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A total of 389 rodent captures in five unequally disturbed habitats in a Costa Rican montane cloud forest corresponded to 185 individuals (seven species, two faroilies). Species richness was similar for al l habitats, averaging 4-5 species/habitat. Population density and capture frequency were higher i n moderately disturbed habitats; Peromyscus mexicanus and Scotinomys xerampelinus were four to five times more cornmon than other murids. These species represented 79.4 % of all captures and 73.5 % of all captured individuals. Heteromyid species were rarely trapped. The importance of disturbance-mediated within-habitat microenvironmental heterogeneity fOI terrestrial small-sized rodent populations is stressed Se estudió la distribución y diversidad de roedores terrestres en cinco hábitats perturbados en un área de bosque montano nuboso en Costa Rica. Un total de 3 89 capturas correspondió a 185 individuos (siete especies en 2 Ca- , milias). La riqueza de especies resultó muy similar para todos los hábitats,c on 4-5 especieslhábitat. La densidad de población y la frecuencia de captura fueron más altas en hábitats con niveles intennedios de perturbación; Peromyscus mexicanus y Scotinomys xerampelinus fueron cuatro a cinco veces más comunes que otras especies de Muridae. Estas representaron el 79.4 % de todas las capturas y el 73.5 % de todos los individuos. Se capturo pocos Heteromyidae.

Se muestreó briófitas epífitas sobre tallos pequeños de Quercus copeyensis Müll. en un bosque montano nuboso maduro (Talamanca, Costa Rica). Se muestreó a 0.8-1.8 m en cinco tallos (d.a.p. 1.8 -2.8 cm), hallándose 22 especies de musgos y 22 de hepáticas. La biomasa de briófitas ("briomasa") se correlacionó con la frecuencia, contribuyendo los musgos 54-99%. Un 14% de las especies contribuyó casi el 90% de la briomasa, sobresaliendo Pilotrichella flexilis (Hedw.) Ángstr., Rigodium sp. 1, Porotrichodendron superbum (Taylor) Broth., Prionodon densus (Hedw.) Müll. HaI., Neckera chilensis Schimp. ex Mont. y Plagiochila guilleminiana Nees & Mont. Estas especies podrían jugar un papel importante en la regulación del flujo de agua.

In view of the continued decline in tropical forest cover around the globe, forest restoration has become a key tool in tropical rainforest conservation. One of the main – and least expensive – restoration strategies is natural forest regeneration. By aiding forest seed influx both into disturbed and undisturbed habitats, frugivorous birds facilitate forest regeneration. This study focuses on the tolerance of a frugivorous bird community to anthropogenic habitat disturbance within the broader context of natural forest regeneration with conservation purposes. It was carried out in the tropical cloud forest of Costa Rica’s Talamanca Mountains. Bird community response and tolerance to habitat disturbance was assessed by comparing bird presence and densities along a disturbance gradient, ranging from open pastures to closed mature forests. Birds were censused along nine transects applying the variable width line transect procedure. Forty relevant frugivorous bird species were observed during 102 h of survey time. Densities were calculated for 33 species; nine species responded negatively to increasing level of disturbance and nine others positively. Results indicate that large frugivores are generally moderately tolerant to intermediate, but intolerant to severe habitat disturbance, and that tolerance is often higher for medium and small frugivores. It appears that moderately disturbed habitats in tropical cloud forests are highly suitable for restoration through natural regeneration aided by frugivorous birds. Due to a lack of large forest seed dispersers, severely disturbed habitats appear less suitable.

