Improved probability of detection of ecological "surprises".

Ecological "surprises" are defined as unexpected findings about the natural environment. They are critically important in ecology because they are catalysts for questioning and reformulating views of the natural world, help shape assessments of the veracity of a priori predictions about ecological trends and phenomena, and underpin questioning of effectiveness of resource management. Despite the importance of ecological surprises, major gaps in understanding remain about how studies might be done differently or done better to improve the ability to identify them. We outline the kinds of ecological surprises that have arisen from long-term research programs that we lead in markedly different ecosystems around the world. Based on these case studies, we identify important lessons to guide both existing studies and new investigations to detect ecological surprises more readily, better anticipate unusual ecological phenomena, and take proactive steps to plan for and alleviate "undesirable" ecological surprises. Some of these lessons include: (i) maintain existing, and instigate new, long-term studies; (ii) conduct a range of kinds of parallel and concurrent research in a given target area; (iii) better use past literature and conceptual models of the target ecosystem in posing good questions and developing hypotheses and alternative hypotheses; and (iv) increase the capacity for ecological research to take advantage of opportunities arising from major natural disturbances. We argue that the increased anticipatory capability resulting from these lessons is critical given that ecological surprises may become more prevalent because of climate change and multiple and interacting environmental stressors.

In-stream uptake dampens effects of major forest disturbance on watershed nitrogen export.

Between January 4 and 10, 1998, a severe ice storm impacted large areas of northern New York, New England, and eastern Canada. This storm struck the Hubbard Brook Experimental Forest in New Hampshire on January 7-8, 1998, and caused extensive forest crown damage (>30%) in a narrow elevation band (600-740 m) across the south-facing experimental watersheds. Stream water has been collected and chemically analyzed since 1963 in six experimental watersheds at Hubbard Brook Experimental Forest; thus, we were able to examine the effect of this severe natural disturbance on watershed nutrient export and changes in instream nitrate (NO3-) processing. The ice storm caused large increases in watershed export of NO3- for 2 years after the disturbance, but our examination of in-stream processing suggests that NO3- losses would have been much more dramatic had there not been an increase in in-stream, nitrogen-processing efficiency after the ice storm. The canopy damage that resulted from the ice storm led to increased light availability and large inputs of woody debris to the stream. We suspect that increases in algal production and storage and processing of terrestrial litter account for the increase in inorganic nitrogen processing in these streams. Our results indicate that, without in-stream processing, export of NO3- from the damaged watersheds would have been 80-140% higher than was observed. These results point to an intriguing negative feedback mechanism whereby the same disturbance that causes watershed NO3- loss may simultaneously lead to increased in-stream retention and transformation.

Cadmium toxicity among wildlife in the Colorado Rocky Mountains.

Cadmium is known to be both extremely toxic and ubiquitous in natural environments. It occurs in almost all soils, surface waters and plants, and it is readily mobilized by human activities such as mining. As a result, cadmium has been named as a potential health threat to wildlife species; however, because it exists most commonly in the environment as a trace constituent, reported incidences of cadmium toxicity are rare. Here we have measured trace metals in the food web and tissues of white-tailed ptarmigan (Lagopus leucurus) in Colorado. Our results suggest that cadmium toxicity may be more common among natural populations of vertebrates than has been appreciated to date and that cadmium toxicity may often go undetected or unrecognized. In addition, our research shows that ingestion of even trace quantities of cadmium can influence not only the physiology and health of individual organisms, but also the demographics and the distribution of species.

Transport and fate of trifluoroacetate in upland forest and wetland ecosystems.

Although trifluoroacetate (TFA), a breakdown product of chlorofluorocarbon replacements, is being dispersed widely within the biosphere, its ecological fate is largely unknown. TFA was added experimentally to an upland, northern hardwood forest and to a small forest wetland ecosystem within the Hubbard Brook Experimental Forest in New Hampshire. Inputs of TFA were not transported conservatively through these ecosystems; instead, significant amounts of TFA were retained within the vegetation and soil compartments. More TFA was retained by the wetland ecosystem than by the upland forest ecosystem. Using simulation modeling, TFA concentrations were predicted for soil and drainage water until the year 2040.

