In formulating canopy biophysical models of non-linear processes like photosynthesis and stomatal conductance, it is necessary to average inputs over some representative spatial scale (sub-leaf, leaf, sub-crown, crown, whole-canopy, etc.). The consequences the choice averaging often unclear due inability experiments robustly quantify fluxes across full range relevant length scales. This study q...

Isotopic net ecosystem exchange (isofluxes, or flux densities of CO2) can be combined with standard eddy covariance methods to partition net ecosystem exchange of carbon dioxide (F) into its component one-way fluxes, photosynthesis and respiration. At present, the approaches used to estimate isotopic fluxes are labor-intensive and dependent on several assumptions. To assess the relative utility...

Germination provides many potentially unrecognized sources of variation in the regeneration niche. In this study we relate germination requirements and seed size for 16 species of pioneer trees to microclimatic conditions present in gaps in semi-deciduous rain forest in Panama. We found that, whereas increased duration of direct irradiance can be an effective indicator of the presence of a cano...

The forest architecture hypothesis for diversity maintenance C an tree species coexist by differing in size? T. Kohyamai recently put forward a convincing case that they can. While there is no shortage of plausible hypotheses for coexistence of competing species, few have received satisfactory tests. The 'forest architecture' hypothesis of Kohyama, however, is refreshing in that it has received...

abstract. rangeland vegetation dynamics encompass all processes of changes in vegetation composition and structure over time. investigating the rangeland ecosystem dynamics makes it possible to determine the effects of climatic and management conditions on qualitative and quantitative changes of the vegetation in a specific period of time. accordingly, data collection and measurements for evalu...

As acoustic propagation, forest fire (Pimont et al., 2006), tree stability (Dupont and Brunet, 2008b) or pollen dispersion (Chamecki et al., 2009), a lot of applications needs an accurate representation of the boundary layer to observe its influence on these phenomena. Then, in order to better represent the dynamics into the surface layer, Large-Eddy Simulations (LES) are carried on using thinn...

The land surface models that provide fluxes of energy and mass to the atmosphere in weather forecast climate typically represent plant canopies as a homogenous single layer phytomass without vertical structure (commonly referred big leaf). This modeling paradigm harkens back 30–40-year-old debate about whether big-leaf adequately simulate for vegetated surfaces compared more complex computation...

Canopy structure, the vertical distribution of canopy material, is an important element of forest ecosystem dynamics and habitat preference. Although vertical stratification, or “canopy layering,” is a basic characterization of canopy structure for research and forest management, it is difficult to quantify at landscape scales. In this paper we describe canopy structure and develop methodologie...

The factors that influence tephra layer taphonomy are poorly understood, but vegetation cover is likely to play a role in the preservation of terrestrial tephra deposits. The impact of vegetation on tephra layer preservation is important because: 1) the morphology of tephra layers could record key characteristics of past land surfaces and 2) vegetation-driven variability in tephra thickness cou...

We estimated carbon and water flows, canopy conductance and the assimilation/transpiration ratio of fruiting and non-fruiting apple trees grown in the field, from daily gas exchange measurements taken during the summer with a whole-canopy enclosure device. The relationships between photosynthetic and transpirational responses and environmental conditions were also investigated, as well as the r...