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This article reviews literature and summarizes experiments to investigate the extent to which productivity of tropical montane rain forests is constrained by low nutrient supply. On any one mountain, with increase in altitude foliar N decreases, and P and K usually decrease, but Ca and Mg show no consistent trend. However for a wide range of sites N, P, K, Mg, and Ca show no trends. Litterfall contents of N and P and often K, Ca, and Mg are lower in montane forests than in lowland forests, mainly because of reduced litterfall mass, but N and P concentrations are also lower in forests above 1500 m. Tropical montane soils usually have more soil organic matter per unit ground area; N mineralization levels are lower at higher altitudes in Costa Rica, and extractable and total soil P are lower in sites with lower litterfall P concentrations. We speculate that many lowland forests are limited by P and many montane forests by N. Fertilization studies on ash-derived montane soils in Hawai'i showed a trend for a switch from N limitation on young soils to P, or N and P, limitation on soils over older substrates. Jamaican montane trees were limited by N and by P separately. Venezuelan montane trees were limited by N. The sites in Jamaica and Venezuela have soils of indeterminate age. Taken together these results show that nutrient limitation is widespread in montane soils (all sites have responded to at least one nutrient) and that the particular nutrient(s) that limit(s) production may differ for explicable reasons. First results from lowland forests on sandy soils in Kalimantan show N or simultaneous N and P limitation. Many more experiments, especially in lowland forests, are needed to test our speculation that P usually limits productivity in tropical lowland rain forests and that N limits productivity in tropical montane rain forests. Key words: fertilization experiments; forests in Hawai'i, Jamaica, and Venezuela; growth limitation; montane cf. lowland forests; nitrogen; nutrient limitation of forest growth; nutrients; phosphorus; soil age and nutrient limitation; tropical montane rain forest productivity., INTRODUCTION Among the many factors that vary from lowland to montane tropical forests, decreasing air temperature and increasing cloudiness are probably ultimately and may be primarily - responsible for limiting [...]

A severe hurricane affected Jamaican montane rain forests in 1988. We made local and widespread measurements of tree condition in three periods: prehurricane 19741984 (preh.); hurricane 1984-1989 (h.); and post-hurricane 1989-1992 (post-h.). In the h. period, 7.22% of stems and 4.72% of the total basal area died; crown loss was the most frequent cause of mortality. Among individual tree species, the hurricane caused a large range in mortality (0-26%) and non-fatal damage. Post-h. mortality was greater than mortality in the h. period, and varied among species. Post-h. stem growth rates (all species combined) were more than double the prehurricane rates, but species showed a considerable range from no significant increase to eight times greater. We classified 20 common tree species using damage scores (normalized h. mortality, plus normalized change in mortality from preh. to post-h., plus normalized complete crown loss in h.) and response scores (normalized change, preh. to post-h., in recruitment to the ≥3 cm dbh size class, plus normalized change in growth rate from preh. to post-h., plus normalized frequency of sprouts). Species were assigned to one of four groups: resistant (11 species), with low damage and low response; susceptible (5 species), with high damage and low response; resilient (1 species), with high damage and high response; and usurpers (3 species), with low damage and high responsiveness. The grouping of species was broadly related to their regeneration requirements. Most species with seedlings usually found under closed canopy were resistant; three of the four species with seedlings usually found on landslides were also resistant. Species with seedlings most frequently found in gaps included resilient, susceptible, and usurper species, but were not usually resistant. It is likely that the three species classified as usurpers will increase their relative abundance in the forest in the next decades and that Cyathea pubescens, which was very susceptible, will decrease in relative abundance of adults. Most of the other species are likely to have small changes in their relative abundances. Thus, at present, hurricanes have few long-term effects on the forests, although a change in the disturbance regime may alter this. Key words: disturbance regime; growth rates; hurricane; Jamaica; montane trees; mortality; recruitment; tropical forests., INTRODUCTION In long-lived plant communities, many studies of the effects of disturbance on community stability have focussed on two aspects: resistance (the extent to which communities resist change by disturbance) [...]