Nutrient fluxes in stemflow and throughfall were compared among three successional stages of an upper montane rain forest and related to structural characteristics of the stands (stem density, leaf area, epiphyte abundance). An old-growth forest stand, an early successional (10-y-old) forest stand and a mid-successional (40-y-old) forest stand were studied in the Cordillera Talamanca, Costa Rica. All three sites were dominated by Quercus copeyensis with a variable admixture of other tree species. There was no difference in the average stand leaf area index between the old-growth forest and the early successional forest. A significantly higher leaf area was found in the mid-successional forest. There were large differences in litterfall from non-vascular epiphytes (mosses, liverworts and lichens) which reflected differences in epiphyte abundance, with highest values in the old-growth forest. Total nutrient transfer via stemflow and throughfall from the canopy to the soil showed only minor differences among the stands. The stands differed widely in the ratio of nutrient transport via stemflow to the total nutrient flux by water below the canopy. The K flux with stemflow accounted for 5% of the total in the old-growth forest but it accounted for 17% (early successional forest) and 26% (mid-successional forest) in the secondary forests. It is concluded that differences in canopy structure and epiphyte abundance in old-growth and secondary forests resulted in large differences in the partitioning of nutrient transport into stemflow and throughfall components although total nutrient transfers via water reaching the soil were similar.

Upper montane oak forests in the Cordillera de Talamanca show a high diversity of bryophyte species and great diversification of microhabitats. A complete bryophyte inventory of six hectare of forest yielded 206 species: 100 mosses, 105 hepatics, and one hornwort. Based on similarities in species composition the forest microhabitats cluster into three main groups: 1) forest floor habitats (including tree base), 2) phyllosphere, and 3) other epiphytic habitats. The contribution of forest floor habitats to total bryophyte species richness is much higher than in forests of lower elevational belts. Distribution of species and life forms in different microhabitats reflect the vertical variation of humidity and light regimes. At the same time they show the impact of the pronounced dry season and the structural characters (tree height, stratification, number of host tree species) of these oak forests on epiphytic bryophytes compared to more humid forests and upper montane forests of lower stature.

Current knowledge of effects of climate change on biodiversity is briefly reviewed, and results are presented of a survey of biological research groups in the Netherlands, aimed at identifying key research issues in this field. In many areas of the world, biodiversity is being reduced by humankind through changes in land cover and use, pollution, invasions of exotic species and possibly climate change. Assessing the impact of climate change on biodiversity is difficult, because changes occur slowly and effects of climate change interact with other stress factors already imposed on the environment. Research issues identified by Dutch scientists can be grouped into: (i) spatial and temporal distributions of taxa; (ii) migration and dispersal potentials of taxa; (iii) genetic diversity and viability of (meta) populations of species; (iv) physiological tolerance of species; (v) disturbance of functional interactions between species; and (vi) ecosystem processes. Additional research should be done on direct effects of greenhouse gases, and on interactions between effects of climate change and habitat fragmentation. There are still many gaps in our knowledge of effects of climate change on biodiversity. An interdisciplinary research programme could possibly focus only on one or few of the identified research issues, and should generate input data for predictive models based on climate change scenarios.

Changes in terrestrial vascular plant diversity along a successional gradient were studied in a Costa Rican upper montane Quercus forest. In 1991 and 1992 species presence and cover were recorded in 12 successional 0.1 ha forest plots. A total of 176 species in 122 genera and 75 families were found. Asteraceae was the most speciose family. With the help of TWINSPAN three successional phases were classified: (i) Early Secondary Forest (ESF, 145 spp.), (ii) Late Secondary Forest (LSF, 130 spp.) and (iii) Primary Forest (PF, 96 spp.). Detrended Correspondence Analysis (DCA) species ordination using DECORANA illustrates that different ecological species groups can be distinguished along the time sequence. Alpha diversity (Shannon-Wiener index, among others) in ESF and LSF was significantly greater than in PF. This is probably explained by downslope migration of numerous sub(alpine) species to cleared and recently abandoned montane sites. Beta diversity applying Sorensen's similarity coefficients declined during succession. Using linear regression, the minimum time required for floristic recovery following disturbance and abandonment was calculated at 65.9 years. A comparison with other studies shows that secondary forests in upper montane Costa Rica can be as diverse as in neotropical lowlands.

