The Decline of Lemon Lilies in the Idyllwild Area


Table of Contents

Introduction
What caused the decimation of this population?
Why haven't lemon lilies come back to the Idyllwild Area in their former density?
Plans for Restoration of the population


Introduction

Lemon lilies were once so abundant at San Jacinto Mountain that in 1902, Harvey Monroe Hall wrote, in his botanical flora of the Pine Belt of San Jacinto Mountain:

It was only a few years ago that the showy blossoms were very frequently met with along all the streams and bogs from nearly the lower edge of [the Pine Belt] up to an altitude of 9000 feet.

But in just a few years, the lemon lilies became so infrequent that Hall wrote you had to go to more remote parts of the mountain to see them in profusion.

That rarity has continued to today, 114 years later. On most trails in the Idyllwild area (here defined as being the lower pine belt from the Black Mountain area to the Mountain Center area), one meets with no lemon lilies at all, or at best a handful.

What caused the decimation of this population?

A number of factors are in play, but by far the dominant factor was people collecting bulbs to be sold to gardeners. Hall wrote one party took out over 5000 bulbs in a single season. The bulb collectors probably dug up every single lily they could find, leaving the areas bereft of lemon lilies wherever the collectors went.

For a number of species, this might not have been fatal, and they could have recovered from such a decimation of their population. But several characteristics of lemon lilies made it very hard for them to recover from such a blow:

Removing the bulbs of every lily that can be found in an area is therefore a recipe for extirpating the population in that area, as all these characteristics conspire to make it difficult for the population to recover.

Hall also wrote that there, that there were several consecutive dry summers after the bulb removal, which may have depleted the remaining population if the conditions were not favorable to germinate the remaining seed bank. This may or may not have been a factor, depending on what the winter and spring rain was like in those years.

Why haven't lemon lilies come back to the Idyllwild Area in their former density?

Even if a species is extirpated in a given area, if there are nearby areas where a population still exists, one would expect the species to eventually spread to fill its former range. Some species spread rapidly, due to high seed production; good seed dispersal; and not being fussy about where they live. Other species without those characteristics spread very slowly. It seems likely that lemon lilies spread very slowly, since their seed dispersal capability is poor and they can only survive in areas well-protected from predators and with restricted environmental conditions.

In addition, humans may have altered the habitat in the Idyllwild area so much that lemon lilies can no longer thrive in their former numbers. (Note that there are certainly many still-suitable habitats in the Idyllwild area that could support lilies again, even though few lilies remain there now, and hence restoration of lilies to those areas is a very desirable goal.)

The habitat changes can be summarized under three main categories:

The following are some of the main factors that have changed the habitat in the Idyllwild area, not necessarily in order of importance. It should be kept in mind that the combination of these factors are synergistic, making the individual factors worse than if each was the only factor.

Plans for Restoration of the population


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Copyright © 2016 by Dave Stith and Tom Chester.
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Comments and feedback: Tom Chester
Updated 5 August 2016.