Malcolm L. Hunter

Why geodiversity matters in valuing nature's stage

Geodiversity--the variability of Earths surface materials, forms, and physical processes-is an integral part of nature and crucial for sustaining ecosystems and their services. It provides the substrates, landform mosaics, and dynamic physical processes for habitat development and maintenance. By determining the heterogeneity of the physical environment in conjunction with climate interactions, geodiversity has a crucial influence on biodiversity across a wide range of scales. From a literature review, we identified the diverse values of geodiversity; examined examples of the dependencies of biodiversity on geodiversity at a site-specific scale (for geosites <1 km(2) in area); and evaluated various human-induced threats to geosites and geodiversity. We found that geosites are important to biodiversity because they often support rare or unique biota adapted to distinctive environmental conditions or create a diversity of microenvironments that enhance species richness. Conservation of geodiversity in the face of a range of threats is critical both for effective management of natures stage and for its own particular values. This requires approaches to nature conservation that integrate climate, biodiversity, and geodiversity at all spatial scales.

Effects of Riparian Timber Management on Amphibians in Maine

Abstract Riparian areas are one of the most complex, diverse, and dynamic environments in forested ecosystems. In areas managed for timber, riparian areas are often protected with unharvested forested buffers, but it is unclear whether these buffers are adequate to maintain the floral and faunal diversity of riparian areas. Amphibians are sensitive to forest management, have high diversity in riparian areas, and are among the most abundant vertebrates in temperate forests; therefore, they are excellent candidates to use in a study of the effects of riparian timber management. We conducted a field experiment with 15 headwater streams in western Maine, USA, randomly assigned to 5 silvicultural treatments. We examined amphibian abundance for 1 year prior to and 2 years following treatment. We also undertook a retrospective study on 12 headwater streams representing 3 treatments where harvests had occurred 4–10 years earlier. We used pitfall traps with drift fences and cover-controlled, active-searches to sample terrestrial and stream amphibians. Wood frogs (Rana sylvatica), eastern red-backed salamanders (Plethodon cinereus), and spotted salamanders (Ambystoma maculatum) were sensitive to timber harvesting along headwater streams. American toads (Bufo americanus) were either unaffected or increased in abundance postharvest. Buffers ranging in width from 11 to 35 m appeared to partially mitigate the effects of timber harvest because abundances were generally higher within the buffer than in the adjacent clearcut for wood frogs, American toads, and to a lesser extent red-backed salamanders. Partial harvests adjacent to headwater streams had the least effect on the riparian amphibian community and should be considered for harvests along headwater streams when managing at the stream scale. Our results show that managers can conduct riparian timber harvesting in a manner that allows a diverse suite of amphibian species to persist in the first years after harvest. It is plausible that these same practices may also mitigate the effects of timber harvesting on other forest species. Long-term effects of riparian timber harvesting on amphibians and other forest species population persistence and viability is a logical next step.

A Cyclic Red-Backed Vole (Clethrionomys gapperi) Population and Seedfall over 22 Years in Maine

Abstract Vole population dynamics are well characterized in Europe, Fennoscandia, and Japan, but long-term studies of vole dynamics in North America are rare and much needed. Summer relative abundance of southern red-backed voles (Clethrionomys gapperi) fluctuated periodically during 22 years (1983–2004) at the Holt Research Forest, Maine, suggesting an outbreak or cyclic dynamic. The time series had a 4.4-year period, and 2nd-order lagged relative abundance was significant in an autoregressive model. This was consistent with vole series in Fennoscandia and Japan. Above-average white pine (Pinus strobus) seed crops preceded C. gapperi peaks in 4 of 5 peak phases. In a model including P. strobus seeds, both seeds and 2nd-order lagged abundance terms were significant. Relative importance of P. strobus seeds to this omnivore needs to be established. High and low phases of C. gapperi corresponded with those of sympatric white-footed mice (Peromyscus leucopus). The 2nd-order autoregressive process, 4.4-year periodicity, and synchrony with P. leucopus indicated the C. gapperi dynamic was cyclic. This was a unique finding for the northeastern United States.

The complementary niches of anthropocentric and biocentric conservationists

A divergence of values has become apparent in recent debates between conservationists who focus on ecosystem services that can improve human well-being and those who focus on avoiding the extinction of species. These divergent points of view fall along a continuum from anthropocentric to biocentric values, but most conservationists are relatively closer to each other than to the ends of the spectrum. We have some concerns with both positions but emphasize that conservation for both people and all other species will be most effective if conservationists focus on articulating the values they all share, being respectful of divergent values, and collaborating on common interests. The conservation arena is large enough to accommodate many people and organizations whose diverse values lead them to different niches that can, with good will and foresight, be far more complementary than competitive.

Biomass and species richness of aquatic macrophytes in four Maine (U.S.A.) lakes of different acidity

Macrophyte communities of 2 pairs of oligotrophic head-water lakes of different acidity were described. The acidic lakes had fewer species of macrophytes than the circumneutral lakes. Biomass in the circumneutral lakes ranged from 14.0 to 157.86 g m−2; values for the acidic lakes were intermediate (33.8 and 74.6 g m−2).

Forest landscape change and biodiversity conservation

Forest landscapes are changing at unprecedented rates in many regions of the world. This may have profound consequences for the diversity and resilience of forest ecosystems and may impose considerable challenges for their management. In this chapter, we review the different types of change that can occur in a forest landscape, including modifications in forest habitat amount, quality, fragmentation, connectivity, and heterogeneity. We describe the conceptual differences and potential interactions among these changes and provide a summary of the possible responses of forest species depending on their degree of habitat specialization, dispersal abilities, and other factors. We review the main current drivers of change in different regions of the world and how they are affecting (often synergistically) forest biodiversity: deforestation, climate change, forest fires, abandonment of rural land, land-use intensification, spread of invasive species, forest management, and the increasing amount of plantation forest. We conclude by providing a summary of recommendations and strategies for mitigating and minimizing the undesirable effects of landscape change on forest biodiversity.