Value Of Long-term Monitoring Research Articles

Long term monitoring reveals the importance of large, long unburnt areas and smaller fires in moderating mammal declines in fire‐prone Savanna of northern Australia

Abstract Biodiversity loss is often attributable to multiple interacting pressures that are moderated across environmental gradients. These processes contribute to complex responses that are challenging to interpret and understand. Well‐designed and well‐implemented monitoring can play a vital role in this but is rarely undertaken. Mounting evidence suggests that current fire regimes across Savanna ecosystems have contributed to the decline of a range of biota. Hence, contemporary fire regimes are at odds with conservation goals. Using an extensive spatiotemporal monitoring dataset from three large National Parks in northern Australia, we applied generalised linear mixed models to examine: (1) trends in mammal richness and abundance through time and variation across environmental gradients such as productivity or landscape position (e.g. terrain ruggedness); and (2) how fire, a potential driver, is moderated by environmental gradients. Across 24 years, major declines in mammal richness and abundance were observed with greater reductions in less rugged and less mesic habitats. Patterns of decline were related to multiple aspects of fire regimes, but not changes in vegetation structure and composition, or cane toads, Rhinella marina, arrival and concomitant poisoning of predatory animals during consumption. More pronounced declines occurred in sites that were exposed to larger fires, had less long unburnt (>5 years without fire) vegetation and were more distant from large, long unburnt patches. Relationships between mammal persistence and fire varied among vegetation communities, with the strongest fire effects observed in lowland woodland—drier with few barriers to fire spread—where the availability of long unburnt areas moderated declines more than in other vegetation communities. Synthesis and applications. Current fire regimes are contributing to mammal declines in northern Australian Savanna. Collectively, our results highlight: (1) the value of long term monitoring, and importance of considering landscape position when assessing faunal responses to landscape‐level perturbations like fire; (2) that significant improvements in fire regimes are required to ameliorate mammal declines; and (3) the need to shift management focus from retaining small, short‐lived unburnt patches toward preserving relatively large contiguous areas of long unburnt habitat, particularly in less rugged lowland and sandstone woodlands.

Species Richness of Cypress Dome Vegetation in West-Central Florida, USA

Cypress domes are relatively small forested depressional wetlands common in the southeastern United States. The vegetative species richness of cypress domes is quantified using 15 years of annual vegetation data for 41 relatively unimpacted cypress domes in west-central Florida. Wetland species richness was normally distributed, with a median of 73 species and standard deviation of 16 species. Across the sample, 396 species representing 204 genera and 92 families were observed, with the jackknife estimator predicting a species richness of 516, much higher than previous observed or predicted values for cypress domes. Using a bootstrapping technique, the effects of increasing the sampled number of years and wetlands on species richness estimates were assessed, with fewer years or wetlands resulting in considerably lower estimates of richness. The results demonstrate the major contribution of cypress domes to regional biodiversity and the value of long-term monitoring at multiple wetlands.

Species Richness of Cypress Dome Vegetation in West-Central Florida, USA

Cypress domes are relatively small forested depressional wetlands common in the southeastern United States. The vegetative species richness of cypress domes is quantified using 15 years of annual vegetation data for 41 relatively unimpacted cypress domes in west-central Florida. Wetland species richness was normally distributed, with a median of 73 species and standard deviation of 16 species. Across the sample, 396 species representing 204 genera and 92 families were observed, with the jackknife estimator predicting a species richness of 516, much higher than previous observed or predicted values for cypress domes. Using a bootstrapping technique, the effects of increasing the sampled number of years and wetlands on species richness estimates were assessed, with fewer years or wetlands resulting in considerably lower estimates of richness. The results demonstrate the major contribution of cypress domes to regional biodiversity and the value of long-term monitoring at multiple wetlands.

Biogeochemical shifts and zooplankton responses in post-CAAA northeastern lakes: The success of acid recovery, complexity of biological recovery, and value of long-term monitoring

Lakes in the northeastern U.S., as in other regions, experienced significant declines in water quality and ecosystem health in the mid to late 20th century as atmospheric deposition from industrial emissions caused surface waters to acidify. After the Clean Air Act Amendments of 1990 enhanced regulations to limit emissions of sulfur and nitrogen, many lakes in the Northeast recovered from acidification. The organisms that inhabit lakes are susceptible to these shifts, and zooplankton can serve as valuable indicators of lake ecosystem responses to shifts due to their position as primary consumers in the food web. We evaluated a large historical dataset from the U.S. Environmental Protection Agency (EPA) Eastern Lake Survey (ELS) of 143 lakes throughout the northeastern U.S. to understand how recovery from acidification and subsequent chemical changes influenced zooplankton body size and community composition. We observed significant changes in chemistry; surface water sulfate concentrations decreased by 22% in the ELS lakes between the two sample years of 1986 and 2004. Increasing concentrations of DOC are common from the combined influence of deacidification and climate change, and the ELS lakes experienced a 26% increase in DOC. Notably, in the more developed regions of our study area, chloride concentration in lakes tripled, likely due to increased use of road deicers, and this is related to a subsequent increase in calcium and magnesium base cations. Zooplankton body size increased significantly between 1986 and 2004 across all taxa, and body size of Daphnia species, which require higher amounts of calcium than other zooplankton taxa, was positively associated with high calcium lakes. Shifts in zooplankton community structure, however, were most strongly influenced by variation in ANC, sulfate, and DOC. Our findings indicate that, while surface water acidity has a strong influence on zooplankton community structure, zooplankton populations are likely on a different trajectory than a simple recovery due to multiple chemical changes, such as increased chloride, occurring in lakes undergoing acid recovery. These, along with changes in climate and land-use, elicit multiple simultaneous responses in zooplankton communities.

