Tropical Alpine Research Articles

Australasian sky islands act as a diversity pump facilitating peripheral speciation and complex reversal from narrow endemic to widespread ecological supertramp.

The Australasian archipelago is biologically extremely diverse as a result of a highly puzzling geological and biological evolution. Unveiling the underlying mechanisms has never been more attainable as molecular phylogenetic and geological methods improve, and has become a research priority considering increasing human-mediated loss of biodiversity. However, studies of finer scaled evolutionary patterns remain rare particularly for megadiverse Melanesian biota. While oceanic islands have received some attention in the region, likewise insular mountain blocks that serve as species pumps remain understudied, even though Australasia, for example, features some of the most spectacular tropical alpine habitats in the World. Here, we sequenced almost 2 kb of mitochondrial DNA from the widespread diving beetle Rhantus suturalis from across Australasia and the Indomalayan Archipelago, including remote New Guinean highlands. Based on expert taxonomy with a multigene phylogenetic backbone study, and combining molecular phylogenetics, phylogeography, divergence time estimation, and historical demography, we recover comparably low geographic signal, but complex phylogenetic relationships and population structure within R. suturalis. Four narrowly endemic New Guinea highland species are subordinated and two populations (New Guinea, New Zealand) seem to constitute cases of ongoing speciation. We reveal repeated colonization of remote mountain chains where haplotypes out of a core clade of very widespread haplotypes syntopically might occur with well-isolated ones. These results are corroborated by a Pleistocene origin approximately 2.4 Ma ago, followed by a sudden demographic expansion 600,000 years ago that may have been initiated through climatic adaptations. This study is a snapshot of the early stages of lineage diversification by peripatric speciation in Australasia, and supports New Guinea sky islands as cradles of evolution, in line with geological evidence suggesting very recent origin of high altitudes in the region.

Growth models based on radial increment observations for eight pine species in Angola

Growth models for the Central Highlands of Angola were developed in this study for Pinus pseudostrobus Lindl., P. kesiya Royle ex Gordon, P. devoniana Lindl., P. chiapensis (Martinez) Andresen, P. elliottii Engelm., P. greggii Engelm. ex Parl., P. montezumae Lamb. and P. oocarpa Schiede ex Schltdl. for simulating the development of stand characteristics. The model set included dominant height, individual-tree diameter increment, individual-tree height and self-thinning models. The study was based on radial increment observations obtained from increment cores from 16 plots located in the Tchianga research station in the Angolan Highlands. The model set enables the simulation of stand development on an individual tree basis. The developed models are among the first models for these species in Africa. They showed good accuracy when the simulated stand development was compared to the observed development. Therefore, they can be used as a management planning tool in tropical pine plantations in Angola.

Agroecosystem Analysis of the Choke Mountain Watersheds, Ethiopia

Tropical highland regions are experiencing rapid climate change. In these regions the adaptation challenge is complicated by the fact that elevation contrasts and dissected topography produce diverse climatic conditions that are often accompanied by significant ecological and agricultural diversity within a relatively small region. Such is the case for the Choke Mountain watersheds, in the Blue Nile Highlands of Ethiopia. These watersheds extend from tropical alpine environments at over 4000 m elevation to the hot and dry Blue Nile gorge that includes areas below 1000 m elevation, and contain a diversity of slope forms and soil types. This physical diversity and accompanying socio-economic contrasts demand diverse strategies for enhanced climate resilience and adaptation to climate change. To support development of locally appropriate climate resilience strategies across the Blue Nile Highlands, we present here an agroecosystem analysis of Choke Mountain, under the premise that the agroecosystem—the intersection of climatic and physiographic conditions with agricultural practices—is the most appropriate unit for defining adaptation strategies in these primarily subsistence agriculture communities. To this end, we present two approaches to agroecosystem analysis that can be applied to climate resilience studies in the Choke Mountain watersheds and, as appropriate, to other agroecologically diverse regions attempting to design climate adaptation strategies. First, a full agroecoystem analysis was implemented in collaboration with local communities. It identified six distinct agroecosystems that differ systematically in constraints and adaptation potential. This analysis was then paired with an objective landscape classification trained to identify agroecosystems based on climate and physiographic setting alone. It was found that the distribution of Choke Mountain watershed agroecosystems can, to first order, be explained as a function of prevailing climate. This suggests that the conditions that define current agroecosystems are likely to migrate under a changing climate, requiring adaptive management strategies. These agroecosystems show a remarkable degree of differentiation in terms of production orientation and socio-economic characteristics of the farming communities suggesting different options and interventions towards building resilience to climate change.

