Know Your Biomes IX: Chaparral

Fynbos in the Western Cape, South Africa*

As much as any biome or global ecoregion is a challenge to group, differentiate or otherwise generalize, the chaparral or Mediterranean woodlands (scrubland/heathland/grassland) biome may be the best example such classification difficulties. There’s perhaps more general agreement regarding the features of this biome, even if the name tends to change from author to author. Many texts will not even include this biome in their list of major regions, instead making a small reference to it in the section regarding deserts. However, these areas, considering their combined territory, contain about 20 percent of the world’s species of plants, many of them endemic gems found nowhere else. On the flipside, due to the often environmentally heterogeneous nature of this biome, organisms that are prominent, integral members of other biome classifications are found in the chaparral as well. For the sake of consistency in this post, I’ll continue to refer to this biome as chaparral, as incomplete a descriptive designation as that may be.

Specifically, chaparral biomes exist in five major regions: South Africa, South/Southwest Australia, Southwestern California/Mexico, Central Chile and in patches wrapped around the Mediterranean Sea, including Southern Europe and Northern Africa. These regions are unified by their hot, dry summers and mild winters, referred to as an archetypal Mediterranean climate at 40 degrees north and south approximately.

The vast majority of rainfall usually comes with the cold fronts of winter. Annually, chaparral can experience anywhere from 250 mm of rain all the way up to 3000 mm in isolated subregions like the west portion of Fynbos in South Africa.

Plants in chaparral areas tend to be sclerophyllous (Greek: “hard-leaved”), meaning the leaves are evergreen, tough and waxy. This adaptation allows plants to conserve water in an area where rainfall is discontinuous, but probably evolved to compensate for the low levels of phosphorous in ancient weathered soils, particularly in Australia where there have been relatively few volcanic events to reestablish nutrients over millions of years. Obviously, these plants also happen to do very well during the xeric summers of the chaparral where drought is always a threat.

Because of the aridity and heat, the chaparral plant communities are adapted to and often strategically dependent on fire. Evolutionary succession scenarios constructed by scientists typically point to fire as one of the major factors that created much of chaparral areas in Australia and South Africa from Gondwanaland rainforest. (Fire ecology really deserves at least a post of its own, which I’d like to discuss given the time in the future.)

Some of the regions in the chaparral are exceptional. In South Africa, the area known as the Fynbos constitutes its own floristic region (phytochorion) among phytogeographers, the Cape Floristic Region. While it is the smallest of these floral kingdoms, it contains some 8500 species of vascular plants, 70 percent of which are endemic. The March rose (Oromthamnus zeyheri) is one of the standout specimens of the group as well as the national flower of South Africa, the King protea (Protea cynaroides). P. cynaroides is a “resprouter” in its fire-prone habitat, growing from embedded buds in a subterranean, burl-like structure. Another endemic species, the Cape sugarbird, is shown feeding on a King protea below**.

There is one unique threat to the chaparral: anthropogenic fire. In the past, if nature had not provided a fire to burn back the accumulated brush in these areas, often the native peoples would do so, and generally speaking, the fires seemed to be controlled and effective. But increased frequency of fires due to negligence or downed power lines can potentially cause catastrophic, unrecoverable fire. Only so much tolerance to such a destructive force can be built by evolutionary processes.

*Image by Chris Eason
**Image by Derek Keats

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The history of the Joshua tree, threats new and old

Aug 25 2010 Published by under [Biology&Environment]

And the LORD said unto Joshua, Stretch out the spear that is in thy hand toward Ai; for I will give it into thine hand. And Joshua stretched out the spear that he had in his hand toward the city.

And the ambush arose quickly out of their place, and they ran as soon as he had stretched out his hand: and they entered into the city, and took it, and hasted and set the city on fire.

And when the men of Ai looked behind them, they saw, and, behold, the smoke of the city ascended up to heaven, and they had no power to flee this way or that way: and the people that fled to the wilderness turned back upon the pursuers.

And when Joshua and all Israel saw that the ambush had taken the city, and that the smoke of the city ascended, then they turned again, and slew the men of Ai.

And the other issued out of the city against them; so they were in the midst of Israel, some on this side, and some on that side: and they smote them, so that they let none of them remain or escape.

And the king of Ai they took alive, and brought him to Joshua.

And it came to pass, when Israel had made an end of slaying all the inhabitants of Ai in the field, in the wilderness wherein they chased them, and when they were all fallen on the edge of the sword, until they were consumed, that all the Israelites returned unto Ai, and smote it with the edge of the sword.

