Cloud Forest Zone Research Articles

Land use scenarios, seasonality, and stream identity determine the water physicochemistry of tropical cloud forest streams.

Land use is a major factor determining stream water physicochemistry. However, most streams move from one land use type to another as they drain their watersheds. Here, we studied three land use scenarios in a tropical cloud forest zone in Mexico. We addressed three main goals, to: (1) assess how land use scenarios generate different patterns in stream physicochemical characteristics; (2) explore how seasonality (i.e., dry, dry-to-wet transition, and wet seasons) might result in changes to those patterns over the year; and (3) explore whether physicochemical patterns in different scenarios resulted in effects on biotic components (e.g., algal biomass). We studied Tropical Mountain Cloud Forest streams in La Antigua watershed, Mexico. Streams drained different three scenarios, streams with (1) an upstream section draining forest followed by a pasture section (F-P), (2) an upstream section in pasture followed by a forest section (P-F), and (3) an upstream forest section followed by coffee plantation (F-C). Physicochemistry was determined at the upstream and downstream sections, and at the boundary between land uses. Measurements were seasonal, including temperature, dissolved oxygen, conductivity, and pH. Water was analyzed for suspended solids, alkalinity, silica, chloride, sulfate, magnesium, sodium, and potassium. Nutrients included ammonium, nitrate, and phosphorus. We measured benthic and suspended organic matter and chlorophyll. Streams presented strong seasonality, with the highest discharge and suspended solids during the wet season. Scenarios and streams within each scenario had distinct physicochemical signatures. All three streams within each scenario clustered together in ordination space and remained close to each other during all seasons. There were significant scenario-season interactions on conductivity (F = 9.5, P < 0.001), discharge (F = 56.7, P < 0.001), pH (F = 4.5, P = 0.011), Cl- (F = 12.2, P < 0.001), SO42- (F = 8.8, P < 0.001) and NH4+ (F = 5.4, P = 0.005). Patterns within individual scenarios were associated with stream identity instead of land use. Both P-F and F-C scenarios had significantly different physicochemical patterns from those in F-P in all seasons (Procrustes analysis, m12 = 0.05-0.25; R = 0.86-0.97; P < 0.05). Chlorophyll was significantly different among scenarios and seasons (F = 5.36, P = 0.015, F = 3.81, P = 0.42, respectively). Concentrations were related to physicochemical variables more strongly during the transition season. Overall, land use scenarios resulted in distinctive water physicochemical signatures highlighting the complex effects that anthropogenic activities have on tropical cloud forest streams. Studies assessing the effect of land use on tropical streams will benefit from assessing scenarios, rather than focusing on individual land use types. We also found evidence of the importance that forest fragments play in maintaining or restoring stream water physicochemistry.

Apex Liminality: Comprehending Lord Howe Island’s Cloud Forest and Related Island Ecosystems

Elevated isolated habitats that occur on mountain peaks and ridges are commonly referred to as sky islands. Sky islands are islands in a biogeographical sense but can also occur on islands. In these contexts, habitat islanding is effectively doubled, leading to highly distinct ecosystems. One subset of sky islands occurs in areas frequently covered by water vapour. These are commonly referred to as cloud forests but might be better characterised as elevated cloudy ecosystems in recognition of their nature as dynamic assemblages of vaporous, material and animate elements.&amp;nbsp;The limited extent of these elevated areas and their reliance on cloaking vapour to maintain their habitats makes them particularly vulnerable to a range of Anthropocene pressures.&amp;nbsp;Following a discussion of the limitations of analogous naming practices for such ecosystems, the article provides a general characterisation of elevated cloudy habitats and explores notions of atmospheres and of visibility with particular regard to Lord Howe Island and human perceptions of and experiences within its cloud forest zone. Moving to more comparative analyses, the article refers to various interventions that have either undermined or attempted to maintain similar island ecosystems and the prospects for these at a time of increasing global climate change. In considering such aspects, the article identifies the manner in which the elevated cloudy ecosystems of some islands are as integrated with and dependent on water vapour as they are on the islands' surrounding seas and merit recognition as a distinct phenomenon in this regard.

