A Sustainability Index for Karst Environments

With growing populations and ever increasing pressure on resources, the need to live sustainably with our environment has increased in significance. When considering such anthropogenic pressures, karst landscapes are as vulnerable, if not more so, than any other environment. Such vulnerability arises from the rapid transit times of percolating water, the poor filtering ability of carbonate bedrock, and the highly specialized biota of subterranean karst. The Karst Sustainability Index (KSI) was created as a standardized metric of sustainable development practices in karst settings. The KSI uses predetermined targets to ascertain the overall sustainability of a karst region. Indicators are designed to incorporate common measures of sustainability for the three domains of social, environmental, and economic resource use. Benchmarking the current state of karst environments allows the comparison of sustainability practices temporally and spatially to highlight areas where remedial policies or actions are needed. This is the first index to incorporate the emerging field of environmental sustainability with karst landscape assessment. To test the applicability of the KSI, a study was undertaken in the Tampa Bay Metropolitan Area, which encompasses four counties that are entirely karst. The TBMA was found to be progressing towards the sustainable management of karst resources, and the KSI provided a robust measure of sustainability

Human Disturbance of the Waitomo Catchment, New Zealand

The karst disturbance index (KDI) consists of 31 environmental indicators categorized within the five broad categories of geomorphology, hydrology, atmosphere, biota, and culture. This article discusses the application of the KDI to the rural karst region of Waitomo, New Zealand. Previous applications of the KDI measured disturbance to urban areas as delineated by geo-political boundaries while this study used a physical boundary of a small karst catchment. Such an approach ensures greater environmental specificity of measured disturbance levels compared to those determined according to arbitrary, politically defined areas. The study included a comparison of a local resource manager and a visiting karst expert\u27s determinations of disturbance levels for the catchment. Overall, the Waitomo catchment was found to be moderately disturbed. The only significant, direct disturbances were deforestation and erosion; however, these lead to the indirect disturbance of cave biota, water quality and accelerated sedimentation of the catchment\u27s waterways. We have a high degree of confidence in the validity of these results due to the ability to assess all of the applicable indicators in the index, and the consistency of scoring by both individuals who applied the index. The benefit of applying the KDI at the catchment level is the greater accuracy measuring disturbance as opposed to applying the index within geo-political boundaries that incorporate both karst and non-karst terrains. With disturbance data for a highly specific area, the Waitomo resource managers have the improved ability to effectively identify, target, remediate, and manage human disturbance of the karst landscape

Application of the Karst Disturbance Index as a Raster-based Model in a Developing Country

Karst landscapes are important assets that provide a source of water, host rare and endangered biota, and serve as sites of significant human historical artifacts. Previous studies have attempted to ascertain the extent of anthropogenic disturbance within karst areas using various standardized methods. A common limitation of these earlier approaches included lack of assessment of spatial variability. This paper recognizes the importance of spatial heterogeneity by using a spatially-explicit calculation of the Karst Disturbance Index (KDI) in a Geographic Information System (GIS) and applying it to a sub-catchment of the Biosfera de la Reserva Selve el Ocote in Chiapas, Mexico. With a raster-based GIS approach, this particular application is the highest resolution spatial representation of the KDI ever undertaken. As the study area is in a developing country, much of the data required for applying the KDI were drawn from remotely sensed data. The final disturbance scores found low to moderate levels of disturbance indicative of lightly populated area. However, this particular study can serve as a benchmark for future applications of the KDI in the study area, as well as in other karst watersheds in developed or developing countries. With the potential of future development looming, land managers can use the zones of pristine-to low-levels of disturbance to begin monitoring programs and justify mitigation and land management decisions

Karst-Specific Composite Model for Informed Resource Management Decisions on the Biosfera de la Reserva Selva el Ocote, Chiapas, Mexico