Avaliação da estabilidade dimensional de espécies de Pinus tropicais

The objective of this research was to evaluate the dimensional stability of tropical pine species and establish correlations between shrinkage, anisotropy, and density. Seven species of tropical pines were utilized: Pinus caribaea var. bahamensis, Pinus caribaea var. caribaea, Pinus caribaea var. hondurensis, Pinus chiapensis, Pinus maximinoi, Pinus oocarpa, and Pinus tecunumanii; Pinus taeda was also used as reference. The samples were from 17 and 18-year-old experimental plantings located in the municipalities of Ventania, State of Parana and Itarare, State of Sao Paulo. Dimensional stability was evaluated according to the COPANT 462 (1972c) norm. The results indicated that Pinus chiapensis is an unstable species (Ac > 2.6), and that other tropical pine species and Pinus taeda presented low average stability (2.1 to 2.5). There were no strong correlations between the properties proposed probably due to the presence of resin and extractives, which can alter density and inhibit contraction.

Reconstruction of fire history in Mexican tropical pines using tree rings

A dendropyrochronological study was conducted in pine-dominated forest in the Sierra de Manantlán Biosphere Reserve located in the Sierra Madre del Sur mountain range in Mexico. Tropical pines present several difficulties for tree-ring research including missing, false and diffuse rings. This paper discusses the methods that were used to analyze tree rings in order to reconstruct fire history based on the dating of fire scars sampled from tropical pines.

Plant–plant interactions in tropical alpine environments

Plant–plant interactions are increasingly recognized as a key driver of community organization and ecosystem processes in alpine environments. However, patterns and mechanisms of plant–plant interactions remain largely uncharacterized in tropical alpine ecosystems (TAE) which represent as much as 10% of the total surface area of alpine ecosystems worldwide. In this paper, we review (1) the ecological and environmental features that are specific to TAE in comparison with other alpine ecosystems, (2) the existing literature on plant–plant interactions in TAE, and (3) whether patterns and mechanisms of plant–plant interactions established in extratropical alpine zones can be extended to TAE. TAE are located predominantly in South America, East Africa, and South-East Asia where they show a unique combination of environmental characteristics, such as absence of persisting snow cover, high frequency of diurnal freeze–thaw cycles and needle-ice activity, and a decrease in precipitation with increasing altitude. These environmental characteristics result in the presence of giant growth forms with a great architectural diversity. These biotic and abiotic characteristics influence the outcome of plant–plant interactions by imposing other types of environmental constraints than those found in extratropical alpine environments, and by potentially generating distinctive patterns of niche differentiation/complementarity between species and populations. To generalize the conceptual framework of plant–plant interactions in alpine environments, we advocate that TAE should be investigated more thoroughly by applying designs, methods and hypotheses that are used currently in temperate areas and by conducting studies along large latitudinal gradients that include tropical regions.

