Seed crop size variation in the dominant South American conifer Araucaria angustifolia

Souza, Alexandre F.; Matos, Daniele Uarte de; Forgiarini, Cristiane; Martinez, J.C. Gimeno

doi:10.1016/j.actao.2009.11.001

Cited by 22 publications

(17 citation statements)

References 46 publications

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“…It is currently unknown what factors determine whether a grass individual will flower during a given year. Reproductive effort is known to be controlled by nutrient resources (Curtis & Partch 1950;Snook, Camara-Cabrales & Kelty 2005;Hay, Kelly & Holdaway 2008;Way et al 2010) and climatic factors (Montserrat-Marti et al 2009;Souza et al 2010) in some plant species. In addition, it has been suggested that carbon acquisition by an individual grass tiller may be the primary driver of flowering, where a threshold of carbon gained by the plant must be met to trigger flowering (Gifford & Evans 1981;Colvill & Marshall 1984;Bouwmeester, Smid & Loman 1995).…”

Section: Introductionmentioning

confidence: 99%

Explaining temporal variation in above-ground productivity in a mesic grassland: the role of climate and flowering

et al. 2011

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Summary1. Annual above-ground net primary productivity (ANPP) in mesic grasslands is known to be highly temporally variable. While yearly precipitation or average yearly temperature can explain some of this temporal variability, much of the variation in ANPP remains unexplained. 2. Here we address the heretofore unexplained variation in 25 years of productivity data from a mesic grassland at Konza Prairie (north-eastern Kansas) by examining the effects of precipitation and temperature during periods relevant to the phenology and growth cycle of the dominant C 4 grasses and the flowering stalk production of these species. We assessed both the direct effects and indirect effects via flowering of phenologically relevant climate periods on ANPP using structural equation modelling (SEM). 3. We found ANPP to be strongly positively influenced by flowering stalk production of the dominant C 4 grasses, precipitation during periods relevant to vegetative growth (15 April-14 July) and flowering stalk elongation (15 July-14 August) of the dominant grasses, and fire. In addition, flowering stalk production was negatively influenced by high temperatures during the flowering stalk elongation period, which therefore resulted in a negative indirect effect on ANPP. We found little evidence for the effects of the previous year's total annual precipitation or mean annual temperature on ANPP. 4. By including flowering stalk production and separating climate variables into phenologically relevant periods we were able to increase the percentage of observed variance in ANPP explained by six models, relating to different topographic positions and burn regimes, from an average of 22% to 48%, with the best model explaining 61% of variation in ANPP. 5. Synthesis. The link between climatic periods relevant to the phenology and growth of dominant C 4 grasses, flowering stalk production of these grasses and ANPP shown here improves our ability to predict productivity in mesic grasslands, an ecologically and economically important ecosystem.

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Section: Introductionmentioning

confidence: 99%

Explaining temporal variation in above-ground productivity in a mesic grassland: the role of climate and flowering

et al. 2011

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“…First, A. angustifolia seeds fulfill all the requirements for being considered, a priori , a keystone resource (Peres ), as they are abundant and reliable, consumed by many species, and produced during periods of overall food scarcity (Paise & Vieira ; Iob & Vieira ; Souza et al . ). For these reasons, A. angustifolia seeds provide an excellent model to test hypotheses about short‐term food limitation in high‐productivity ecosystems.…”

Section: Discussionmentioning

confidence: 97%

“…Seed removal mimicked the traditional methods used by local people, who harvest seeds annually every autumn–winter (April–July) in Araucaria forests, mainly from the ground but also directly from tree crowns (Souza et al . ). Seeds were collected across the entire area of each seed‐removal plot (72 × 72 m), plus a boundary strip of 10 m width around the plots.…”

Section: Methodsmentioning

confidence: 97%

“…; Paise & Vieira ; Perini ), and (iv) are highly abundant during the period of production (Souza et al . ). Previous studies, using cameras and comparing seed removal rates within experimental exclosures and open plots, have shown that the main consumers of A. angustifolia seeds are small rodents (Iob & Vieira ; Brum et al .…”

Section: Introductionmentioning

confidence: 97%

“…trees do not exhibit mast seeding behavior, Souza et al . ), (iii) are produced during a period of overall food shortage, i.e. autumn–winter, when the availability of other seeds, fruit, and invertebrates is low (Mantovani et al .…”

Section: Introductionmentioning

confidence: 99%

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The importance of food supply in high‐productivity ecosystems: Short‐term experimental tests with small rodents

Prevedello

Vieira

et al. 2016

Austral Ecology

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Food availability is considered to be a primary factor affecting animal populations, yet few experimental tests have been performed to evaluate its actual importance in species-rich ecosystems such as rainforests. It has been suggested that in such systems certain plant species may act as "keystone" resources for animals, but the importance of presumed keystone resources for populations has not been quantified experimentally. Using complementary seed removal and seed-addition experiments, we determined how the supply of a presumed keystone resource, seeds of Araucaria angustifolia, affects short-term demography of their main consumer group (small rodents) in a biodiversity hotspot, the Brazilian Atlantic Forest. We hypothesized that (i) the harvest of A. angustifolia seeds by human populations has negative impacts on rodents, and (ii) these seeds are a limiting resource for rodent populations. To test these hypotheses, we monitored populations of two species of numerically dominant rodents (Delomys dorsalis and Akodon montensis) within replicated control-experimental plots. Manipulations of seed supply over 2 years had little effect on population size, body condition, survival, or reproduction of the two rodents, suggesting that, in the short-term (within one generation), their populations are not food limited in Araucaria forests. Despite apparently having all the characteristics of a keystone resource, as currently defined in the literature, the seeds of A. angustifolia had limited influence on the short-term demography of their main consumer group. In situations where purported keystone resources are seasonally abundant, their actual importance may be lower than generally assumed, and these resources then may have only localized and temporary effects on consumer populations.

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Latitudinal variation in seeds characteristics of Acer platanoides and A. pseudoplatanus

et al. 2014

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Seed crop size variation in the dominant South American conifer Araucaria angustifolia

Cited by 22 publications

References 46 publications

Explaining temporal variation in above-ground productivity in a mesic grassland: the role of climate and flowering

Explaining temporal variation in above-ground productivity in a mesic grassland: the role of climate and flowering

The importance of food supply in high‐productivity ecosystems: Short‐term experimental tests with small rodents

Latitudinal variation in seeds characteristics of Acer platanoides and A. pseudoplatanus

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