Lower Montane Rain Forest Research Articles

FOOD HABITS OF THE MADAGASCAR LONG-EARED OWL ASIO MADAGASCARIENSIS IN TWO HABITATS IN SOUTHERN MADAGASCAR

Summary Goodman, S. M., Langrand, O. & Raxworthy, C. J. 1993. Food habits of the Madagascar Long-eared Owl Asio madagascariensis in two habitats in southern Madagascar. Ostrich 64:79-85. Food remains recovered from regurgitated pellets of the Madagascar Long-eared Owl Asio madagascariensis were collected at two sites on Madagascar with different habitats and weather regimes. The localities are Beza Mahafaly, a sub-arid thorn scrub area in the southwest, and Bezavona Forest, a lower montane rain forest in southeastern Madagascar. At Beza Mahafaly prey composition varied according to season. Vertebrate prey included: frogs, lizards, birds, terrestrial insectivores, bats, lemurs and rodents. The total biomass of lemurs (Microcebus) represented varies from approximately 8 to 40%. Two samples from the Bezavona Forest included: frogs, geckos, birds, bats, lemurs and rodents. Lemurs (Microcebus and either Hapalemur or Avahi) made up a total biomass of 24 % at this locality. At both sites a significant proportion...

Fine-root biomass and soil properties in a semideciduous and a lower montane rain forest in Panama

The distribution of root biomass and physical and chemical properties of the soils were studied in a semideciduous and in a lower montane rain forest in Panama. Roots and soil samples were taken by means of soil cores (25 cm deep) and divided into five, 5-cm deep sections. Soils were wet-sieved to retrieve the roots that were classified in four diameter classes: very fine roots (<1 mm), fine roots (1–2 mm), medium roots (2–5 mm) and coarse roots (5–50 mm). Soil samples were analyzed for organic carbon, total nitrogen, available phosphorus, exchangeable bases, cation exchange capacity, pH, aluminium and exchangeable acidity. Total root biomass measured with the soil corer (roots <50 mm in diameter) was not different between the forests (9.45 t ha-1), while biomass of very fine roots was larger in the mountains (2.00 t ha-1) than in the lowlands (1.44 t ha-1). The soils in the semideciduous forest were low in available phosphorus, while in the mountains, soils had low pH, high exchangeable aluminium and exchangeable acidity, and low concentration of exchangeable bases. Phosphorus was in high concentration only in the first 5 cm of the soil. In both forests, there was an exponential reduction of root biomass with increasing depth, and most of the variation in the vertical distribution of roots less than 2 mm in diameter was explained by the concentration of nitrogen in the soils. The results of this study support the hypothesis that a large root biomass in montane forests is related to nutrients in low concentration and diluted in organic soils with high CEC and low bulk density, and that fine root biomass in tropical forests in inversely related to calcium availability but not a phosphorus as has been suggested for other forests.

Forest Structure Before and After Hurricane Hugo at Three Elevations in the Luquillo Mountains, Puerto Rico

Hurricane Hugo struck Puerto Rico on 18 September 1989 and radically altered the canopy structure of forests in the Luquillo Mountains. We measured canopy structure before and after the hurricane in hectare-sized plots of tabonuco (subtropical wet forest) at 350 m elevation, (lower montane wet forest) at 750 m, and cloud (lower montane rain forest) at 1000 m. In all three plots the chief effect of the hurricane was to reduce significantly the vegetation cover in upper height intervals. Foliage profiles (showing percent vegetation cover in height intervals above ground) changed significantly, average maximum canopy height decreased (by as much as 50%), and the amount of low canopy area (vegetation ?2 m high) markedly increased (up to 60fold) in all three plots. In the colorado forest plot the hurricane caused more damage on ridges than in valleys; whereas, the doud forest plot sustained equal damage on windward and leeward slopes. Overall, the hurricane altered forest structure so much that forest composition and dynamics could be affected for many years. Local variation in hurricane damage can contribute to forest complexity in the Luquillo Mountains.