Interactions between payments for hydrologic services, landowner decisions, and ecohydrological consequences: synergies and disconnection in the cloud forest zone of central Veracruz, Mexico

Asbjornsen, H., R. Manson, J. Scullion, F. Holwerda, L. E. Munoz-Villers, M. Alvarado-Barrientos, D. Geissert, T. E. Dawson, J. J. McDonnell, and L. Adrian Bruijnzeel. 2017. Interactions between payments for hydrologic services, landowner decisions, and ecohydrological consequences: synergies and disconnection in the cloud forest zone of central Veracruz, Mexico. Ecology and Society 22(2):25. https://doi.org/10.5751/ES-09144-220225

The variation of productivity and its allocation along a tropical elevation gradient: a whole carbon budget perspective.

Why do forest productivity and biomass decline with elevation? To address this question, research to date generally has focused on correlative approaches describing changes in woody growth and biomass with elevation. We present a novel, mechanistic approach to this question by quantifying the autotrophic carbon budget in 16 forest plots along a 3300m elevation transect in Peru. Low growth rates at high elevations appear primarily driven by low gross primary productivity (GPP), with little shift in either carbon use efficiency (CUE) or allocation of net primary productivity (NPP) between wood, fine roots and canopy. The lack of trend in CUE implies that the proportion of photosynthate allocated to autotrophic respiration is not sensitive to temperature. Rather than a gradual linear decline in productivity, there is some limited but nonconclusive evidence of a sharp transition in NPP between submontane and montane forests, which may be caused by cloud immersion effects within the cloud forest zone. Leaf-level photosynthetic parameters do not decline with elevation, implying that nutrient limitation does not restrict photosynthesis at high elevations. Our data demonstrate the potential of whole carbon budget perspectives to provide a deeper understanding of controls on ecosystem functioning and carbon cycling.

Blakea nareliana (Melastomataceae), una nueva especie del Alto Huallaga, en el norte del Perú

A new Peruvian species of Blakea(Melastomataceae) is described. Blakea nareliana is a small tree, endemic to the cloud forest zone in the northern Andean Huallaga area of Peru. This region is highly diverse and under-collected due to difficult access. Currently the new species is only known from one population at the type locality. However, extensive collections in the wider region have led to the discovery of many previously unknown populations of other rare Melastomataceae. It is to be hoped that future collecting efforts in the region will yield more material of Blakea nareliana.

Plant management and biodiversity conservation in Náhuatl homegardens of the Tehuacán Valley, Mexico

BackgroundThe Tehuacán Valley is one of the areas of Mesoamerica with the oldest history of plant management. Homegardens are among the most ancient management systems that currently provide economic benefits to people and are reservoirs of native biodiversity. Previous studies estimated that 30% of the plant richness of homegardens of the region are native plant species from wild populations. We studied in Náhuatl communities the proportion of native plant species maintained in homegardens, hypothesizing to find a proportion similar to that estimated at regional level, mainly plant resources maintained for edible, medicinal and ornamental purposes.MethodsWe analysed the composition of plant species of homegardens and their similarity with surrounding Cloud Forest (CF), Tropical Rainforest (TRF), Tropical Dry forest (TDF), and Thorn-Scrub Forest (TSF). We determined density, frequency and biomass of plant species composing homegardens and forests through vegetation sampling of a total of 30 homegardens and nine plots of forests, and documented ethnobotanical information on use, management, and economic benefits from plants maintained in homegardens.ResultsA total of 281 plant species was recorded with 12 use categories, 115 ornamental, 92 edible, and 50 medicinal plant species. We recorded 49.8 ± 23.2 (average ± S.D.) woody plant species (shrubs and trees) per homegarden. In total, 34% species are native to the Tehuacán Valley and nearly 16% are components of the surrounding forests. A total of 176 species were cultivated through seeds, vegetative propagules or transplanted entire individual plants, 71 tolerated, and 23 enhanced. The highest species richness and diversity were recorded in homegardens from the CF zone (199 species), followed by those from the TRF (157) and those from the TDF (141) zones.ConclusionHomegardens provide a high diversity of resources for subsistence of local households and significantly contribute to conservation of native biodiversity. The highest diversity was recorded in homegardens where the neighbouring forests had the least diversity, suggesting that management of homegardens aims at compensating scarcity of naturally available plant resources. Cultivated species were markedly more abundant than plants under other management forms. Diversity harboured and management techniques make homegardens keystones in strategies for regional biodiversity conservation.

