Dwarf Forest Research Articles

Dwarf Beech Forests in Coastal New England: Topographic and Edaphic Controls on Variation in Forest Structure

Abstract We characterize structural variation of forests dominated by American beech (Fagus grandifolia) on Naushon Island, Massachusetts with respect to edaphic and environmental conditions, and describe dwarf beech forests that are rare throughout the eastern U.S. Age structure reconstructions and historical references confirm that dwarf beech stands have persisted in the study area for >100 y. Dwarf beech are characterized by extremely slow radial growth rates, with some individuals growing 25 y, and ages up to 200 y. In the most severely stunted stands, all beech stems are <2 m tall and <8 cm basal diameter. In contrast, adjacent tall-stature forests support beech trees of similar age that are 20–30 m tall and up to 70 cm diameter (at 1.4 m). Variation in vegetation structure is strongly related to topographic position and edaphic conditions. Dwarf stands occur on morainal knobs and ridges characterized by excessively-drained sandy soils and well-developed E-horizons; soil organi...

Chilling damage in a changing climate in coastal landscapes of the subtropical zone: a case study from south Florida

AbstractFreeze events significantly influence landscape structure and community composition along subtropical coastlines. This is particularly true in south Florida, where such disturbances have historically contributed to patch diversity within the mangrove forest, and have played a part in limiting its inland transgression. With projected increases in mean global temperatures, such instances are likely to become much less frequent in the region, contributing to a reduction in heterogeneity within the mangrove forest itself. To understand the process more clearly, we explored the dynamics of a Dwarf mangrove forest following two chilling events that produced freeze‐like symptoms, i.e., leaf browning, desiccation, and mortality, and interpreted the resulting changes within the context of current winter temperatures and projected future scenarios. Structural effects from a 1996 chilling event were dramatic, with mortality and tissue damage concentrated among individuals comprising the Dwarf forest's low canopy. This disturbance promoted understory plant development and provided an opportunity for Laguncularia racemosa to share dominance with Rhizophora mangle. Mortality due to the less severe 2001 event was greatest in the understory, probably because recovery of the protective canopy following the earlier freeze was still incomplete. Stand dynamics were static over the same period in nearby unimpacted sites. The probability of reaching temperatures as low as those recorded at a nearby meteorological station (≤3 °C) under several warming scenarios was simulated by applying 1° incremental temperature increases to a model developed from a 42‐year temperature record. According to the model, the frequency of similar chilling events decreased from once every 1.9 years at present to once every 3.4 and 32.5 years with 1 and 4 °C warming, respectively. The large decrease in the frequency of these events would eliminate an important mechanism that maintains Dwarf forest structure, and promotes compositional diversity.

The Critically Endangered black crested gibbon Nomascus concolor on Wuliang Mountain, Yunnan, China: the role of forest types in the species' conservation

The Critically Endangered black crested gibbon Nomascus concolor of China, Laos and Vietnam is threatened by deforestation and habitat destruction but there have been no studies of how it uses its forest habitat, probably because of the typically rugged topography and the species' shyness of humans. We studied the forest use of one habituated group between March 2005 and April 2006 on the border of Wuliangshan Nature Reserve, Wuliang Mountain, Yunnan, southern China. The group spent most of its time in the primary forest but preferred secondary forest in February when Leucosceptrum canum blossomed. They used dwarf forest occasionally but never used Eupatorium adenophorum grassland. Primary forest provided sleeping and singing trees, most food resources, safe cover and suitable locomotion supports. This forest is crucial for their survival but regenerates slowly. Even though secondary forest in the area has been regenerating for &gt;50 years it provides only limited food resources for the gibbons. It may, however, comprise a good corridor for their dispersal. Dwarf forest provides a potential corridor for the group to disperse to a population on the other side of the mountain. Selective logging and agriculture encroachment should be forbidden in the primary forest on Wuliang Mountain. We recommend Alnus nepalensis, Myrica esculenta, L. canum and Betula alnoides as the pioneer species to recover the E. adenophorum grassland and for dispersal corridors.