High permeability and rapid recharge in karst aquifers make them susceptible to contamination. We combined a groundwater vulnerability map with an environmental disturbance index to give an adaptable spatial tool for developing management strategies for a karst environment in the Reserva de la Biosfera Selva el Ocote (el Ocote), Chiapas, Mexico. Seventy-two per cent of the study area is classified as an area of least concern for management, with 60% falling within el Ocote. Consequently, although there are concerns regarding the vulnerability of the karst ecosystem, the lack of development and the natural protection of the ecosystem, the immediate need for remedial action by the area\u27s managers is currently minimal. About 27% of the study area is classified by the composite model as of moderate concern, with 34% within el Ocote. This reflects a balance between areas of moderate and high vulnerability, but little disturbance. Based on the management zones created by this study, much of the sub-catchment is zoned as of least or moderate concern, where disturbance has not occurred. As such, the opportunity exists to prevent major human impacts on vulnerable areas and the entire ecosystem, but only if local stakeholders are incorporated into this process of limiting development

Late Holocene Environmental Reconstruction using Cave Sediments from Belize

Cave sediments collected from Reflection Cave on the Vaca Plateau, Belize show variations in the δ13C values of their fulvic acids (FAs), which indicate periods of vegetation change caused by climatic and Maya influences during the late Holocene. The δ13C values range from − 27.11‰ to − 21.52‰, a shift of ∼ 5.59‰, which suggests fluctuating contributions of C3 and C4 plants throughout the last 2.5 ka, with C4 plant input reflecting periods of Maya agriculture. Maya activity in the study area occurred at different intensities from ∼ 2600 cal yr BP until ∼ 1500 cal yr BP, after which agricultural practices waned as the Maya depopulated the area. These changes in plant assemblages were in response to changes in available water resources, with increased aridity leading to the eventual abandonment of agricultural areas. The Ix Chel archaeological site, located in the study area, is a highland site that would have been among the first agricultural settlements to be affected during periods of aridity. During these periods, minimal water resources would have been available in this highly karstified, well-drained area, and supplemental groundwater extraction would have been difficult due to the extreme depth of the water table

Interregional Comparison of Karst Disturbance: West-central Florida and Southeast Italy

The karst disturbance index (KDI) consists of 31 environmental indicators contained within the five broad categories: geomorphology, hydrology, atmosphere, biota, and cultural. The purpose of this research is to apply the KDI to two distinct karst areas, west Florida, USA, and Apulia, Italy. Through its application, the utility of the index can be validated and other important comparisons can be made, such as differences in the karst legislations implemented in each region and the effect of time exposure to human occupation to each karst terrain. Humans have intensively impacted the karst of southeast Italy for thousands of years compared to only decades in west-central Florida. However, west-central Florida\u27s higher population density allows the region to reach disturbance levels comparable to those reached over a longer period in Apulia. Similarly, Italian karst is more diverse than the karst found in west-central Florida, creating an opportunity to test all the KDI indicators. Overall, major disturbances for southeast Italy karst include quarrying, stone clearing, and the dumping of refuse into caves, while west-central Florida suffers most from the infilling of sinkholes, soil compaction, changes in the water table, and vegetation removal. The application of the KDI allows a benchmark of disturbance to be established and later revisited to determine the changing state of human impact for a region. The highlighting of certain indicators that recorded high levels of disturbance also allows regional planners to allocate resources in a more refined manner

Variable Calcite Deposition Rates as Proxy for Paleo-Precipitation Determination as Derived from Speleothems in Central Florida, U.S.A.

Deposition rates derived from speleothems have been shown to be a useful paleoclimatic proxy. Past studies have shown that the most common climatic parameter measured by variable deposition rates is precipitation, where increased precipitation leads to increased calcite deposition. This was the premise of our study, where three Floridian stalagmites’ deposition rates were measured and compared to paleohydrologic indicators taken from the sample or from other regional records. Deposition rates were measured by determining the volume of calcite precipitated between TIMS U-series dates (mm3 yr21 ), thereby accounting for morphological changes on the stalagmite over its depositional history. Most prior research relied on a simple linear interpolation between known ages to calculate rate (mm yr21 ). Results show three distinct periods of increased deposition for our stalagmites centered on 2.0, 1.25 and 0.5 ka BP. A comparison with Mg/Ca and Sr/Ca ratios and calcite deposition tentatively shows elevated elemental ratios during the three aforementioned periods. Elevated trace element ratios have been shown to be correlated with increased residence time of percolation waters in the overlying bedrock above caves and consequently decreased rainfall. To corroborate this finding, paleo-precipitation records from Little Salt Spring, Florida and Lake Miragoane, Haiti, were examined for coeval arid periods with our stalagmites. Both records do possess similar dry periods and provide added support that the region experienced periods of abrupt aridity over the last two millennia. The combined effect of a change in the mean position of the Intertropical Convergence Zone and the easterly winds associated with the North Atlantic High appear to be the major causes for these times of aridity

