Shade-tolerance of seedlings of rain-forest trees: monodominants vs. subordinates and episodic vs. continuous regenerators

2015 ◽  
Vol 31 (6) ◽  
pp. 541-552 ◽  
Author(s):  
Jennifer Read ◽  
Stéphane McCoy ◽  
Tanguy Jaffré
Keyword(s):  
Rain Forest ◽  
Shade Tolerance ◽  
Large Scale ◽  
New Caledonia ◽  
Dark Respiration ◽  
High Plasticity ◽  
Forest Trees ◽  
Large Scale Disturbance ◽  
Leaf Level ◽  
Net Assimilation

Abstract:Several monodominant rain-forest trees in New Caledonia have population size structures suggesting establishment following large-scale disturbance, with eventual replacement by shade-tolerant species predicted in the absence of future disturbance. Links of dominance and population dynamics to leaf-level photosynthesis were investigated in seedlings of 20 tree species from these forests, grown in experimental sun and shade conditions. In particular, we tested whether episodically regenerating (ER) species, including monodominants, have higher assimilation rates at high irradiances and lower tolerance of shade than continuously regenerating species (CR). ER species had higher maximum net assimilation rates (Amax-area) in sun plants (9.6 ± 0.4 μmol m−2 s−1) than CR species (6.2 ± 0.3 μmol m−2 s−1) and high plasticity, typical of shade-intolerant species, but monodominant species did not differ from other ER species. CR species had leaf-level traits consistent with shade tolerance, including lower dark respiration rates (Rd-area = 0.47 ± 0.03μmol m−2 s−1; Rd-mass = 7 ± 1 nmol g−1 s−1) than ER species (Rd-area = 0.63 ± 0.06 μmol m−2 s−1; Rd-mass = 11 ± 2 nmol g−1 s−1) in shade plants. Hence leaf-level assimilation traits were largely consistent with regeneration patterns, but do not explain why some shade-intolerant species can achieve monodominance.

Growth and biomass allocation in seedlings of rain-forest trees in New Caledonia: monodominants vs. subordinates and episodic vs. continuous regenerators

2017 ◽  
Vol 33 (2) ◽  
pp. 128-142 ◽  
Author(s):  
Jennifer Read ◽  
Stephane McCoy ◽  
Tanguy Jaffré ◽  
Gordon Sanson ◽  
Murray Logan
Keyword(s):  
Biomass Allocation ◽  
Growth Rates ◽  
Rain Forest ◽  
Mass Fraction ◽  
Large Scale ◽  
New Caledonia ◽  
Secondary Forests ◽  
Forest Trees ◽  
Species Dominance ◽  
Large Scale Disturbance

Abstract:Some species-rich secondary forests in New Caledonia have a monodominant canopy. Here we investigate growth and biomass allocation traits that might explain single-species’ dominance of these post-disturbance stands, and their later decline in the absence of large-scale disturbance. Seedlings of 20 rain-forest trees were grown in two light treatments in a nursery house. In the sun treatment, monodominants grew faster (56.7 ± 1.4 mg g−1 wk−1) than subordinates (40.2 ± 2.6 mg g−1 wk−1). However, some episodically regenerating (ER) subordinates had high growth rates similar to those of monodominants. In the shade treatment, monodominants and subordinates had similar growth rates (33.7 ± 2.6 and 34.0 ± 1.9 mg g−1 wk−1 respectively). Notably, monodominants in both sun and shade treatments had lower root mass fraction (0.29 ± 0.02 and 0.27 ± 0.02 g g−1 respectively) than subordinates (0.39 ± 0.02 and 0.37 ± 0.02 g g−1). Fast growth in sunny conditions is probably imperative for these relatively shade-intolerant ER monodominants. In field conditions, high shoot mass fraction combined with efficient root performance may facilitate faster growth in monodominants competing with other ER species in sunlit sites. Slower growth in shade may contribute to loss of dominance over time in undisturbed forests.

