Mycorrhizal community resilience in response to experimental plant functional type removals in a woody ecosystem.

URCELAY, C; DÍAZ, SM; GURVICH, DE; CHAPIN, FS III; CUEVAS, E; DOMÍNGUEZ, LS

JOURNAL OF ECOLOGY (PRINT)

Año: 2008

0022-0477

Abstract Dominant plant functional types (PFTs) are expected to be primary determinants of  communities of other above- and below-ground organisms. Here we report the effects of the  experimental removal of different PFTs on arbuscular mycorrhizal fungi (AMF) communities in  a shrubland ecosystem in central Argentina. . On the basis of the biomass-ratio hypothesis and plant resource use strategy theory, we expected  the effect of removal of PFTs on AMF colonization and spores to be proportional to the biomass 24 removed and to be stronger when more conservative PFTs were removed. The treatments 25 applied were: undisturbed control (no plant removed), disturbed control (mechanical 26 disturbance), no shrub (removal of deciduous shrubs), no perennial forb (removal of perennial 27 forbs), no graminoid (removal of graminoids) and no annual forb (removal of annual forbs). 28 AMF colonization was assessed after 5, 17 and 29 months. Total density of AMF spores, 29 richness and evenness of morphotaxa, and AMF functional groups were quantified after 5, 17, 30 29, 36 and 39 months. 31 3. Five months after the initial removal we found a significant reduction in total AMF colonization 32 in all plots subjected to PFT removals and in the disturbed control plots, as compared to the 33 undisturbed controls. This effect disappeared afterwards and no subsequent effect on total 34 colonization and colonization by arbuscules was observed. In contrast, a significant increase in 35 colonization by vesicles was observed in months 17 and 29, mainly in no graminoid plots. In 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no 28 AMF colonization was assessed after 5, 17 and 29 months. Total density of AMF spores, 29 richness and evenness of morphotaxa, and AMF functional groups were quantified after 5, 17, 30 29, 36 and 39 months. 31 3. Five months after the initial removal we found a significant reduction in total AMF colonization 32 in all plots subjected to PFT removals and in the disturbed control plots, as compared to the 33 undisturbed controls. This effect disappeared afterwards and no subsequent effect on total 34 colonization and colonization by arbuscules was observed. In contrast, a significant increase in 35 colonization by vesicles was observed in months 17 and 29, mainly in no graminoid plots. In 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no 27 forbs), no graminoid (removal of graminoids) and no annual forb (removal of annual forbs). 28 AMF colonization was assessed after 5, 17 and 29 months. Total density of AMF spores, 29 richness and evenness of morphotaxa, and AMF functional groups were quantified after 5, 17, 30 29, 36 and 39 months. 31 3. Five months after the initial removal we found a significant reduction in total AMF colonization 32 in all plots subjected to PFT removals and in the disturbed control plots, as compared to the 33 undisturbed controls. This effect disappeared afterwards and no subsequent effect on total 34 colonization and colonization by arbuscules was observed. In contrast, a significant increase in 35 colonization by vesicles was observed in months 17 and 29, mainly in no graminoid plots. In 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no 28 AMF colonization was assessed after 5, 17 and 29 months. Total density of AMF spores, 29 richness and evenness of morphotaxa, and AMF functional groups were quantified after 5, 17, 30 29, 36 and 39 months. 31 3. Five months after the initial removal we found a significant reduction in total AMF colonization 32 in all plots subjected to PFT removals and in the disturbed control plots, as compared to the 33 undisturbed controls. This effect disappeared afterwards and no subsequent effect on total 34 colonization and colonization by arbuscules was observed. In contrast, a significant increase in 35 colonization by vesicles was observed in months 17 and 29, mainly in no graminoid plots. In 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no no shrub (removal of deciduous shrubs), no perennial forb (removal of perennial 27 forbs), no graminoid (removal of graminoids) and no annual forb (removal of annual forbs). 28 AMF colonization was assessed after 5, 17 and 29 months. Total density of AMF spores, 29 richness and evenness of morphotaxa, and AMF functional groups were quantified after 5, 17, 30 29, 36 and 39 months. 31 3. Five months after the initial removal we found a significant reduction in total AMF colonization 32 in all plots subjected to PFT removals and in the disturbed control plots, as compared to the 33 undisturbed controls. This effect disappeared afterwards and no subsequent effect on total 34 colonization and colonization by arbuscules was observed. In contrast, a significant increase in 35 colonization by vesicles was observed in months 17 and 29, mainly in no graminoid plots. In 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no 28 AMF colonization was assessed after 5, 17 and 29 months. Total density of AMF spores, 29 richness and evenness of morphotaxa, and AMF functional groups were quantified after 5, 17, 30 29, 36 and 39 months. 31 3. Five months after the initial removal we found a significant reduction in total AMF colonization 32 in all plots subjected to PFT removals and in the disturbed control plots, as compared to the 33 undisturbed controls. This effect disappeared afterwards and no subsequent effect on total 34 colonization and colonization by arbuscules was observed. In contrast, a significant increase in 35 colonization by vesicles was observed in months 17 and 29, mainly in no graminoid plots. In 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no no graminoid (removal of graminoids) and no annual forb (removal of annual forbs). 28 AMF colonization was assessed after 5, 17 and 29 months. Total density of AMF spores, 29 richness and evenness of morphotaxa, and AMF functional groups were quantified after 5, 17, 30 29, 36 and 39 months. 31 3. Five months after the initial removal we found a significant reduction in total AMF colonization 32 in all plots subjected to PFT removals and in the disturbed control plots, as compared to the 33 undisturbed controls. This effect disappeared afterwards and no subsequent effect on total 34 colonization and colonization by arbuscules was observed. In contrast, a significant increase in 35 colonization by vesicles was observed in months 17 and 29, mainly in no graminoid plots. In 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, no no graminoid plots. In 36 general, treatments did not significantly affect AMF spores in the soil. On the other hand, nono 37 annual forb promoted transient (12 – 18 months) higher ammonia availability, and no shrubannual forb promoted transient (12 – 18 months) higher ammonia availability, and no shrub 38 promoted lower nitrate availability in the longer term (24 – 28 months). 39 4. Synthesis. Our experiment, the first to investigate the effects of the removal of different PFTs on 40 AMF communities in natural ecosystems, indicates that AMF communities are resilient to 40 AMF communities in natural ecosystems, indicates that AMF communities are resilient to Synthesis. Our experiment, the first to investigate the effects of the removal of different PFTs on 40 AMF communities in natural ecosystems, indicates that AMF communities are resilient to Journal of Ecology Page 2 of 48 For Peer Review Urcelay et al. 3 changes in the soil and in the functional composition of vegetation. F 41 urthermore, it does not 42 provide consistent evidence in support of the biomass-ratio hypothesis or differential trait-based 43 direct or indirect effects of different PFTs on AMF in this particular system.