Dead logs as a substrate for rain forest trees in Dominica

Dead logs, or 'nurse logs', have been reported as an important substrate for germination and establishment of a few tree species in wet temperate forests of New Zealand (Beveridge 1973) and coastal Washington, USA (Franklin & Dyrness 1973) and in an exposed cloud forest in Costa Rica (Lawton & Putz 1988). These environments are con-tin-uously wet and, in all, dead logs are a prominent feature on the ground. Hartshorn (1980) stated that dead logs were not important as sites for tree regeneration in lowland Neotropical rain forests except in swamps, but in rain forests in the Commonwealth of Dominica (West Indies), the common tree Miconia mirabilis (Aubl.) L.O.Wms. had a complex system of stilt roots that sometimes appeared to penetrate dead wood (Figure 1). As part of a study on forest dynamics an investigation was made to see whether this, or any other species, was associated with dead wood as a substrate. Four sites in different parts of the island were studied, totalling 7500 m' and ranging from 300 m to 650 m in altitude. These had the 'rain forest' to 'lower montane rain forest' formations of Beard (1948), dominated particularly by Dacryodes excelsa Vahl.. The forests remain fairly wet throughout the year, but there is a distinct dry season in most years. They are never waterlogged (personal observation and discussion with Forestry Division staff). The canopy, at 3040 m, was fairly complete in sites 2 and 3, but in site 1 had been broken up by hurricane 'David' in 1979 (see Lugo el al. 1983) and, in site 4, this hurricane had destroyed all but a few canopy trees (most regrowth was c. 10 m high). Four common species of Melastomataceae were studied, Miconia mirabilis (Aubl.) L.O.Wms. (syn. M. guianensis Cogn. of Beard 1948), a tree up to 18 m in height, Miconia furfuracea (Vahl.) Griseb. and Miconia trichotoma (Desr.) DC., both large shrubs up to 10 n in height and Clidemia umbrosa (Sw.) Cogn., an undershrub up to 3 m, along with Cecropia sc/zreberiana Miq. (Cecropiaceae), a

Preliminary studies on forest structure and floristics on Volcán Barva, Costa Rica

ABSTRACTVolcán Barva, Costa Rica, has on its northern slope an unbroken sequence of rain forest on volcanic parent materials from near sea level at La Selva Field Station up to its summit at 2906 m. It provides a good area to study forest changes with altitude and their causes. In the present paper we describe the forests as a background for soil and litterfall studies from 1 ha plots at each of the following altitudes: 100 m, 500 m, 1000 m, 1500 m, 2000 m and 2600 m. The canopy heights (with height of the highest emergent in parentheses) ranged from 35–40 m (45 m) at 100 m to 20–23 m (32 m) at 2600 m; basal area was least (22.7 m2) at 100 m and highest (51.2 m2) at 2600 m; the tree (≥10 cm dbh) density ranged from 391 ha–1at 500 m to 617 ha–1 at 2600 m. Most trees were identified and on samples of them we recorded presence of buttresses, lianes, skiophytic climbers, vascular epiphytes and bryophytes; and drew profile diagrams. In the classification of Whitmore (1984) the two lower plots are evergreen lowland rain forests; the other four are lower montane rain forest. Species richness was highest in the plot at 500 m, with at least 135 species of tree, and least at 2600 m, with at least 35 species. The Volcán Barva forest altitudinal sequence is briefly compared with those elsewhere.

Rain Forests of the Ok Tedi Headwaters, New Guinea: An Ecological Analysis

The basin of the upper Ok Tedi rises from 500 to 2900 m and has been an isolated rain forested region of great antiquity. It is the wettest region within the southern mid-altitude fringe of New Guinea (>7000 mm of rainfall p.a.). There are 4 natural vegetation zones of which only Lower Montane Rain Forest is regularly inhabited and cultivated, though all zones are exploited for natural resources. The flora and fauna are rich and diverse. Heavy rainfall and persistent cloudiness compresses ecological zonation producing extremely diversified biota in a comparatively small area with high levels of locally endemic species. Although flora and fauna show moderate levels of similarity to other localities in eastern New Guinea, biogeographic relationship in many respects are more to the west. -from Authors

Tropical Forest Bird Counts and the Effect of Sound Attenuation

Tropical Forest Bird Counts and the Effect of Sound Attenuation

Altitudinal changes in the incidence of crassulacean acid metabolism in vascular epiphytes and related life forms in Papua New Guinea.