During the last century, substantial parts of old-growth forest (OGF) in the Cordillera de Talamanca, Costa Rica, were clear-cut. However, in many areas, secondary forests (SEC) have become established on abandoned agricultural land. Based on new and published data, this chapter compares upper montane OGF and SEC stands on the Pacific slope of the Cordillera in terms of differences in plant diversity, stand structure, biogeochemical cycles, and forest use. Furthermore, an attempt is made to assess the potential for, and timescale of, recovery of various forest characteristics during regrowth. Oak species ( Quercus spp.) are present in all successional stages. Alpha-diversity of terrestrial, vascular plant species is significantly higher in early- and mid-successional stands than in OGF, probably due to downslope migration of sub-alpine and alpine terrestrial herb species to cleared and abandoned sites. Beta-diversity is seen to decline during succession. Values of stand leaf area in early-successional stages were similar to those observed in OGF, but biomass of epiphytes was significantly lower in SEC (160–520 kg ha −1 ) compared to OGF (3400 kg ha −1 ). Rainfall interception was much higher in OGF (25% of gross precipitation) than in SEC (9% and 15% for early- and mid-successional SEC, respectively), despite similar leaf area for OGF and SEC. A combined experimental and modeling study suggested that the epiphyte layer contributed little (6%) to overall rainfall interception in the OGF and could, therefore, not explain the observed hydrological differences between the various successional stages. Instead, these are thought rather to reflect differences in canopy roughness. […]

The altitudinal distribution of vascular plant species and communities has been intensively studied in neotropical montane forests (e.g., Cleef et al. 1984; Kappelle and Zamora 1995; Kappelle et al. 1995a; Lieberman et al. 1996; Chap. 4). However, still little is known about the population ecology of individual species and their responses to environmental factors along elevational gradients. Population structure studies of single species in relation to environmental factors have proven to be powerful in explaining ecological behavior in temperate regions (Wassen et al. 1990; Oostermeijer et al. 1994; Hegland et al. 2001), but such data are relatively scarce for tropical regions. So far, the main emphasis in the tropics has been on population dynamics of lowland rainforest canopy trees (e.g., Arriaga et al. 1988; Martinez-Ramos et al. 1988; Alvarez-Buylla and Martinez-Ramos 1992; Olmsted and AlvarezBuylla 1995), rather than on non-canopy species (Oyama 1990). Tropical studies directly relating population structure to environmental variables have not received much attention from scientists (Witkowski and Liston 1997; Hicks and Mauchamp 2000). To date, population dynamics of highland forest plant species are even rarer (but see Wesselingh et al. 1999, and Chaps. 14 and 18). In order to gain further insight into environmental factors (e.g., temperature, light availability) that may determine the population structure of vascular plant species on tropical mountains, we studied the relative proportions of different life stages of two tropical montane understory species in response to environmental changes occurring along an altitudinal gradient in Costa Rican montane oak forests.

Frugivorous birds play an important role in seed dispersal (Levey et al. 2005), especially in the tropics (Stiles 1985; Guevara et al. 1986; Corlett 1998). Their role in lowland rainforest recovery on abandoned pastures has been extensively documented (Debussche et al. 1982; McDonnell and Stiles 1983; Guevara et al. 1986; Gorchov et al. 1993; Guevara and Laborde 1993; MartinezRamos and Soto-Castro 1993; McClanahan and Wolfe 1993; Robinson and Handel 1993; Galindo-Gonzalez et al. 2000). Numerous bird species thrive well in secondary growth tropical lowland habitats where croplands, shrublands and pastures alternate (Estrada et al. 1993; Gorchov et al. 1993). In such patchy landscapes, isolated remnant forest trees may offer protection to birds, and serve as stepping stones during their journey in search for closed old-growth forest fragments (Guevara et al. 1986; McClanahan and Wolfe 1987). In this way, isolated bird-dispersed forest trees may act as ‘seed-trapping’ centers of succession following lowland rainforest clearing (Debussche et al. 1982; McDonnell and Stiles 1983; Guevara et al. 1986; Guevara and Laborde 1993). To date, however, little is known on the ecology of frugivorous birds in human-influenced tropical montane forest landscapes. Neither do we know much about their role in the recovery of cleared upland forest (Stiles 1985; Kappelle et al. 1994; Poulsen 1994; Long 1995; Shiels and Walker 2003). Even less is known on the interaction between frugivorous bird species and specific ornithochorous tree species in relation to montane forest succession (Chap. 25). To further gain insight into these processes, we studied the role of frugivorous, seed-dispersing birds in montane oak forest recovery following clearing, burning and grazing in Costa Rica’s Talamanca highlands.

