Cushion shrubs encroach subhumid rangelands and form fertility islands along a grazing gradient in Patagonia

Vogel, Braian; Rostagno, César Mario; Molina, Lucía; Antilef, Marcos; Manna, Ludmila La

doi:10.1007/s11104-022-05398-1

Cited by 13 publications

(6 citation statements)

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“…In the shrub–grass and grass steppes, only the cover of highly preferred grasses was reduced, but this reduction was partially offset by an increase in the ground cover and individual plant size of shrubs. This pattern has been well documented in many drylands, where intensive grazing promotes species replacement and woody encroachment (Aguiar et al., 1996; Bertiller & Bisigato, 1998; Van Auken, 2000; Bestelmeyer et al., 2004; Fensham et al., 2010; Gatica et al., 2020; Merdas et al., 2021; Vogel et al., 2022). The main mechanism behind this replacement is the selective grazing on grasses that releases resources and changes competitive interactions (Sala et al., 1989).…”

Section: Discussionmentioning

confidence: 75%

“…Solid lines indicate significant relationships (p < 0.05) and dotted lines indicate non-significant relationships (p > 0.1) within each community. Bestelmeyer et al, 2004;Fensham et al, 2010;Gatica et al, 2020;Merdas et al, 2021;Vogel et al, 2022). The main mechanism behind this replacement is the selective grazing on grasses that releases resources and changes competitive interactions (Sala et al, 1989).…”

Section: Discussionmentioning

confidence: 99%

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Effects of livestock grazing intensification on plant communities of Patagonian drylands increase with increasing aridity

Carboni,

Yahdjian,

Oñatibia

2023

Applied Vegetation Science

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QuestionLivestock grazing affects plant communities in drylands worldwide. However, our current understanding of the Patagonian drylands has primarily been derived from comparing exclosures with grazing conditions or from single‐site grazing gradients. The pending question is: do impacts of grazing intensification on Patagonian plant communities change along aridity gradients?LocationPatagonia, Argentina.MethodsWe surveyed vegetation cover of perennial species in paddocks with different sheep‐grazing pressure (ungrazed, lightly, moderately, and intensively grazed, based on long‐term stocking rates), in three plant communities located along a regional aridity gradient: a semi‐desert (arid), a shrub–grass steppe (semi‐arid), and a grass steppe (dry sub‐humid). In these communities, we analyzed the effects of grazing pressure on the total cover of vegetation, the cover of dominant plant life‐forms (grasses and shrubs), the plant species diversity, and the traits of dominant plant species.ResultsIntensification of sheep grazing significantly decreased total vegetation cover in the semi‐desert, but not in the steppes. Although grazing decreased the cover of grasses (particularly of the highly preferred ones) in all communities, in the shrub–grass and grass steppes this reduction was offset by an increase in the cover and size of shrubs. Plant diversity was not consistently affected by grazing pressure in these communities. Traits of dominant plant species partially explained community responses to grazing intensification.ConclusionsLivestock grazing intensification reduces the forage quantity and quality of Patagonian plant communities, but the severity depends on plant community types. In semi‐deserts (the most arid), grasses were drastically affected, while in the steppes, the grazing effects on grasses were low and partially compensated by an increase in the cover and size of shrubs, which fulfill critical roles other than forage provision. It is fundamental that grazing pressure be adapted to forage resource availability for each community type to achieve sustainable management in the context of climate change.

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Section: Discussionmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 99%

Effects of livestock grazing intensification on plant communities of Patagonian drylands increase with increasing aridity

Carboni,

Yahdjian,

Oñatibia

2023

Applied Vegetation Science

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“…It can even show all of the necessary properties (Díaz‐Sierra et al, 2017). Recently, the RII has been applied to quantify the magnitude of fertile islands by estimating the net effect of shrub patches on soil C, N, and P (Cai et al, 2020; Ding & Eldridge, 2021; Vogel et al, 2022; Zhao & An, 2021). The numerical values of this index are limited (ranging from −1 to +1) and symmetrical around zero (equal absolute value with opposite sign represents equal intensity in the effect from a contrary driver).…”

Section: Methodsmentioning

confidence: 99%

Does the fertile island effect in tamarisk nebkhas enhance in the northern Tarim Basin in the context of global warming?

