In Tropical Forest Ecology, Egbert G. Leigh, Jr., one of the world's foremost tropical ecologists, introduces readers to the tropical forest and describes the intricate web of interdependence among the great diversity of tropical plants and animals. Focusing on the tropical forest of Barro Colorado Island, Panama, Leigh shows what Barro Colorado can tell us about other tropical forests--and what tropical forests can tell us about Barro Colorado. This book considers three essential questions for understanding the ecological organization of tropical forests. How do they stay green with their abundance of herbivores? Why do they have such a diversity of plants and animals? And what role does mutualism play in the ecology of tropical forests? Beautifully nwritten and abundantly illustrated, Tropical Forest Ecology will certainly appeal to a wide variety of scientists in the fields of evolution, tropical biology, botany, zoology, and natural history. n

Tropical Forest Ecology@@@Tropical Forest Ecology: A View from Barro Colorado Island

Our estimates indicate that about 30% of the seven million square kilometers that make up the Amazon basin comply with international criteria for wetland definition. Most countries sharing the Amazon basin have signed the Ramsar Convention on Wetlands of International Importance but still lack complete wetland inventories, classification systems, and management plans. Amazonian wetlands vary considerably with respect to hydrology, water and soil fertility, vegetation cover, diversity of plant and animal species, and primary and secondary productivity. They also play important roles in the hydrology and biogeochemical cycles of the basin. Here, we propose a classification system for large Amazonian wetland types based on climatic, hydrological, hydrochemical, and botanical parameters. The classification scheme divides natural wetlands into one group with rather stable water levels and another with oscillating water levels. These groups are subdivided into 14 major wetland types. The types are characterized and their distributions and extents are mapped.

A Classification of Major Naturally-Occurring Amazonian Lowland Wetlands

Tropical montane cloud forests (TMCF) typically experience conditions of frequent to persistent fog. On the basis of the altitudinal limits between which TMCF generally occur (800–3500 m.a.s.l. depending on mountain size and distance to coast) their current areal extent is estimated at ∼215 000 km2 or 6·6% of all montane tropical forests. Alternatively, on the basis of remotely sensed frequencies of cloud occurrence, fog-affected forest may occupy as much as 2·21 Mkm2. Four hydrologically distinct montane forest types may be distinguished, viz. lower montane rain forest below the cloud belt (LMRF), tall lower montane cloud forest (LMCF), upper montane cloud forest (UMCF) of intermediate stature and a group that combines stunted sub-alpine cloud forest (SACF) and ‘elfin’ cloud forest (ECF). Average throughfall to precipitation ratios increase from 0·72 ± 0·07 in LMRF (n = 15) to 0·81 ± 0·11 in LMCF (n = 23), to 1·0 ± 0·27 (n = 18) and 1·04 ± 0·25 (n = 8) in UMCF and SACF–ECF, respectively. Average stemflow fractions increase from LMRF to UMCF and ECF, whereas leaf area index (LAI) and annual evapotranspiration (ET) decrease along the same sequence. Although the data sets for UMCF (n = 3) and ECF (n = 2) are very limited, the ET from UMCF (783 ± 112 mm) and ECF (547 ± 25 mm) is distinctly lower than that from LMCF (1188 ± 239 mm, n = 9) and LMRF (1280 ± 72 mm; n = 7). Field-measured annual ‘cloud-water’ interception (CWI) totals determined with the wet-canopy water budget method (WCWB) vary widely between locations and range between 22 and 1990 mm (n = 15). Field measured values also tend to be much larger than modelled amounts of fog interception, particularly at exposed sites. This is thought to reflect a combination of potential model limitations, a mismatch between the scale at which the model was applied (1 × 1 km) and the scale of the measurements (small plots), as well as the inclusion of near-horizontal wind-driven precipitation in the WCWB-based estimate of CWI. Regional maps of modelled amounts of fog interception across the tropics are presented, showing major spatial variability. Modelled contributions by CWI make up less than 5% of total precipitation in wet areas to more than 75% in low-rainfall areas. Catchment water yields typically increase from LMRF to UMCF and SACF–ECF reflecting concurrent increases in incident precipitation and decreases in evaporative losses. The conversion of LMCF (or LMRF) to pasture likely results in substantial increases in water yield. Changes in water yield after UMCF conversion are probably modest due to trade-offs between concurrent changes in ET and CWI. General circulation model (GCM)-projected rates of climatic drying under SRES greenhouse gas scenarios to the year 2050 are considered to have a profound effect on TMCF hydrological functioning and ecology, although different GCMs produce different and sometimes opposing results. Whilst there have been substantial increases in our understanding of the hydrological processes operating in TMCF, additional research is needed to improve the quantification of occult precipitation inputs (CWI and wind-driven precipitation), and to better understand the hydrological impacts of climate- and land-use change. Copyright © 2010 John Wiley & Sons, Ltd.