Growth and yield of nine pine species in Angola

A species introduction experiment including several tropical pines and eucalypts was established in 1966/1967 in the Tchianga research station in Angolan Highlands. Despite 27 years of political conflict (1975–2002) and lack of management, the research experiment has remained relatively well conserved. We measured the best conserved plots that were 41 years old in 2007 to obtain information on the growth of different pine species. We calculated stand characteristics including basal area, dominant height, mean diameter, and stand volume for Pinus patula Schiede ex Schiltdl. Et Cham., Pinus pseudostrobus Lindl., Pinus kesiya Royle ex Gordon, Pinus devoniana Lindl., Pinus chiapensis (Martinez) Andresen, Pinus elliottii Engelm., Pinus greggii Engelm. Ex Parl., Pinus montezumae Lamb. and Pinus oocarpa Schiede ex Schltdl. The growing stock volume at 41 years was the highest in P. pseudostrobus, 1,325 m3·ha−1, followed by P. kesiya with 1,200 m3·ha−1. The widely planted P. patula had a growing stock volume of 892 m3·ha−1. P. oocarpa and P. pseudostrobus had the highest stand basal area, over 80 m2·ha−1. Using increment core analyses we studied the temporal development of stand characteristics. Analysis of the mean annual increment (MAI) showed that rotation lengths of 20–30 years would maximize wood production. With these rotation lengths, the MAI of P. pseudostrobus would be 35 m3·ha−1. Other productive species were P. kesiya, P. oocarpa and P. chiapensis. P. patula had a maximum MAI of 20 m3·ha−1. P. greggii had the lowest mean annual volume production, only about 13 m3·ha−1.

COMPARISON OF THE FROST RESISTANCE OF BARLEY (HORDEUM VULGARE L.) LANDRACES OF UPLAND ETHIOPIA USING ELECTROLYTE-LEAKAGE AND CHLOROPHYLL FLUORESCENCE

Barley is the most important crop in the highlands of Ethiopia at altitudes above 2600 m, where its productivity is limited by cold stress. We studied 25 Ethiopian barley landraces in order to identify cold tolerant types and to describe characteristics and acclimation potentials of these landraces to cold stress. Barley plants were grown from seeds in a temperature-controlled greenhouse (20/15°C) for six weeks prior to investigation. Membrane leakage, assayed by electric conductivity, was investigated before and after the plants had been subjected to freeze-thaw cycles at different sub-freezing temperatures down to -10°C. The critical temperature (CT 50 ), at which the frost-induced damage was 50% of the maximal injury, ranged for most landraces between -5.6 and -8.6°C. Maximum difference in sensitivity to frost among the various races was observed at -5.0°C. Neither the altitude of the habitat, from where the seeds had been collected, nor the maturation time of the landraces were correlated with the degree of frost tolerance of the landraces. The influence of the growth conditions on the capability of frost hardening of cold-tolerant and sensitive landraces was investigated using chlorophyll a fluorescence. Barley seedlings were grown under three different regimes: In a temperature controlled greenhouse (20/15°C, day/night), under simulated tropical alpine conditions (tropical-alpine greenhouse, 16/0°C, 12 h light period), and in a phytotrone at constant 2°C day and night. Effective quantum yield of photosynthesis was measured at several temperatures in the course of freeze-thaw cycles (+20 to -10 to +20°C). Whereas growth and the effective photosynthetic quantum yield of the plants in the phytotrone were low, cold hardening was effective as shown by the recovery of the photosynthetic quantum yield upon re-warming of the frozen plants. Effective quantum yield of the plants grown in the tropical alpine greenhouse was as high as with the control plants, but only 2 of 6 investigated landraces showed immediate recovery of the photosynthetic quantum yield after freezing. Landraces which showed the highest cold tolerance were found to acclimatize best.

