Soil nitrogen mediates the effect of climatic distance on herbivory rates in a tropical herb

Moutouama, Jacob K.; Gaoue, Orou G.

doi:10.1111/btp.13082

Cited by 3 publications

(2 citation statements)

References 97 publications

(95 reference statements)

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“…Consistent with our results, previous studies demonstrate that an increase of nitrogen in soil can significantly increase plant species probability of extinction (Gotelli & Ellison, 2002). In our study system, high soil nitrogen concentration was associated with high herbivory (Moutouama & Gaoue, 2022b), suggesting that the negative effect of soil nitrogen on population dynamics could be due to excessive herbivory. The detrimental effects of nitrogen could be also explained by its saturation in the soil and a resulting decrease in nitrogen retention in the soil (Heil & Diemont, 1983).…”

Section: Discussionsupporting

confidence: 92%

Effects of range and niche position on the population dynamics of a tropical plant

Moutouama

Gaoue

2023

Ecology

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The center‐periphery hypothesis predicts a decline in population performance toward the periphery of a species' range, reflecting an alteration of environmental conditions at range periphery. However, the rare demographic tests of this hypothesis failed to disentangle the role of geography from that of ecological niche and are biased toward temperate regions. We hypothesized that, because species are expected to experience optimal abiotic conditions at their climatic niche center, (1) central populations will have better demographic growth, survival, and fertility than peripheral populations. As a result, (2) central populations are expected to have higher growth rates than peripheral populations. Peripheral populations are expected to decline, thus limiting species range expansion beyond these boundaries. Because peripheral populations are expected to be in harsh environmental conditions, (3) population growth rate will be more sensitive to perturbation of survival‐growth rather than fertility in peripheral populations. Finally, we hypothesized that (4) soils properties will drive the variations in population growth rates for narrowly distributed species for which small scale ecological factors could outweigh landscape level drivers. To test these hypotheses, we studied the demography of Thunbergia atacorensis (Acanthaceae), a range‐limited herb in West Africa. We collected three years of demographic data to parameterize an integral projection model (IPM) and estimated population level demographic statistics. Demographic vital rates and population growth rates did not change significantly with distance from geographic or climatic center, contrary to predictions. However, populations at the center of the geographic range were demographically more resilient to perturbation than those at the periphery. Soil nitrogen was the main driver of population growth rate variation. The relative influence of survival‐growth on population growth rates exceeded that of fertility at the geographic range center while we observed the opposite pattern for climatic niche. Our study highlights the importance of local scale processes in shaping the dynamics and distribution of range‐limited species. Our findings also suggest that the distinction between geographic distribution and climatic niche is important for a robust demographic test of the center‐periphery hypothesis.

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Section: Discussionsupporting

confidence: 92%

Effects of range and niche position on the population dynamics of a tropical plant

Moutouama

Gaoue

2023

Ecology

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“…To estimate the total number of plant species per family (dependent variable), we installed 91 plots of 5 m × 5 m from the center to the edge of each village, ensuring that it covered the habitats utilised by local people. We selected 5 m × 5 m based on previous studies in the same study area (Moutouama & Gaoue, 2022). In each plot, we recorded the botanical name and density of each species.…”

Section: Data Collectionmentioning

confidence: 99%

A phylogenetic evaluation of non‐random medicinal plants selection around an African biosphere reserve

Moutouama,

Gaoue

2023

People and Nature

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Theory in ethnobiology suggests that the selection of medicinal plants by local people in a given region is not random and evolutionary closely related species may have similar medicinal uses. Additionally, plants selection by local people is often driven by plant therapeutic efficacy, plant availability, plant versatility or local knowledge on medicinal plants. We tested the hypothesis of non‐random selection of medicinal plants as well as the potential mechanisms explaining such non‐random plants selection. We also tested for phylogenetic signal in medicinal plants. Our study was based in four villages across Benin, West Africa, where the local communities have deep knowledge about medicinal plants. We installed 91 plots around these four villages to establish the total list of plant species and their abundance. We then conducted ethnobotanical surveys in the same villages to identify medicinal plants used in the local pharmacopoeia. To test whether the selection of medicinal plants used in the region was non‐random and whether plant selection was driven by plant therapeutic efficacy, plant availability, plant versatility or local knowledge, we used a generalized linear model. Furthermore, we used the D‐statistic to test whether evolutionary closely related species are more commonly used as medicinal than other species. We found support for non‐random medicinal plant selection. Such a non‐random plant selection was driven by plant medicinal versatility. Plant availability and secondary compounds have no significant influence on plant selection. Local people's knowledge on medicinal plants was significantly affected by individuals' literacy but not by their gender, their age or the ethnic group they belong to. We found a weak phylogenetic signal in medicinal plant uses. Our study reveals that the most used families are not necessarily the ones that have more secondary compounds or that are the most available to the local people, but are the most versatile plants. The high level of medicinal flora used at the local scale, which contrasts with the country‐level analysis found by previous studies, suggests new methodological guidance in testing the theory of non‐random medicinal plants selection. Read the free Plain Language Summary for this article on the Journal blog.

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Soil nitrogen mediates the effect of climatic distance on herbivory rates in a tropical herb

Moutouama

Gaoue

2022

Biotropica

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The center‐periphery hypothesis predicts that species are most abundant at the center of their distribution range. Differential herbivory rates between center and periphery populations can explain this variation in species abundance. However, if the geographic center of a species distribution coincides with its ecological optimum, the resource availability hypothesis predicts higher herbivory rates and tolerances at the center compared to the periphery. Biogeographical studies on herbivory have treated these two mechanisms separately, limiting our mechanistic understanding of the role of herbivory in shaping species range limits. We analyzed the role of resource availability on herbivory variation from center to periphery using data collected across the distribution of Thunberbia atacorensis, a range‐limited species of West Africa. We used two types of distances: geographic distance (the distance from each plot to the geographic center of all populations) and climatic distance (the distance from each plot to the preferendum of the species). We found no increase in herbivory toward the periphery of the climatic and geographic ranges. However, herbivory rates increased with soil nitrogen. Soil nitrogen decreased from the center to the periphery of the climatic range. Phylogenetic diversity and competition from surrounding plants did not affect herbivory rates. Our study provides insights into how nutrient limitation can shape species center‐periphery distribution by altering spatial variation in herbivory rates.

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Soil nitrogen mediates the effect of climatic distance on herbivory rates in a tropical herb

Cited by 3 publications

References 97 publications

Effects of range and niche position on the population dynamics of a tropical plant

Effects of range and niche position on the population dynamics of a tropical plant

A phylogenetic evaluation of non‐random medicinal plants selection around an African biosphere reserve

Soil nitrogen mediates the effect of climatic distance on herbivory rates in a tropical herb

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