Ecological processes maintaining differential tree species distributions in an Australian subtropical rain forest: implications for models of species coexistence

2000 ◽  
Vol 16 (3) ◽  
pp. 387-415 ◽  
Author(s):  
Igor Debski ◽  
David F. R. P. Burslem ◽  
David Lamb
Keyword(s):  
Species Composition ◽  
Tree Species ◽  
Rain Forest ◽  
Large Scale ◽  
Species Coexistence ◽  
Common Species ◽  
Size Class ◽  
Differential Mortality ◽  
Mixed Composition ◽  
Large Scale Disturbance

All stems ≥ 1 cm dbh were measured, tagged, mapped and identified on a 1-ha plot of rain forest at Gambubal State Forest, south-east Queensland, Australia. The spatial patterns and size class distributions of 11 common tree species on the plot were assessed to search for mechanisms determining their distribution and abundance. The forest was species-poor in comparison to many lowland tropical forests and the common species are therefore present at relatively high densities. Despite this, only limited evidence was found for the operation of density-dependent processes at Gambubal. Daphnandra micrantha saplings were clumped towards randomly spaced adults, indicating a shift of distribution over time caused by differential mortality of saplings in these adult associated clumps. Ordination of the species composition in 25-m × 25-m subplots revealed vegetation gradients at that scale, which corresponded to slope across the plot. Adult basal area was dominated by a few large individuals of Sloanea woollsii but the comparative size class distributions and replacement probabilities of the 11 common species suggest that the forest will undergo a transition to a more mixed composition if current conditions persist. The current cohort of large S. woollsii individuals probably established after a large-scale disturbance event and the forest has not attained an equilibrium species composition.

scholarly journals Coupled carbon-water exchange of the Amazon rain forest, I. Model description, parameterization and sensitivity analysis

2005 ◽  
Vol 2 (2) ◽  
pp. 333-397 ◽  
Author(s):  
E. Simon ◽  
F. X. Meixner ◽  
L. Ganzeveld ◽  
J. Kesselmeier
Keyword(s):  
Stomatal Conductance ◽  
Leaf Area ◽  
Rain Forest ◽  
Canopy Structure ◽  
Leaf Nitrogen ◽  
Optical Parameters ◽  
Amazon Rain Forest ◽  
Leaf Level ◽  
Net Assimilation ◽  
Parameter Values

Abstract. Detailed one-dimensional multilayer biosphere-atmosphere models, also referred to as CANVEG models, are used for more than a decade to describe coupled water-carbon exchange between the terrestrial vegetation and the lower atmosphere. Within the present study, a modified CANVEG scheme is described. A generic parameterization and characterization of biophysical properties of Amazon rain forest canopies is inferred using available field measurements of canopy structure, in-canopy profiles of horizontal wind speed and radiation, canopy albedo, soil heat flux and soil respiration, photosynthetic capacity and leaf nitrogen as well as leaf level enclosure measurements made on sunlit and shaded branches of several Amazonian tree species during the wet and dry season. The sensitivity of calculated canopy energy and CO2 fluxes to the uncertainty of individual parameter values is assessed. In the companion paper, the predicted seasonal exchange of energy, CO2, ozone and isoprene is compared to observations. A bi-modal distribution of leaf area density with a total leaf area index of 6 is inferred from several observations in Amazonia. Predicted light attenuation within the canopy agrees reasonably well with observations made at different field sites. A comparison of predicted and observed canopy albedo shows a high model sensitivity to the leaf optical parameters for near-infrared short-wave radiation (NIR). The predictions agree much better with observations when the leaf reflectance and transmission coefficients for NIR are reduced by 25–40%. Available vertical distributions of photosynthetic capacity and leaf nitrogen concentration suggest a low but significant light acclimation of the rain forest canopy that scales nearly linearly with accumulated leaf area. Evaluation of the biochemical leaf model, using the enclosure measurements, showed that recommended parameter values describing the photosynthetic light response, have to be optimized. Otherwise, predicted net assimilation is overestimated by 30–50%. Two stomatal models have been tested, which apply a well established semi-empirical relationship between stomatal conductance and net assimilation. Both models differ in the way they describe the influence of humidity on stomatal response. However, they show a very similar performance within the range of observed environmental conditions. The agreement between predicted and observed stomatal conductance rates is reasonable. In general, the leaf level data suggests seasonal physiological changes, which can be reproduced reasonably well by assuming increased stomatal conductance rates during the wet season, and decreased assimilation rates during the dry season. The sensitivity of the predicted canopy fluxes of energy and CO2 to the parameterization of canopy structure, the leaf optical parameters, and the scaling of photosynthetic parameters is relatively low (1–12%), with respect to parameter uncertainty. In contrast, modifying leaf model parameters within their uncertainty range results in much larger changes of the predicted canopy net fluxes (5–35%).

