白蚁堪称非洲草原生态系统之星

The majestic¹ animals most closely associated with the African savanna²（热带草原） -- fierce（凶猛的，暴躁的） lions, massive elephants, towering giraffes（长颈鹿） -- may be relatively³ minor⁴ players when it comes to shaping the ecosystem⁵. The real king of the savanna appears to be the termite⁶（白蚁） , say ecologists who've found that these humble⁷ creatures contribute mightily⁸ to grassland⁹ productivity in central Kenya via a network of uniformly distributed colonies. Termite mounds¹¹（堆） greatly enhance plant and animal activity at the local level, while their even distribution over a larger area maximizes ecosystem-wide productivity.

The finding, published this week in the journal PLoS Biology, affirms a counterintuitive（违反直觉的） approach to population ecology: Often it's the small things that matter most.

"It's not always the charismatic（神赐能力的，超凡魅力的） predators¹² -- animals like lions and leopards¹³ -- that exert（运用，发挥） the greatest control on populations," says Robert M. Pringle, a research fellow at Harvard University. "As E.O. Wilson likes to point out, in many respects it's the little things that run the world. In the case of the savanna, it appears these termites¹⁴ have tremendous influence and are central to the functioning of this ecosystem."

Prior research on the Kenya dwarf¹⁵（侏儒） gecko（壁虎） initially¹⁶ drew Pringle's attention to the peculiar¹⁷ role of grassy¹⁸ termite mounds, which in this part of Kenya are some 10 meters in diameter and spaced some 60 to 100 meters apart. Each mound¹⁰ teems¹⁹ with millions of termites, who build the mounds over the course of centuries.

After observing unexpectedly high numbers of lizards²⁰ in the vicinity of（在……附近） mounds, Pringle and his colleagues began to quantify ecological²¹ productivity relative to mound density²². They found that each mound supported dense²³ aggregations²⁴（雌虫聚集） of flora²⁵ and fauna²⁶（动植物群） : Plants grew more rapidly the closer they were to mounds, and animal populations and reproductive rates fell off appreciably²⁷（相当地，明显地） with greater distance.

What was observed on the ground was even clearer in satellite imagery. Each mound -- relatively inconspicuous（不显眼的） on the Kenyan grassland -- stood at the center of a burst of floral productivity. More importantly, these bursts were highly organized in relation to one another, evenly dispersed²⁸ as if squares on a checkerboard（棋盘） . The result, says Pringle, is an optimized²⁹ network of plant and animal output closely tied to the ordered distribution of termite mounds.

"In essence, the highly regular spatial³⁰ pattern（空间格局） of fertile mounds generated by termites actually increases overall levels of ecosystem production. And it does so in such a profound way," says Todd M. Palmer, assistant professor of biology at the University of Florida and an affiliate³¹（隶属的机构） of the Mpala Research Centre in Nanyuki, Kenya. "Seen from above, the grid-work of termite mounds in the savanna is not just a pretty picture. The over-dispersion, or regular distribution of these termite mounds, plays an important role in elevating the services this ecosystem provides."

The mechanism³² through which termite activity is transformed into far-reaching effects on the ecosystem is a complex one. Pringle and Palmer suspect termites import coarse particles into the otherwise fine soil in the vicinity of their mounds. These coarser particles promote water infiltration³³（渗透） of the soil, even as they discourage disruptive（破坏的，分裂性的） shrinking and swelling³⁴ of topsoil in response to precipitation（坠落，沉淀） or drought.

The mounds also show elevated levels of nutrients³⁵ such as phosphorus（磷） and nitrogen. All this beneficial soil alteration³⁶ appears to directly and indirectly³⁷ mold ecosystem services far beyond the immediate³⁸ vicinity of the mound.

While further studies will explore the mechanism through which these spatial patterns of termite mounds emerge, Pringle and Palmer suggest that the present work has implications beyond the basic questions of ecology.

"Termites are typically viewed as pests, and as threats to agricultural and livestock³⁹ production," Pringle says. "But productivity -- of both wild and human-dominated landscapes -- may be more intricately（杂乱地） tied to the pattern-generating organisms of the larger natural landscape than is commonly understood."

The findings also have important implications for conservation, Palmer says.

"As we think restoring degraded（退化的，堕落的） ecosystems⁴⁰, as we think about restoring coral reefs, or restoring plant communities, this over-dispersed pattern is teaching us something," he says. "It's saying we might want to think about doing our coral restoration or plant restoration in a way that takes advantage of this ecosystem productivity enhancing phenomenon."