Drought effect on plant biomass allocation: A meta‐analysis

Abstract

Drought is one of the abiotic stresses controlling plant function and ecological stability. In the context of climate change, drought is predicted to occur more frequently in the future. Despite numerous attempts to clarify the overall effects of drought stress on the growth and physiological processes of plants, a comprehensive evaluation on the impacts of drought stress on biomass allocation, especially on reproductive tissues, remains elusive. We conducted a meta‐analysis by synthesizing 164 published studies to elucidate patterns of plant biomass allocation in relation to drought stress. Results showed that drought significantly increased the fraction of root mass but decreased that of stem, leaf, and reproductive mass. Roots of herbaceous plants were more sensitive to drought than woody plants that reduced reproductive allocation more sharply than the former. Relative to herbaceous plants, drought had a more negative impact on leaf mass fraction of woody plants. Among the herbaceous plants, roots of annuals responded to drought stress more strongly than perennial herbs, but their reproductive allocation was less sensitive to drought than the perennial herbs. In addition, cultivated and wild plants seemed to respond to drought stress in a similar way. Drought stress did not change the scaling exponents of the allometric relationship between different plant tissues. These findings suggest that the allometric partitioning theory, rather than the optimal partitioning theory, better explains the drought‐induced changes in biomass allocation strategies.

Compensatory mechanisms to climate change in the widely distributed species Silene vulgaris

“…We detected a 23% decrease in biomass, an 8% decrease in plant height and number of leaves as well as a 14% decrease in number of flowers under the lowest precipitation treatment. These results are in line with other studies where drought stress decreased stem and leaf biomass (Dubois, Claeys, Van den Broeck, & Inzé, 2017;Eziz et al, 2017;Prieto, Peñuelas, Llusià, Asensio, & Estiarte, 2009). Decreased overall biomass under increasing drought was also found in alpine S. vulgaris in a study by Hamann, Kesselring, and Stöcklin (2018).…”

“…We measured biomass, plant height, number of flowers, number of branches, number of leaves, leaf area and specific leaf area (SLA) as fitness‐related plant traits. These traits have been shown to negatively respond to drought and temperature stress (Eziz et al., ; Khan, Raza, Farooq, & Jabran, ; Rucker, Kvien, Holbrook, & Hook, ; Wellstein et al., ; Zeiter, Schärrer, Zweifel, Newbery, & Stampfli, ). Thus, we hypothesized that biomass‐related traits will have lower values under drought and increased temperature treatments.…”

Sensitivity of dryland plant allometry to climate

“…Larger sample sizes to separate C 4 and CAM strategies could be informative because CAM species use internally stored water (Tissue, Yakir, & Nobel, ), that should make their growth and growth form somewhat independent from short‐term water availability. Altogether, our results align with recent meta‐analysis of organ‐specific plant allometries, which documented significant differences among annuals versus perennials and herbaceous versus woody plants in the patterns of biomass partitioning among roots, leaves or reproductive tissues under experimental drought (Eziz et al, ).…”

“…For instance, a recent study revealed that dry years reduced the steepness of the relationship between community biomass and non‐destructive proxies, such as the normalized difference vegetation index (NDVI) (Onodi et al, ). Meta‐analysis of 164 studies suggested that sensitivity of within‐plant organ allometry is common: drought experiments altered plant biomass partitioning ratios, favouring root over shoot biomass and altering ratios of reproductive to vegetative biomass (Eziz et al, ). Similarly, treatments such as competition (Yu & Gao, ) or nitrogen addition (Dziedek et al, ) can alter patterns of biomass partitioning (but see Bernacchi, Coleman, Bazzaz, & McConnaughay, ; Peng & Yang, ).…”

Effects of grafting on host plant resistance in ash (Fraxinusspp.) to emerald ash borer (Agrilus planipennisFairmaire)

“…However, the effect of water stress on trees may be different from that of grafting. Water stress influences resource allocation within the plant, whereas stress caused by grafting is typically related to issues caused by poor development of xylem connections between scion and rootstock, lowering hydraulic conductivity and reducing growth potential (Atkinson et al ., ; Johkan et al ., ; Eziz et al ., ).…”