The forest vegetation of Ramal de Guaramacal in the Venezuelan Andes

Montane forest community composition of Ranial de Guaramacal, Venezuelan Andes, was studied along the altitudinal gradient on both sides of the range with different slope expositions. Thirty five 0.1 ha plots were Surveyed, with variable intervals of 30 to 150 meters between 1350 in and 2890 in and mile plots of variable size (50 m(2) to 400 m(2)) Were surveyed in dwarf forests located between 2800-3050 m. A total of 388 morphospecies with dbh >= 2.5 cm, corresponding to 189 genera and 78 families of vascular plants, were recorded from a total of 45 forest plots. The TWINSPAN phytosociological classification, based on both floristic composition and species relative abundance, revealed seven forest communities,it association level, grouped in three alliances and one montane forest order group. Three subandean forest (LMRF) communities and four Andean - high Andean forest (UMRF-SARF) communities are distinguished and described according to the Zurich-Montpellier method. The Geonomo undatae-Posoquerion coriaceae alliance contains two subandean forest communities (Simiro erythroxyli-Quararibeetum magnificae and Conchocarpo larensis-Coussarectum moritzianae); the Farameo killipii-Prunion moritzianae alliance contains one subandean forest community, (Croizatio brevipetiolatae-Wettinietum praemorsae) and one Andean forest community (Schefflero ferrugineae-Cybianthetum laurifolii) and the Ruilopezio paltonioides-Cybianthion marginatii alliance includes one Andean (Geissantho andini-Miconietum jahnii) and two high Andean forest communities (Gaultherio anastomosantis-Hesperomeletum obtusifoliae and the Libanothamnetum griffinii). Altitudinal zonation, forest floristic diversity, composition and forest structure is discussed between slopes and along the altitudinal gradient and compared, where possible, to other montane forests. In LMRF, Rubiaceae, Lauraceae and Melastomataceae are the most speciose of woody families. In UMRF, the Lauraceae family is still the most diverse, followed by Melastomataceae and Myrtaceae, while in SARF the Asteraceae and Ericaceae are the most species rich families. The structure of the montane forests of Ramal de Guaramacal becomes more compressed towards higher elevations. LMRF are dense and of medium height, with canopies up to 25 in tall, while UMRF canopies can reach up to IS in, and those of SARF are only 6-8 (10) m tall. Basal area was slightly increased on the North than on the South slopes and shows different patterns against altitude between slopes. More diversity and density of palms, lianas and climbers is clearly observed in LMRF, but richness of liana species is also important in SARF forests. Forest altitudinal zonation is variable between the North and South slopes of Guaramacal, with the forest zones of UMRF on the windward South slope, tending toward reaching lower elevations than on the opposite and drier North slope. There is a low altitudinal limit of the upper forest (Upper Forest Line or UFL) apparently caused by the top effect

Effects of soil microarthropods on plant litter decomposition across an elevation gradient in the Wuyi Mountains

Soil microarthropods are considered to be among the strongest determinants of plant litter decomposition in warm, humid sites. Little is known, however, about the regulation of plant litter decomposition dynamics along an elevation gradient in such sites. Our study examined the contributions of soil microarthropods to leaf litter decomposition of a single substrate ( Castanopsis carlesii) along an elevation gradient across four types of zonal vegetations in southeastern China: evergreen broadleaf forest (EVB): coniferous forest (COF): dwarf forest (DWF): and alpine meadow (ALM) during April 2007 to March 2008. Leaf litter decomposition of C. carlesii was significantly accelerated by the presence of fauna in all four sites. After 360 days in the field, mass loss rates with the full decomposer assemblage and in the reduction of microarthropods were 62.9% and 41.2% in EVB, 48.1% and 30.6% in COF, 36.4% and 27.8% in DWF, 30.3% and 23.7% in ALM, respectively. The percentage of total decomposition due to the presence of soil fauna was 37% in EVB, 25% in COF, 12% in DWF, and 8% in ALM, thus showing strong systematic variation along the elevational gradient. The mass losses in control plots at the four sites were significantly correlated with the abundances of total Acari, Collembolans, and Mesostigmata mites. Although the proportion of Oribatid mites at EVB was not the highest among the four sites, there were elevated proportions of Mesostigmatid and Prostigmata mites, many of which were microbe-consuming species and induce an indirect influence on litter decomposition. Moreover, Shannon Index ( F = 2.455, p = 0.093) and Group Number ( F = 5.830, p = 0.005) both decreased along the elevation gradients. Mass losses were also found to be distinctively related to H′ ( r 2 = 0.984, p = 0.016), and GN ( r 2 = 0.952, p = 0.048) across the four sites. Our results suggest that the faunal contribution to plant litter decomposition varies markedly across environmental gradients that differ in litter faunal diversity.