The water and energy exchange of a shaded coffee plantation in the lower montane cloud forest zone of central Veracruz, Mexico

The water and energy fluxes of a shaded coffee plantation in the lower montane cloud forest (LMCF) zone of central Veracruz, Mexico, were measured over a two-year period (September 2006–August 2008) using the eddy covariance method. Complementary measurements of throughfall and stemflow were made to study rainfall interception. The sum of the observed sensible (H) and latent (λE) heat fluxes was almost 95% of the net radiation (Rn) minus the canopy heat storage fluxes, indicating very good energy balance closure. The mean annual evapotranspiration was 1066mm, and 95% of the corresponding FAO Penman-Monteith reference evapotranspiration (ET0) of 1117mm yr−1. Interception loss was 8% of annual rainfall (1386mm). Both the eddy covariance, and the throughfall and stemflow measurements showed average wet-canopy evaporation rate to be very low (0.05mmh−1) compared to the corresponding rainfall rate (3.06mmh−1). As a result, and despite the low canopy storage capacity of the coffee plantation (Cm, 0.50mm), interception was dominated by post-event evaporation of intercepted water rather than by within-event evaporation. Comparing the results for the coffee plantation with interception data from mature and secondary LMCFs in the study area suggests that the conversion of LMCF to shade-coffee may lead to a decrease in interception loss of 8−18% of incident rainfall. This decrease is caused by a three- to seven-fold decrease in Cm, probably due to the lower leaf area and smaller epiphyte biomass of the coffee plantation. The mean annual dry-canopy evaporation was 992mm, and 89% of ET0. Comparing the eddy covariance-based estimate of dry-canopy evaporation for the coffee plantation with sapflow-based estimates of transpiration for the LMCFs did not show any clear differences.

Successional vegetation patterns in abandoned pastures of the lower montane cloud forest zone in the Venezuelan Andes

Successional vegetation patterns in abandoned pastures of the lower montane cloud forest zone in the Venezuelan Andes

Variability of the radial profile of sap velocity in Pinus patula from contrasting stands within the seasonal cloud forest zone of Veracruz, Mexico

Characterizing the variability of the radial profiles of sap velocity (vs) is a critical step to improve upscaling point measurements of vs to whole-tree sap flow. One promising approach is the use of a probability distribution function (pdf) to model radial profiles of vs, because shape parameters could potentially be generalized to trees of the same species based on the premise that the shape remain consistent regardless of the tree size and age, and over time, even though the magnitude of vs may vary with environmental conditions. The objective of this study was to characterize and assess the variability of the radial profile and to examine the validity of the premises underlying this approach by applying it to Pinus patula, one of the most widely planted tree species in the uplands of central-eastern Mexico. We measured vs with the Heat Ratio method at various sapwood depths in 18 P. patula trees with a dbh between 7.3 and 59.7cm and age between of 10 and 34 years, over a period of 1.5 years. Trees were growing in two stands: a mature forest stand and a young plantation. By fitting the Beta-pdf to hourly radial profiles of vs, we derived a lumped shape parameter (ρ) to denote the radial position relative to sapwood depth with average vs and a scaling parameter (cs). The typical radial profile was unimodal, asymmetrical and with peak vs generally within the outermost 20–33% of the sapwood depth. However, tree-to-tree variability in ρ was considerable among trees within the same stand and also across stands. Long-term and day-to-day variation of ρ was marginal. The hourly dynamics of the radial profile, characterized by cs, can be explained by a linear combination of incoming shortwave radiation, vapor pressure deficit, the hour of day and their interaction (r2=0.74). An independent field evaluation confirmed that a radial profile of fixed shape can be effectively used to estimate whole-tree sap flow with relatively low bias (4–26% underestimation) relative to cut-tree water uptake, particularly for trees for which vs observations covered at least 60% of the sapwood depth. Our findings emphasize the importance of conducting multiple vs point measurements covering most of the sapwood depth for accurate characterization of the radial profile, and demonstrate the utility of fitting a pdf to point vs measurements in order to assess the variability of vs radial profiles as well as to compute sap flow at the whole-tree level.