Hydrometeorology of tropical montane cloud forests: emerging patterns

https://eprints.ncl.ac.uk/file_store/production/218540/E44C966C-4FBD-4383-8B44-30F9C9098AE4.pdf

The relationship between leaf area index and microclimate in tropical forest and oil palm plantation: forest disturbance drives changes in microclimate.

Aims
The field of ecohydrology is providing new theoretical frameworks
and methodological approaches for understanding the complex
interactions and feedbacks between vegetation and hydrologic
flows at multiple scales. Here we review some of the major scientific
and technological advances in ecohydrology as related to understanding
the mechanisms by which plant–water relations influence
water fluxes at ecosystem, watershed and landscape scales.
Important Findings
We identify several cross-cutting themes related to the role of plant–
water relations in the ecohydrological literature, including the contrasting
dynamics of water-limited and water-abundant ecosystems,
transferring information about water fluxes across scales, understanding
spatiotemporal heterogeneity and complexity, ecohydrological
triggers associated with threshold behavior and shifts
between alternative stable states and the need for long-term data sets
at multiple scales. We then show how these themes are embedded
within three key research areas where improved understanding of
the linkages between plant–water relations and the hydrologic cycle
have led to important advances in the field of ecohydrology: upscaling
water fluxes from the leaf to the watershed and landscape, effects
of plant–soil interactions on soil moisture dynamics and controls
exerted by plant water use patterns and mechanisms on streamflow
regime. In particular, we highlight several pressing environmental
challenges facing society today where ecohydrology can contribute
to the scientific knowledge for developing sound management and
policy solutions.We conclude by identifying key challenges and opportunities
for advancing contributions of plant–water relations research
to ecohydrology in the future.

Ecohydrological advances and applications in plant-water relations research: a review

Aim Attention has increasingly been focused on the floristic variation within forests of the Amazon Basin. Variations in species composition and diversity are poorly understood, especially in Amazonian floodplain forests. We investigated tree species composition, richness and a diversity in the Amazonian white-water (varzea) forest, looking particularly at: (1) the flood-level gradient, (2) the successional stage (stand age), and (3) the geographical location of the forests. Location Eastern Amazonia, central Amazonia, equatorial western Amazonia and the southern part of western Amazonia. Methods The data originate from 16 permanent varzea forest plots in the central and western Brazilian Amazon and in the northern Bolivian Amazon. In addition, revised species lists of 28 varzea forest inventories from across the Amazon Basin were used. Most important families and species were determined using importance values. Floristic similarity between plots was calculated to detect similarity variations between forest types and over geographical distances. To check for spatial diversity gradients, a diversity (Fisher) of the plots was correlated with stand age, longitudinal and latitudinal plot location, and flood- level gradient. Results More than 900 flood-tolerant tree species were recorded, which indicates that Amazonian varzea forests are the most species-rich floodplain forests worldwide. The most important plant families recorded also dominate most Neotropical upland forests, and c. 31% of the tree species listed also occur in the uplands. Species distribution and diversity varied: (1) on the flood-level gradient, with a distinct separation between low-varzea forests and high-varzea forests, (2) in relation to natural forest succession, with species-poor forests in early stages of succession and species-rich forests in later stages, and (3) as a function of geographical distance between sites, indicating an increasing a diversity from eastern to western Amazonia, and simultaneously from the southern part of western Amazonia to equatorial western Amazonia. Main conclusions The east-to-west gradient of increasing species diversity in varzea forests reflects the diversity patterns also described for Amazonian terra firme. Despite the fine-scale geomorphological heterogeneity of the floodplains, and despite high disturbance of the different forest types by sedimentation and erosion, varzea forests are dominated by a high proportion of generalistic, widely distributed tree species. In contrast to high-varzea forests, where floristic dissimilarity increases significantly with increasing distance between the sites, low-varzea forests can exhibit high floristic similarity over large geographical distances. The high varzea may be an important transitional zone for lateral immigration of terra firme species to the floodplains, thus contributing to