Why Are Predators More Sensitive to Habitat Size than Their Prey? Insights from Bromeliad Insect Food Webs

Ecologists have hypothesized that the exponent of species-area power functions (z value) should increase with trophic level. The main explanation for this pattern has been that specialist predators require prior colonization of a patch by their prey, resulting in a compounding of the effects of area up trophic levels. We propose two novel explanations, neither of which assumes trophic coupling between species. First, sampling effects can result in different z values if the abundances of species differ (in mean or evenness) between trophic levels. Second, when body size increases between trophic levels, effects of body size on z values may appear as differences between trophic levels. We test these alternative explanations using invertebrate food webs in 280 bromeliads from three countries. The z value of predators was higher than that of prey. Much of the difference in z values could be explained by sampling effects but not by body size effects. When damselflies occurred in the species pool, predator z values were even higher than predicted, as damselflies avoid small, drought-prone bromeliads. In one habitat, dwarf forests, detrital biomass became decoupled from bromeliad size, which also caused large trophic differences in z values. We argue that there are often simpler explanations than trophic coupling to explain differences in z values between trophic levels.

Comment on “Hot, dry, wet, cold or toxic? Revisiting the ecological significance of leaf cuticular micromorphology” by M. Haworth and J.C. McElwain [Palaeogeography, Palaeoclimatology, Palaeoecology 262 (2008) 79-90

Haworth and McElwain (2008) reach the illogical conclusion that xeromorphic features of plants are not xeromorphic because of confusion between genetic and descriptive terminology. Descriptive terms for the suite of plant features including thick cuticles are scleromorph, sclerophyte, or sclerophyll (Greek σκληρον meaning “hard, harsh, rough, stiff”), not xeromorph, and descriptive redefinition of “xeromorph” by Haworth and McElwain (2008, inter alia) is confusing. Xeromorph is a form attributed to dry climate, and is thus unavoidably genetic: xeromorphic implies that scleromorphic features were induced by dry climate. Scleromorphy can also be produced by other environmental hardships, such as nutrient shortage (peinomorphy of Walter, 1973) and high salinity (halophyty, e.g. Rich et al., 2008: “halomorphic” is generally used for soils rather than plants, e.g. Mendoza et al., 2005). Haworth and McElwain's (2008) failure to mention halophytes is puzzling, because there are several published interpretations of their chosen example, Pseudofrenelopis parceramosa, as a mangrove or salt marsh plant (Retallack and Dilcher, 1986). Halophyty is a common explanation for the hard leaves and succulence of mangroves and glassworts (Walter, 1973). Peinomorphy is a commonexplanation for small stiff leaves of coastal heaths or pygmy forest in silica–iron soils (Spodosols) or on mineral-poor peats (Histosols: Walter, 1973; Jenny, 1980; Retallack, 1997). Peinomorphy may also be created by the acidic leaching environments of elevated atmospheric CO2 and in areas of SO2 gases from volcanic fumaroles, because both gases have the effect of acidifying substrates to make nutrient acquisition difficult (Retallack, 2001). A final possibility not mentioned by Haworth andMcElwain (2008) is that scleromorphymay have no environmental significance in itself. Krausel (1923) argued from

Ecological correlates and short-term effects of relocation of a rare epiphytic orchid after Hurricane Georges

