In Pursuit of Logic: Part IV of V
Native plants and animals have a right to be left alone.
Left alone, Nature is beautiful, as it has been for millions of years. Without us.
A fair number of people are threatened by that independence.
Long before hominids diverged from their ape brethren and began the evolutionary journey to consciousness, the ebb and flow of habitat decorated the mountains, the foothills, and the coastal plain of what would become California, with soft grass, aromatic sage, dense chaparral, and walls of wood. Grizzlies roamed, jaguars courted, Wrentits sang, horned lizards waited, and walking sticks walked on all six. Adapting to herbivory, drought, and fire, the greenery thrived. Dormant seeds waiting for the right signal to burst open with life. Thick bark to protect from frequent, little fires; thin bark where fires were too hot to put up a fight – why waste the energy? Sparse forests, dense forests, denser chaparral for mile upon mile upon mile.
Life, habitat, and countless creations of the evolutionary journey everywhere.
Then we arrived. Humans. Years of fascinating research, from genetics to footprints, has helped us approximate our arrival to North America around 23,000 years ago, give or take. For a while, our impact was minimal.
Fifteen thousand years ago the climate began to dry, deserts expanded, the chaparral began to retreat. A teenage girl found herself trapped (or perhaps laid to rest) in the tarry, sticky mess in what would become the La Brea tar pits about 10,000 years ago. Cultures grew, diversified by the same geographic features that isolated, then created, new populations, then new species, across the Californian landscape. The diversity of human language and culture in California was rivaled by only the island landmass that would eventually be known as New Guinea.
As with all other places humans have discovered, Europe, New Zealand, Easter Island, our impact on the California environment grew until we pushed vulnerable species toward extinction. In our trash dumps (shell middens) along the coast and rivers, bones of large animals and easily captured prey, piled up at the lower, oldest levels. As the pile grew, remains of lower calorie catches replaced the richer ones, then at the top, lowly mollusk shells. We picked off the easy protein sources that had no fear of us at first, then moved on to the rest. It’s what humans do and have always done.Read More
In Pursuit of Logic: Part II of V
Continuing our description of conversations we’ve had recently concerning chaparral, fire, and illogical thinking, Part II of our series shares an often-encountered opinion that in someway, somehow, one of our favorite chaparral shrubs is an unnatural, alien invader. In this case, hoary leaved ceanothus (Ceanothus crassifolius).
With pretty white blossoms and gnarly leaves with fuzzy undersides, this chaparral shrub can be found in large stands decorating foothill areas from San Diego to Santa Barbara.
The Invasion of the Alien Brush!
During a discussion about a proposed 30-35 mile long, 200-300 foot wide “fuel” break near San Rafael in Marin County at the base of Mt. Tamalpais, a renowned fire scientist suggested that a stand of ceanothus could be unnatural. And is often the case lately, his characterization was tied to the latest trend in promoting habitat clearance that we discussed in Part I of this series, past Native American fire use.
“Given that the area was likely burned frequently by First People, and if that was the case, then the greatest human impact on the ecosystems has been the lack of ecologically appropriate fire to sustain the post-Pleistocene landscape. When I was at the Fire Lab in Riverside, I occasionally asked the question regarding the baseline of consideration for what was a “native” condition. For example, from my limited understanding, an early Forest Reserve survey of Mt. Wilson (San Gabriel Mtns.) indicated significant oak-grass cover that is now largely Ceanothus crassifolius. Just a thought and curiosity regarding the Audubon and Native Plant Society concerns.”
This statement reveals several common themes in anti-chaparral chatter, shrub phobia and the pastoral bias favoring open grasslands.
How Did the Ceanothus Seeds Get There – Aliens from Mars?
Suggesting that ceanothus in the San Gabriel Mountains somehow replaced an historical oak/grassland due to the “lack of ecologically appropriate fire” demonstrates a serious misunderstanding of chaparral ecology.
C. crassifolius could not exist on a site that was not naturally characterized by infrequent, high-intensity fire.
Why? It’s a fascinating ecological story.
C. crassifolius is an obligate seeding species, meaning the species’ response to fire is the death of adult shrubs and the germination of their seed in the soil seed bank, in this case facilitated by heat (a pore in the seed coat is modified by heat, allowing water to enter, and thus stimulating the seed embryo to grow). Additional explanations (with photos) of this and other types of fire response chaparral plants have evolved can be found on our website here.
Under extreme, long-term drought conditions over many decades, C. crassifolius shrubs can die and disappear from a site. This is starting to happen now in the Santa Monica Mountains, featuring the characteristic curvy bundle of stems and twigs that dead ceanothus form – closing in on themselves as they sadly bid farewell to the world. The empty space left behind is usually filled in by other shrubs. However, the species still exists! Hiding in the soil seed bank are thousands of tiny seeds just waiting for a fire to kick them into action.The next high-intensity fire will cause an amazing population explosion of feisty, little ceanothus seedlings.
There is no other natural way for obligate seeding ceanothus to be present.