Gregarious flowering and death of understorey bamboo slow litter decomposition and nitrogen turnover in a southern temperate forest in Patagonia, Argentina

Abstract

Summary1. The massive synchronized flowering and subsequent mortality of understorey bamboo species occur in infrequent and unpredictable intervals in temperate and subtropical forests around the world. Because of the sporadic occurrence of these flowering episodes and the long intervals between events, very little is known about their consequences on biogeochemical cycling in natural ecosystems. 2. In 2001, a synchronized flowering and dieback of the native bamboo, Chusquea culeou E. Desv., occurred, covering more than 200 000 ha in the north-west region of Patagonia, Argentina. We explored the impacts of this gregarious flowering event on litter decomposition and nitrogen turnover in an old-growth southern beech forest for 3 years after the flowering event.3. Bamboo litter decomposed significantly slower than overstorey tree litter, and decomposition in flowered patches overall was significantly reduced compared to remnant live understorey patches. In addition, soil mineral nitrogen was reduced in flowered patches, and nitrogen transformations were altered, most notably in the third year after the flowering event.4. This infrequent phenomenon of gregarious flowering could have consequences for carbon and nutrient cycling, as low-quality standing dead biomass is gradually incorporated into soil organic matter pools. This study demonstrates that large biotically mediated perturbations of understorey vegetation can impact biogeochemical cycles in temperate forest ecosystems by reducing carbon turnover and altering nitrogen availability and transformations, even in the absence of physical disturbance.

Understory bamboo flowering provides a very narrow light window of opportunity for canopy-tree recruitment in a neotropical forest of Misiones, Argentina

“…Decomposition of bamboo litter was slower on average than rates of mass loss in other subtropical forests (Deka and Mishra, 1982;Singh and Singh, 1999), and substantially reduced compared to the subdominant tree species such as S. bonplandii. Our results were similar to the findings of Liu et al (2000) in a subtropical mountain forest in China for the bamboo Sinarundinaria nitida, which requires more than 6 years to lose 95% of their initial mass, and consistent with another study of Chusquea bamboo flowering which demonstrated significantly slower decomposition of bamboo litter, particularly stem tissue (Austin and Marchesini, 2011). The slow decomposition rates of C. ramosissima leaves could be the result of several factors.…”

“…The short-term effects on tree sapling growth were due to significant increment in light availability during the first year after bamboo flowering which was quickly reverted due to rapid colonization by other herbaceous understory species. At the same time, many other environmental characteristics such as litter decomposition and soil nutrient concentrations were largely unaffected by the flowering event, which is contrasts with results from temperate Argentine forests (Giordano et al, 2009;Austin and Marchesini, 2011). Successful tree growth in gaps following bamboo flowering appears to be restricted to a very narrow window of increased resource availability, and only some already established individuals were able to take advantage of the increasing resources.…”

“…Nevertheless, although differences in litter quality and decomposition were observed, they did not appear to affect nutrient availability in the soil during the period of study. In temperate forest ecosystems, the impacts of synchronous bamboo flowering on biogeochemical cycling may be perceived in the medium to long-term, when low quality senescent material is decomposed and incorporated into the soil organic matter pools, and microbial immobilization of nutrients occur (Austin and Marchesini, 2011). In contrast in this subtropical forest, the input of senescent material (dead bamboo) aboveground was immediate and litter quality of bamboo does not differ strongly among leaves, branches and stems due to the relatively rapid decomposition overall and the similar contribution to aerial senescent biomass in control and flowered plots, ecosystem-level decomposition was not impacted by the flowering event.…”

Bamboo Flowering from the Perspective of Comparative Genomics and Transcriptomics

“…Variations in flowering time are not only diverse among species, but also at the population level. For instance, in the case of gregarious flowering all the individuals of a species growing over a wide geographical area bloom within a brief interval of time, and then all die after flowering (Nadgauda et al, 1997; Bhattacharya et al, 2009; Marchesini et al, 2009; Austin and Marchesini, 2012; Chaubey et al, 2013; Xie et al, 2016). In contrast, for sporadic flowering only a few culms of a population flower at a time (Ramanayake and Yakandawala, 1998; Bhattacharya et al, 2006; Xie et al, 2016).…”

Termites amplify the effects of wood traits on decomposition rates among multiple bamboo and dicot woody species

“…). Austin & Marchesini () showed that leaf and stem litters of understorey bamboo ( Chusquea culeou E. Desv.)…”