Changes in the Flora of San Jacinto Mountain With Time
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Table of Contents
Introduction
Effects of People and Non-Native Weeds
Effects of Drought
Effects of Fire
The xxx Memorial Day Campground Fire
The 2013 Mountain Fire
The 2018 Cranston Fire
Effects of Unusual Heavy Rains
Local Changes in Species Abundance
Changes Happening Right Now
Introduction
Tom began studying the flora of the higher elevations of San Jacinto Mountain in 2002, and Dave joined him in 2006. By 2009, we had produced at least preliminary plant trail guides to all the major high-elevation trails, and many of the mid-elevation trails, and done a full survey of the entire lengths of Tahquitz and Willow Creeks in Tahquitz Valley. That work has given us a 14 year baseline to directly observe changes in the flora with time.
We never would have thought that we could observe significant changes in such a short time interval, but we have been surprised at the number of changes we have seen. This webpage is a start at recording the changes we have observed.
This page also lists other changes in the flora that we know of over longer time periods. In particular, Harvey Monroe Hall did a flora of the Pine Belt of San Jacinto Mountain in 1902, which allows us to note changes in the flora over a period of 119 years.
Effects of People and Non-Native Weeds
Near extinction of lemon lilies at SnJt by bulb collectors.
Intentional introduction of non-native species that have spread, such as Elytrigia intermedia in Tahquitz Meadow, and giant sequoias at Black Mountain.
Spread of non-native weeds. Bromus tectorum in Long Valley. Phleum pratense in Long Valley Meadow. Poa pratensis?
Tanacetum parthenium and Lathyrus latifolius spreading in drainages from Idyllwild.
Spread of plants, especially non-native weeds, from fire-fighting equipment.
Diversion of water for Idyllwild and Pine Cove.
Effects of Drought
~1999 to ~2001: Massive death of white firs in Idyllwild Area due to drought allowing bark beetles to kill trees.
Disappearance of meadow species in seep area at top of Devils Slide Trail
Effects of Fire
The xxx Memorial Day Campground Fire
This Fire gave us a preview, on a small scale, of what was to come from the 2013 Mountain Fire, including massive germination of Ceanothus cordulatus; death of trees; germination of trees.
The 2013 Mountain Fire
Massive germination of Ceanothus cordulatus; death of trees; germination of trees.
Spread of non-native Bromus tectorum and Cirsium vulgare.
Surprising appearance of lower elevation species at much higher elevations in the burn area.
Fire followers at 5000 feet and below.
The 2018 Cranston Fire
Effects of Unusual Heavy Rains
The San Jacinto Mountains have experience some very unusual heavy rain events in the lasst decade, which probably are related to the warming of the climate and/or drying of the vegetation.
2013 Monsoonal / Fire thunderstorm knocked out a large number of lemon lilies.
14 February 2019 storm that took out SR243 and SR74.
April 2022(?) rain storm that caused massive erosion and deposition in washes.
Local Changes in Species Abundance
Devils Slide Trail: gophers took out all plants of one stand of Boechera repanda, and another stand of Phacelia mutabilis.
Antennaria stand extirpated on PCT below Chinquapin Junction.
Changes Happening Right Now
Gold-spotted oak borer taking out Q. agrifolia, Q. chrysolepis, and Q. kelloggii. A number of trees at Humber Park have already been killed and removed.
Global warming.