Soil water repellency and pH soil change under tropical pine plantations compared with native tropical forest

Summary In temperate climates, soil water repellency (SWR) has been documented to develop with land-use change from native forest to pine plantations. In the tropics a sparse evidence base has been documented for the observation of SWR, but no investigation has been conducted to determine the consequences of changing land-use from native forest to pine plantations with regard to SWR. In our research we broaden the evidence base for tropical SWR by comparing the SWR behavior of seven tropical pine plantations in Trinidad with co-located native forest. We found that SWR occurred under both pine and native forest, but was more persistent and less heterogeneous under pine. The SWR was water content dependent with a threshold ∼0.2 m3 m−3, it showed a linear dependence with litter depth, and it was also found to be higher in more acidic soils. The forest floor pH, contrary to convention for temperate climates, was observed to increase under some pine plantations, as compared with native tropical forest. This only occurred in the very acidic tropical soils (pH

Modelos volumétricos para Pinus tropicais, em povoamento homogêneo, no Estado de Rondônia

This study aimed to adjust volumetric models to tropical pines, in pure stand, in the municipality of Vilhena, Rondonia State. The data came from 20 felled trees of Pinus caribaea var. hondurensis and 10 Pinus tecunumanii trees with discs collected at fixed positions of 0.20 m, 0.70 m, 1.30 m and in distances of one meter along the stem, for later counting and measurement of the growth rings at ages from 4 to 12 years. Eight volumetric models were adjusted. The selection criteria used were: standard error of estimate, adjusted coefficient of determination, F test, significance of regression coefficients, mean deviation, standard deviation of the differences, sum of square of the relative residual, percentage of the residuals and graphic analysis of residuals. The models from Naslund modified and from Spurr presented, respectively, best fit to estimate the volume for Pinus caribaea var. hondurensis submitted to the first thinning and for Pinus tecunumanii , with ages between 4 and 12 years, in Vilhena, Rondonia State, Brazil. doi: 10.4336/2011.pfb.31.67.173

Unexpected mechanisms sustain the stress gradient hypothesis in a tropical alpine environment

AbstractQuestionsDoes facilitation among plants increase with elevation in a humid tropical alpine system in which climatic and ecological conditions differ from other alpine environments? What mechanisms are involved in the interactions?LocationVolcano Antisana, Eastern Cordillera of the Ecuadorian Andes (00°28′S, 78°09′W).MethodsWe selected the cushion‐forming Azorella aretioides as a potential nurse plant along an altitudinal gradient (4400, 4550 and 4700 m) in the high tropical Andes. We quantified its effects on other plants at species and community levels by comparing the product vegetation cover × number of individuals of every vascular species found inside and outside 265 cushions, using the relative interaction index. We inferred potential mechanisms behind the interactions through analysis of microclimate, soil moisture and soil nutrient measurements inside and outside cushions.ResultsPredictions of the stress gradient hypothesis (SGH) were corroborated at community level, with transition from competitive or neutral effects of A. aretioides at 4400 and 4550 m to facilitative effects at 4700 m. Strong species‐specific effects were observed along the altitudinal gradient, with a substantial effect of local habitat disturbance on the outcome of plant–plant interactions. Surprisingly, cushions lowered air and soil temperatures and air humidity, which reduced at higher elevations. Facilitation appeared to be caused by higher soil moisture and nutrient content beneath cushions.ConclusionsOur data extend the framework of the SGH by corroborating it for the first time in a tropical alpine system. However, the mechanisms underlying plant–plant interactions differed from those generally reported from alpine environments, with facilitation varying according to resource‐mediated stress (nutrients). It remains to be tested whether this is specific to tropical alpine systems.

Mites of the family Phytoseiidae Berlese from Kenya (Acari: Mesostigmata)