In the Caribbean, hurricanes are common and can result in the loss of a large compo- nent of the epiphytic community as a result of felled tress; the re-establishment of such epiphytic communities is a slow process. Consequently, it is important to determine whether the management of endangered epiphytic plants could include the relocation of individuals from felled to standing trees after hurricanes. If plants can be successfully re-established on standing trees, can new viable populations be established? In this study, ecological correlates and the immediate effect of relocation of a rare endangered epiphytic orchid post Hurricane Georges are examined. Seedlings, juveniles and adults of the protected orchid Lepanthes eltoroensis Stimson were relocated from felled trees onto standing trees along a 5 km stretch of elfin forest and surveyed after 6 and 12 mo. Plants were relocated onto trees that had or were adjacent to trees with con-specific orchids. The effect of this manipulation on survivorship and growth of orchids was evaluated, and the effect of relocating the orchids on occupied and un-occupied phorophytes was compared. L. eltoroensis is preferentially dis- tributed at elevations of 800 to 900 m above sea level, and no preference for specific species of trees was observed. Orchid population size was not correlated with percent moss cover on standing trees. Relocation of orchids from felled trees to standing trees as a management tool for this species was positive, as most individuals (73%) survived the first year; however, this was significantly less than non-relocated plants on standing trees (94%). Management should include re-locating orchids as soon as possible after a hurricane to maximize individual survivorship of this endangered species.

Two sympatric new species of Phrynopus (Anura: Strabomantidae) from Yanachaga Chemillen National Park (central Peruvian Andes)

Two sympatric new species of Phrynopus (Anura: Strabomantidae) are described from elfin forests and puna grasslands (3363–3589 m) of the eastern slopes of the Andes of Departamento Pasco in central Peru. Phrynopus miroslawae sp. nov. is a medium-sized species characterized by lacking vomerine teeth and tympanic membrane, and by having dorsolateral folds, areolate ventral skin, dorsum gray with black spots, venter cream with small scattered black blotches, and iris bronze. Phrynopus nicoleae sp. nov. is a small species characterized by lacking tympanic membrane and by having vomerine teeth, an X-shaped middorsal fold, ventral skin areolate, dorsum tan with black stripes and bluish tubercles, and iris bronze with black reticulations.

Dwarf Forest Recovery after Disturbances in the Luquillo Mountains of Puerto Rico

Dwarf forest in Puerto Rico's Luquillo Mountains varies according to substrate and topography with very short, dense forest growing on exposed, rocky sites. High elevation level sites suffered considerable damage during past hurricanes whereas the trees on certain lower slopes were protected by ridges or spurs. Post-disturbance recovery of dwarf forest on two types of sample plots near East Peak was slow. Nearly 37 years after a 1968 airplane crash, Cyathea bryophila (R. Tryon) Proctor and Eugenia borinquensis Britton accounted for 71% of the 25.3 t ha-1 total aboveground dry weight biomass (hereafter biomass) on 780 m2 of the crash site. This is only 30% of the 80 t ha-1 average biomass of the surrounding dwarf forest prior to Hurricane Hugo of 1989. Also, six 250 m2 permanent plots (stratified by topography with sites on ridges, slopes, and ravines) showed delayed post-hurricane mortality, declining in mean stem numbers from 2,956 stems ha-1 in 1990 to 2,268 stems ha-1 in 2005. Average plot biomass decreased from 72.8 t ha-1 in 1990 to 61.6 t ha-1 in 2000, increasing slightly to 62.9 t ha-1 in 2005. Recovery on all sites was characterized by an immediate invasion of grass cover along with an influx of ferns, followed by dicotyledonous seedlings and saplings, and finally small trees. More than one-half of the arborescent species growing in dwarf forest are endemic to Puerto Rico where they play a prominent role in post disturbance recovery; moreover, 85% of the trees do not exceed 15 m in height anywhere in the Luquillo Mountains.