1 Tree seedlings of Alchornea latifolia (Euphorbiaceae), Clethra occidentalis (Clethraceae), and Vaccinium meridionale (Ericaceae), were transplanted into five recent 'debris flow' landslides, and five adjacent understorey areas, in montane forest between 1450 m and 1770 m in the Blue Mountains, Jamaica. Organic fertilizer and protective barriers were applied in a 2 X 2 factorial design. 2 Mortality (all species) in the 15 months following transplanting was 30% on landslides, and 46% in the understorey. Mortality was significantly higher in the understorey than on landslides for Alchornea and Vaccinium, but was not different for Clethra. In the understorey there was a peak of mortality for Alchornea and Vaccinium in the dry season, but no associated peak on landslides. There was no effect of fertilizer or barrier treatment on seedling survival. 3 Height growth of unfertilized Clethra and Vaccinium (but not Alchornea) seedlings was greater on landslides than in the understorey. On landslides fertilization increased biomass (but had no effect on height) for all species. There were no significant effects of fertilizer in the understorey. 4 Soil nutrient concentrations were much higher in understorey soils than landslide soils, pH values were similar. 5 Foliar nitrogen concentrations for transplanted seedlings were lower on landslides than in the understorey, while foliar phosphorus concentrations were not different. Fertilization did not change foliar nitrogen concentrations on either landslides or the understoreys, whereas there was a significant increase in phosphorus concentration in fertilized seedlings on landslides. 6 Soil water content varied less on landslides than in understoreys; soils from three of the landslides were judged to be near field capacity throughout the year. In the understoreys there were significant shortages of water in the dry season which correlated with increased mortality in the transplanted seedlings. 7 Thus we have shown that growth of seedlings on landslides is limited by nutrient supply; water supply and soil movement do not limit growth of established seedlings. In the understoreys seedling growth is limited by photosynthetically active radiation, nutrient supplies may limit seedling growth due to root competition, and seasonal drought is correlated with increased mortality. Keywords: Alchornea latifolia, barrier, Blue Mountains, Clethra occidentalis, fertilizer, nutrients, seedling, soil moisture, tropical, understorey, Vaccinium meridionale

In a montane rain forest at [is nearly equal] 2500 m in Venezuela we fertilized plots with N, with P, or with N and P for 4.5 yr. We measured trunk growth in circumference in control plots and in those fertilized with N and P, and measured litterfall in all four treatments. There were five 12 x 12 m plots per treatment. N was applied at 225 kg.[ha.sup.-1.yr.sup.-1] and P at 75 [kg.hr.sup.-1.yr.sup.-1] for the first 2 yr, and subsequently N was applied at 150 [kg.hr.sup.-1.yr.sup.-1] and P at 50 [kg.ha.sup.-1.yr.sup.-1]. Rates of trunk growth in N and P fertilized plots were roughly double those in control plots (1.4 vs. 0.6 mm/yr). Total litterfall average 4.3 [Mg.ha.sup.-1.yr.sup.-1] in the control plot. In the 4th yr after fertilization was significantly higher in plots fertilized with N + P (1.50 [g.m.sup.-2.d.sup.-1]) than in control plots (1.00 [g.m.sup.-2.d.sup.-1). There were no significant differences in rates of litterfall between treatments during the first 3 yr after the first fertilization. The changes of rates litterfall with time were significantly different between treatments. Litterfall in control fell by 9% per year, that in P-fertilized plots fell by 5% per year, and litterfall in N- and in N + P-fertilized plots remained approximately constant. Nitrogen concentrations in litterfall were unaffected by fertilization with N or with P. Phosphorus concentrations were significantly increased by P fertilization. We conclude that N is more limiting than P in this forest. Key words: fertilizers; forest; litterfall; nitrogen phosphorus; tropical; trunk growth.