Axinaea fernando‐cabiesii and A. reginae spp. nov. (Melastomataceae) from upper Amazonia of Peru, with notes on the conservation status of A. flava

Two new Peruvian species of Axinaea (Melastomataceae) are described. Axinaea francisco‐cabiesii and Axinaea reginae are small trees, endemic to the cloud forest zone in the northern Andean region of Peru. The border region of Peru and Ecuador is one of the Earth's most biologically diverse areas. The Huancabamba depression of the central Andean Cordillera allows for dispersal of flora and fauna between the Amazon Basin and the Pacific lowlands. Additionally, the region is characterized by a fast transition between the humid mountain forests of the northern Andes and the dry, deciduous forests of the northern Peruvian lowlands, making it a hotspot for endemic species. Field observations indicate that both new Axinaea species have small population sizes, occurring in a very restricted habitat. Axinaea flava was described only a few years ago from the cloud forest – paramo transition zone in southernmost Ecuador between 3400 and 3800 m a.s.l. This small tree is the only yellow‐flowered species of the genus. The original assessment counted about 100 individuals. In the last decade, livestock grazing and widespread burning have intensified in the region, and a new assessment yielded only 10 individuals, four of which were damaged by fire. This puts the species in danger of extinction. We encourage search for other populations in southern Ecuador and northern Peru.

Native and Alien Carabidae (Coleoptera) Share Lanai, an Ecologically Devastated Island

The carabid beetle fauna of Lanai includes nine native Hawaiian species, and four extralimital alien species. The three species of Mecyclothorax Sharp precinctive to Lanai—M. filipes (Sharp), M. mundanus (Sharp), and M. flavipes, new species—are taxonomically revised. Lanai non-native carabid species include Metacolpodes buchanani (Hope) (new island record), Gnathaphanus picipes (MacLeay), G. multipunctatus (MacLeay) (new island record), and Perigona nigriceps (Dejean) (new island record). A key to species of Harpalini introduced to the Hawaiian Islands is provided. Historical records of native Lanai carabid species indicate that they occurred in both summit cloud forest and in riparian corridors of the mesic and dry forest communities. Present-day records indicate restriction of these species solely to the cloud forest zone. The known historical diminution of summit cloud forest establishes a minimum area that has supported persistent populations for several of Lanai's native carabid taxa. Three of the four alien species have been recorded from cloud and mesic forest communities as well as lowland dry forest not known to support native carabid beetles. Currently, native and non-native species exhibit extensive distributional overlap. However, based on fine-scale, field-collection data, this geographic sympatry overstates the extent of ecological interactions between native and non-native taxa. Whereas native species occur in the cloud forest community, non-native species are more broadly distributed in anthropogenically-disturbed situations including the ecologically devastated dry forest community as well as smaller patches of disturbance within the native cloud forest.

The vertical distribution of pronophiline butterflies (Nymphalidae, Satyrinae) along an elevational transect in Monte Zerpa (Cordillera de Mérida, Venezuela) with remarks on their diversity and parapatric distribution

AbstractAim The distribution of neotropical butterflies of the tribe Pronophilini (Lepidoptera, Satyridae) was analysed with the aim of determining (i) the elevational ranges of distribution of each species (ii) the elevational gradient in diversity, and (iii) the existence of parapatric distributions of some closely related species pairs.Location The field study was carried out in the middle and upper section of the valley of the Río Albarregas, a tributary of the Río Chama on the southern slopes of the Serranía de la Culata, in the central part of the Cordillera de Mérida, Venezuela.Methods The material was collected along an elevational transect set on a trail leading from Merida to the Páramo de Los Conejos in the area known as Monte Zerpa. It consisted of a series of 32 collection sites set at every 25 m of altitude and covered an elevation from 2250 m to 3025 m.Results The ranges of Lymanopoda obsoleta, L. albocincta, L. zapatoza, Corades chelonis, C. pannonia, C. medeba, Mygona irmina, Pedaliodes epidipnis, P. japhleta, P. montagna and P. panyasis were all restricted to the lower half of the cloud forest zone and L. diezti, C. pax, P. polla, P. ornata and P. ferratilis were all restricted to the upper part. Two species, Erethris porphyria and Steroma bega, crossed the entire elevational range of the cloud forest zone.The biodiversity, as measured by Shannon’s index, attained a maximum at 2700 m, beyond which it gradually decreased. A parapatric distribution was confirmed for three pairs of closely related species: L. obsoleta and L. diezti, C. chelonis and C. pax and P. montagna and P. ferratilis.Main conclusions The peak in diversity at middle elevations seems to result from the overlapping ranges of species distributed over lower and upper parts of the cloud forest. Correlation of species composition at particular transect sites with elevation showed that increase in elevation was associated with an increase in species composition difference. Post‐mating isolation was suggested as a primary factor responsible for maintaining the parapatric distributions of species occupying the upper and lower zones and preventing their respective distributions from expanding.

