tropics. During the late 1940s in Puerto Rico, forest covered only 6% of the island, but a shift from agriculture to industry has led to the increase of secondary forest. This study focuses on the regeneration of forest following the abandonment of pastures and coffee plantations located in the karst region of Puerto Rico. Alluvial terraces and sinkholes were the principal features used for pastures, shifting agriculture, and coffee plantations, whereas mogotes (limestone hills of conical shape) were burned periodically or cut for charcoal or wood production. Abandoned pasture sites had a greater woody species diversity in comparison with coffee sites. The density of woody stems was greater in the abandoned pasture sites and Spathodea campanulata was the dominant species. In coffee sites Guarea guidonia was the most abundant species. There was no difference in basal area between the two land uses. Canonical Correspondence Analysis applied separately to adults and seedlings clearly separated each community according to land use. Seedling composition in coffee sites indicates a resistance to change in terms of the dominant species while in the pasture sites the composition will change as the dominant species S. campanulata is replaced with more shade tolerant species. Patches of forest that remained on the steep sides of mogotes and the presence of bats appears to have enhanced forest recovery, but the land use history of these sites has affected the pattern of regeneration and will continue to affect forest dynamics for many years. The karst area is a critical environment for water resources and biodiversity and its conservation and restoration is essential.

Crecimiento y rendimiento del pino hondureno sin entresacar

A base de sobrevivencia, crecimiento y rendimiento, se evaluó el espaciamiento, sin entresacar, de pino hondureno (Pinus caribaea var. hondurensis Morelet) con edades de 23.3 a 25 años en cuatro rodales en Puerto Rico. Los resultados demostraron diferencias significativamente marcadas entre los promedios de sobrevivencia, diámetro y altura de árboles en rodales con espaciamientos que fluctuaron desde 1.5 x 1.5 m a 4.3 x 4.3 m. Sin embargo, debido a la disminución de crecimiento en diámetro y altura y al aumento en la mortalidad en los rodales de espaciamientos más estrechos (1.5 m y 2.1 m), y al crecimiento rápido en diámetro en los rodales con espaciamientos más anchos (3.0 m y 4.3 m), no hubo diferencias significativas entre tratamientos en área basal, volumen total bajo la corteza y promedio de incremento de volumen anual. Se recomiendan espaciamientos anchos en plantaciones donde no sean posibles los entresaques tempranos.

Observations on Spread and Fragmentation of Blue Grama Clones in Disturbed Rangeland

Establishment of blue grama (Bouteloua gracilis [H.B.K.] Lag ex. Steud.) depends on adequate precipitation at critical times and on reduced competition from associated vegetation. These conditions rarely occur on Central Plains rangelands. Therefore, rapid vegetative spread of new seedlings is desirable for colonizing disturbed rangeland. Blue grama genotypes selected for rapid spread would also be desirable for rangeland seeding. For 6 years, we followed the rate of spread of 19 blue grama clones originating from seedlings which emerged in 1980 and grew under natural competition. We observed a 4.5-fold difference in basal area and a 16.3-fold difference in above-ground biomass of these clones, perhaps because of genetic differences among clones and varying levels of competition. Clones must be tested under uniform competition with clonal replication to obtain reliable estimates of their capacity to spread.

Thinning Response of Immature White Pine

Abstract A study of response of immature white pine to thinning showed no significant difference in 8-year net basal area per acre production between three treatments: (A) thinning to B-line stocking; (B) thinning to release approximately 80 crop trees per acre; (C) controls. Plots, located in six stands in southern New Hampshire, produced an 8-year average of 45 ft 2 of basal area per acre regardless of thinning intensity. B-line thinning gave greatest response over controls for 4-in trees. Crop tree thinning showed best response over controls for 8-in trees, the average crop tree size. Differences in basal area production among stands were attributed to site characteristics. Results indicate that immature white pine responds well to treatment and that growth by size class can be controlled by thinning method to meet different management objectives. North. J. Appl. For. 3:148-150, Dec. 1986.