Disentangling the Effects of Precipitation Amount and Frequency on the Performance of 14 Grassland Species.

Teresa J Didiano,Tim P Duval,Marc T J Johnson,Jose Luis Gonzalez-Andujar

doi:10.1371/journal.pone.0162310

Abstract

Climate change is causing shifts in the amount and frequency of precipitation in many regions, which is expected to have implications for plant performance. Most research has examined the impacts of the amount of precipitation on plants rather than the effects of both the amount and frequency of precipitation. To understand how climate-driven changes in precipitation can affect grassland plants, we asked: (i) How does the amount and frequency of precipitation affect plant performance? (ii) Do plant functional groups vary in their response to variable precipitation? To answer these questions we grew 14 monocot and eudicot grassland species and conducted a factorial manipulation of the amount (70 vs 90mm/month) and frequency (every 3, 15, or 30 days) of precipitation under rainout shelters. Our results show that both the amount and frequency of precipitation impact plant performance, with larger effects on eudicots than monocots. Above- and below-ground biomass were affected by the amount of precipitation and/or the interaction between the amount and frequency of precipitation. Above-ground biomass increased by 21–30% when the amount of precipitation was increased. When event frequency was decreased from 3 to 15 or 30 days, below-ground biomass generally decreased by 18–34% in the 70 mm treatment, but increased by 33–40% in the 90 mm treatment. Changes in stomatal conductance were largely driven by changes in event frequency. Our results show that it is important to consider changes in both the amount and frequency of precipitation when predicting how plant communities will respond to variable precipitation.

Highlights

Within the century, climate change will cause alterations in annual and seasonal precipitation, as well as increased precipitation variability [1,2,3]
Our results show that the relative allocation of above- and below-ground biomass for E. perfoliatum and E. riparius was strongly affected by the interaction between the amount and frequency of precipitation (Table 1)
We experimentally tested the impacts of variable precipitation on plant performance of temperate grassland species and show that changing precipitation regimes can have both positive and negative effects on plant performance

Summary

Introduction

Climate change will cause alterations in annual and seasonal precipitation, as well as increased precipitation variability [1,2,3]. In some regions throughout the world, summer precipitation regimes will be characterized by large, infrequent precipitation events with longer intervening dry periods [1, 4, 5]. Changing the size and timing of precipitation events will introduce novel hydrological conditions that could influence plant community.

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