The preceding chapters of this book discuss scientific research results on natural and managed oak forests growing in the highlands of the American Tropics. Chapter authors highlight evolutionary, ecological and socioeconomic aspects of specific oak forests and identify existing gaps in our understanding. Their work and studies published elsewhere forms the basis for this chapter’s overview of the current state of knowledge on ecological patterns and processes which determine the structure and functioning of these magnificent forests. The increasingly important human use and much needed conservation of these biodiverse and threatened habitats are dealt with as well. Cross-cutting trends and issues are discussed and conclusions drawn. Neotropical montane oak forests are a special type of tropical montane forests (Kappelle 2004), in which tall oak trees (Quercus) dominate a 30to 60-m-high forest canopy, often in pure stands or mixed with pines (Pinus) or other predominant trees. Though Neotropical oak forest history, structure, species diversity, species interactions, ecosystem functioning, post-disturbance recovery, and human use may vary considerably over short geographical ranges, regional trends are now becoming evident. Research presented in this book clearly illustrates these large-scale trends. The following sections in this chapter synthesize our knowledge for each of these trends and themes.

Results are generally consistent with those presented by Lanzewizki (1991), and Johnson and Vaughan (1993), who recorded five myomorph species of which P. mexicanus (P. nudipes, in their study) and S. xerampelinus were most common. Our study revealed seven species of terrestrial myomorph rodents, including O. albigularis and H. oresterus as new local records. Both datasets indicate the importance of within-habitat micro-environmental heterogeneity for rodent populations in these forests.

Part I Introduction to Neotropical montane oak forests 1. Global and Neotropical distribution and diversity of oak (genus Quercus) and oak forests Kevin C. Nixon Part II Paleo-ecology and biogeography 2. Immigration of oak into northern South America: a paleo-ecological document Henry Hooghiemstra 3. Effects of the Younger Dryas cooling event on Late Quaternary montane oak forest in Costa Rica Gerald A. Islebe and Henry Hooghiemstra 4. Altitudinal zonation of montane oak forests along climate and soil gradients in Costa Rica Maarten Kappelle and Jan-Gerrit van Uffelen 5. Saprotrophic and ectomycorrhizal macrofungi of Costa Rican oak forests Gregory M. Mueller, Roy E. Halling, Julieta Carranza, Milagro Mata, and John P. Schmit 6. Diversity and biogeography of lichens in neotropical montane oak forests Harrie J. M. Sipman 7. Epiphytic communities of bryophytes and macrolichens in a Costa Rican montane oak forest Ingo Holz Part III Stand structure and composition 8. Composition and structure of humid montane oak forests at different sites in central and eastern Mexico Isolda Luna Vega, Othon Alcantara Ayala, Carlos Alberto Ruiz-Jimenez, and Raul Contreras-Medina 9. Oak forests of the hyper-humid region of La Chinantla, northern Oaxaca Range, Mexico Jorge A. Meave, Armando Rincon and Marco A. Romero-Romero 10. Structure and composition of Costa Rican montane oak forests Maarten Kappelle 11. Structure and composition of Colombian montane oak forests Maria T. Pulido, Jaime Cavelier, and Sandra P. Cortes Part IV Population dynamics 12. Regeneration and population dynamics of Quercus rugosa at the Ajusco Volcano, Mexico Consuelo Bonfil 13. Ecology of acorn dispersalby small mammals in montane forests of Chiapas, Mexico Fabiola Lopez Barrera and Robert H. Manson 14. Establishment, survival and growth of tree seedlings under successional montane oak forests in Chiapas, Mexico Neptali Ramirez-Marcial, Angelica Camacho-Cruz, Mario Gonzalez-Espinosa, and Fabiola Lopez-Barrera 15. Population structures of two understory plant species along an altitudinal gradient in Costa Rican montane oak forests Thomas V.M. Groot, Marc Stift, J. Gerard B. Oostermeijer, Antoine M. Cleef, and Maarten Kappelle Part V Ecosystem disturbance and regeneration 16. Secondary Succession in montane pine-oak forests of Chiapas, Mexico Mario Gonzalez-Espinosa, Neptali Ramirez-Marcial, and Luis Galindo-Jaimes 17. Changes in diversity and structure along a successional gradient in a Costa Rican montane oak forest Maarten Kappelle 18. Regeneration dynamics in a Costa Rican montane oak forest after reduced-impact logging Manuel R. Guariguata, Grace P. Saenz, and Lucio Pedroni 19. Growth and physiological responses of oak, pine and shrub seedlings to edge gradients in a fragmented Mexican montane oak forest Heidi Asbjornsen, K.A. Vogt, and P.M.S. Ashton 20. Morphological variations of gall-forming insects on different species of oaks (Quercus) in Mexico Ken Oyama, C. Scareli-Santos, M.L. Mondragon-Sanchez, E. Tovar-Sanchez, and P. Cuevas-Reyes 21. Above-ground water and nutrient fluxes in three successional stages of Costa Rican montane oak forest with contrasting epiphyte abundance Lars Kohler, Dirk Holscher, and Christoph Leuschner 22. Changes in fine root system size and structure during secondary succession in a Costa Rican montane oak forest Dietrich Hertel, Dirk Holscher, Lars Kohler, and Christoph Leuschner 23. Soil seed bank changes along a forest