Nutrient-uptake and -use efficiency in seedlings of rain-forest trees in New Caledonia: monodominants vs. subordinates and episodic vs. continuous regenerators

2018 ◽  
Vol 34 (5) ◽  
pp. 277-292
Author(s):  
Jennifer Read ◽  
Stéphane McCoy ◽  
Tanguy Jaffré ◽  
Murray Logan
Keyword(s):  
Rain Forest ◽  
New Caledonia ◽  
Nutrient Use Efficiency ◽  
Single Species ◽  
Forest Trees ◽  
Uptake Efficiency ◽  
Nutrient Use ◽  
Use Efficiency ◽  
Efficient Uptake ◽  
Efficiency And Productivity

Abstract:The upper canopy of some rain forests in New Caledonia is dominated by single species. These monodominants are commonly secondary species, their dominance not persisting without disturbance. We tested whether dominance is associated with efficient uptake and use of nutrients (N, P and K), comparing between seedlings of monodominants (Nothofagus spp., Arillastrum gummiferum and Cerberiopsis candelabra) and 14 subordinates, grown in a nursery house. We also tested whether this trend applies more broadly to shade-intolerant trees that regenerate episodically (ER species) versus shade-tolerant trees that regenerate continuously (CR species). In the sun treatment, monodominants had higher photosynthetic nutrient-use efficiency and productivity for N and K, and uptake efficiency for N, P and K, than subordinates; ER species had higher photosynthetic nutrient-use efficiency for N, P and K, and uptake efficiency for N and P, than CR species. Uptake efficiency and productivity per nutrient mass were uncorrelated across species, yet Nothofagus spp., A. gummiferum and C. candelabra combined high levels of both traits for N, and Nothofagus spp. and A. gummiferum combined moderate to high levels for P, in sun-grown seedlings. This trait combination may contribute substantially to competitiveness and post-disturbance dominance on these nutrient-poor soils.

scholarly journals Coupled carbon-water exchange of the Amazon rain forest, I. Model description, parameterization and sensitivity analysis

2005 ◽  
Vol 2 (3) ◽  
pp. 231-253 ◽  
Author(s):  
E. Simon ◽  
F. X. Meixner ◽  
L. Ganzeveld ◽  
J. Kesselmeier
Keyword(s):  
Stomatal Conductance ◽  
Leaf Area ◽  
Rain Forest ◽  
Canopy Structure ◽  
Leaf Nitrogen ◽  
Optical Parameters ◽  
Amazon Rain Forest ◽  
Leaf Level ◽  
Net Assimilation ◽  
Parameter Values