Paleoclimate Reconstruction derived from Speleothem Strontium and δ\u3csup\u3e13\u3c/sup\u3eC in Central Florida

Variability of strontium and carbon isotopes are reported from a speleothem from Central Florida, USA. Thermal ionization mass spectrometry of uranium–thorium isotopes indicate the speleothem was precipitated during the last 4000 years. Sr concentrations are negatively correlated with δ13C, a relationship inferred to record changes in soil productivity. Coeval changes in the Sr content and δ13C signals, as induced by soil productivity, are explained by changing precipitation above the cave. Both proxies record a 170–180-year solar cycle that has also been found in the Gulf of Mexico marine records and elsewhere. Consequently, this result provides evidence of an extraterrestrially driven modulator of precipitation in Central Florida

An Experimental Study of the Utility of Adventitious Roots for Determining the Hydroperiod in Isolated Wetlands

Accurate measurement of the hydroperiod in isolated wetlands currently relies upon the installation and frequent monitoring of devices such as piezometers and staff gauges. Observations of biological indicators of the hydroperiod can provide supplemental data to these devices and potentially replace them as a means of accurately determining this hydrologic interval. In this preliminary study, our objective is to determine whether adventitious root formation and maturation on buttonbush (Cephalanthus occidentalis) is a viable indicator of the hydroperiod in isolated wetlands. Buttonbush seedlings were flooded in a controlled environment over a three month period in the summer of 2011. During this time, the length and complexity of adventitious roots observed were recorded. We found a significant positive relationship between average lengths of primary adventitious roots and time of inundation. The sequential appearance of secondary, tertiary and quaternary roots also corresponded with the length of the hydroperiod. From these preliminary results, we see a strong potential of using adventitious roots on buttonbush to help determine the hydroperiods of isolated wetland systems. Ideally, future studies will extend the period of investigation beyond our three month interval and calibrate these findings with examples from natural wetlands

Groundwater Vulnerability Mapping for a Sub-Catchment of the Rio La Venta Watershed, Chiapas, Mexico

Karst systems are particularly vulnerable to overexploitation and pollution due to their high hydraulic conductivity and points of rapid infiltration that allow quick influx of runoff and pollutants into the aquifer. The sustainability of non-contaminated groundwater in these systems is imperative for both humans and groundwater-dependent ecosystems. An important practice in managing groundwater sustainability involves assessing aquifer vulnerability. This study created the first groundwater vulnerability map (GVM) for a sub-catchment of the Rio La Venta watershed in Chiapas, Mexico, using an adaptation of the hazard–pathway–target method. This project also conducted the first tracer study in the Rio la Venta watershed to establish connectivity between the catchment and the Rio La Venta Canyon. Finally, this study evaluated the results of the GVM through a sensitivity analysis. Results of the GVM clearly demarcate areas of very high, high, moderate, and low vulnerability within the study area most of which being classified as low vulnerability. The zones of high vulnerability were successfully validated through two dye tracer tests that measured rapid groundwater flow velocities. With the limited resources available to land managers in this area, a problem common in many developing countries, tools that quickly and inexpensively highlight areas that require special protection to help maintain or improve water quality in their watersheds have great utility. Conveying this information to land managers and policymakers can lead to potential changes in current land use practices and allow for the reallocation of resources in support of reducing future negative human–landscape interactions