Características de la avifauna en un gradiente altitudinal de un bosque nublado andino en La Paz, Bolivia

El presente trabajo analiza la diversidad y composición de la avifauna en tres localidades ubicadas dentro del Parque Nacional y Área Natural de Manejo Integrado de Cotapata, La Paz, Bolivia. Las tres localidades se distribuyeron en gradiente altitudinal y tres tipos de bosques húmedos andinos (ceja de monte a 3170 m, bosque nublado a 2620 m y bosque nublado secundario a 1850 m) de la zona Yungas. Se realizó un esfuerzo total de 3286 horas-red niebla, 324 horas de caminatas y 216 horas de conteos por puntos en los tres lugares de estudio. Un total de 220 especies fueron registradas, la mayoría capturadas en redes (100 spp., 45%). Veinticinco familias fueron representadas en las capturas por redes y 42 mediante los censos. Tyrannidae y Thraupidae fueron las más representativas mediante ambos métodos. Las curvas acumulativas de especies fueron similares en todos los sitios. La riqueza de especies para la ceja de monte, bosque nublado y bosque secundario a partir de las capturas y censos fueron de 44, 40, 44 especies y 69, 57, 86 especies, respectivamente. Un total de 16 especies de rango restringido fueron registradas (p.e. Odontophorus balliviani, Andigena cucullata). La diversidad para la ceja de monte fue H´= 1,41; para el bosque nublado (H´= 0,98) y el bosque nublado secundario (H´= 0,96). La diversidad beta fue 0,74 basada en datos de capturas con redes y 0,79 basada en datos de censos en las tres alturas.

Altitudinal patterns of the flora of seed plants of Dawei Mountain in Yunnan Province, south China

Altitudinal gradient incorporates multiple resource gradients, which vary continuously in different fashions. It is important to study the mountain floristic patterns along altitudinal gradients, which reveal the regular pattern of the flora along the environmental gradients, the changing trend of biodiversity patterns along the altitudinal gradient, and relevance of biological fitness. To explore the compositional characteristics and ecological significance of floristic patterns along altitudinal gradient in China National Nature Reserve of Dawei Mountain in the southeast of Yunnan Province, field investigations have been made to the flora along the two routes of the southwest slope and the northeast slope of the said reserve, including a vertical vegetation transect. Meanwhile, further investigations have also been made to the flora of Dawei Mountain, which has been accounted for in the literature, as Flora Yunnan, The Seed Plant in Yunnan, and so on. The structural characteristics of the flora and the altitudinal distribution pattern of its floristic components were analyzed. By applying systematic cluster analysis, the altitudinal position of the dividing line of floristic changes along altitudinal gradient was detected, and the effects of the montane climate on the vertical variation of floristic composition were studied. Conclusions were put forward. This paper can be summarized as follows: (1) The obvious boundary that differentiates tropical floristic elements is located at the altitude of approximately 1,500 m; it is reasonable to stipulate the boundary line between tropical rain forests and the evergreen broad-leaved forests. (2) The vertical vegetation spectrum made by cluster analysis shows that humid rain forests are below 700 m a.s.l, montane rain forests are between 700 and 1,500 m, monsoon evergreen broad-leaved forests are between 1,300 and 1,800 m, and montane mossy evergreen broad-leaved forests are above 1,800 m a.s.l. Nonrepresentative montane mossy dwarf forests (above 2,100 m) in the area are distributed in windward sides and in barren land on the mountain slopes.

Rapid uptake of 15N-ammonium and glycine- 13C, 15N by arbuscular and ericoid mycorrhizal plants native to a Northern California coastal pygmy forest

