Physical stress modifies top‐down and bottom‐up forcing on plant growth and reproduction in a coastal ecosystem

Daleo, Pedro; Alberti, Juan; Bruschetti, Carlos Martin; Pascual, Jesús; Iribarne, Oscar; Silliman, Brian R.

doi:10.1890/14-1776.1

Cited by 22 publications

(20 citation statements)

References 69 publications

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“…, Daleo et al. ). Fertilizer was spread into six artificial holes (5 cm deep, 1 cm diameter) evenly distributed in each plot that were then filled with mud.…”

Section: Methodsmentioning

confidence: 98%

“…Crab-exclusion plots were surrounded using a plastic mesh (10 mm opening) fence 0.6 m high and supported by iron stakes. Crab exclosures have been widely used in this system and the use of cage controls revealed that there are no associated cage artifacts (Daleo et al 2015). Salt addition plots received 20 g (~40 g/m 2 ) of commercial pelletized salt spread superficially every 2 weeks.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…Salt addition plots received 20 g (~40 g/m 2 ) of commercial pelletized salt spread superficially every 2 weeks. This salt loading increased plant tissue salinity at least up to 35%, leaf surface salinity by near 400% (Canepuccia et al 2010) and decreased plant growth by 50% (Daleo et al 2015). Nutrient addition treatments received 60 g (~120 g/m 2 ) of a slow-release pelletized fertilizer (NPK: 29:5:5) monthly.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…Nutrient addition treatments received 60 g (~120 g/m 2 ) of a slow-release pelletized fertilizer (NPK: 29:5:5) monthly. This fertilization rate increased biomass production by more than 400%, increased sediment nitrates by more than an order of magnitude (i.e., from 1.37 AE 0.14 lmol/L to 85.24 AE 24.28 lmol/L) and doubled S. densiflora leaf N content (Alberti et al 2011, Daleo et al 2015. Fertilizer was spread into six artificial holes (5 cm deep, 1 cm diameter) evenly distributed in each plot that were then filled with mud.…”

Section: Experimental Set-upmentioning

confidence: 99%

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Nitrogen enrichment suppresses other environmental drivers and homogenizes salt marsh leaf microbiome

Daleo

Alberti

Jumpponen

et al. 2018

Ecology

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Microbial community assembly is affected by a combination of forces that act simultaneously, but the mechanisms underpinning their relative influences remain elusive. This gap strongly limits our ability to predict human impacts on microbial communities and the processes they regulate. Here, we experimentally demonstrate that increased salinity stress, food web alteration and nutrient loading interact to drive outcomes in salt marsh fungal leaf communities. Both salinity stress and food web alterations drove communities to deterministically diverge, resulting in distinct fungal communities. Increased nutrient loads, nevertheless, partially suppressed the influence of other factors as determinants of fungal assembly. Using a null model approach, we found that increased nutrient loads enhanced the relative importance of stochastic over deterministic divergent processes; without increased nutrient loads, samples from different treatments showed a relatively (deterministic) divergent community assembly whereas increased nutrient loads drove the system to more stochastic assemblies, suppressing the effect of other treatments. These results demonstrate that common anthropogenic modifications can interact to control fungal community assembly. Furthermore, our results suggest that when the environmental conditions are spatially heterogeneous (as in our case, caused by specific combinations of experimental treatments), increased stochasticity caused by greater nutrient inputs can reduce the importance of deterministic filters that otherwise caused divergence, thus driving to microbial community homogenization.

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“…, Daleo et al. ). Fertilizer was spread into six artificial holes (5 cm deep, 1 cm diameter) evenly distributed in each plot that were then filled with mud.…”

Section: Methodsmentioning

confidence: 98%

Section: Experimental Set-upmentioning

confidence: 99%

Section: Experimental Set-upmentioning

confidence: 99%

Section: Experimental Set-upmentioning

confidence: 99%

See 2 more Smart Citations

Nitrogen enrichment suppresses other environmental drivers and homogenizes salt marsh leaf microbiome

Daleo

Alberti

Jumpponen

et al. 2018

Ecology

Self Cite

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“…It is later recognized that both top‐down (e.g., predators) and bottom‐up (e.g., nutrient availability) driving forces can act in concert with communities after decades of intense debate (Daleo et al. , Vidal and Murphy ). Disentangling the relative contributions of top‐down and bottom‐up forces can help explain the abundance and patterns of plants.…”