The occurrence of Crassulacean acid metabolism (CAM), as judged from δ13C values, was investigated in epiphytes and some related plant species at a series of sites covering the approximate altitudinal range of epiphytes in Papua New Guinea. Comprehensive collections were made at each site and the occurrence of water storage tissue and blade thickness was also determined. Some 26% of epiphytic orchids from a lowland rainforest (2-300 m.a.s.l) showed δ13C values typical of obligate CAM and possessed leaves thicker than 1 mm. A second group of orchids, mostly with succulent leaves, possessed intermediate δ13C values between -23 and -26% and accounted for 25% of the total species number. Some species of this group may exhibit weak CAM or be facultative CAM plants. The remainder of the lowland rainforest species appeared to be C3 plants with δ13C values between -28 and -35%. and generally possessed thin leaves. Obligate CAM species of orchids from a lower montane rainforest (1175 m.a.s.l) comprised 26% of the species total and mostly possessed thick leaves. The remainder of the species were generally thin-leaved with δ13C values between -26 and -35%. largely indicative of C3 photosynthesis. Orchids with intermediate δ13C values were not found in the lower montane rainforest. Obligate CAM appeared to be lacking in highland epiphytes from an upper montane rainforest and subalpine rainforest (2600-3600 m.a.s.l). However the fern, Microsorium cromwellii had a δ13C value of -21.28%. suggesting some measure of CAM activity. Other highland ferns and orchids showed more negative °13C values, up to-33%., typical of C3 photosynthesis. The highland epiphytic orchids possessed a greater mean leaf thickness than their lowland C3 counterparts due to the frequent occurrence of water storage tissue located on the adaxial side of the leaf. It is suggested that low daytime temperatures in the highland microhabitats is a major factor in explaining the absence of CAM. The increased frequency of water storage tissue in highland epiphytes may be an adaptation to periodic water stress events in the dry season and/or an adaptation to increased levels of UV light in the tropicalpine environment.

Ecological Observations in the Dwarf Cloud Forest of the Luquillo Mountains in Puerto Rico

Five species accounted for 95 percent of the stems of at least 10 cm DBH on three plots totaling 0.22 ha in the dwarf cloud forest of the Luquillo Mountains in Puerto Rico. Mean density for stems of at least 10 cm DBH was 3671 ? 516 stems/ha, and mean basal area was 49.1 ? 8.2 m2/ha. The aboveground woody biomass on two small plots of 0.0036 ha, one located on a ridge and the other 100 m to the leeward, was 48 and 110 t/ha, respectively. Leaf area index on the ridge was 1.99 m2/m2, leaf biomass was 288 g/m2, and specific leaf weight was 14.5 mg/cm2. Mean annual litterfall rates averaged only 0.85 g/m2/day (3.10 t/ha/yr), of which 79 percent was leaf litter, 9 percent wood litter, and 12 percent miscellaneous material. The rate at which nutrients returned to the soil (kg/ha/yr) averaged 23.9 for nitrogen, 0.7 for phosphorus, 4.3 for potassium, 16.3 for calcium, and 7.6 for magnesium. The annual increment in tree diameter was low, averaging only 0.03 ? 0.01 cm/yr. For trees at least 2.5 cm in diameter, aboveground biomass accumulated at an average rate of 45 g/m2/yr. Net primary productivity was 3.84 t/ha/yr. ZONATION OF FORESTS WITHIN MONTANE HABITATS on tropical islands is condensed into a narrow altitudinal range, a phenomenon known as the Massenerhebung effect. One example is the Luquillo Mountains of northeastern Puerto Rico, which abruptly rise to 1060 m in only 15 km. As elevation increases, the number of arborescent stems/ha increases, while decreases occur in average height of dominants, average DBH, basal area/ha, and number of species per unit area (White 1963). The dwarf forest, an association in the lower montane rain forest (sensu Holdridge 1967, Ewel & Whitmore 1973) on the upper slopes and summits of the Luquillo Mountains, is short, frequently contorted, and densecovered with epiphytes including bromeliads, liverworts, and mosses-and includes only a few species of trees (Beard 1949, Wadsworth 1951, Howard 1968). The climate is wet, with nearly 5000 mm/yr of rainfall. Mean monthly temperatures range from 18 to 20?C (Weaver et al. 1973). The vegetation is commonly saturated with moisture and frequently enveloped in clouds. Both aerial and superficial roots are common (Lyford 1969). Saturated soils, impeded root respiration, physiological drought, high winds, high soil leaching, low nutrient availability, low temperatures, high fog incidence, reduced solar insolation, high humidity, reduced transpiration rates, and shallow soil have all been suggested as causal agents in stunting, either individually or in combination (Gleason & Cook 1927, Beard 1944, Wadsworth & Bonnet 1951, Holdridge 1967, Odum 1968, Baynton 1969, Grubb 1971, Weaver et al. 1973). Similar forests elsewhere in the Caribbean and Central America have been discussed by La Bastille and Pool (1978). Despite the abundance of hypotheses regarding the cause of dwarf cloud forests, little information is available on their growth rates, net primary productivity (NPP), and nutrient cyding. The purpose of this study is to determine species composition and standing biomass of the dwarf forest, and to estimate the rates of NPP, litterfall, and diameter and biomass growth of arborescent species. Rates of nutrient return to the soil are also in-

Nutrient content of litterfall in coniferous forest plantations in central Java, Indonesia

