Location

Parker-Reed, SSWAC

Start Date

1-5-2014 10:00 AM

End Date

1-5-2014 11:00 AM

Project Type

Poster

Description

Forest restorations aim to maximize the number of species and the productivity at the community level. In a tropical rainforest restoration, often limited number of species are available from local growers; so manipulating the number of individuals of each species (the evenness) might best achieve the goals of restoration. Planting equal numbers of individuals of each species may allow for the most complementary use of soil nutrients; however fertilizer may change this dynamic. Moreover, in a community where there is one dominant species, the productivity of the community may depend upon the identity of that dominant species. We asked whether evenness among species in the community influences the growth of tree seedlings in a tropical forest restoration, and whether community productivity depends on nutrient availability. We altered the relative abundance of tree seedlings in 16 plots within a nonnative bamboo plantation in Costa Rica. The number and composition of species were consistent across plots. The identity of the dominant species varied among low-evenness plots. Half of the plots were fertilized five times over two wet seasons; trees were measured after 18 months. Seedlings grew largest in fertilized, high evenness plots. There was a significant interaction between the fertilizer and evenness treatments due to the fact that not all species responded to the addition of nutrients. When fertilized, sun loving species showed the most dramatic growth response, while shade-tolerant and shade loving species had less biomass. Thus, the reduced overall response to fertilizer that we observed in low evenness plots was likely due to species-specific responses. Our results suggest that at an early stage of restoration, maximizing evenness can increase biomass production.

Sponsoring Department

Colby College. Biology Dept.

CLAS Field of Study

Natural Sciences

Event Website

http://www.colby.edu/clas

ID

65

Included in

Biology Commons

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May 1st, 10:00 AM May 1st, 11:00 AM

Nutrient Availability and Species Evenness Influence Productivity During Early Stages of a Tropical Forest Restoration

Parker-Reed, SSWAC

Forest restorations aim to maximize the number of species and the productivity at the community level. In a tropical rainforest restoration, often limited number of species are available from local growers; so manipulating the number of individuals of each species (the evenness) might best achieve the goals of restoration. Planting equal numbers of individuals of each species may allow for the most complementary use of soil nutrients; however fertilizer may change this dynamic. Moreover, in a community where there is one dominant species, the productivity of the community may depend upon the identity of that dominant species. We asked whether evenness among species in the community influences the growth of tree seedlings in a tropical forest restoration, and whether community productivity depends on nutrient availability. We altered the relative abundance of tree seedlings in 16 plots within a nonnative bamboo plantation in Costa Rica. The number and composition of species were consistent across plots. The identity of the dominant species varied among low-evenness plots. Half of the plots were fertilized five times over two wet seasons; trees were measured after 18 months. Seedlings grew largest in fertilized, high evenness plots. There was a significant interaction between the fertilizer and evenness treatments due to the fact that not all species responded to the addition of nutrients. When fertilized, sun loving species showed the most dramatic growth response, while shade-tolerant and shade loving species had less biomass. Thus, the reduced overall response to fertilizer that we observed in low evenness plots was likely due to species-specific responses. Our results suggest that at an early stage of restoration, maximizing evenness can increase biomass production.

http://digitalcommons.colby.edu/clas/2014/program/151