We surveyed the phytoseiid mites in four different geographical zones of Kenya: Zone I, upper highland and tropical alpine (2400–4400m); Zone II, lower highland (1800–2400 m); Zone III, midland (800–1800 m); Zone IV, tropical, hot and humid (0–800 m). A total of 107 species was found. In the subfamily Amblyseiinae there were 14 species in the genus Neoseiulus Hughes, one in Asperoseius Chant, one in Paraphytoseius Swirski & Schechter, five in Typhlodromips De Leon, five in Transeius Chant & McMurtry, one in Graminaseius Chant & McMurtry, 11 in Amblyseius Berlese, one in Arrenoseius Wainstein, two in Typhlodromalus Muma, seven in Ueckermannseius Chant & McMurtry, one in Amblydromalus Chant & McMurtry, 20 in Euseius Wainstein, one in Iphiseius Berlese, one in Phytoseiulus Evans and one in Gynaeseius Ehara & Imano. In the subfamily Phytoseiinae Berlese, there were four species in the genus Phytoseius Ribaga. In the subfamily Typhlodrominae Wainstein, there were four species in the genus Kuzinellus Wainstein, and 27 in Typhlodromus Scheuten.

Initiation of somatic embryogenesis from immature zygotic embryos of Oocarpa pine (Pinus oocarpa Schiede ex Schlectendal)

The focus of the current project was to establish somatic embryogenesis protocols for the tropical pine species Pinus oocarpa using immature zygotic embryos (ZEs) as explants. Somatic embryogenesis is best supported by mimicking natural seed-embryo developmental conditions, through a tissue culture medium formulation based on the mineral content of the seed nutritive tissue [megagametophyte (MG)]. A novel culture medium (P. oocarpa medium, PO) was tested in combination with different plant growth regulator (PGR) concentrations and compared with standard Pinus taeda media for the initiation of somatic embryogenesis from immature ZEs of P. oocarpa. Immature MGs containing immature ZEs of two mother trees were used with 12 and 8% extrusion rates for mother tree genotypes 3 and 5, respectively. In both mother trees the percentage capture was 2%. Multiplication of two captured cell lines (T5C2S01 and T5C1S12) was improved by lowering the concentrations of PGRs to 2.5 µM each 2,4-dichlorophenoxyacetic acid and abscisic acid (ABA) plus 1.0 µM each 6-benzylaminopurine and kinetin. Mature somatic embryos formed on 40 µM ABA, 6% (w/v) maltose, 12% (w/v) PEG 8000 and 0.6% (w/v) Phytagel. While PO medium appeared suboptimal for somatic embryo induction, it did exhibit potential for enhanced culture proliferation and subsequent improved maturation with cell line T5C2S01, where microscopic analysis revealed better embryo morphology on PO medium than on 1250 medium. However, this enhancement was not observed with cell line T5C1S12. Germination was preceded by partial desiccation for a period of 2-3 weeks before transferring the embryos to germination medium. Germination was observed after 7 days under low light, and apical primordia slowly expanded after transfer to ex vitro conditions. To our knowledge, this is the first report on the production of somatic seedlings in P. oocarpa.

Impacts of Fire on SouthEast Asia Tropical Forests Biodiversity: A Review

Forest fires have affected millions of hectares of tropical forests and other vegetation types annually. Over the past decades, the increase occurrence of fires has caused degradation of the tropical forest ecosystem and caused impacts to the environment. The objective of this paper was to review the impacts of the fires to the tropical forest ecosystem in Southeast Asia. Forest fires affect vegetation by suppressing certain species and promoting other species causing changes in vegetation structure and altering successional pattern. It also rejuvenate tropical pines. Fire causes reduction in soil macroorganism diversity and change soil bacterial composition. Knowledge of fire effects on biodiversity may benefit forest managers. Fire adaptive vegetation can be used as important species in rehabilitation of burned area.

The evolution and biogeography of alpine species in Ranunculus (Ranunculaceae): A global comparison

