Ecophysiological performance of a threatened shrub under restored and natural conditions in a harsh tropical mountaintop environment

Silvana A B Castro,Fabiana A Mourão,Camila E M Sá,G Wilson Fernandes,José P Lemos-Filho,Heitor M Duarte

doi:10.1590/0102-33062015abb0178

Abstract

Ecophysiological responses of plants are useful for monitoring the success of ecological restoration projects that target species conservation. In this study we evaluated the ecophysiological traits of individuals of Chamaecrista semaphora from a natural population and from a site under restoration. Water potential and chlorophyll a fluorescence parameters were measured both in adult and young plants of the two populations. No difference in water potential was found between sites, but individuals in the restored site had higher water potential at predawn. Adults in the natural site presented lower daily values of potential quantum yield, indicating the occurrence of photoinhibition. Individuals in the restored site also presented higher maximum relative electron transport rate (ETRMAX). No difference was found in leaf carbon isotope discrimination values (σ13C) between plants growing in restored and natural sites, suggesting similar water use efficiency. These results indicate that C. semaphora individuals in the restored site had similar or better photosynthetic and water economy performances than individuals at the natural site. Methodologies traditionally employed to assess stress response of plants, such as chlorophyll a fluorescence and procedures used to evaluate the efficiency of water use, allowed us to verify the success of restoration procedures using an endangered species.

Highlights

Rupestrian grassland, one of the physiognomies of the Cerrado biome (Savannah), is a mosaic of grassland types or habitats with scattered shrubs and trees growing among rocky outcrops at elevations between 900 m and 1200 m, mainly in the Espinhaço mountain range (Giulietti et al 1997)
These results indicate that C. semaphora individuals in the restored site had similar or better photosynthetic and water economy performances than individuals at the natural site
We addressed two main questions: 1) Do young and adult individual plants growing in the restored site exhibit water status and carbon isotope discrimination similar those of individuals in a natural site? 2) Is photosynthetic performance, assessed from chlorophyll a fluorescence measurements, similar between the two sites? Similar or better ecophysiological performance of plants of the restoration site compared to those of the natural site would indicate that the technique of using an endangered species in the restoration of a degraded area of rupestrian grassland was successful

Summary

Introduction

Rupestrian grassland, one of the physiognomies of the Cerrado biome (Savannah), is a mosaic of grassland types or habitats with scattered shrubs and trees growing among rocky outcrops at elevations between 900 m and 1200 m, mainly in the Espinhaço mountain range (Giulietti et al 1997). Soil erosion is seen in many places in the southern portion of the Espinhaço range (Serra do Cipó) due to mining activities and paving of dirt roads and highways (see Fernandes et al 2014) These activities facilitate the introduction of invasive species, one of the greatest threats to the native flora of rupestrian grasslands (Barbosa et al 2010; Fernandes et al 2014; 2015).

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Conclusion