Species richness and endemism of plant and bird communities along two gradients of elevation, humidity and land use in the Bolivian Andes

Abstract.We studied the patterns of species richness and range–size rarity (as a measure of endemism) of two plant groups (Pteridophyta, Bromeliaceae) and birds along two gradients of elevation, humidity and human land use in a forested Andean valley. Both transects covered the transition from an arid valley bottom through a cloud forest zone to relictual high‐elevation Polylepis forest, but transects differed in overall precipitation. Plants were surveyed in 88 plots of 400 m2 each, while birds were detected primarily through visual observations and tape recordings over areas of 0.3–1.5 km2. Global range sizes of all species were mapped on 1°‐grids and range‐size rarity was calculated as the mean inverse range size of all species recorded in elevational steps of 200 m. Patterns of species richness and range–size rarity were mainly unrelated between and within study groups. Monotonic increases and decreases and hump‐shaped patterns were observed for species richness as well as range–size rarity. Several of these patterns can be interpreted in the light of the ecological requirements of each taxonomic group, e.g. dependence of fern species richness on humidity or of bird richness on habitat complexity. Species richness of ferns and birds peaked at higher elevations along the less rainy transect, possibly as a result of higher levels of solar radiation and ecosystem productivity. Patterns of species richness and endemism of the study groups are causally unrelated and cannot be used to predict those of other groups at the spatial scale of this study. Human impact was highest in areas of mostly low to intermediate species richness, but was often high in zones of high endemism.

Bird Species Diversity on an Andean Elevational Gradient

This paper analyzes patterns of bird species diversity on an elevational transect of the Cordillera Vilcabamba, Peru. Major changes in climate and vegetation are encompassed by the transect which extended from the Apurimac Valley floor at 500 m to the summit ridge of the range at &gt;3,500 m. Four vegetation zones are easily discerned–lowland rain forest, montane rain forest, cloud forest, and elfin forest. In progressing upwards there is a monotonic trend toward decreasing canopy stature and reduced number of plant strata. The vegetation gradient provided the opportunity to examine the relation between bird species diversity and habitat complexity in an entirely natural setting. The decrease in forest stature with elevation was closely paralleled by decreasing avian syntopy (the total number of bird species cohabiting the forest at a given elevation). Bird species diversity was shown to be highly correlated with foliage height diversity, using either four or five layers in the foliage height diversity calculation (r = .97), and less well correlated using three layers, as defined previously by MacArthur (r = .84). At this superficial level the trend in bird species diversity seemed to be adequately explained as a response to the vegetation gradient. This preliminary conclusion was found to be illusory when the elevational trend in syntopy was reexamined separately for three major trophic subdivisions of the fauna. The number of insectivores decreased 5.2—fold from the bottom to the top of the gradient, frugivores decreased by a factor of 2.3, and nectarivores showed no change. It was now clear that the diversity in each of these trophic categories was responsive to environmental influences other than, or in addition to, the gradient in habitat structure. Additional factors implicated by the available evidence are competitive interactions with other taxa at the same trophic level, changing composition of the resource base as a function of elevation, and declining productivity at high elevations. Analysis of netted bird samples revealed an unexpected diversity maximum in the lower cloud forest zone. The immediate cause of this was a relaxation of the vertical stratification of foraging zones, such that an anomalously large fraction of the species present entered the nets. The excess diversity was found to consist almost entirely of insectivores. Several factors appear to contribute to the ultimate causes of the diversity maximum: greater patchiness of the montane forest due to the rugged topography, a higher density of foliage near the ground, and possibly increased resource productivity. A correlation between diversity and density in the netting results suggested a causal connection mediated via resource levels. The conclusion in that diversity is a complex property that is responsive to many types of influences beyond simply the structure of the habitat.