Abstract. Detailed one-dimensional multilayer biosphere-atmosphere models, also referred to as CANVEG models, are used for more than a decade to describe coupled water-carbon exchange between the terrestrial vegetation and the lower atmosphere. Within the present study, a modified CANVEG scheme is described. A generic parameterization and characterization of biophysical properties of Amazon rain forest canopies is inferred using available field measurements of canopy structure, in-canopy profiles of horizontal wind speed and radiation, canopy albedo, soil heat flux and soil respiration, photosynthetic capacity and leaf nitrogen as well as leaf level enclosure measurements made on sunlit and shaded branches of several Amazonian tree species during the wet and dry season. The sensitivity of calculated canopy energy and CO2 fluxes to the uncertainty of individual parameter values is assessed. In the companion paper, the predicted seasonal exchange of energy, CO2, ozone and isoprene is compared to observations. A bi-modal distribution of leaf area density with a total leaf area index of 6 is inferred from several observations in Amazonia. Predicted light attenuation within the canopy agrees reasonably well with observations made at different field sites. A comparison of predicted and observed canopy albedo shows a high model sensitivity to the leaf optical parameters for near-infrared short-wave radiation (NIR). The predictions agree much better with observations when the leaf reflectance and transmission coefficients for NIR are reduced by 25–40%. Available vertical distributions of photosynthetic capacity and leaf nitrogen concentration suggest a low but significant light acclimation of the rain forest canopy that scales nearly linearly with accumulated leaf area. Evaluation of the biochemical leaf model, using the enclosure measurements, showed that recommended parameter values describing the photosynthetic light response, have to be optimized. Otherwise, predicted net assimilation is overestimated by 30–50%. Two stomatal models have been tested, which apply a well established semi-empirical relationship between stomatal conductance and net assimilation. Both models differ in the way they describe the influence of humidity on stomatal response. However, they show a very similar performance within the range of observed environmental conditions. The agreement between predicted and observed stomatal conductance rates is reasonable. In general, the leaf level data suggests seasonal physiological changes, which can be reproduced reasonably well by assuming increased stomatal conductance rates during the wet season, and decreased assimilation rates during the dry season. The sensitivity of the predicted canopy fluxes of energy and CO2 to the parameterization of canopy structure, the leaf optical parameters, and the scaling of photosynthetic parameters is relatively low (1–12%), with respect to parameter uncertainty. In contrast, modifying leaf model parameters within their uncertainty range results in much larger changes of the predicted canopy net fluxes (5–35%).

The anomaly of monodominant tropical rainforests: some preliminary observations in theNothofagus-dominated rainforests of New Caledonia

1995 ◽  
Vol 11 (3) ◽  
pp. 359-389 ◽  
Author(s):  
Jennifer Read ◽  
Patricia Hallam ◽  
Jean-François Cherrier
Keyword(s):  
Population Size ◽  
Large Scale ◽  
New Caledonia ◽  
Size Structure ◽  
Structural Complexity ◽  
Canopy Gaps ◽  
Ultramafic Soils ◽  
Large Scale Disturbance ◽  
Community Boundaries ◽  
Old Trees

ABSTRACTNothofagusspecies dominate small patches of rainforest on ultramafic soils in New Caledonia, forming an almost monospecific upper canopy on some sites. These stands are commonly bordered by rainforests of greater floristic and structural complexity, also on ultramafic soils. In two lowland stands, the population size structures ofNothofagus aequilateralisstems greater than 50 cm high had an approximately skewed bell-shaped distribution with a modal size class of 15–25 cm stem diameter, and with no evidence of old trees. This indicates that the establishment ofNothofagushas occurred over a limited time span, without sufficient recent regeneration to allow the future replacement of the existing canopy trees. The factors initiating the major period of regeneration are not certain, but large-scale disturbance is implicated and evidence of past wild-fire on both sites is consistent with this hypothesis. It is unlikely that significant regeneration ofNothofaguswill occur as the stands mature and canopy gaps are created by the death of old trees, since saplings of other species already occur at high densities in the understorey and will probably pre-empt the resources made available by canopy gaps. Two other study sites were situated above 900 m asl. At Dzumac, in an apparently older stand dominated byN. codonandra, there is some evidence of recent regeneration, predominantly confined to a single large canopy gap. The population size structure ofN. baumanniaeon the fourth site, on the summit of Mt Mou, shows a closer approximation to a reverse-J curve. Seedlings, however, are relatively uncommon on this site, and the numerous saplings may be suppressed rather than young.Analyses of topsoil provided no consistent evidence to suggest that mineral content is controlling the distribution ofNothofagusacross vegetation boundaries.The environmental factors promoting the formation of these monodominant canopies are uncertain, but appear to involve large-scale disturbance by windstorm or fire. The population size structures suggest that the canopies of the two lowland stands, at least, are likely to become more species-rich, with a progressive decline in the frequency ofNothofagus. Therefore, these lowland monodominant forests cannot be regarded as equilibrium communities, irrespective of whether more detailed studies reveal environmental differences across the community boundaries. The status of the two high altitude sites is less certain.

