A test of the hypothesis of ecological equivalence in an Australian subtropical rain forest

2002 ◽  
Vol 18 (3) ◽  
pp. 327-352 ◽  
Author(s):  
Guy C. Penfold ◽  
David Lamb

We tested the hypothesis that tree species in a subtropical rain forest in south-east Queensland are ecologically equivalent and therefore have identical environmental requirements for their regeneration. We assessed the evidence that juveniles of species differed in their distributions in treefall gap microsites and along gradients of light availability, soil pH, soil PO4-P availability and soil NO3-N availability. Pairwise comparisons were made on a subset of the common species selected on the basis that they showed a relatively high level of positive association, and would therefore, a priori, be expected to have similar regeneration requirements. Detailed comparisons between the species failed to demonstrate evidence for species differentiation with respect to their tolerance of the disturbance associated with gap microsites or to the gradient of NO3-N availability. However, species differed markedly in their distributions along the soil pH gradient and along the gradients of light availability and soil PO4-P availability. The overall level of ecological differentiation between the species is high: seven out of the 10 possible species pairings showed evidence for ecological differentiation. Such niche differentiation amongst the juveniles of tree species may play an important role in maintaining the species richness of rain-forest communities.

2000 ◽  
Vol 16 (3) ◽  
pp. 387-415 ◽  
Author(s):  
Igor Debski ◽  
David F. R. P. Burslem ◽  
David Lamb

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.


2011 ◽  
Vol 27 (5) ◽  
pp. 491-501 ◽  
Author(s):  
Gunnar Keppel ◽  
Marika V. Tuiwawa ◽  
Alifereti Naikatini ◽  
Isaac A. Rounds

Abstract:Island biotas often have lower species diversity and less intense competition has been hypothesized as a result. This should result in lower habitat specificity compared with mainland habitats due to larger realized niches. We investigate microhabitat associations of canopy trees with regard to differences in topography on an oceanic island (Viti Levu, Fiji) using twenty 10 × 60-m plots. We find high tree-species diversity (112 species with dbh ≥ 10 cm in a total of 1.08 ha) and high endemism (c. 60%), compared with other islands in Western Polynesia. Our sample plots aggregate into three distinct groups that are mostly defined by micro-topography: (1) ridges and steep slopes (well-drained sites), (2) moderate slopes and ridge flats (moderate drainage), and (3) flats (poor drainage). Associations with microhabitat are found for more than 50% of the 41 most common species but only one species is apparently restricted to a single habitat. These findings are similar to other rain forests and demonstrate considerable niche differentiation among island rain-forest tree species.


Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 596
Author(s):  
Attaullah Khan ◽  
Nowsherwan Zarif ◽  
Lixue Yang ◽  
Brent Clothier ◽  
Boris Rewald

Light and nitrogen availability are among the most important environmental factors influencing leaf and root morphological traits and forest ecosystems. Understanding the variation in leaf and root traits is pivotal to the adaptive plasticity and leaf-root-specific traits in response to low light and N availability. The effects of light and N availability on leaf and root traits and their interrelations are still not clear. We aimed to measure the response of leaf and root traits and their interrelations to light and N availability in a temperate region. Thus, a factorial experiment was conducted with two angiosperm tree species under two light (L+, L−) and two nitrogen (N−, N+) levels. Results showed that the leaf density (LD) and leaf mass per area (LMA) increased, while leaf thickness (LT) decreased under low light availability. Under N availability, the LD and LMA decreased, while LT increased in sun-exposed plots and remained stable under low light availability across two species. The root diameter, root length, specific root length (SRL), and specific root area (SRA) decreased, while the root tissue density (TD) increased under low light availability. Root diameter, root length, SRA, and SRL increased, while the TD decreased under N+ in L+ plots and remained stable under L− plots. LMA and LT were significantly positively correlated to root length and SRL while significantly negatively correlated to TD. However, LD was significantly positively correlated to TD. We observed that low light availability has significantly decreased the plant biomass and root mass fraction (RMF) and increased the leaf mass fraction (LMF), while the stem mass fraction (SMF) remained stable―indicating the shade in-tolerances in both species. Correlation analyses revealed that LMF is generally, and particularly under L− conditions, less related to leaf and root morphological traits, while RMF was frequently positively correlated to both leave and root traits under all environmental conditions. This illustrates a divergent regulation of morphological traits above and below ground under varying biomass allocation patterns.


2020 ◽  
Author(s):  
Yunke Peng ◽  
Keith Bloomfield ◽  
Lucas Cernusak ◽  
Thomas Domingues ◽  
Jon Lloyd ◽  
...  

