Effects of drought and fire on resprouting capacity of 52 temperate Australian perennial native grasses

Abstract

It remains uncertain how perennial grasses with different photosynthetic pathways respond to fire, and how this response varies with stress at the time of burning. Resprouting after fire was examined in relation to experimentally manipulated pre-fire watering frequencies. We asked the following questions: are there response differences to fire between C and C grasses? And, how does post-fire resprouting vary with pre-fire drought stress? Fifty-two perennial Australian grasses (37 genera, 13 tribes) were studied. Three watering frequencies were applied to simulate increasing drought. Pre-fire tiller number, tiller density, specific leaf area and leaf dry matter content were measured as explanatory variables to assess response. Most species (90%) and individuals (79%) resprouted following experimental burning. C grasses had higher probabilities of surviving fire relative to C grasses. Responses were not related to phylogeny or tribe. High leaf dry matter content reduced the probability of dying, but also reduced the re-emergence of tillers. Post-fire tiller number increased with increasing drought, regardless of photosynthetic type, suggesting that drought plays a role in the ability of grasses to recover after fire. This has implications for understanding the persistence of species in landscapes where fire management is practiced.

Grasses and fire: the importance of hiding buds

“…A recent example of a resprouting study in grasses is the experiment performed on 52 Australian native grasses that combined fire and drought treatments (Moore et al ., ). The results of this study are: (1) C 4 grasses survive better fire than C 3 ; (2) survival increased with leaf dry matter content (LDMC); and (3) drought increased postfire resprouting in both C 3 and C 4 species.…”

“…Ripley et al ., ). But apparently this was not the case (Moore et al ., ). This suggests that carbon reserves are not the only limiting factor for resprouting.…”

“…To test this prediction, we use the data from Moore et al . () and added to their models a variable related to the position of the resprouting buds with three categories (see Supporting Information Methods S1): stolons (aboveground), crown (root–shoot transition), and rhizome (belowground).…”

Dominant C3 tussock grasses are resilient to the re‐introduction of fire in long‐unburned temperate grasslands

“…tussocks had a smaller range of size classes, fewer live tillers per tussock, and had a lower basal area compared to Themeda triandra tussocks, but none of these features made them inherently less capable of surviving fire. Both grass types respond to fire by resprouting from bud banks located at the base of the tussock (Moore, Camac, & Morgan, ) and tillers recovered at comparable rates in the seven weeks after fire. Tussock survival was independent of tussock size for Themeda triandra but smaller‐sized (<10 cm circumference) Austrostipa spp.…”

Effect of fire regimes on the demographic parameters of the perennial tussock grasses of a humid savanna

“…These grasses are adapted to fires. Indeed, their aboveground biomass burns while belowground biomass tends to stay alive (Monnier, 1968;Sarmiento, 1992), which allows the quick regrowth of tussocks after fire Abbadie, Gignoux, Lepage, & Le Roux, 2006;Moore, Camac, & Morgan, 2019;Sarmiento, 1992). Nevertheless, fires and fire regimes likely impact the demographic parameters of grass tussocks: mortality (Zimmermann, Higgins, Grimm, Hoffmann, & Linstädter, 2010), retrogression, i.e., decrease in tussock size (Canales, Trevisan, Silva, & Caswell, 1994), growth, i.e., increase in tussock size (Yuan, Liang, & Zhang, 2016), fragmentation, i.e., the division of a tussock into several smaller tussocks which leads to a form of clonal reproduction (Fair, Lauenroth, & Coffin, 1999;Hartnett & Bazzaz, 1985), and fecundity (Brys, Jacquemyn, & De Blust, 2005).…”