ABSTRACTProduction and nutrient content of small litterfall were studied for one year in four plantations of Agathis dammara ranging in age from 7 to 35 years old, in a 12-year-old stand of Pinus merkusii and in an approximately three-year-old shrub community dominated by Eupatorium species. The dense Pinus plantation produced considerably more litter (10 t/ha/yr, with 5.5 t/ha as needles) than any of the Agathis stands (2.6–6.2 t/ha/yr; 2.3–3.5 t/ha as leaves) or nearby Lower Montane Rain Forest (6.8 t/ha/yr; 5.4 t/ha as leaves). Litterfall in the Agathis forests increased with stand age. The shrubs produced sizeable amounts of litter (3.4 t/ha/yr). The various species responded differently to a drought occurring during the study period.Pine litter generally exhibited low nutrient concentrations (on average 9.2, 1.9, 2.5, 0.4 and 6.0 mg/g of calcium, magnesium, potassium, phosphorus and nitrogen respectively in needle litter), whilst concentrations in shrub litter were generally high (37.8, 4.9, 1.4, 1.05 and 21.5 mg/g for the same elements); Agathis litter usually showed nutrient concentrations that were intermediate between those for pine or shrub litterfall with only minor differences between stands. Comparison of the present findings with observations at other tropical sites suggests that nutrient content of litterfall in plantation forests may approach that of natural forests when the former become about 20 years old. Pine plantations may constitute an exception in this regard.

A numerical analysis of arborescent communities in the rain forest of the Luquillo mountains, Puerto Rico

Cluster analysis and canonical ordination were used as complementary techniques to identify major associations in a lower montane rain forest in Puerto Rico. These techniques were applied to forestry inventories from both secondary and primary communities. Eight major forest types were identified from the analyses and were confirmed by field checks. Distribution of these types was strongly correlated with past land-use and topographic position.

Studies of Mineral Cycling in a Montane Rain Forest in New Guinea: I. The Distribution of Organic Matter in the Vegetation and Soil

(1) As a preliminary to studies on mineral cycling in a tropical montane system, where slow release of minerals from organic matter may be an important feature of the environment for olants, estimates have been made of the amounts of organic matter in a Lower Montane Rain forest and its soil at 6 ?S and altitude c. 2500 m in New Guinea. (2) A detailed destructive study was made of a plot 20 x 20 m, and derived estimates of biomass were made for various other plots using a regression of dry weight on the square of trunk diameter at breast height. On a 0-24 ha plot considered representative of the forest at large the total biomass was estimated at c. 350 t ha-1, made up of c. 40 t ha-' in roots, 295 t ha-' in above-ground parts of trees of gbh 3 30 cm, c. 4 t ha-' in climbers and scramblers, c. 2 t ha-' in epiphytes, c. 2 t ha-' in the 0-1 m layer and c. 7 t ha-' in the other plants. (3) Determinations of specific leaf area were made for seventeen tree species (range 37-127 cm2 g-', mean 58 cm2 g1), and for four common climbers (45-81 cm2 g') and a scrambling bamboo (216 cm2 g-1). The leaf area index was estimated as. c 5 5 m2 m 2 on the plot of 20x20m. (4) The ash contents of 140 representative plant samples were determined; they ranged from c. 10% for the 0-1 m layer to 2% in the trunks. The organic matter content of the soil was taken to be twice the organic carbon content, which was c. 19% dry weight at 0-2 cm and c. 13% at 2-10 cm, falling to c. 9% at 100 cm depth. The organic matter content of the plants on the 0-24 ha plot was estimated at c. 340 t ha 1, and that of the soil at c. 1200 t ha-'. About 1 t ha-' of soil (4% ash) had accumulated in the crowns of the larger trees, formed largely from the remains of epiphytes. (5) Comparisons are made with other tropical forests, and the inadequacy of sampling in most studies is emphasized. (6) The ratio of organic matter in the soil to that in the plants is 3-4: 1 in the New Guinean forest. This may be compared with probable values of 0-7-4-0:1 in other Lower Montane forests and measured values within the range 0-2 0-6:1 in Lowland forests. The very large amount of organic matter in the soil of the New Guinean forest is tentatively related to fixation by amorphous clays.