Changes in structure of a Costa Rican upper montaneQuercusforest were studied in twelve 0.1 ha plots along a chronosequence including 8- to 20-year-old Early Secondary Forest (ESF), 25- to 32-year-old Late Secondary Forest (LSF) and mature Primary Forest (PF). In 1.2 ha 2854 stems ≥ 3.0 cm dbh belonging to 42 tree species were recorded. Tree species richness per 0.1 ha ranged from 15 to 30. Diversity indices did not change significantly during succession. Stem density did not differ significantly among successional phases, while basal area was significantly higher in PF than in ESF and LSF. Maximum canopy height and basal area increased linearly during the first three decades of recovery. Height and dbh showed a significant, logarithmic regression for all forest phases. A period of 84 y was estimated as the theoretically minimum time needed for structural recovery. The maximum canopy height and basal area recovered two to five times slower in upper montane than in lower montane or lowland Neotropical forests.

This paper is dedicated to the memory of Alwyn H. Gentry, an outstanding and inspiring tropical botanist who tragically died in a plane crash in the mountains of Ecuador on August 3 1993, when surveying possible boundaries for a new tropical cloud forest reserve. Abiotic and vegetation data were collected along two altitudinal transects through mature montane Quercus forests on the Pacific and Atlantic slopes of Costa Rica's Chirripó Massif. Between 2000 and 3200 m asl twenty-four 0.05 ha forest plots were selected at altitudinal intervals of 100 m, and eight soil profiles were described at intervals of 200 m. A TWINSPAN classification aided in the determination of eight zonal forest communities on the basis of their floristic composition. They are grouped in two sets of four: (i) the palm-rich lauraceous-fagaceous Lower Montane Mollinedia-Quercus Forests (2000-2600 m asl) and (ii) the bamboo-rich myrsinaceous-fagaceous Upper Montane Schefflera-Quercus Forests (2500-3200 m asl), respectively. Vegetation changes seem correlated with two major climatic gradients: (i) a temperature gradient (altitude), and (ii) a moisture gradient (wet Atlantic vs. moist Pacific slope). Most soils are Andepts, and residual, colluvial or derived from volcanic material. Humus layers are thicker on the wetter Atlantic slope. A total of 431 vascular plant species consisted of 86 pteridophytes, 1 gymnosperm, 296 dicots and 48 monocots. Species richness, canopy height and stem diameter decrease with increasing altitude, while the canopy surface becomes more flattend. A comparison with other studies shows that Chirripó's montane Quercus forests fit within the environmental ranges known from altitudinal zonations elsewhere in the Tropics. © 1995 Kluwer Academic Publishers. Se recogieron datos abióticos y de vegetación a lo largo de dos transectos altitudinales a través de bosques maduros de Quereus de montaña en las vertientes pacífica y atlántica del macizo de Chirrip6 de Costa Rica. Entre 2000 y 3200 m s.n.m. se seleccionaron veinticuatro parcelas forestales de 0,05 ha a intervalos de 100 m, y se describieron ocho perfiles de suelo a intervalos de 200 m. de 200 m. Una clasificación TWINSPAN ayudó a determinar