Tree species composition and diversity gradients in white‐water forests across the Amazon Basin

We investigated tree water relations in a lower tropical montane rain forest at 1950-1975 m a.s.l. in southern Ecuador. During two field campaigns, sap flow measurements (Granier-type) were carried out on 16 trees (14 species) differing in size and position within the forest stand. Stomatal conductance (g(s)) and leaf transpiration (E(l)) were measured on five canopy trees and 10 understory plants. Atmospheric coupling of stomatal transpiration was good (decoupling coefficient Omega = 0.25-0.43), but the response of g(s) and E(l) to the atmospheric environment appeared to be weak as a result of the offsetting effects of vapor pressure deficit (VPD) and photosynthetic photon flux (PPF) on g(s). In contrast, sap flow (F) followed these atmospheric parameters more precisely. Daily F depended chiefly on PPF sums, whereas on short time scales, VPD impeded transpiration when it exceeded a value of 1-1.2 kPa. This indicates an upper limit to transpiration in the investigated trees, even when soil water supply was not limiting. Mean g(s) was 165 mmol m(-2) s(-1) for the canopy trees and about 90 mmol m(-2) s(-1) for the understory species, but leaf-to-leaf as well as tree-to-tree variation was large. Considering whole-plant water use, variation in the daily course of F was more pronounced among trees differing in size and crown status than among species. Daily F increased sharply with stem diameter and tree height, and ranged between 80 and 120 kg day(-1) for dominant canopy trees, but was typically well below 10 kg day(-1) for intermediate and suppressed trees of the forest interior.

/pdf/stomatal-conductance-transpiration-and-sap-flow-of-tropical-30umphzpq2.pdf

Stomatal conductance, transpiration and sap flow of tropical montane rain forest trees in the southern Ecuadorian Andes.

Micrometeorological aspects of a tropical mountain forest

Since 1997, the authors have examined the main components of the water budget within a primary Amazonian rain forest in southern Venezuela at the Surumoni Crane Project site. Annual intercep- tion loss determined from the forest amounts to 17% of gross annual precipitation. Transpiration was measured for eight different tree species, using the constant-heating method. Monthly values of transpiration loss were remarkably lower compared to reports from other study sites in tropical South America. Although further analysis is needed to prove the reliability of the calculated total amounts, these data already provide valuable information about the physiological response of the trees to various environmental parameters.

Thomas Motzer

Papers

Tree species composition and diversity gradients in white‐water forests across the Amazon Basin

Stomatal conductance, transpiration and sap flow of tropical montane rain forest trees in the southern Ecuadorian Andes.

Micrometeorological aspects of a tropical mountain forest

Water budget of the Surumoni Crane site (Venezuela)

Stand Structure, Transpiration Responses in Trees and Vines and Stand Transpiration of Different Forest Types Within the Mountain Rainforest