Should we be concerned about gregarious flowering and dying of bamboos?
In 2010, the news of flowering and dying of temperate bamboo ¬†(Thamnocalamus spathiflorus Borinda grossa Yushania microphylla ) along the Pelela and Yotola passes (Wangdue and Trongsa Dzongkhags) appeared in two issues of Kuensel ( ¬†January 27, 2010 and February 1, 2010)¬† expressing¬† concerns over dying, extending to a large area and its impact on rural economy. This stimulated a lot of exciting questions about bamboo flowering and dying among foresters, researchers and development workers. The uneasiness and anxiety feelings over ill-impact of bamboo dying are still remain amongst people as evident from the recent news in the Kuensel (¬† August 22, 2011 ) and a few questions again re-surfacing ¬†in Bhutan ¬†e- forest group forum ( July 2011).
Here, an attempt is made to compile and answer some of the common questions asked by people when they see gregarious flowering and dying of bamboos. Hope, these answers would inform public more about mass flowering and dying of bamboos and clarify some of the concerns expressed in the media and forum.
1. Why gregarious flowering is so much cause of concern?
Much of the concerns expressed in the national media (Newspapers, Forest e-groups) about gregarious bamboo flowering are true but they ¬†become grimmer when seen through the riddles of myths and facts. ¬†In rural cultures associated with bamboo, flowering of bamboo is believed to be an ill omen, leading to famine, death and natural disasters ( Ramanayake 2006) Factually, documented from the north-eastern India ( Monohar 2008) , when bamboo flowers gregariously, it leads to economic, social and ecological problems. During gregarious flowering, large quantities of seeds are accumulated on the ground. Rodents and many other animals eat this nutritious source of food and reproduce fast to increase in number. Once the seeds are depleted due to their germination, the rats turn to the adjoining farmlands and destroy crops causing famine. These famines have occurred in years associated with the gregarious flowering. Also, once the bamboo dies after flowering, the people whose livelihood depended on the bamboo resource are severely affected. The dead culms are a fire hazard. The land becomes bare as it takes time for the new generation to establish. Bare land could be disastrous in mountainous areas leading to landslides. In fact, this could also happen in Bhutan too. Gregarious flowering and dying of bamboo might have occurred in the past, but no grave events associated with the bamboo flowering and dying had been experienced or recorded in Bhutanese history.
2. What efforts are made by Ministry of Agriculture and Forests (MoAF)?
Bamboos in Bhutan are represented by 15 genera and 30 species occurring naturally in subtropical to alpine forests ( Stapleton 1994). A few larger species of¬†¬† Dendrocalamus,¬† Bambusa and Borinda are cultivated around settlements and used for basketry, house roofs, walls and floors, edible shoots and fodder. No recorded data about the past flowering and dying of Bhutanese bamboo is available. ¬†Lyonpo C. Dorji, ( July 2011, Bhutan e-forest)¬† reported observing¬† gregarious flowering and dying of sub-tropical bamboo in 1963 in Lhamoi Zingkha and subsequently regeneration established naturally through seeds. Also, extensive flowering and dying of another sub-tropical bamboo (Dendrocalamous sikkimmenis) was reported in 1999 from the southern and eastern part of the country (personal observation ) while mass dying of Borinda grossa in Saktan Wildlife Sanctuary was first recorded in 2005 ( Norbu et al. 2005). Since then, Council for RNR Research of Bhutan (CoRRB) ¬†through RNR-Research and Development Centre (RDCs), have started observing and studying the phenomenon of mass bamboo flowering (viz. Borinda grossa, Thamnocalamus spathiflorus and Yushania microphylla) in many locations across the country particularly along the highway passes of Dochula, Pelela and Yotongla. The study found that there is profuse regeneration after flowering and it takes c. 2 years for natural regeneration seedlings to establish themselves ( Wangda et al). Also, there have been confirmed reports that regeneration of Dendrocalamus sikkimenis in the eastern and southern parts of the country and Borinda grossa in Sakten Wildlife Sanctuary, have been re-established successfully ( personal communication 2011). Also, there had been no report of crop damage caused by rodents in association with dying of these bamboos in these areas.¬† For more technical information, interested readers are asked to refer the article by Wangda et. al ( 2011) entitled ¬†‚ÄúThamnocalamus spathiflorus, a temperate bamboo flowering and regeneration along Yotongla and Pelela Pass.‚ÄĚ in Bhutan RNR Journal , September 2011, ¬†published by CoRRB.
3.Why does gregarious flowering occur and what opportunity does it offer?
There is no need to worry seeing bamboo flowering and dying and it is a natural fact or process that takes place once in bamboo‚Äôs lifetime. Most bamboo species flower at the end of a long number of years of vegetative growth once in their life time. They flower gregariously over the whole area producing huge amount of seeds followed by mass dying of the clumps. Although a wide range of research is going on, the phenomenon of gregarious flowering of bamboo is still unexplained and many results point out the cause to genetic heritability of the bamboo species. The bamboo regeneration takes about 2-3 years before it establishes profusely under the dead bamboo clumps ( Wangda et al. 2011). After dying of bamboos, large quantities of seeds produced are washed away by the rain or eaten by rodents. The viability of seeds of many bamboos remains for only 3-4 weeks. This offers an opportunity to collect seeds at the right time for multiplication and conservation of the flowered species thereby adding more genetic variations among the populations. RNR-Research and Development Centre (RDC), Yusipang had successfully raised seedlings from the seeds of Borinda grossa clumps of Sakten Wildlife Sanctuary, that died a few years ago and planted them in the temperate region of western and eastern Bhutan. Currently, also research on plantation, domestication and propagation of bamboo are underway at RDCs-Bajo, Yusipang, Bhur and Research Sub-centre-Darla.
The livelihoods of people who are solely dependent on bamboo resource may be affected temporarily while waiting for bamboo to mature for its use. But, the effect cannot be as drastic as it seems, in the light of changing rural life-style, ¬†from what Sephu gup Rinchen Penjor ¬†said on seeing dying of¬† Borinda grossa in Sephu gewog in the Kuensel ( 27th January 2010) ¬†¬†‚Äú it will not affect the people much since most people have left the bamboo craft tradition‚ÄĚ. The case can be different for the people of Bjoka Geog, Zhemgang, whose about 66% of the ¬†household income comes from selling Bachung and other products made out of Yula bamboo ¬†(Neomicrocalamus andropogonifolius) (Moktan et al. 2004 ). In Bjoka, efforts are underway to in improve management of natural Yula resource under CNRM regime and also domesticate Yula bamboo using planting stocks from different locations in order to broaden the genetic base. However, it is also seen that when the first choice of bamboo is not available for making the products, rural people tend to switch to alternative bamboos that are abundant in forests (Personal observation ).
While saying not to worry about bamboo dying does not mean that one has to be complacent and do nothing about it. In order to get the bamboos back in our forests and gardens in its near to original state, opportunities are opened to us to engage ourselves in numerous tasks. One has to continue monitoring the come-back of bamboo natural regeneration, and watch out for population increase in rodents and its ill- impacts on forest seed banks and adjoining crops.¬† The others task is to collect bamboo seeds and grow a new generation in nurseries, gardens and plantations. ¬†Also, nearby farmers should take care of fire out breaks in the bamboo flowered sites as such wild fire may destroy the fallen seeds of bamboo on the ground.
Submitted by: Council for RNR Research of Bhutan (CoRRB)