Bulk deposition of organic and inorganic nitrogen in southwest China from 2008 to 2013

China is regarded as one of the nitrogen deposition hotspots in the world. Measurements to-date have focused mainly on the North China Plain, ignoring the fact that atmospheric chemical and physical properties vary across the country and that there may be other hotspots regions that should be investigated. For this reason we have conducted a six year study, measuring the bulk deposition of reduced (NH4-N), oxidized (NO3-N), and dissolved organic nitrogen (DON) at three contrasting sites in the Sichuan province, southwest China. The study sites were a high altitude forest in the Gongga Mountains (GG), an agriculture dominated region in Yanting (YT) and an urban site in the mega city Chengdu (CD). The annual average bulk deposition fluxes of total dissolved nitrogen (TDN) were 7.4, 23.1 and 36.6 kg N ha−1 yr−1 at GG, YT and CD sites, respectively, during the study period 2008 to 2013. The contributions of NH4-N, NO3-N and DON to the TDN were in the range of 48.4–57.8%, 28.8–43.7%, and 8.0–15.6%, respectively. DON bulk deposition was mainly dominated by agricultural activities. TDN bulk deposition fluxes showed increasing trends at the agricultural and urban sites from 2008 to 2013, but there was little change at the remote forest (GG) site. While reduced N dominated bulk N deposition at all the three sites, its contribution showed a decreasing trend, suggesting a gradual increase in the importance of oxidized N. These results reveal the value of long term monitoring in detecting changes in the atmospheric chemical composition of this rapidly changing region, and their inclusion in the policy debate regarding which sources should be controlled in order to reduce the long term impacts of N deposition, especially for southwest China, where there are few measurements of N deposition.

Population dynamics of the Critically Endangered Euryops virgatus: Highlighting the value of long-term monitoring by citizen scientists

Population dynamics of the Critically Endangered Euryops virgatus: Highlighting the value of long-term monitoring by citizen scientists

Environmental influences on movements and distribution of a wild horse (Equus caballus) population in western Nevada, USA: a 25-year study

Wild horse populations in the American West have been heavily managed to regulate horse numbers since the inception of the Free-Roaming Wild Horse and Burro Act of 1971. The Montgomery Pass Wild Horse Territory (MPWHT) on the California/Nevada border is unique in the absence of human intervention there across the past 30 years. This has provided the opportunity to observe long-term patterns in the natural relationship between wild horses and their environment and to examine environmental impacts on the horse population and its activities, movements and distribution on the range. In this study multiple variables in the physical environment and in horse behaviour were monitored seasonally across 25 years beginning in 1987. Distinct summer (higher elevations) and winter (lower elevations) range use was characteristic for more than 60% of the population during the first 7 study years, with subsequent gradual but marked reduction in use of summer range. While approximately 20% of the population continued to annually use the historical summer range, the majority divided into two geographically and functionally separate subpopulations that resided year round in the historical winter range and adjacent areas on opposite sides of the MPWHT. Mountain lion predation on foals was restricted to the summer range, and exodus of horses from the summer range resulted in increased foal survival where horse subpopulations eventually resided. The long-term consequences of increased horse numbers in the MPWHT remain under continued study. The present study has shown that wild horses are highly adaptive and individually varied in response to environmental pressures. It has also demonstrated the value of long-term monitoring of wild horse populations to reveal underlying dynamics and their potential management implications.

Near infrared high resolution spectroscopy and spectro-astrometry of gas in disks around Herbig Ae/Be stars

In this review, we describe how high resolution near infrared spectroscopy and spectro-astrometry have been used to study the disks around Herbig~Ae/Be stars. We show how these tools can be used to identify signposts of planet formation and elucidate the mechanism by which Herbig Ae/Be stars accrete. We also highlight some of the artifacts that can complicate the interpretation of spectro-astrometric measurements and discuss best practices for mitigating these effects. We conclude with a brief discussion of the value of long term monitoring of these systems.