Limits...
Mutual positive effects between shrubs in an arid ecosystem.

Tirado R, Bråthen KA, Pugnaire FI - Sci Rep (2015)

Bottom Line: However, reciprocal positive effects benefiting two interacting species have seldom been reported and, in recent reviews, conceptually considered merely as facilitation when in fact there is room for adaptive strategies and evolutionary responses.We found that the spatial association between Maytenus senegalensis and Whitania frutescens, two shrub species of roughly similar size intimately interacting in our community, resulted in mutual benefit for both species.Benefits included improved water relations and nutritional status and protection against browsing, and did occur despite simultaneous competition for resources.

View Article: PubMed Central - PubMed

Affiliation: Estación Experimental de Zonas Áridas, Consejo Superior de Investigaciones Científicas, Ctra. Sacramento s/n, La Cañada, E-04120 Almería, Spain.

ABSTRACT
One-way facilitation in plants has been found in many harsh environments and their role as structural forces governing species composition in plant communities is now well established. However, reciprocal positive effects benefiting two interacting species have seldom been reported and, in recent reviews, conceptually considered merely as facilitation when in fact there is room for adaptive strategies and evolutionary responses. We tested the existence of such reciprocal positive effects in an arid environment in SE Spain using spatial pattern analysis, a species removal experiment, and a natural experiment. We found that the spatial association between Maytenus senegalensis and Whitania frutescens, two shrub species of roughly similar size intimately interacting in our community, resulted in mutual benefit for both species. Benefits included improved water relations and nutritional status and protection against browsing, and did occur despite simultaneous competition for resources. Our data suggest two-way facilitation or, rather, a facultative mutualism among higher plant species, a process often overlooked which could be a main driver of plant community dynamics allowing for evolutionary processes.

No MeSH data available.


Dry mass of branches (A) and number of new twigs per branch (B) of Whitania plants without protection and protected by thorny shrubs.N = 20 Whitania plants. Data are mean ± 1 SE; statistically significant differences (U Mann-Whitney test) noted by **(P < 0.001).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4588512&req=5

f4: Dry mass of branches (A) and number of new twigs per branch (B) of Whitania plants without protection and protected by thorny shrubs.N = 20 Whitania plants. Data are mean ± 1 SE; statistically significant differences (U Mann-Whitney test) noted by **(P < 0.001).

Mentions: Whitania shrubs living isolated in gaps were strongly affected by browsing. Most sampled branches in isolated shrubs had been eaten and lost nearly 50% of their mass (Fig. 4A), being shorter (16.6 ± 1.1 cm vs 24.7 ± 2.0 cm, P < 0.01) and with less twigs than protected branches (Fig. 4B). Differences in branch width at the base were not statistically significant (5.34 ± 0.38 mm protected vs. 6.20 ± 0.35 mm unprotected; P = 0.19) but differences in leaf mass were (0.68 ± 0.10 g vs. 0.18 ± 0.03 g; P < 0.0001) while woody stem mass did not differ between protected and unprotected branches (2.24 ± 0.51 g vs. 1.57 ± 0.42 g; P = 0.27). Whitania shrubs living isolated in gaps were strongly affected by browsing in comparison to shrubs protected from Maytenus, with number of scars on twigs being five times higher (Fig. 5).


Mutual positive effects between shrubs in an arid ecosystem.

Tirado R, Bråthen KA, Pugnaire FI - Sci Rep (2015)

Dry mass of branches (A) and number of new twigs per branch (B) of Whitania plants without protection and protected by thorny shrubs.N = 20 Whitania plants. Data are mean ± 1 SE; statistically significant differences (U Mann-Whitney test) noted by **(P < 0.001).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4588512&req=5

f4: Dry mass of branches (A) and number of new twigs per branch (B) of Whitania plants without protection and protected by thorny shrubs.N = 20 Whitania plants. Data are mean ± 1 SE; statistically significant differences (U Mann-Whitney test) noted by **(P < 0.001).
Mentions: Whitania shrubs living isolated in gaps were strongly affected by browsing. Most sampled branches in isolated shrubs had been eaten and lost nearly 50% of their mass (Fig. 4A), being shorter (16.6 ± 1.1 cm vs 24.7 ± 2.0 cm, P < 0.01) and with less twigs than protected branches (Fig. 4B). Differences in branch width at the base were not statistically significant (5.34 ± 0.38 mm protected vs. 6.20 ± 0.35 mm unprotected; P = 0.19) but differences in leaf mass were (0.68 ± 0.10 g vs. 0.18 ± 0.03 g; P < 0.0001) while woody stem mass did not differ between protected and unprotected branches (2.24 ± 0.51 g vs. 1.57 ± 0.42 g; P = 0.27). Whitania shrubs living isolated in gaps were strongly affected by browsing in comparison to shrubs protected from Maytenus, with number of scars on twigs being five times higher (Fig. 5).

Bottom Line: However, reciprocal positive effects benefiting two interacting species have seldom been reported and, in recent reviews, conceptually considered merely as facilitation when in fact there is room for adaptive strategies and evolutionary responses.We found that the spatial association between Maytenus senegalensis and Whitania frutescens, two shrub species of roughly similar size intimately interacting in our community, resulted in mutual benefit for both species.Benefits included improved water relations and nutritional status and protection against browsing, and did occur despite simultaneous competition for resources.

View Article: PubMed Central - PubMed

Affiliation: Estación Experimental de Zonas Áridas, Consejo Superior de Investigaciones Científicas, Ctra. Sacramento s/n, La Cañada, E-04120 Almería, Spain.

ABSTRACT
One-way facilitation in plants has been found in many harsh environments and their role as structural forces governing species composition in plant communities is now well established. However, reciprocal positive effects benefiting two interacting species have seldom been reported and, in recent reviews, conceptually considered merely as facilitation when in fact there is room for adaptive strategies and evolutionary responses. We tested the existence of such reciprocal positive effects in an arid environment in SE Spain using spatial pattern analysis, a species removal experiment, and a natural experiment. We found that the spatial association between Maytenus senegalensis and Whitania frutescens, two shrub species of roughly similar size intimately interacting in our community, resulted in mutual benefit for both species. Benefits included improved water relations and nutritional status and protection against browsing, and did occur despite simultaneous competition for resources. Our data suggest two-way facilitation or, rather, a facultative mutualism among higher plant species, a process often overlooked which could be a main driver of plant community dynamics allowing for evolutionary processes.

No MeSH data available.