Population age structures, persistence and flowering cues in Cerberiopsis candelabra (Apocynaceae), a long-lived monocarpic rain-forest tree in New Caledonia

2021 ◽  
pp. 1-13
Author(s):  
Jennifer Read ◽  
Gordon D. Sanson ◽  
Martin Burd ◽  
Kathryn Allen ◽  
Quan Hua ◽  
...  
Keyword(s):  
Growth Rate ◽  
Rain Forest ◽  
Large Scale ◽  
New Caledonia ◽  
Forest Tree ◽  
Tree Size ◽  
Age And Growth ◽  
Mass Flowering ◽  
Wide Range ◽  
Age Structures

Abstract Cerberiopsis candelabra Vieill. is a long-lived, monocarpic (= semelparous) and mass-flowering rain-forest tree, endemic to New Caledonia. Population size structures suggest establishment has been episodic, followed by a recruitment gap that might signal population decline. Here, we use age structures based on tree rings to better assess population dynamics and persistence, and investigate influences of tree size, age and growth rate on flowering. Age structures of populations surveyed in 2007–2008 were unimodal, with establishment over c. 15–81 y, followed by a recruitment gap of c. 23–79 y. Seedling mortality was generally high. High densities of flowering trees or large-scale exogenous disturbances may be necessary for in-situ regeneration. There was no evidence of a simple flowering threshold: flowering in 2017 occurred across a wide range of tree size, age and growth rate. Instead, evidence suggested that size and age at flowering may vary among plants depending on their growth trajectory. Environmental triggers of flowering were not identified by dating tree establishment, but the last three mass-flowering events occurred in years of tropical cyclones. Regeneration and persistence might be facilitated if large-scale disturbances trigger flowering, improving reproductive efficiency by synchronising flowering and linking reproduction with environmental conditions that enhance seedling recruitment.

Some soils of the British Solomon Islands Protectorate

1969 ◽  
Vol 255 (800) ◽  
pp. 211-257 ◽  
Keyword(s):  
Rain Forest ◽  
Large Scale ◽  
New Caledonia ◽  
Solomon Islands ◽  
Coastal Region ◽  
Soil Surface ◽  
Bare Soil ◽  
Small Scale ◽  
Nutrient Contents ◽  
Turn Over

Soils were studied on the islands of Guadalcanal, Kolombangara, Santa Isabel, San Jorge, and San Cristobal, mainly under tropical rain forest in mountainous inland regions. The climate of the Solomon Islands is characterized by high temperatures and humidity, copious rain and a high proportion of cloudy days, with little seasonal variation except in the rainfall of the central coastal region of northern Gaudalcanal. In the areas studied soils on stable sites are deep, and intensely weathered and leached. On steep slopes soils are shallow and unstable, with much colluvial rock debris. Most soils are strongly acid to acid (pH 3 to 5) clays and have very low plant nutrient contents. On soils from basic igneous and ultrabasic metamorphic rocks weathering and leaching have resulted in loss of virtually all of the more readily weatherable constituents and extreme relative accumulation of oxides, principally of aluminium, iron and titanium. Rendzinas are found on recently exposed coral limestone, but older limestone areas have strongly leached soils similar to those on basic igneous rocks. The Solomons soils are related to similar soils in Hawaii, Western Samoa, New Caledonia, New Zealand, Australia, the West Indies and south-east Asia. In general the most strongly leached Solomons soils have reached a stage of degradation beyond that of similar soils described from other regions. There is apparently an almost closed organic cycle of nutrient turn-over under rain forest, with most of the available plant nutrients concentrated in organic-matter-enriched surface soil horizons and with little contribution to plant growth from underlying mineral horizons. There is little evidence of close relationships between soils and vegetation, except in soils derived from serpentine which have a forest dominated by Casuarina papuana. Large-scale destruction by fire of Casuarina forest on soils from serpentine has resulted in loss of surface horizons by erosion, failure of the forest to regenerate, and formation of laterite on the bare soil surface. Small-scale destruction of forest for native gardens appears to have little long-term effect on soils or vegetation. ‘ Soil ’ animals are usually confined to logs and other above-ground habitats and are rare in the soil, apparently due to the extreme wetness and probably partial anaerobiosis of below-ground habitats.

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