AbstractThe origin and evolution of alpine floras potentially can be shaped by immigration via long‐distance dispersal or migration over mountain chains. Alternatively, origins of alpine species may be referred to regional speciation via origins from lowland ancestors and adaptation to high altitudes. Moreover, evolutionary histories of alpine species have also been influenced by Quaternary glaciations. Range fluctuations due to climatic oscillations have caused vicariant speciation and secondary con‐ tact hybridization. However, comparative phylogenetic studies on alpine floras from mountain systems of different continents are scarce. Here we review the phylogenetic relationships of alpine species of Ranunculus, an almost cosmopolitan genus with alpine representatives in all major mountain systems of the world. Based on molecular phylogenetic analysis of 245 alpine and lowland species (based on a combined dataset of ITS, matK, trnK and psbJ‐petA sequences), we try to elucidate origins of alpine buttercups. Results suggest that most major mountain systems (European Alpine System, Irano‐Turanian mountains, Himalayas, Central Asian mountains, African mountains, and Andes) have been colonized multiple times independently; only the North American alpine species fall all into one clade. In the European and Irano‐Turanian mountains, recruitment of alpine species from lower altitudes of the same area, and migration within the Tethyan area might have played a major role. The alpine species of the Himalayas, the Central Asian mountains, the North American alpine species and the Arctic species fall into another, distinct clade, which may suggest a northern migration route. The North American alpine clade comprises many lowland species and might have diversified via adaptive radiation. In contrast, the Himalayan species have no lowland source flora and might have originated from immigrants of the Central Asian mountains. Tropical alpine Ranunculi in the mountains of Eastern Africa and in Taiwan have originated after long‐distance dispersal from other continents. The origin of the New Zealand alpines could have been referred to long‐distance dispersal, probably following southern migration routes via the Antarctic and South America. The Andes have been colonized multiple times by related genera of Ranunculus. We conclude that autochthonous origins and regional diversification of buttercups play a major role in northern hemispheric mountain systems, where alpine species could have evolved from rich lowland source floras. In subtropical to tropical mountain systems, and in the Southern Hemisphere, alpine species have been rather recruited via immigration, including long‐distance dispersal from other continents. A high adaptive potential of Ranunculus to alpine habitats might have helped to evolve alpine species all over the world.

Comparison of the Growth of SixEucalyptusSpecies in Angola

Eucalyptusspecies have been planted in Angola since the early twentieth century. The species introduction experiment of Tchianga, in the Angolan Highlands, was established in 1966/1967. The experiment included several tropical pines and eucalypts. The plots were 43 years old when measured in 2009. Species includedEucalyptus salignaSm.,E. camaldulensisDehnh.,E. macarthuriiH. Deane & Maiden,E. resiniferaSm.,E. siderophloiaBenth., andE. grandisHill ex. Maiden.E. salignahad the highest stand volume at 43 years (1427 m3 ha−1), followed byE. grandis(1006 m3 ha−1).E. macarthuriiandE. camaldulensishad the lowest stand volume (423 and 511 m3 ha−1, resp.). Using X-ray analyses of increment cores, it was possible to study the temporal development of the stand characteristics. An analysis of the mean annual increment showed that the optimal rotation length for most of the studied eucalypts is around 22 years with the exception ofE. resinifera, for which 12–15 years is the best.E. salignahad the highest maximum mean annual increment (MMAI) of 37 m3 ha−1attained at 22 years of age.E. grandisreached its MMAI of 25 m3 ha−1at 28 years. The results suggest thatE. salignais the most recommendedEucalyptusspecies for new plantations in Angola.

Genetic factors associated with population size may increase extinction risks and decrease colonization potential in a keystone tropical pine.

Pioneer species are essential for forest regeneration and ecosystem resilience. Pinus chiapensis is an endangered pioneer key species for tropical montane cloud forest regeneration in Mesoamerica. Human activities have severely reduced some P. chiapensis populations, which exhibited a small or null colonization potential suggesting the involvement of genetic factors associated with small populations. We explored the relationships between (i) population genetic diversity (allozymes) and population size, including sampling size effects, (ii) fitness estimates associated with colonization potential (seed viability and seedling performance) in a common environment and population size, and (iii) fitness estimates and observed heterozygosity in populations with sizes spanning five orders of magnitude. All the estimates of genetic diversity and fitness increased significantly with population size. Low fitness was detected in progenies of small populations of disturbed and undisturbed habitats. Progenies with the lowest observed heterozygosity displayed the lowest fitness estimates, which, in turn, increased with heterozygosity, but seed viability peaked at intermediate heterozygosity values suggesting inbreeding and outbreeding depression. Inbreeding depression appears to be the most immediate genetic factor in population decline. Conservation efforts should try to maintain large and genetically diverse populations, enhance gene flow by restoring connectivity between adjacent populations, and avoid genetically distant individuals.

