LILIES - RHS Lily Group

Lilium dauricum is mainly a coastal plant on Hokkaido. The bulbs establish
their roots in coastal grassland or on shelves of the steep coastal cliffs. Lilium
dauricum’s communities in coastal grasslands have been reduced by environmental
effects, as their habitat has been altered by the installation of drainage systems for
ranches, and/or by road building. Moreover, some populations are unable to selfpropagate
well from seed, as the young roots of seedlings are prevented from
working their way into the soil by a thick layer of grass thatch. This thatch is now
thicker than in the past, as fewer horses are grazed on coastal grasslands, now
that tractors are used instead. Another possible cause of decline in L. dauricum
is a reduction in the number of its pollinators. It is suggested that the pollinators
of L. dauricum are the largeish butterflies, Aporia crataegi (black-veined white)
and Papilio machaon (swallowtail). Both eat each host plants in their caterpillar
stage. Malus sieboldii (Japanese crabapple) and M. baccata var. mandshurica
(a variety of Siberian crabapple) are the host plants of A. crataega; Glehnia
littoralis (silvertop) is the host plant of P. machaon. In the past, good stands
of these host plants were present near sites of L. dauricum. Now, however,
the host plants have disappeared from some habitats. Malus sieboldii and M.
baccata var. mandshurica have in some places been destroyed by controlled
burning in early spring. The young shoots of G. littoralis were cleanly picked out
as the ingredient of a seasonal salad. G. littoralis lived on the coast of Ishikari
close to my residence, but is now absent around declining communities of the
lily. Although G. littoralis still thrives bravely in the nature refuge ten kilometers
away, pollinators cannot survive outside the refuge.
In nature the range of L. dauricum was limited to coastlines and to some of
the high mountains in Hokkaido. However, in the last 20 years this lily has been
increasingly visible on roadside verges. As its distribution is expanded along
roadsides in the high mountains, there is a fear that this artificial expansion of its
distribution could contaminate relict communities.
Villagers in most L. japonicum regions campaign actively for the protection
of this lily. There are two motivations behind this. Many people are fired by
nostalgia, wanting to recreate the view filled with L. japonicum in full flower,
which villagers used to see as a matter of course every year in the old days. Others
hope to boost their secluded mountain hamlets by attracting a lot of visitors to
see a hillside full of L. japonicum in bloom. Both groups talk about how the lily
has been declining. Conservation activists and the Environment Ministry allege
that the decline is caused by collecting, but my own belief is that it is caused by
lifestyle changes at these mountain village, and by forestry depression.
Ishima, which I visited in 2004, is a small island nine and half a kilometers
around, located east of Sikoku Island. Junior high school students here are
absolutely committed to conserving communities of L. japonicum Ishima form.
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