And so it was, that all that fell that day, both of men and women, were twelve thousand, even all the men of Ai.

For Joshua drew not his hand back, wherewith he stretched out the spear, until he had utterly destroyed all the inhabitants of Ai.

Only the cattle and the spoil of that city Israel took for a prey unto themselves, according unto the word of the LORD which he commanded Joshua.

And Joshua burnt Ai, and made it a heap for ever, even a desolation unto this day.

And the king of Ai he hanged on a tree until eventide: and as soon as the sun was down, Joshua commanded that they should take his carcass down from the tree, and cast it at the entering of the gate of the city, and raise thereon a great heap of stones, that remaineth unto this day.

-Joshua 8: 18 - 29

ResearchBlogging.orgWhen Captain John C. Frémont first beheld the Joshua tree, he saw not what the Mormons are purported to have seen in its limbs: the spear-tip of Joshua in its sharp leaves, bent and raised at the enemies of God, relentlessly held aloft until the inhabitants of Ai were slain, stones of the city were heaped the scattered desert rocks and their king was dangled from the upper reaches of a tree perhaps not so different than the giant yucca itself. Frémont noted only “their stiff and ungraceful forms” and declared the Joshua tree “the most repulsive tree in the vegetable kingdom.” His contempt was mild compared to the violent myth behind the honorific given by the Latter Day Saints.

When a pack mule toppled over a cliff, Frémont lost his botanical collection, including the information gathered regarding the Joshua tree. The yucca was finally described by modern science in 1871 after samples were collected during a War Department railroad survey of the Southwest.

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Communicating environmental realities: framing and fiction

Aug 03 2010 Published by under [Biology&Environment], [Science in Society]

ResearchBlogging.orgI finally found the time yesterday evening to read through a few of the papers from the latest Frontiers in Ecology and the Environment, which is focused on science/environmental communication this time around. The majority of the articles are driven by Nisbet's ideas about framing in general, but I don't really want to dive back into that mire of rhetoric, at least on a broadside.

I'll start out by saying that I do agree to some extent that the idea of stewardship is a good one in that it has been adopted by folks with very different worldviews. I think overall Wilson's The Creation took a good step of putting aside some of the more tedious ideological blockers between materialism and spiritualism in regard to feeling a connection to nature in any affectionate sense compelling enough to engender stewardship. Since it was published (and I'm sure before then) much work has been done to piece together a much more diverse, welcoming environmental movement.

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A hobbit's contemporaries: Biogeography and insular evolution on Flores

Jul 15 2010 Published by under [Biology&Environment]


ResearchBlogging.org
Painters create networks. The subject of the piece, even if it’s a simple splotch of color, garners the most attention, but without a descriptive background or other kinds of supporting elements to contextualize the portion of the painting where the artist wants you to look, the intended focus is lost. The subject loses a certain clarity of interpretation in the absence of those elements.

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Southeast Asia in the Pleistocene, from grassland to rain forest

Jun 09 2010 Published by under [Biology&Environment]

ResearchBlogging.orgI’ve been trying to keep up with the Gulf situation, so most of my reading of late has been dominated by those details, and the unread numbers in my RSS folders were a little intimidating, but I finally found some time to read some of the papers I’ve earmarked in the past month or so.

This study from the Journal of Biogeography attempts a new method to assemble the paleoecology and paleoenvironment of Southeast Asia in the late Pleistocene and runs a lengthy comparison against the results of previous studies, corroborating the evidences. The interest in reconstructing these environments is largely generated from more recent discoveries of hominins that lived there in the Pleistocene. Data regarding hominin-mammal interactions is important and can be used to determine evolutionary nuances. If the environments in which these hominins lived can be interpreted, it can give us more details about how they lived, how they continued to disperse and even give scientists better clues as to where remains and artifacts can be found.

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Defining edge effects by resource and sensitivity

Apr 30 2010 Published by under [Biology&Environment]

ResearchBlogging.orgIn 2004 Leslie Ries and Thomas D. Sisk published a study in Ecology asking a simple and surprisingly unaddressed question: Considering the number of studies published describing habitat fragmentation and edge effects, why has the pattern and framework of these effects on ecosystems not been described? Ries and Sisk proposed a conceptual model in that paper that can account and predict, to some extent, the variability of an organism’s responses to different edges, usually indicated through an increase or decrease of abundance at the edge, or no change at all. The model is based on resources, predicting how organisms will be distributed across the edge between patches by the quality and quantity of resources available in the three zones (patch1 – edge – patch2).

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