Models as multiple working hypotheses: hydrological simulation of tropical alpine wetlands

Tropical alpine grasslands, locally known as paramos, are the water towers of the northern Andes. They are an essential water source for drinking water, irrigation schemes and hydropower plants. But despite their high socio-economic relevance, their hydrological processes are very poorly understood. Since environmental change, ranging from small scale land-use changes to global climate change, is expected to have a strong impact on the hydrological behaviour, a better understanding and hydrological prediction are urgently needed. In this paper, we apply a set of nine hydrological models of different complexity to a small, well monitored upland catchment in the Ecuadorian Andes. The models represent different hypotheses on the hydrological functioning of the paramo ecosystem at catchment scale. Interpretation of the results of the model prediction and uncertainty analysis of the model parameters reveals important insights in the evapotranspiration, surface runoff generation and base flow in the paramo. However, problems with boundary conditions, particularly spatial variability of precipitation, pose serious constraints on the differentiation between model representations.

Tropical and Temperate: Evolutionary History of Páramo Flora

Biogeography of the tropical alpine flora of South and Central America, the paramo flora, has been studied by dividing genera into tropical, temperate, and cosmopolitan chorological flora elements. Published molecular phylogenies of paramo genera are reviewed to summarize knowledge about evolutionary history of the paramo flora and to assess congruence between chorological and phylogenetic approaches. Molecular phylogenies suggest that both the tropical and temperate regions have been important source areas for evolution of the paramo flora. Conclusions derived from chorological patterns regarding origin of genera in paramo are mostly supported by phylogenetic data. Nevertheless, in Chuquiraga, Halenia, Huperzia, and Perezia the chorological scenario is rejected, and in Chusquea-Neurolepis, Elaphoglossum, Gunnera, Halenia, Jamesonia-Eriosorus, and Lasiocephalus independent colonization events from one or several source areas are suggested. Tropical and temperate genera contributed equally to modern species richness of the paramo flora. Among temperate genera, the northern hemisphere genera gave rise to more species in paramo than did genera from the southern hemisphere. So far, no unequivocal evidence has been provided for migration of paramo genera to the temperate zones.

Soil seed bank and the effect of needle litter layer on seedling emergence in a tropical pine plantation

The soil seed bank is the basis for community establishment and permanence and plays a primary role in natural restoration of degraded or altered ecosystems. As part of a restoration project, this study aimed to quantify the soil seed bank and to evaluate the effect of the needle litter layer on seedling emergence. Soil samples from a pine plantation were collected at random in the field and set to germinate in a greenhouse. Half of them were covered by a 6cm layer of dead pine needles simulating field conditions. In the field, 20 x 20cm plots were established, half were left intact and half were cleaned from the litter needles. All four treatments had 15 replicates and seedling emergence was recorded during six months. Soil seed bank density was 1 222/m2 from 17 morphotypes. In the field, the number of morphotypes and seedlings was only 9% and 6% respectively, of those emerged in the greenhouse, possibly due to watering and lack of predation in the latter. In both cases, herbs and graminoids were the dominant emerging seedlings, making up to 70-90% of the total. The needle layer didn't prevent seeds from reaching the soil but strongly reduced (> 50%) seedling emergence, although high variability within treatments resulted in no statistically significant differences. These results show that the needle layer hinders germination and/or emergence of seedlings from the seed bank. Its removal may be a recommended technique to accelerate natural restoration in pine plantations.