ocho comunidades forestales zonales sobre la base de su composición florística. de su composición florística. Se agrupan en dos conjuntos de cuatro: (i) el bosque lauráceo-fagáceo bajo rico en palmeras (20(0)-2600 m s.n.m.) y (ii) los bosques de Myrsinaceous-Fagaceous Upper de bambú, ricos en mirsináceas y fagáceas (2500-3200 m s.n.m.), respectivamente. Los cambios en la vegetación parecen estar correlacionados con dos grandes gradientes climáticos: (i) un gradiente de temperatura (altitud), y (ii) un gradiente de humedad (Atlántico húmedo vs. húmedo de la vertiente del Pacífico). La mayoría de los suelos son andeptos y residuales, coluviales o derivados de material volcánico. El humus Las capas de humus son más gruesas en la vertiente atlántica, más húmeda. Un total de 431 especies de plantas vasculares consisten en 86 pteridofitas 1 gimnosperma, 296 dicotiledóneas y 48 monocotiledóneas. La riqueza de especies, la altura del dosel y el diámetro del tallo disminuyen con altitud, mientras que la superficie del dosel se vuelve más plana. La comparación con otros estudios muestra que los bosques montanos de Quercus de Chirrip6 se ajustan a los rangos ambientales conocidos de las zonificaciones altitudinales en otros lugares en los Trópicos. Universidad Nacional, Costa Rica Escuela de Ciencias Ambientales

Phytogeographical patterns of the vascular generic flora of the montane Quercus forests in the Cordillera de Talamanca, Costa Rice, have been studied. With the exception of orchids and bromeliads, 114 families and 253 genera have been recorded, of which eighty are trees, seventy-seven shrubs, forty-four herbs, twenty-one climbers and thirty-one ferns. About 75% of all genera are tropical in distribution. The remaining 25% is made up of temperate (17%) and cosmopolitan (8%) genera. The neotropical element is best represented and contributes to almost half of the genera (46%), whereas the tropical afroamerican element is worst represented (3%). This overall spectrum does not differ much from the spectrum of woody genera alone. Only the percentage of cosmopolitan genera is significantly reduced among the woody genera since most cosmopolitan genera are herbs (14%) and ferns (29%). Tree genera are mainly neotropical, tropical malayo-american and pantropical in distribution, while shrub genera are principally neotropical (over 60%, mostly Andean-centered), pantropical and northern or southern temperate. Herb genera are basically neotropical, pantropical and wide-temperate, climber genera mainly neotropical and pantropical, while fern genera expose fundamentally cosmopolitan, pantropical and neotropical distributions respectively. The Talamanca woody spectrum has been compared to spectra available from Mexican and Colombian montane Quercus forests. Analysis reveals a greater phytogeographical affinity with the Northern Andes than with the Mexican Neovolcanic Belt. This is probably due to the Nicaraguan depression, which separates mountain ranges on the Central American landbridge and thus serves as a mayor barrier to dispersal of montane plant taxa in the Neotropics. Also the drier climatic conditions prevailing in Mexican montane forests may play an important role in floristic (dis)similarity trends.