Yin,

Shi,

Zhou

et al. 2023

Ecosphere

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With the intensification of global warming, uncertainty regarding ecosystem evolution trends in drylands has increased. The objective of this article was to test whether the desertification process of tamarisk shrubland was intensified by comparing fertile island effects and soil ecological stoichiometry characteristics at different time periods. The tamarisk shrubland in the “shrubland” and “shrub duneland” stages in the northern Tarim Basin was selected, and soil samples were collected from the tamarisk nabkhas and from the interspaces between tamarisk nebkhas at the 0‐ to 30‐cm soil layers in 2009 and 2018. Soil carbon (C), nitrogen (N), and phosphorous (P) were analyzed, and the C/N, C/P, and N/P ratios were calculated. In comparison with 2009, fertile island effects were completely collapsed in the shrub duneland stage, with no obvious changes in the shrubland stage in 2018. The average soil C/N ratio decreased from a value greater than 25 in both stages. The average value of soil C/P ratio was below 200 in the shrubland and shrub duneland stages, with almost no marked change after nine years. The soil N/P ratio in our study significantly increased in 2018 than in 2009, but the soil N/P ratio was still much less than 11.9. Significantly positive correlations were observed between the relative interaction index (RII) of soil organic carbon (SOC) and soil total nitrogen (TN) and the soil C/P and N/P ratios in the tamarisk nebkhas. These results suggested that (1) fertile island effects were positive in relation to soil stoichiometry in tamarisk nebkhas in most cases; (2) the desertification process was accelerated in the shrub duneland stage, with no obvious progress during the shrubland stage; and (3) the loss of soil C from the collapsed fertile islands could therefore accelerate global warming.

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“…Se han documentado modificaciones en la composición de especies en el estrato herbáceo de bosques abiertos de todo el mundo inducidas por el pastoreo (Vogel et. al 2022).…”

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Composición florística y funcional del pastizal natural del centro de la Argentina: Efecto del pastoreo bovino y el fuego

et al. 2022

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oeste ha intensificado la actividad ganadera en zonas semiáridas, disminuyendo la probabilidad de encontrar sitios que no estén severamente antropizados con fines productivos. Los objetivos de este trabajo fueron caracterizar la composición florística y funcional del estrato herbáceo de bosques de caldén en un sitio excluido del pastoreo doméstico en los últimos 50 años, y compararla con otras dos situaciones: una, con un evento de fuego invernal y posterior exclusión del pastoreo de ganado bovino; y otra, con pastoreo rotativo. En cada uno de los tres sitios se estimó la cobertura de especies herbáceas dentro de 10 marcos de 1x1 m mediante el método de Braun-Blanquet. En primer lugar, se analizó la composición florística en cuanto a riqueza y diversidad. En segundo lugar, se realizó un análisis de NMDS para caracterizar las comunidades vegetales. Por último, se comparó la cobertura de los grupos funcionales (palatabilidad, ciclo de vida y origen) entre los sitios mediante un análisis de Kruskal-Wallis. La riqueza y la diversidad medias fueron similares en las tres condiciones, mientras que la riqueza total fue mayor en el sitio excluido. La composición florística varió entre sitios, mientras que la composición funcional resultó similar entre el sitio excluido y pastoreado. El sitio excluido al pastoreo es una oportunidad para caracterizar la vegetación local sin influencia del pastoreo por el ganado bovino, dado que se encuentran muy pocas áreas que no hayan sido explotadas con fines económicos durante un período de tiempo tan extenso.[Palabras clave: comunidad vegetal, disturbios, ganadería] A��. Floristic and functional composition of natural grasslands in central Argentina: The effect of ca�le grazing and fire. The state and conservation of the natural resources involved in production systems is of global concern. In Argentina, the expansion of the agricultural frontier from the Humid Pampa to the west has intensified livestock activity in semi-arid areas, decreasing the probability of finding sites that are not severely anthropized for productive purposes. The objectives of this work were to characterize the floristic and functional composition of the herbaceous stratum of caldén forests in a site excluded from domestic grazing in the last 50 years and to compare it with two other situations: one, with a winter fire event and subsequent exclusion of ca�le grazing; and the other, with rotational grazing. In each of the three sites, the cover of herbaceous species within ten 1x1 m frames was estimated using the Braun-Blanquet method. First, the floristic composition was analysed in terms of richness and diversity. Secondly, an NMDS analysis was carried out to characterize the plant communities. Finally, the coverage of functional groups (palatability, life cycle and origin) was compared between sites using a Kruskal-Wallis analysis. Mean richness and diversity were similar in the three conditions, while total richness was higher in the excluded site. Floristic composition varied between sites, while funct...

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Cushion shrubs encroach subhumid rangelands and form fertility islands along a grazing gradient in Patagonia

Cited by 13 publications

References 130 publications

Effects of livestock grazing intensification on plant communities of Patagonian drylands increase with increasing aridity

Effects of livestock grazing intensification on plant communities of Patagonian drylands increase with increasing aridity

Does the fertile island effect in tamarisk nebkhas enhance in the northern Tarim Basin in the context of global warming?

Composición florística y funcional del pastizal natural del centro de la Argentina: Efecto del pastoreo bovino y el fuego

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