Section: Introductionmentioning

confidence: 99%

Human activities accelerated the degradation of saline seepweed red beaches by amplifying top‐down and bottom‐up forces

Xiao

Wei

et al. 2018

Ecosphere

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. 2018. Human activities accelerated the degradation of saline seepweed red beaches by amplifying top-down and bottom-up forces.Ecosphere 9(7):e02352. 10. 1002/ecs2.2352 Abstract. Salt marshes dominated by saline seepweed (Suaeda heteroptera) provide important ecosystem services such as sequestering carbon (blue carbon), maintaining healthy fisheries, and protecting shorelines. These salt marshes also constitute stunning red beach landscapes, and the resulting tourism significantly contributes to the local economy. However, land use change and degradation have led to a substantial loss of the red beach area. It remains unclear how human activities influence the top-down and bottom-up forces that regulate the distribution and succession of these salt marshes and lead to the degradation of the red beaches. We examined how bottom-up forces influenced the germination, emergence, and colonization of saline seepweed with field measurements and a laboratory experiment. We also examined whether top-down forces affected the red beach distribution by conducting a field survey for crab burrows and density, laboratory feeding trials, and waterbird investigations. The higher sediment accretion rate induced by human activities limited the establishment of new red beaches. The construction of tourism facilities and the frequent presence of tourists reduced the density of waterbirds, which in turn increased the density of crabs, intensifying the top-down forces such as predators and herbivores that drive the degradation of the coastal red beaches. Our results show that sediment accretion and plant-herbivory changes induced by human activities were likely the two primary ecological processes leading to the degradation of the red beaches. Human activities significantly shaped the abundance and distribution of the red beaches by altering both top-down and bottom-up ecological processes. Our findings can help us better understand the dynamics of salt marshes and have implications for the management and restoration of coastal wetlands.

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Timing of disturbance affects biomass and flowering of a saltmarsh plant and attack by stem‐boring herbivores

Pennings

2017

Ecosphere

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Citation: Li, S., and S. C. Pennings. 2017. Timing of disturbance affects biomass and flowering of a saltmarsh plant and attack by stem-boring herbivores. Ecosphere 8(2):e01675. 10.1002/ecs2.1675Abstract. In salt marshes, disturbance by wrack (floating mats of dead vegetation) is common and affects plant productivity and species composition, but little is known about how the timing of disturbance mediates these effects, nor how it interacts with herbivory. Using a field experiment on the Georgia coast, we simulated the effects of wrack disturbance at different times of the year on the marsh grass Spartina alterniflora and its stem-boring herbivorous insects. The timing of disturbance throughout the growing season strongly affected fall biomass, stem height, the proportion of stems flowering, and the proportion of stems colonized by stem-boring herbivorous insects. End-of-season biomass in plots disturbed in March did not differ from undisturbed controls, but biomass was reduced by 50% in plots disturbed in May, and by over 90% in plots disturbed in September. Disturbance in March and May stimulated flowering, but disturbance later in the growing season suppressed it. Plots disturbed late in the growing season had a low frequency of stem-boring herbivores. Stems containing stem borers rarely flowered. These results indicate that the timing of disturbance matters in coastal salt marshes. Late-season disturbances had the strongest effects on S. alterniflora and its herbivores. Disturbances early in the growing season did not affect endof-season biomass, and stimulated flowering, suggesting parallels between fire disturbance in grasslands and wrack disturbance in salt marshes. Late-season disturbance did reduce herbivory by stem-boring insects, but not enough to compensate for the direct effects of disturbance on the plants. Future studies of disturbance in salt marshes should consider how the timing of experimental disturbance treatments relates to the timing of natural disturbances.

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Physical stress modifies top‐down and bottom‐up forcing on plant growth and reproduction in a coastal ecosystem

Cited by 22 publications

References 69 publications

Nitrogen enrichment suppresses other environmental drivers and homogenizes salt marsh leaf microbiome

Nitrogen enrichment suppresses other environmental drivers and homogenizes salt marsh leaf microbiome

Human activities accelerated the degradation of saline seepweed red beaches by amplifying top‐down and bottom‐up forces

Timing of disturbance affects biomass and flowering of a saltmarsh plant and attack by stem‐boring herbivores

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