Pennings, S. C., and R. M. Callaway. 1992. Salt marsh plant zonation: the relative importance of competition and physical factors. Ecology 73:681–690. Questions 1. What three factors did the authors investigate in this study? 2. Summarize the design used for the two Salicornia experiments. Describe the predictor variables, including their treatment levels, response variables, and number of replicates used in each experiment. Explain how randomization was incorporated into the study. Provide a visual diagram of the experimental design. 3. The authors state that as marsh elevation increases, stress from flooding decreases, while stress from salinity increases. Did their results support this assertion? Which figures (number and letter) present the results for flooding (soil waterlogging) and salinity (soil water potential)? 4. The authors state that one potential problem with the transplant experiment is that transplanting itself may have an adverse effect. Did transplanting affect mortality? If yes, provide documentation from the paper. Did transplanting affect growth? If yes, provide documentation from the paper. 5. What evidence (cite relevant figures—number and letter) supports the author’s contention that competition with Salicornia limits Arthrocnemum in the high Salicornia zone? What evidence (cite relevant figures—number and letter) supports their contention that competition with Arthrocnemum limits Salicornia in the Arthrocnemum zone? 6. Do the authors support their contention that multiple factors, both physical stresses and interspecific competition, influence the zonation patterns observed in the salt marsh? Solution 1. Flooding, soil salinity and competition 2. Two experiments were performed to investigate the relative importance of biological factors in Salicornia and Arthrocnemum zoneation. Growth rate and biomass in several marsh zones were measured initially followed by the reciprocally transplanted both species. Mass of green portions, total mass and final percent were the prdictor variables. Growth of the plants were also monitored and this is comes under response variables. Totally 3 replicates were used. 3. The broader marsh zones are determined by Salicornia greater flooding tolerance and it allowing exist low in the marsh as well as Arthrocnemum greater tolerance to high salinity. Figure 6-8 indicated that growth and survival of Salicornia and they are affected by both soil water potential and flooding. Waterlogging affects redox potential and also affects the availability of nutrients in the soil. 4. Survival of transplants was lower than the Salicornia, because survival and growth are affected due to transplantation. 5 Figure 7 and Figure 8. Both species, not grown well in transition zone even through flooding is much reduced. It is mainly due to the high salinity of the transition zone soil 6. Field patterns are ususlly determined by two physical factors that operating in a combination with interspecific competition..

1. Pennings, S. C., and R. M. Callaway. 1992. Salt marsh plant zonation: the relative importance of
competition and physical factors. Ecology 73:681–690.
Questions 1. What three factors did the authors investigate in this study?
2. Summarize the design used for the two Salicornia experiments. Describe the predictor
variables, including their treatment levels, response variables, and number of replicates used in
each experiment. Explain how randomization was incorporated into the study. Provide a visual
diagram of the experimental design.
3. The authors state that as marsh elevation increases, stress from flooding decreases, while
stress from salinity increases. Did their results support this assertion? Which figures (number and
letter) present the results for flooding (soil waterlogging) and salinity (soil water potential)?
4. The authors state that one potential problem with the transplant experiment is that
transplanting itself may have an adverse effect. Did transplanting affect mortality? If yes,
provide documentation from the paper. Did transplanting affect growth? If yes, provide
documentation from the paper.
5. What evidence (cite relevant figures—number and letter) supports the author’s contention that
competition with Salicornia limits Arthrocnemum in the high Salicornia zone? What evidence
(cite relevant figures—number and letter) supports their contention that competition with
Arthrocnemum limits Salicornia in the Arthrocnemum zone?
6. Do the authors support their contention that multiple factors, both physical stresses and
interspecific competition, influence the zonation patterns observed in the salt marsh?
Solution
1. Flooding, soil salinity and competition
2. Two experiments were performed to investigate the relative importance of biological factors in
Salicornia and Arthrocnemum zoneation. Growth rate and biomass in several marsh zones were
measured initially followed by the reciprocally transplanted both species. Mass of green portions,
total mass and final percent were the prdictor variables. Growth of the plants were also
monitored and this is comes under response variables. Totally 3 replicates were used.
3. The broader marsh zones are determined by Salicornia greater flooding tolerance and it
allowing exist low in the marsh as well as Arthrocnemum greater tolerance to high salinity.
Figure 6-8 indicated that growth and survival of Salicornia and they are affected by both soil
water potential and flooding. Waterlogging affects redox potential and also affects the
availability of nutrients in the soil.
4. Survival of transplants was lower than the Salicornia, because survival and growth are affected

2. due to transplantation.
5 Figure 7 and Figure 8. Both species, not grown well in transition zone even through flooding is
much reduced. It is mainly due to the high salinity of the transition zone soil
6. Field patterns are ususlly determined by two physical factors that operating in a combination
with interspecific competition.