While it is well established that plants are able to acquire nitrogen in inorganic form, there is less information on their ability to ‘short circuit’ the N cycle, compete with microbes, and acquire nitrogen in organic form. Mycorrhizal fungi, known to enhance nutrient uptake by plants, may play a role in organic N uptake, particularly ericoid mycorrhizas. We asked the question—Can mycorrhizal fungi increase the ability of plants to take up organic N, compared to inorganic N? Here, we report on the abilities of three plant species, ericoid mycorrhizal Rhododendron macrophyllum and Vaccinium ovatum and arbuscular mycorrhizal Cupressus goveniana ssp. pigmaea, to acquire C and/or N from an organic and an inorganic N source. All three species are native to a California coastal pygmy forest growing in acidic, low-fertility, highly organic soils. In a pot study, glycine- α 13C, 15N and 15N-ammonium were applied to pygmy forest soil for 17 or 44 h. Ericoid mycorrhizal species did not demonstrate a preference for either inorganic or organic sources of N while Cupressus acquired more NH 4-N than glycine-N. For all species, glycine-N uptake did not increase after 17 h suggesting glycine uptake and glycine immobilization occurred rapidly. Both glycine-N and glycine-C were recovered in shoots and in roots suggesting that all species acquired some N in organic form. Regression analyses of glycine-N and glycine-C recovery in root tissue indicate that much of the glycine was taken up intact and that the minimum proportion of glycine-N recovered in organic form was 85% ( Cupressus) and 70% ( Rhododendron). Regressions were non-significant for Vaccinium. For all species, glycine-N remained predominantly in roots while glycine-C was transferred to shoots. In contrast, NH 4-N remained in roots of ericoid plants but was transferred to shoots of arbuscular mycorrhizal Cupressus. Since net N mineralization rates in pygmy forest soils are low, our results suggest that organic N may be an important N source for plants in this temperate coniferous ecosystem regardless of mycorrhizal type. Acquisition of amino acid C by these species also may partially offset the carbon cost to plants of hosting mycorrhizal fungi.

Effects of Wind on the Allometry of Two Species of Plants in an Elfin Cloud Forest

ABSTRACTThigmomorphogenesis includes the effects of mechanical perturbation on plant growth. To test whether thigmomorphogenesis is evident at different scales within plants, we investigated the effect of wind on allometric relationships between specific plant parts. We chose two species from the elfin cloud forest of Puerto Rico that have contrasting growth habits, the shrub Clibadiun erosum (Asteraceae) and the palm Prestoea acuminata var. montana (Arecaceae), and subjected them to barrier‐protected and wind‐exposed treatments. For C. erosum, we compared the allometry of stems and branches against three allometric models that predict that plant height or branch length increases at the 1, 2/3, and 1/2 power of stem diameter. Only the geometric similarity model (scaling exponent of 1) seemed to hold when plants were exposed to the wind. We found relatively fewer leaves per number of branches produced and fewer leaves per increment of branch diameter in the plants of C. erosum exposed to the wind. Mean petiole length ratios (petiole length/basal radius) of P. acuminata were higher on leaves of barrier‐protected plants for both simple and compound leaves, indicating that petioles were stouter and mechanically safer in the wind‐exposed plants. We suggest that alteration of the allometric relationships of plant parts, organs, or plant modules (stems and branches of C. erosum and leaves of P. acuminata) and alteration of the number of plant parts (leaves and branches of C. erosum) are adaptive responses resulting from the mechanical perturbation induced by wind in the elfin forest.

Fine root respiration in the mangrove Rhizophora mangle over variation in forest stature and nutrient availability

Root respiration uses a significant proportion of photosynthetically fixed carbon (C) and is a globally important source of C liberated from soils. Mangroves, which are an important and productive forest resource in many tropical and subtropical countries, sustain a high ratio of root to shoot biomass which may indicate that root respiration is a particularly important component in mangrove forest carbon budgets. Mangroves are often exposed to nutrient pollution from coastal waters. Here we assessed the magnitude of fine root respiration in mangrove forests in Belize and investigated how root respiration is influenced by nutrient additions. Respiration rates of excised fine roots of the mangrove, Rhizophora mangle L., were low (4.01 +/- 0.16 nmol CO(2) g(-1) s(-1)) compared to those measured in temperate tree species at similar temperatures. In an experiment where trees where fertilized with nitrogen (N) or phosphorus (P) in low productivity dwarf forests (1-2 m height) and more productive, taller (4- 7 m height) seaward fringing forests, respiration of fine roots did not vary consistently with fertilization treatments or with forest stature. Fine roots of taller fringe trees had higher concentrations of both N and P compared to dwarf trees. Fertilization with P enhanced fine root P concentrations in both dwarf and fringe trees, but reduced root N concentrations compared to controls. Fertilization with N had no effect on root N or P concentrations. Unlike photosynthetic C gain and growth, which is strongly limited by P availability in dwarf forests at this site, fine root respiration (expressed on a mass basis) was variable, but showed no significant enhancements with nutrient additions. Variation in fine root production and standing biomass are, therefore, likely to be more important factors determining C efflux from mangrove sediments than variations in fine root respiration per unit mass.

