Delayed Flowering in Bamboo: Evidence from Fargesia qinlingensis in the Qinling Mountains of China.

Gregarious flowering of bamboo species impacts ecosystem properties and conservation, but documentation of these periodic events is difficult. Here, we compare the characteristics of flowering sites and un-flowered patches of an arrow bamboo (Fargesia qinlingensis) in the Qinling Mountains, China, over a 5-year period (2003-2007) after a mast flowering event (2003). We examined flowering culm and seedling characteristics in relation to questions regarding the evolution of delayed flowering. Density of live culms decreased over the 5 years in both flowering sites and un-flowered patches. New shoots regenerated only in un-flowered patches. Chemical constituent allocation varied among culm parts (stems, branches, and leaves). Crude protein and extract ether in branches and leaves were less in flowering culms than in un-flowered culms. Seedling density was lower than expected based on floret counts, suggesting predation of seeds. Seedling density was significantly greater in flowering sites than in un-flowered patches and decreased over time. Seedlings performed better in flowering sites than in un-flowered patches based on their height, leaf number per seedling, and average leaf length, while fertilization on flowering sites had no significant effect on seedling growth, suggesting a saturation of resources. This study suggested that the characteristics of bamboos and bamboo stands were dramatically altered during this flowering event, enhancing seedling establishment and growth, and supporting mostly the habitat modification hypothesis of delayed reproduction.

Long-term population demography of Trillium recurvatum on loess bluffs in western Tennessee, USA.

BACKGROUND AND AIMS: Understanding the demography of long-lived clonal herbs, with their extreme modularity, requires knowledge of both their short- and long-term survival and ramet growth patterns. The primary objective of this study was to understand the dynamics of a clonal forest herb, Trillium recurvatum, by examining temporal and small-scale demographic patterns. We hypothesized: (i) there would be more variability in the juvenile age class compared with non-flowering adult and flowering adult classes due to year-to-year fluctuations in recruitment; (ii) rates of population growth (λ) and increase (r) would be highest in non-flowering ramets due to a combination of transitions from the juvenile stage and reversions from flowering adults; and (iii) inter-ramet distances would be most variable between flowering and juvenile ramets due to a combination of clonal growth, seed dispersal by ants and ramet death over time. METHODOLOGY: Census data were collected on the total number of stems in the population from 1990 to 2007, and placed within one of three life stages (juvenile, three-leaf non-flowering and three-leaf flowering). Modified population viability equations were used to assess temporal population viability, and spatial structure was assessed using block krigging. Correlations were performed using current and prior season weather to current population demography. PRINCIPAL RESULTS: The first hypothesis was rejected. The second hypothesis was supported: population increase (r) and growth rate (λ) were highest in non-flowering ramets. Finally, the third hypothesis was rejected: there was no apparent density dependence within this population of Trillium and no apparent spatial structure among life stages. CONCLUSIONS: Overall population density fluctuated over time, possibly due to storms that move soil, and prior year's temperature and precipitation. However, density remained at some dynamic stable level. The juvenile age class had greater variability for the duration of this study and population growth rate was greatest for non-flowering ramets.

Biotic diversity of Natchez Trace State Forest, western Tennessee.

We carried out a multiple-scale assessment of biotic resources within Natchez Trace State Forest (NTSF) in western Tennessee, focusing on the relation between biotic communities and seven previously developed ecological land types (ELT, based on topography and soils). We wanted to test the functional ability of ELTs for biodiversity stewardship. Woody and herbaceous flora as well as herpetofauna and avifauna communities had substantial differences between upland and lowland forests. However, none of the faunal communities distinguished among upland ELTs. In addition, herbaceous taxa also failed to distinguish upland ELTs. The results suggest the present use of ELTs at NTSF will not be a helpful guide to land stewardship focusing on biodiversity. The disturbance history of the Forest and the mobility of animals are given as potential explanations for a poor relationship between abiotic ELTs and the resident biota.