1 Are more diverse ecosystems more or less resistant to disturbance? Does diversity increase in a forest after being hit by a hurricane? We answer these questions using a 30-year study of four Jamaican forests, which differ in soil fertility and diversity, and which were hit by Hurricane Gilbert in 1988; the decades were: pre-Gilbert (1974u84), Gilbert (1984u94), and post-Gilbert (1994u2004). 2 Diversity (Shannon index) was always higher in the three forests (Col H' 3.00, Mull H' 2.91 and Slope H' 2.99) on more fertile soils (C : N ratios 10u13, N : P 16u24), and significantly lower in the Mor forest (H' 2.26) with the least fertile soil (C : N ratio 24, N : P ratio 44). Diversity increased during the Gilbert decade in two of the more diverse forests (Mull and Slope), it did not increase in the least diverse, Mor forest. The overall increase in diversity during the Gilbert decade was due to the recruitment of eight, mostly light-demanding, species and the increased abundance of uncommon species. 3 We used turnover rates (the average of mortality and recruitment of stems) as a measure of resistance. We equate low turnover with high resistance to hurricane damage. Turnover increased during the Gilbert decade in all forests, but increased more in the three more diverse forests (Mull 1.5% year1 1974u84 to 3.1% year1 1984u94; Slope 1.3u2.6; Col 1.5u3.2); than in the least diverse Mor forest (1.2u1.9). 4 Stem diameter growth rates pre-Gilbert were very low in all forests and were lowest in the Mor forest (Mor 0.3 mm year1, Mull 0.4, Slope 0.5, Col 0.6). They increased during the Gilbert decade and remained, in the post-Gilbert decade, double those of the pre-Gilbert decade (Mor 0.6 mm year1, Mull 0.6, Slope 0.8, Col 1.1). Smaller stems increased growth more than larger stems. The stems recruited during the Gilbert and post-Gilbert decades grew faster than those present in 1974. 5 Thus, in montane forest in Jamaica the least diverse forest was most resistant to hurricane damage, and although there was a strong similarity in species rank abundances over 30 years including a hurricane, the hurricane increased diversity.

Studies the regeneration on landslides in montane rain forests in Jamaica. Transplantation of tree seedlings in landslides and understorey areas; Effect of on the mortality of the plants; Examination of height growth, foliar nutrient concentrations and soil water.

Investigates tree sprouting in Jamaican montane forests after damages from hurricanes. Comparison between species; Relationship between sprouting and regeneration by seed; Short term fate of the sprouts; Correlations between production of sprouts and survival of stems.

(1) Concentrations of N, P, K, Ca and Mg were measured in the biomass of two 10 10 m plots at about 1550 m altitude in the Jamaican mountains: one in Mor Ridge forest and one in well-developed Mull Ridge forest. (2) Arithmetic mean concentrations in leaf and composite stem samples in Mor Ridge forest were, respectively (in mg g[SUP-1]), N, 11.1, 2.0; P, 0.64, 0.5; K, 4.3, 1.6; Ca, 8.0, 1.9; Mg, 3.3, 0.80. The corresponding concentrations for well-developed Mull Ridge forest were N, 17.8, 3.1; P, 0.76, 0.13; K, 11.7, 3.1; Ca, 10.0, 3.0; Mg, 4.6, 0.61. Concentrations calculated by dividing the total weight of an element by the biomass dry weight were lower than arithmetic means in every case. (3) Concentrations per unit area (kg ha[SUP-1]) and (in parentheses) per unit dry weight (mg g[SUP-1]) of above-ground standing crop were lower in the lower stature, slower growing Mor Ridge forest: N, 426 (2.0); P, 29.7 (0.14); K, 272 (1.3); Ca, 353 (1.7); Mg, 155 (0.74) than in the well-developed Mull Ridge forest; N, 857 (2.5); P, 41.2 (0.12); K, 829 (2.5); Ca, 940 (2.8); Mg, 193 (0.57). (4) First estimates of the amounts of nutrients used in trunk growth in the Mor Ridge forest each year are 1.9% of extractable soil N (NO[SUB3] + NH[SUB4]), 0.4% of exchangeable soil K, 2.3% of exchangeable soil Ca and 0.08% of exchangeable soil Mg. For well developed Mull Ridge forest the corresponding values are N, 2.0%; K, 1.2%; Ca, 1.1%: Mg, 0.3%. (5) The impoverishment of the Mor Ridge forest compared to the well-developed Mull Ridge forest is probably due to the limitation of growth by the supply of N and K, and possibly by P and Ca. (6) The impoverishment of the Jamaican Upper Montane Rain forest compared to better-developed Montane Rain forests at higher altitudes on larger mountains is probably not a result of poor supply of N, K, Ca or Mg, though the role of P is still not clear. (7) Tropical montane rain forests in general may be short of N, P, K and Ca... [ABSTRACT FROM AUTHOR]