New records and a status assessment of a rare dwarf brocket deer from the montane forests of Bolivia

AbstractTwo skeletons, tracks, faecal pellets, photographs and local reports are described and compared with the few previous records of dwarf Andean deer from Bolivia and Peru. Tarsal bones and incisor teeth were diagnostic traits for Mazama and not for Pudu, while skull measurements, ear shape, body colour and facial patterns were consistent with descriptions of Mazama chunyi. Twenty‐five new localities (including more than 60 sites in La Paz and Cochabamba) extended significantly the previously known range for M. chunyi in Bolivia. It occurs in Madidi, Apolobamba, Pilón Lajas, Cotapata, Carrasco and probably Isiboro Sécure protected areas, in habitats ranging from grasslands and Polylepis elfin forests of the ‘ceja de Yungas’ at 3600 m to sub‐Andean forests at 1000 m. A geographical information system modelled geographic distribution area based on altitude and ecological zone estimates a potential range of about 45 717 km2 in Bolivia. About 36% of this range (or 41% of the extent of occurrence) is degraded and fragmented, but the rest seems to be in relatively good conservation status. Habitat decline and a limited area of occupancy estimated for Bolivia (and suspected for Peru) suggest that M. chunyi's conservation status should be updated from Data Deficient to Vulnerable VU A4c; B2a+b(iii).

Spatial modelling of evapotranspiration in the Luquillo experimental forest of Puerto Rico using remotely-sensed data

Actual evapotranspiration (aET) and related processes in tropical forests can explain 70% of the lateral global energy transport through latent heat, and therefore are very important in the redistribution of water on the Earth's surface [Mauser, M., Schadlich, S., 1998. Modelling the spatial distribution of evapotranspiration on different scales using remote sensing data. J. Hydrol. 212-213, 250-267]. Unfortunately, there are few spatial studies of these processes in tropical forests. This research integrates one Landsat Thematic Mapper (TM) image and three Moderate Resolution Imaging Spectroradiometer (MODIS) images with a hydrological model [Granger, R.J., Gray, D.M., 1989. Evaporation from natural nonsaturated surfaces. J. Hydrol. 111, 21-29] to estimate the spatial pattern of aET over the Luquillo Experimental Forest (LEF) - a tropical forest in northeastern Puerto Rico - for the month of January, the only month that these remotely sensed images were acquired. The derived aETs ranged from 0 to 7.22 mm/day with a mean of 3.08 ± 1.35 mm/day which were comparable to other estimates. Simulated aET was highest in the low elevation forest and decreased progressively toward higher elevations. Because of differences in solar radiation at different elevations, aspects and topographic positions, aET tended to be higher on south slopes and along ridges than on north slopes and in valleys. In addition, the Bowen ratio (the ratio of sensible heat to latent heat) varied across different vegetation types and increased with elevation, thus reflecting differences in the distribution of net solar radiation incident on the earth's surface. Over a day, the highest simulated aET occurred at around noon. We also applied this model to simulate the average monthly aET over an entire year based on the cloud patterns derived from at least two MODIS images for each month. The highest simulated aET occurred in February and March and the lowest in May. These observations are consistent with long term data. The simulated values were compared with field measurements of the sap flow velocity of trees at different elevations and in different forest types. These comparisons had good agreement in the low elevation forest but only moderate agreement in the elfin forest at high elevations.

Habitat preferences of the Andean bear (Tremarctos ornatus) in the Bolivian Andes

AbstractHabitat preferences of the Andean bear Tremarctos ornatus were studied within two adjacent protected areas in the north‐western Bolivian Andes. Standard transects measuring habitat variables and bear sign frequency were used spanning seven different vegetation types. Andean bears were present at 28 of 33 sampled sites and actively preferred high‐elevation elfin forest and upper montane humid forests, and used high‐elevation humid ‘páramo’ grasslands and middle montane humid forests according to their availability. Bears were absent from dry montane and Andean foothill forests and relative abundance was low in lower montane humid forests. Elevation and basal area of food items were the variables most closely related to the relative abundance.