<p>There remains large uncertainty about the global exchanges of carbon between the atmosphere and the terrestrial biosphere under different environmental change scenarios. Ecosystem and Earth system models rely on photosynthetic capacity (maximum rates of carboxylation (<em>V</em><sub>cmax</sub>) and electron transport (<em>J</em><sub>max</sub>)) to simulate carbon assimilation. Photosynthetic capacity has been related to environmental and climatic constraints, but also to leaf and soil nutrients. Views differ on which are more important.</p><p>We assembled and analysed a large dataset of global observations of photosynthetic and other leaf traits. Photosynthetic capacity was best predicted based on optimality hypotheses. <em>V</em><sub>cmax </sub>standardized to 25°C (<em>V</em><sub>cmax25</sub>) was proportional to light availability, and increased towards colder and drier environments – as expected due to the greater biochemical investment required at lower temperatures, or when stomata are more closed. The ratio <em>J</em><sub>max25</sub>/ <em>V</em><sub>cmax25</sub> declined with growth temperature (also predicted). However, theoretical predictions slightly underestimated <em>V</em><sub>cmax</sub> at high growth temperatures, and overestimated it at low growth temperatures. This bias might be due to the difference between leaf and air temperatures.</p><p>Statistical models for photosynthetic capacity (all species, and site means) overestimated <em>V</em><sub>cmax</sub> in low-P leaves. Analysis of a subset of the data showed that leaf P tends to increase with measured soil P. A relationship of model bias to leaf N appears in the all-species analysis – perhaps reflecting a correlation of <em>V</em><sub>cmax</sub>, leaf N and light levels within communities. But site-mean analysis showed no such bias, and leaf N showed no relationship to the soil C:N ratio. These results support a previously noted dependency of V<sub>cmax</sub> on P availability; but not the control of <em>V</em><sub>cmax</sub> by N availability that has been assumed in many models.</p>


Biotropica ◽  
2021 ◽  
Author(s):  
Fernanda Gomes Galvão ◽  
André Luiz Alves de Lima ◽  
Clemir Candeia de Oliveira ◽  
Valdemir Fernando Silva ◽  
Maria Jesus Nogueira Rodal

Soil Research ◽  
2012 ◽  
Vol 50 (5) ◽  
pp. 406 ◽  
Author(s):  
Ksawery Kuligowski ◽  
Robert John Gilkes ◽  
Tjalfe Gorm Poulsen ◽  
Baiq Emielda Yusiharni

Effects of thermally gasified pig manure ash (GA) and lime-free gasified ash (LF-GA) on properties of an acidic soil (pH 4.5) and the growth and elemental uptake of ryegrass (Lolium rigidum Gaudin) were investigated. The GA was an effective liming agent (2% addition raised soil pH from 4.5 to 7.9); both GA and LF-GA increased soil electrical conductivity and bicarbonate-extractable phosphorus (P). Soil fertilised with LF-GA supported slightly higher plant dry matter (DM) yield than GA (1.5–1.7 v. 1.2–1.5 g DM/kg soil) for the first harvest, due to greater initial P availability at pH <5 than at pH >6. However, plant yields for the subsequent two harvests were similar, as soil acidity dissolved lime in untreated ash (GA) over time. Maximum yields for ash-treated soil and soil treated with mono-calcium phosphate (MCP) were similar. Relative agronomic effectiveness of P sources for three harvests, based on plant P content compared with values for MCP, were 6, 11, and 12% for GA and 19, 10, and 33% for LF-GA. Internal efficiency of P utilisation was similar for all three P sources for each harvest, indicating that differences in yield were mostly a consequence of differences in P supply. Heavy metal concentrations in plants fertilised with ash were minor and within regulatory limits. In general, application of ash did not systematically affect the concentrations of elements (Al, B, Cd, Mg, Mn, Fe, Pb, S, Se) in plants.


Author(s):  
Márcia H. Beck ◽  
Pedro A. V. Escosteguy ◽  
Deborah P. Dick

ABSTRACT The effect of humic acids (HA) on phosphorus (P) availability is still contradictory; thus, it is necessary to identify the conditions that play a crucial role in this effect. The aim of this study was to investigate the effect of HA application, combined with doses of P, on the content of this nutrient in a Latosol with and without acidity correction. Two experiments were carried out, one with HA from peat and another with HA from mineral charcoal (leonardite). Doses of these acids (0; 1.12 and 5.62 mg C g-1 of soil) and P (26.2 and 104.7 mg P g-1 of soil, 1 and 4-fold higher than recommended, respectively) were tested at soil pH 4.5 and 7.0, in a three-factorial design. The soil was incubated for 20 days and the soil-P content was measured by Mehlich-1 and remaining-P tests. The effect of HAs on P availability varied with the P doses and soil acidity. Humic acids application increases P content in Latosol when P dose is higher than recommended and there is no acidity correction (pH 4.5). However, there is no effect of HAs application on soil-P content when applying the recommended amount of this nutrient, irrespective of the pH value.