Acid rain: china, United States, and a remote area.

The composition of precipitation in China is highly influenced by fossil fuel combustion and agricultural and cultural practices. Compared to the eastern United States, precipitation in China generally has higher concentrations of sulfate, ammonium, and calcium. Wet deposition rates of sulfur in China are 7 to 130 times higher than those in a remote area in the Southern Hemisphere. In many areas of the world, significant ecological changes have occurred in ecosystems that have acid deposition rates substantially less than those currently existing in China.

Changes in Na influx and outflux in Daphnia magna (Straus) as a function of elevated Al concentrations in soft water at low pH.

The effects of aluminum (Al) on sodium (Na) regulation by the freshwater crustacean Daphnia magna were determined. (22)Na influx and outflux experiments were conducted in soft water adjusted to pH 4.5, 5.0, and 6.5 (reference pH) with either ambient (0.02 mg/liter) or high (1.02 mg/liter) concentrations of total Al. The results indicate that Al toxicity was pH dependent. Aluminum increased the rate of morbidity of D. magna at pH 6.5, had no additional effect to those of hydrogen ions (H(+)) at pH 5.0, and reduced the rate of morbidity at pH 4.5. Both H(+) and total Al concentrations interfered with Na regulation, although it was possible to distinguish between their respective effects by using (22)Na. At pH 6.5, Al decreased (22)Na influx (by 46%) and increased (22)Na outflux (by 25%), which led to a net loss of Na. At pH 5.0, Al reduced (22)Na influx (by 58%) but had no additional effect to that of H(+) on (22)Na outflux. At pH 4.5, (22)Na influx was significantly inhibited (by 73%) compared with the reference pH 6.5 treatment even in the absence of Al. Aluminum decreased (22)Na outflux (by 31%) at pH 4.5, which reduced the net loss of Na and temporarily prolonged survival of the daphnids. These results indicate that Al affects both (22)Na influx and outflux in D. magna. The lower rate of Na uptake may involve a denaturation of the enzyme responsible for the active uptake of Na. At pH 6.5, the increased outflux of (22)Na may be due to either increased membrane permeability or increased renal losses (or both). At pH 4.5, the reduced outflux of (22)Na resembles the amelioration that occurs in the presence of elevated Ca concentrations.

Acid precipitation: natural versus anthropogenic components.

The concentrations of H(+), SO(4)(2-), and NO(3)(-) in the precipitation of eastern North America are greater now than they were historically as a result of fossil-fuel combustion. Because of a lack of data prior to 1950, the absolute increases in the concentrations of these three ions are unknown. This problem can be addressed by comparing the composition of precipitation from areas sensitive to acidic deposition with that of precipitation from remote areas. An analysis of precipitation data indicates that many areas of eastern North America receive precipitation with substantially greater H(+), SO(4)(2-), and NO(3)(-) concentrations than remote areas. For example, SO(4)(2-), the most ecologically significant indicator of change, is enriched 2 to 16 times in eastern North American precipitation relative to its concentration in remote areas.

Carbon flow in four lake ecosystems: a structural approach.

Direct and indirect carbon fluxes in lakes Marion (British Columbia), Findley (Washington), Wingra (Wisconsin), and Mirror (New Hampshire) are compared, using budgets and input-output analysis. Overall differences in carbon flow between the lakes are shown with cycling indices of .031, .108, .572, and .661, respectively. The results suggest that lake ecosystems may be considered unique aggregatins of similar components.

Nitrogen budget for an aggrading northern hardwood forest ecosystem.

Long-term analyses of the structure and function of a northern hardwood ecosystem have resulted in measurement of the salient features of the nitrogen cycle. These data allow an evaluation of the importance of the various components and provide a framework for more efficient forest management.

Acid Precipitation in the Northeastern United States: pH and Acidity.

Detailed chemical analyses reveal that acid precipitation (pH < 5.6) in the northeastern United States is caused by the strong mineral acids sulfuric and nitric. There is a large array of other proton sources in precipitation, weak acids and Bronsted acids; however, although these other acids contribute to the total acidity of precipitation, they have a minimal influence on the free acidity (ambient pH) of acid precipitation.