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Populations, pools, and peccaries: simulating the impact of ecosystem engineers on rainforest frogs.

Ringler M, Hödl W, Ringler E - Behav. Ecol. (2015)

Bottom Line: Following the supplementation, population size almost doubled as a result of increased autochthonous recruitment driven by a higher per-capita reproduction of males and a higher proportion of reproducing females.The effect was evenly distributed across the population.Our study shows that management and conservation must consider nontrophic relationships and that human "ecosystem engineering" can play a vital role in efforts against the "global amphibian decline."

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Zoology , University of Vienna , Althanstrasse 14 , A-1090 Vienna , Austria and.

ABSTRACT

"Ecosystem engineering" describes habitat alteration by an organism that affects another organism; such nontrophic interactions between organisms are a current focus in ecological research. Our study quantifies the actual impact an ecosystem engineer can have on another species by using a previously identified model system-peccaries and rainforest frogs. In a 4-year experiment, we simulated the impact of peccaries on a population of Allobates femoralis (Dendrobatidae) by installing an array of artificial pools to mimic a forest patch modified by peccaries. The data were analyzed using a gradual before-after control-impact (gBACI) model. Following the supplementation, population size almost doubled as a result of increased autochthonous recruitment driven by a higher per-capita reproduction of males and a higher proportion of reproducing females. The effect was evenly distributed across the population. The differential response of males and females reflects the reproductive behavior of A. femoralis, as only the males use the aquatic sites for tadpole deposition. Our study shows that management and conservation must consider nontrophic relationships and that human "ecosystem engineering" can play a vital role in efforts against the "global amphibian decline."

No MeSH data available.


Spatial arrangement of the treatment plot with artificial pools (small squares) and control plots; numbers and color/shading indicate the distance level (1–4) from the treatment plot (0); creeks and the Arataye River in dark gray; elevation lines in light gray.
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Figure 1: Spatial arrangement of the treatment plot with artificial pools (small squares) and control plots; numbers and color/shading indicate the distance level (1–4) from the treatment plot (0); creeks and the Arataye River in dark gray; elevation lines in light gray.

Mentions: The A. femoralis population is located near the field station “Saut Pararé” (4°02ʺN, 52°41ʺW; WGS84) in the nature reserve “Les Nouragues” in French Guiana. The lowland rainforest here is characterized in detail by Bongers et al. (2001), and the study area and the naturally delimited spatial setup of the A. femoralis population are described in detail by Ursprung et al. (2011a). The “study plot” of the latter is termed “study area” in this study, to avoid confusion with the 17 “study plots” that we used here for demographic analyses (Figure 1). Pluviometric data from the closest permanent weather station (Cacao, ~60 km from Pararé) were obtained from the French national meteorological service. Cumulative rainfall in hydrological years (beginning of rainy season to end of dry season; October to September) varied between 3205 and 4081mm from 2006 to 2010, and the driest months, September and October, received on average 71 and 90mm during this time, respectively. Two peccary species potentially occur in the region, Pecari tajacu (collared peccary) and Tayassu pecari (white-lipped peccary), though the latter has not been sighted in the Nouragues Reserve during the last 10 years (Hibert et al. 2011; Richard-Hansen et al. 2014). Prior to our study, we searched the whole study area for water bodies potentially serving as tadpole deposition sites. We found several depressions close to the bordering river and creeks (Figure 1), which filled up during heavy rains and flooding. However, during our study, none of these pools persisted for more than 5 days. No peccary wallows were present during our study. We concluded that, prior to our experiment, the A. femoralis males here had mainly relied on small ephemeral water-filled structures such as palm bracts, nuts, leaves or puddles on fallen tree trunks, as reported previously for this species (Gascon 1995; Ringler et al. 2009; Beck et al. 2010). The population was monitored for 4 seasons (28 January–24 April 2008; 17 January–16 March 2009; 16 January–16 March 2010; 30 January–24 February 2011) with a varying number of coworkers, totaling 150, 227, 200, and 182 people-days in the field, respectively. Surveys took place daily from 0900 to 1900 hours, with an equal time effort spent per unit area per day to ensure equal sampling across time and space within any season. We identified individual frogs manually based on their unique ventral pattern using the pattern matching program Wild-ID (Bolger et al. 2012); sex was determined by the presence (males) and absence (females) of skin folds of the vocal sac. All data were recorded in the field on a highly detailed digital map (Ringler et al. 2014), using pocket computers with the mobile GIS software ArcPad™7/8/10 (ESRI, Redlands, CA), and further handled in ArcGIS™9.3.1 (ESRI).


