A restoration project at Lake Tahoe Basin illustrated the managerial limitations to protecting and conserving species for the long-term. The place’s conditions, resulting from past actions, can present major obstacles in restoration. Numerous activities, such as logging, fire suppression, grazing, and human development have altered wildlife communities within the Basin (USDA n.d.). Logging greatly reduced the proportion of old-growth forest in the Lake Tahoe Basin from approximately 55% to 5% (USDA n.d.). Fire suppression has also altered forest structure and composition, resulting in densely packed trees that are susceptible to insect and disease outbreaks and catastrophic fires as a result of increased fuel loads (USDA n.d.). Unregulated cattle and sheep grazing in the 1860s and 1870s resulted in severe overgrazing in several meadow and lake-level areas throughout the Lake Tahoe Basin (USDA n.d.). Although grazing was limited to allotments in the 1930s, grazing pressure was still heavy at that time and continued to be relatively widespread into the late 20th century, leaving a lasting mark in some areas (USDA n.d.). Development pressures also have decreased the natural diversity and integrity of ecosystems in the Lake Tahoe Basin (USDA n.d.). From 1900 to the present, there has been rapid development and habitat degradation (USDA n.d.). These factors, in part, led to the degradation and reduction of ecologically important ecosystems such as marshes, bogs, fens, aspen groves, meadows, and riparian areas (USDA n.d.). Unfortunately, past action has led to irreversible damage that presents a challenge to natural resource managers.
An essential component of long-term, quality restoration is incorporating ecological requirements of key animal species (USDA n.d.). While developing and maintaining a functioning ecosystem in the desired condition will provide habitat and niche components for the majority of species, it is unlikely that all key requirements for targeted species can be achieved in this manner given the degraded environments that exist (USDA n.d.). For any restoration project, such a framework must consider the surrounding environmental conditions because successful restoration is unlikely if immigration and emigration are impossible, or if predators or competitors cannot be managed either within the project area or on surrounding lands (USDA n.d.). Thus, in addition to rehabilitation of vegetative structure and hydrologic functions, additional actions may need to be considered as part of the restoration actions or subsequent management actions to account for the niche components of targeted animal species (USDA n.d.). Further, data collected in the Lake Tahoe Basin since 2004 illustrated the fluctuations of desired condition species and lend credence to the need for multi-year pre- and post-restoration monitoring. Additionally, delisting is a complex process that can take many generations of population growth (Sparling 2014). The time it takes to monitor along with budgetary constraints and legal mandates in the process make long-term conservation of a species quite the challenge.
Sparling, Donald W. 2014. Natural Resource Administration: Wildlife, Fisheries, Forests and Parks. San Diego: Academic Press.
USDA (n.d.). “Wildlife restoration and monitoring: Concepts and development.” https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5150405.pdf
Comment by Fenton Kay:
Great point, Mary. What species are at risk in the Tahoe Basin at the present time? Is there a flexible and sufficiently broad conservation/restoration approach to deal with that/those species? My experience in the ’60s working in the Sierras around Tahoe suggests that some of the habitats/ecosystem components may be more resilient than we realize. Can that play into your planning?
One species at risk in the Tahoe Basin is the Columbia spotted frog (Reno Fish and Wildlife Service). The approach to conserve the Columbia spotted frog is to employ sustainable grazing practices and create ponds where the frog has taken up residence and is successfully breeding (Reno Fish and Wildlife Service). As a result of these collaborative conservation efforts, population numbers of the Great Basin Columbia spotted frog have rebounded (Reno Fish and Wildlife Service). However, restorationists can be even more successful by controlling the introduction of non-native predators such as bullfrogs, bass and predatory freshwater fish species which are believed to contribute to their decline (Reno Fish and Wildlife Service). Yes, since some of the habitats/ecosystem components may be more resilient than we realize, scientists can focus on invasive species control instead of turning so much attention towards restoring habitats.
Reno Fish and Wildlife Service. “Proactive conservation for plants and wildlife”. Accessed January 17 2021. https://www.fws.gov/reno/content/proactive-conservation-plants-and-wildlife
Comment by Fenton Kay:
Good stuff, Mary. What is the scientific name of the frog? I don’t recognize that common name – but I probably knew it by some other name.
Comment by Devon Yuwiler:
Thanks for your interesting post! I appreciated your specific considerations of the vegetative structure and hydrologic functions of the area. Similarly, I think supplemental information about and attention to geologic features can enhance one’s management strategies.
Yes, I would agree attention to geologic features can enhance one’s management strategies. There is a report depicting results from specifically looking at the link between rock type and biodiversity and thus how the achievement of biodiversity targets can be assisted through a better understanding of geology (English Nature). They determined geology has strong ties with biodiversity, in that the nature of the substrate, as usually determined by the nature of the underlying rock, is a key factor in determining the distribution of habitats and species (English Nature). For example, the high levels of magnesium in the soil around serpentine block a plant’s ability to take in soil nutrients, especially calcium (English Nature). Since they are shallow and low in organic material and clay, serpentine soils also cannot hold water or nutrients particularly well (English Nature). To live in dry, magnesium-rich, nutrient-poor, and, in some cases, toxic soils, most serpentine plants have developed special adaptations in form or internal chemistry (English Nature). By deriving the condition of the soil from geological features, scientists can then understand how to approach biodiversity management.
English Nature. “Linking Geology and Biodiversity”. English Nature Research Reports. 562. https://www.cbd.int/doc/pa/tools/Linking%20Geology%20and%20Biodiversity%20(part%201).pdf
Comment by Devon Yuwiler:
Thank you for your response; I look forward to reading that report! I love geology, and am sure to find it very interesting.