Root Morphology and Anchorage of Six Native Tree Species from a Tropical Montane Forest and an Elfin Forest in Ecuador

Root architecture of tree species was investigated at two different altitudes in tropical forests in Ecuador. Increasing altitude was accompanied by higher wind speeds and more shallow soils, while slope angles of both sites were comparable (20–50� ). Three tree species typical for the montane forest at 1900 m (Graffenrieda emarginata (Ruiz & Pav.) Triana (Melastomataceae), Clethra revoluta (Ruiz & Pav.) Spreng. (Clethraceae), Vismia tomentosa Ruiz & Pav. (Clusiaceae)) and for the elfin forest at 3000 m (Weinmannia loxensis Harling (Cunoniaceae), Clusia spec. (Clusiacaea) Styrax foveolaria Perkins (Styraceae)) were examined. At 1900 m, 92% of the trees grew upright, in comparison to 52% at 3000 m. At 3000 m, 48% of the trees were inclined, lying or even partly uprooted. At this altitude, all trees with tap roots or with shoots connected by coarse rhizomes, 83% of the trees with stilt roots, and 50% of the trees in which stems or roots were supported by other trees grew upright, suggesting that these characteristics were relevant for tree stability. Root system morphology differed markedly between altitudes. In contrast to 1900 m, where 20% of structural roots originated in the deeper mineral soil, root origin at 3000 m was restricted to the forest floor. The mean ratio of root cross sectional area to tree height decreased significantly from 6.1 � 10 )3 m 2 m )1 at 1900 m to 3.2 � 10 )3 m 2 m )1 at 3000 m. The extent of root asymmetry increased significantly from 0.29 at 1900 m to 0.62 at 3000 m. This was accompanied by a significantly lower number of dominant roots at 3000 m (2.3 compared to 3.8 at 1900 m). In conclusion, native tree species growing in tropical montane and elfin forests show a variety of root traits that improve tree stability. Root system asymmetry is less important for tree stability where anchorage is provided by a deep and solid root–soil plate. When deep rooting is impeded, root traits improving the horizontal extension of the root–soil plate are more pronounced or occur more frequently. Furthermore, mutual mechanical support of roots and stems of neighboring trees seems to be an appropriate mechanism to provide anchorage in soils with low bulk density and in environments with high wind speeds. Abbreviations: AR – aspect ratio; CSA – cross sectional area; DBH – diameter at breast height; ZRT – zone of rapid taper

Successional Position of Dry Andean Dwarf Forest Species as a Basis for Restoration Trials

The successional affinity of nine woody species was inferred from the structure, diversity and disturbance history of the vegetation where these occurred. This was done in order to obtain a basis for a restoration experiment, currently in execution, in the dry Andean dwarf forest zone on the edge of the High Plain of Bogota (Colombia), at 2600–2950 m.a.s.l. We laid out 101 relevees in grassland and shrubland types in different stages of recovery, and in relatively little disturbed endemic Condalia thomasiana dwarf forest. The disturbance history of sites over the last ~60 years was inferred from aerial photograph series (1941–1991). CCA and logistic regression were applied to relate species composition to diversity, environment and disturbance history. All species showed a preference for certain structural groups. Also, a clear relation between species occurrence and vegetation diversity was found. Baccharis macrantha, and Dalea coerulea appeared relatively tolerant to grazing, while the remaining seven species reacted negatively. Soil clay content, base availability and organic carbon content was also an important factor for occurrence of each species. Invasion of grasslands by woody species is pioneered by Baccharis macrantha and followed by Dodonaea viscosa. Dalea coerulea was predominantly found on truncated clayey soils, which will probably not support Condalia dwarf forest. The hypothesized classification of the nine planted species to either pioneers or late-successional was fine-tuned. This exploratory study will be of use in the set-up of future succession-based restoration experiments, and for converting exotics afforestations to natural vegetation.