Populations, pools, and peccaries: simulating the impact of ecosystem engineers on rainforest frogs.

Ringler M, Hödl W, Ringler E - Behav. Ecol. (2015)

Spatial arrangement of the treatment plot with artificial pools (small squares) and control plots; numbers and color/shading indicate the distance level (1–4) from the treatment plot (0); creeks and the Arataye River in dark gray; elevation lines in light gray.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4374131&req=5

Figure 1: Spatial arrangement of the treatment plot with artificial pools (small squares) and control plots; numbers and color/shading indicate the distance level (1–4) from the treatment plot (0); creeks and the Arataye River in dark gray; elevation lines in light gray.
Mentions: The A. femoralis population is located near the field station “Saut Pararé” (4°02ʺN, 52°41ʺW; WGS84) in the nature reserve “Les Nouragues” in French Guiana. The lowland rainforest here is characterized in detail by Bongers et al. (2001), and the study area and the naturally delimited spatial setup of the A. femoralis population are described in detail by Ursprung et al. (2011a). The “study plot” of the latter is termed “study area” in this study, to avoid confusion with the 17 “study plots” that we used here for demographic analyses (Figure 1). Pluviometric data from the closest permanent weather station (Cacao, ~60 km from Pararé) were obtained from the French national meteorological service. Cumulative rainfall in hydrological years (beginning of rainy season to end of dry season; October to September) varied between 3205 and 4081mm from 2006 to 2010, and the driest months, September and October, received on average 71 and 90mm during this time, respectively. Two peccary species potentially occur in the region, Pecari tajacu (collared peccary) and Tayassu pecari (white-lipped peccary), though the latter has not been sighted in the Nouragues Reserve during the last 10 years (Hibert et al. 2011; Richard-Hansen et al. 2014). Prior to our study, we searched the whole study area for water bodies potentially serving as tadpole deposition sites. We found several depressions close to the bordering river and creeks (Figure 1), which filled up during heavy rains and flooding. However, during our study, none of these pools persisted for more than 5 days. No peccary wallows were present during our study. We concluded that, prior to our experiment, the A. femoralis males here had mainly relied on small ephemeral water-filled structures such as palm bracts, nuts, leaves or puddles on fallen tree trunks, as reported previously for this species (Gascon 1995; Ringler et al. 2009; Beck et al. 2010). The population was monitored for 4 seasons (28 January–24 April 2008; 17 January–16 March 2009; 16 January–16 March 2010; 30 January–24 February 2011) with a varying number of coworkers, totaling 150, 227, 200, and 182 people-days in the field, respectively. Surveys took place daily from 0900 to 1900 hours, with an equal time effort spent per unit area per day to ensure equal sampling across time and space within any season. We identified individual frogs manually based on their unique ventral pattern using the pattern matching program Wild-ID (Bolger et al. 2012); sex was determined by the presence (males) and absence (females) of skin folds of the vocal sac. All data were recorded in the field on a highly detailed digital map (Ringler et al. 2014), using pocket computers with the mobile GIS software ArcPad™7/8/10 (ESRI, Redlands, CA), and further handled in ArcGIS™9.3.1 (ESRI).

Bottom Line: Following the supplementation, population size almost doubled as a result of increased autochthonous recruitment driven by a higher per-capita reproduction of males and a higher proportion of reproducing females.The effect was evenly distributed across the population.Our study shows that management and conservation must consider nontrophic relationships and that human "ecosystem engineering" can play a vital role in efforts against the "global amphibian decline."

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Zoology , University of Vienna , Althanstrasse 14 , A-1090 Vienna , Austria and.

ABSTRACT

"Ecosystem engineering" describes habitat alteration by an organism that affects another organism; such nontrophic interactions between organisms are a current focus in ecological research. Our study quantifies the actual impact an ecosystem engineer can have on another species by using a previously identified model system-peccaries and rainforest frogs. In a 4-year experiment, we simulated the impact of peccaries on a population of Allobates femoralis (Dendrobatidae) by installing an array of artificial pools to mimic a forest patch modified by peccaries. The data were analyzed using a gradual before-after control-impact (gBACI) model. Following the supplementation, population size almost doubled as a result of increased autochthonous recruitment driven by a higher per-capita reproduction of males and a higher proportion of reproducing females. The effect was evenly distributed across the population. The differential response of males and females reflects the reproductive behavior of A. femoralis, as only the males use the aquatic sites for tadpole deposition. Our study shows that management and conservation must consider nontrophic relationships and that human "ecosystem engineering" can play a vital role in efforts against the "global amphibian decline."

No MeSH data available.