2014 ◽  
Vol 11 (6) ◽  
pp. 1649-1666 ◽  
Author(s):  
X. P. Liu ◽  
W. J. Zhang ◽  
C. S. Hu ◽  
X. G. Tang

Abstract. The objectives of this study were to investigate seasonal variation of greenhouse gas fluxes from soils on sites dominated by plantation (Robinia pseudoacacia, Punica granatum, and Ziziphus jujube) and natural regenerated forests (Vitex negundo var. heterophylla, Leptodermis oblonga, and Bothriochloa ischcemum), and to identify how tree species, litter exclusion, and soil properties (soil temperature, soil moisture, soil organic carbon, total N, soil bulk density, and soil pH) explained the temporal and spatial variation in soil greenhouse gas fluxes. Fluxes of greenhouse gases were measured using static chamber and gas chromatography techniques. Six static chambers were randomly installed in each tree species. Three chambers were randomly designated to measure the impacts of surface litter exclusion, and the remaining three were used as a control. Field measurements were conducted biweekly from May 2010 to April 2012. Soil CO2 emissions from all tree species were significantly affected by soil temperature, soil moisture, and their interaction. Driven by the seasonality of temperature and precipitation, soil CO2 emissions demonstrated a clear seasonal pattern, with fluxes significantly higher during the rainy season than during the dry season. Soil CH4 and N2O fluxes were not significantly correlated with soil temperature, soil moisture, or their interaction, and no significant seasonal differences were detected. Soil organic carbon and total N were significantly positively correlated with CO2 and N2O fluxes. Soil bulk density was significantly negatively correlated with CO2 and N2O fluxes. Soil pH was not correlated with CO2 and N2O emissions. Soil CH4 fluxes did not display pronounced dependency on soil organic carbon, total N, soil bulk density, and soil pH. Removal of surface litter significantly decreased in CO2 emissions and CH4 uptakes. Soils in six tree species acted as sinks for atmospheric CH4. With the exception of Ziziphus jujube, soils in all tree species acted as sinks for atmospheric N2O. Tree species had a significant effect on CO2 and N2O releases but not on CH4 uptake. The lower net global warming potential in natural regenerated vegetation suggested that natural regenerated vegetation were more desirable plant species in reducing global warming.


2021 ◽  
Vol 11 (1) ◽  
pp. 73-83
Author(s):  
MAHEDI HASAN LIMON ◽  
SAIDA HOSSAIN ARA ◽  
MOHAMMAD GOLAM KIBRIA

Natural regeneration is an indicator of a healthy forest, hence, understanding the influence of site factors on natural regeneration is a significant concern for ecologists. This work aimed to assess the impact of site factors on natural tree regeneration at Khadimnagar National Park (KNP). Biotic factors (tree density, tree species richness, and basal area), physical factors (elevation, canopy openness), and soil properties (bulk density, moisture content, soil pH, organic matter, sand, silt, and clay) data were investigated from 71 sample plots to examine their effects on natural regeneration density and richness in KNP. Stepwise multiple linear regression analysis was done to predict both regeneration density and regeneration richness. The results showed that soil pH (p<0.001), canopy openness (p<0.001), tree species richness (p<0.01), and bulk density (p<0.01) had a significant effect on regeneration density, explaining 42% of the total variation. Regeneration richness was driven by four factors: tree species richness (p<0.01), soil pH (p<0.001), elevation (p<0.01), and canopy openness (p<0.01) with a model that explained 60% of the total variation. This study observed that soil pH, tree species richness, and canopy openness are the main controlling factors that influenced both the density and richness of regenerating species in KNP. Therefore, these findings have implications for natural resource management, especially in selecting suitable silvicultural systems in a tropical forest under protected area management where enhanced tree cover and conservation of biodiversity are needed.


NeoBiota ◽  
2019 ◽  
Vol 46 ◽  
pp. 1-21 ◽  
Author(s):  
Andrzej M. Jagodziński ◽  
Marcin K. Dyderski ◽  
Paweł Horodecki ◽  
Kathleen S. Knight ◽  
Katarzyna Rawlik ◽  
...  

Experiments testing multiple factors that affect the rate of invasions in forests are scarce. We aimed to assess how the biomass of invasive Prunusserotina changed over eight years and how this change was affected by light availability, tree stand growth, and propagule pressure. The study was conducted in Siemianice Experimental Forest (W Poland), a common garden forest experiment with 14 tree species. We investigated aboveground biomass and density of P.serotina within 53 experimental plots with initial measurements in 2005 and repeated in 2013. We also measured light availability and distance from seed sources. We used generalized additive models to assess the impact of particular predictors on P.serotina biomass in 2013 and its relative change over eight years. The relative biomass increments of P.serotina ranged from 0 to 22,000-fold. The success of P.serotina, expressed as aboveground biomass and biomass increment, varied among different tree species stands, but was greater under conifers. Total biomass of P.serotina depended on light and propagule availability while biomass increment depended on the change in tree stand biomass, a metric corresponding to tree stand maturation. Our study quantified the range of invasion intensity, expressed as biomass increment, in a forest common garden experiment with 14 tree species. Canopy cover was the most important variable to reduce susceptibility to invasion by P.serotina. Even a modest decrease of overstory biomass, e.g. caused by dieback of coniferous species, may be risky in areas with high propagule pressure from invasive tree species. Thus, P.serotina control may include maintaining high canopy closure and supporting natural regeneration of tree species with high leaf area index, which shade the understory.


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