New Species of Gibsoniothamnus (Scrophulariaceae/Bignoniaceae) and Tournefortia (Boraginaceae) from Eastern Panama and the Choco

Three new species are described from wet forest regions of eastern Panama and the Choco of Colombia-Gibsoniothamnus alatus A. Gentry, Gibsoniothamnus mirificus A. Gentry, and Tournefortia tacarcunensis A. Gentry & Nowicke. Gibsoniothamnus alatus A. Gentry, sp. nov. Frutex epiphyticus. Ramuli irregulariter teretes. Folia elliptica, acuta vel acuminata, cuneata, glabra praeter domatia ciliata. Flores singulares, pedicellis glabris. Calyx late alatus, ad instar stellae, alis ultra 1 cm longis. Corolla (non vidi) alba. Epiphytic shrub. Branchlets irregularly terete to subangulate, very sparsely pilose. Leaves elliptic, acute to acuminate, cuneate at the base, chartaceous to subcoriaceous, glabrous above and below except for ciliate domatia in the axils of the lower secondary nerves, gland dotted below, the margin entire, very slightly or not at all revolute, drying dark olive above, light olive below, the secondary veins plane or slightly impressed above, prominulous to prominent below. Inflorescence a single flower; pedicel glabrous, 1.5-2 cm long. Calyx very broadly winged, glabrous except a few trichomes near the ends of the wings, almost star shaped, ca. 6-7 mm long and wide without the wings, the wings each over 1 cm long, tapering to an acute point. Corolla (not seen) white. Pistil 23 mm long, the ovary globose, the style slender, 18 mm long. Fruit white, covered by the calyx. TYPE: PANAMA. DARIEN: N slopes of Cerro Pirre, lower montane rain forest

Changes in Arthropod Abundance in a Highland Costa Rican Forest

Arthropod populations in the understory of a Costa Rican, lower-montane rain forest were monitored periodically for 19 months by sweep sampling and Malaise trapping. Abundance fluctuated threefold during the study and was highest in the late dry season and early rainy season, April through June, and lowest during the cooler, windy months of November through January. High species diversity (H' and a) in Coleoptera coincided with peak abundance. Average body size in the whole fauna was largest in April, when arthropod numbers were high. Peaks in abundance of some predatory groups lagged behind peaks in other arthropod groups. The annual cycle appears to be composed of a series of short-lived, seasonal subfaunae. Results are discussed relative to plant productivity, climatic factors and findings from other locations. INTRODUCTION Recent studies in neotropical environments (Janzen and Schoener, 1968; Robinson and Robinson, 1970; Janzen, 1973a, 1973b) have shown that in areas with a marked dry season, arthropod populations are low in numbers of individuals and species during the dry period. This article reports on changes in arthropod populations in a middleelevation forest in Costa Rica over a 19-month period.

The Social Status of Agathis in a Rain Forest in Melanesia

Of the small group of conifers which occur in the lowland tropics species of Agathis, Dacrydium and Podocarpus grow mixed with angiosperms in tropical rain forest. Dacrydium and Podocarpus are predominantly montane genera with a few species descending into the lowlands, Agathis has rather more lowland species. In its present distribution (Florin 1963) and habitat Agathis is the most euthermic confer. Mixed conifer-angiosperm forests occur scattered through Malesiat and the southwest Pacific region. Their ecology has scarcely been investigated: this is important because of its bearing on the evolutionary history of the relationships between conifers and angiosperms. Further, tropical conifers, like temperate ones, are sometimes associated with podsolic soils and a study of them might be expected to throw light on the phenomenon of podsolization in the tropics. The temperate podocarp-angiosperm forests in New Zealand, and the forests of Queensland and New Guinea where species of Araucaria grow as emergents from an under-layer of Tropical Lowland and Lower Montane Rain Forest, have received some attention from ecologists. The native vegetation of much of the lowlands of New Zealand is a series of forests which range from pure angiosperm through angiosperm-podocarp mixture to pure podocarp. The main podocarp is Dacrydium cupressinum Soland. There are various hypotheses to explain this series, which Robbins (1962) has summarized. Cockayne considered that it represents an ecological succession, leading from conifer forest to angiosperm forest climax. Poole and Holloway later both suggested alternation of the forest types on any one site. Holloway later abandoned this explanation and suggested that a climatic change about 800 years ago had favoured the angiosperms and was leading to replacement of the conifers, still incomplete. Robbins himself postulated that there are two forest types, an ancient conifer forest and a geologically more recent angiosperm forest; both are found in pure form but in many places they have fused and the angiosperms are exercising a progressive supremacy over the conifers (Robbins 1962). Agathis australis Salisb. occurs in the north of New Zealand around Auckland. Apparently it does not regenerate in its own shade and in the climax vegetation is replaced by other species (Cockayne 1928, p. 127; Mirams 1957). According to Mirams (1957) it invades the secondary vegetation which springs up after clearing and at one stage in the secondary succession is well represented by all size classes; the big trees in