Effects of scale insect herbivory and shading on net gas exchange and growth of a subtropical tree species (Guaiacum sanctum L.)

Global climate models predict changes on the length of the dry season in the Amazon which may affect tree physiology. The aims of this work were to determine the effect of the rainfall regime and fraction of sky visible (FSV) at the forest understory on leaf traits and gas exchange of ten rainforest tree species in the Central Amazon, Brazil. We also examined the relationship between specific leaf area (SLA), leaf thickness (LT), and leaf nitrogen content on photosynthetic parameters. Data were collected in January (rainy season) and August (dry season) of 2008. A diurnal pattern was observed for light saturated photosynthesis (Amax) and stomatal conductance (g s), and irrespective of species, Amax was lower in the dry season. However, no effect of the rainfall regime was observed on g s nor on the photosynthetic capacity (Apot, measured at saturating [CO2]). Apot and leaf thickness increased with FSV, the converse was true for the FSV-SLA relationship. Also, a positive relationship was observed between Apot per unit leaf area and leaf nitrogen content, and between Apot per unit mass and SLA. Although the rainfall regime only slightly affects soil moisture, photosynthetic traits seem to be responsive to rainfall-related environmental factors, which eventually lead to an effect on Amax. Finally, we report that little variation in FSV seems to affect leaf physiology (Apot) and leaf anatomy (leaf thickness).

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Does insect herbivory suppress ecosystem productivity? Evidence from a temperate woodland

10.1101/2021.01.28.428605 ◽

2021 ◽

Author(s):

Kristiina Visakorpi ◽

Sofia Gripenberg ◽

Yadvinder Malhi ◽

Terhi Riutta

Keyword(s):

Gas Exchange ◽

Leaf Area ◽

Primary Productivity ◽

Net Primary Productivity ◽

Leaf Gas Exchange ◽

Insect Herbivory ◽

Ecosystem Productivity ◽

Area Loss ◽

Leaf Area Loss ◽

The Relationship

AbstractOur current understanding of the relationship between insect herbivory and ecosystem productivity is limited. Previous studies have typically quantified only leaf area loss, or have been conducted during outbreak years. These set-ups often ignore the physiological changes taking place in the remaining plant tissue after insect attack, or may not represent typical, non-outbreak herbivore densities. Here, we estimate the amount of carbon lost to insect herbivory in a temperate deciduous woodland both through leaf area loss and, notably, through changes in leaf gas exchange in non-consumed leaves under non-outbreak densities of insects. We calculate how net primary productivity changes with decreasing and increasing levels of herbivory, and estimate what proportion of the carbon involved in the leaf area loss is transferred further in the food web. We estimate that the net primary productivity of an oak stand under ambient levels of herbivory is 54 - 69% lower than that of a completely intact stand. The effect of herbivory quantified only as leaf area loss (0.1 Mg C ha−1 yr−1) is considerably smaller than when the effects of herbivory on leaf physiology are included (8.5 Mg C ha−1 yr−1). We propose that the effect of herbivory on primary productivity is non-linear and mainly determined by changes in leaf gas exchange. We call for replicated studies in other systems to validate the relationship between insect herbivory and ecosystem productivity described here.

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Gas exchange and water use efficiency in seedlings of tree species from caatinga under water levels and potassium

Revista Principia - Divulgação Científica e Tecnológica do IFPB ◽

10.18265/1517-0306a2020v1n53p218-230 ◽

2021 ◽

Vol 1 (53) ◽

pp. 218

Author(s):

Ediglécia Pereira Almeida ◽

Antonio Lucineudo Oliveira Freire ◽

Ivonete Alves Bakke ◽

Cheila Deisy Ferreira

Keyword(s):

Gas Exchange ◽

Water Use Efficiency ◽

Water Use ◽

Tree Species ◽

Water Levels ◽

Use Efficiency

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Photosynthetic traits of five neotropical rainforest tree species: interactions between light response curves and leaf-to-air vapour pressure deficit

Brazilian Archives of Biology and Technology ◽

10.1590/s1516-89132005000600018 ◽

2005 ◽

Vol 48 (5) ◽

pp. 815-824 ◽

Cited By ~ 13

Author(s):

Marcelo Schramm Mielke ◽

Alex-Alan Furtado de Almeida ◽

Fábio Pinto Gomes

Keyword(s):

Gas Exchange ◽

Mathematical Models ◽

Tree Species ◽

Vapour Pressure ◽

Leaf Gas Exchange ◽

Vapour Pressure Deficit ◽

Light Response ◽

Photon Flux ◽

Neotropical Rainforest ◽

Photosynthetic Traits

Measurements of leaf gas exchange at different photosynthetic photon flux density (PPFD) levels were conducted in order to compare the photosynthetic traits of five neotropical rainforest tree species, with a special emphasis on empirical mathematical models to estimate the light response curve parameters incorporating the effects of leaf-to-air vapour pressure deficit (D) on the saturated photosynthetic rate (Amax). All empirical mathematical models seemed to provide a good estimation of the light response parameters. Comparisons of the leaf photosynthetic traits between different species needed to select an appropriate model and indicated the microenvironmental conditions when the data were collected. When the vapour pressure deficit inside the chamber was not controlled, the incorporation of linear or exponencial functions that explained the effects of D on leaf gas exchange, was a very good method to enhance the performance of the models.

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