Investigates the decomposition of leaf litter in montane rain forests in Jamaica. Accumulation and decomposition of leaf litter; Influence of nitrogen and phosphorus concentrations of mature leaves; Anatomical features of the leaves; Rate of decay of the standing crop of leaf litter; Productivity and stature of the forest.

Examines litterfall at four sites in Montane Rain forests in the Blue Mountains in Jamaica and its relation to climate. Rainfall rates; Mean leaf-life; Comparison of the biomass of leaves and the amount of leaf litterfall in the upper Montane Rain forests and published values for Lower Montane and lowland forests.

(1) The biomass of the standing crop in five Upper Montane forest-types in Jamaica was estimated for forty-four plots of 10 × 10 m size. Two plots were destructively sampled, one in Mor Ridge forest and one in well-developed Mull Ridge forest. (2) The total above-ground biomass (kg m[sup -2]) of each forest-type was estimated from regression equations derived from the total above-ground tree biomass on tree area at breast height 22.9 in Mor Ridge forest, 31.2 in Mull Ridge forest, 40.7 in well-developed Mull Ridge forest, 23.0 in Wet Slope forest and 23.8 in Gap forest. (3) Regression equations derived for tree leaf biomass on tree area at breast height were not used to predict tree leaf biomass because of the large amount of variability present in the data. (4) Below-ground biomass was determined only in Mor Ridge forest. An area of 3.5 × 5.0 m was excavated, the biomass of roots and underground stems was estimated as being 5.4 kg m[sup -2]. (5) The biomass of seedlings and saplings, tree ferns, herbs, climbers, epiphytes, hemi-parasites and standing dead trees was also determined. (6) The total leaf area index was 5.5 in the Mor Ridge forest plot and 5.7 in the well-developed Mull Ridge forest plot. (7) First estimates by dendrometers of increase in live biomass of the standing crop (kg m[sup -2] yr[sup -1]) were c 0.05 in Mor Ridge forest, c 0.10 in Mull Ridge forest, c 0.20 in Wet Slope forest and c 0.35 in Gap forest. Estimates of loss of live aboveground biomass of the standing crop (kg m[sup -2] yr[sup -1]) were c 0.20 in Mull Ridge forest, c 0.27 in Wet Slope forest and c 0.06 in Gap forest. (8) Comparison of the Jamaican montane forests with other tropical forests shows that as one ascends wet tropical mountains there is proportionately a greater reduction in forest canopy height than in total above-ground biomass. In contrast, leaf biomass is not less in forests at higher altitudes. [ABSTRACT FROM AUTHOR]

Provides a detailed quantitative description of the tree flora of 38 square plots of 10 x 10 meter in four forest-types at 1550 meter altitude on the ridge between John Crow Peak and Morce's Gap in the Blue Mountains in Jamaica. Basal area; Individuals per unit; Distributions of individuals in girth size-classes; Quantities of nitrate released in soils.