Emily E. Oldfield

Biogeographic patterns in below-ground diversity in New York City's Central Park are similar to those observed globally

Soil biota play key roles in the functioning of terrestrial ecosystems, however, compared to our knowledge of above-ground plant and animal diversity, the biodiversity found in soils remains largely uncharacterized. Here, we present an assessment of soil biodiversity and biogeographic patterns across Central Park in New York City that spanned all three domains of life, demonstrating that even an urban, managed system harbours large amounts of undescribed soil biodiversity. Despite high variability across the Park, below-ground diversity patterns were predictable based on soil characteristics, with prokaryotic and eukaryotic communities exhibiting overlapping biogeographic patterns. Further, Central Park soils harboured nearly as many distinct soil microbial phylotypes and types of soil communities as we found in biomes across the globe (including arctic, tropical and desert soils). This integrated cross-domain investigation highlights that the amount and patterning of novel and uncharacterized diversity at a single urban location matches that observed across natural ecosystems spanning multiple biomes and continents.

Predicting the responsiveness of soil biodiversity to deforestation: a cross‐biome study

The consequences of deforestation for aboveground biodiversity have been a scientific and political concern for decades. In contrast, despite being a dominant component of biodiversity that is essential to the functioning of ecosystems, the responses of belowground biodiversity to forest removal have received less attention. Single-site studies suggest that soil microbes can be highly responsive to forest removal, but responses are highly variable, with negligible effects in some regions. Using high throughput sequencing, we characterize the effects of deforestation on microbial communities across multiple biomes and explore what determines the vulnerability of microbial communities to this vegetative change. We reveal consistent directional trends in the microbial community response, yet the magnitude of this vegetation effect varied between sites, and was explained strongly by soil texture. In sandy sites, the difference in vegetation type caused shifts in a suite of edaphic characteristics, driving substantial differences in microbial community composition. In contrast, fine-textured soil buffered microbes against these effects and there were minimal differences between communities in forest and grassland soil. These microbial community changes were associated with distinct changes in the microbial catabolic profile, placing community changes in an ecosystem functioning context. The universal nature of these patterns allows us to predict where deforestation will have the strongest effects on soil biodiversity, and how these effects could be mitigated.

Challenges and future directions in urban afforestation

Summary 1. Mature urban trees improve air quality, reduce storm water run-off and sequester carbon. Municipal agencies establish forests of native juvenile trees to enhance these and other ecosystem services to cities. Little data exist, however, regarding whether these trees will form mature, native forests. 2. We review urban forestry research that deals specifically with the growth, survival and recruitment of new native urban forests and use these data to identify knowledge gaps and propose research needed to create and maintain native urban forests. 3. Experimental urban forestry studies are few and most are of durations ≤5 years, shorter than the 10–25 year time frame required to understand forest stand dynamics. Studies capturing initial dynamics of urban afforestation (≤5 years) identify invasive species as the primary threat to native tree establishment. Data exploring longer-term dynamics are needed to evaluate whether early-stage afforestation dynamics can be used to infer the composition and function of mature urban forests. 4. Synthesis and applications. Urban afforestation approaches–from natural colonization to large-scale plantings–represent a trade-off in cost vs. efficacy for establishing native forests. A major cost-saving strategy would be to determine whether exotics and natives can co-exist and provide the intended ecosystem services.

Involving Ecologists in Shaping Large-Scale Green Infrastructure Projects

Cities are implementing green infrastructure projects to provide ecosystem services such as storm water mitigation. The efficacy of these projects at providing services is rarely evaluated. Embedding research into project design provides a mechanism for both evaluation and development of the ecological knowledge needed to improve infrastructure for services provision. Ecologists must navigate the politics, economics, and social constraints of working in cities. Additional skills and practices are needed to develop new relationships and improve credibility, to define project roles, to identify new funding, and to integrate multidisciplinay knowledge. We examine a large-scale green infrastructure project that integrates hypothesis-driven experimental research and baseline monitoring with park design, implementation, and maintenance. Drawing on this case study, we recommend strategies to facilitate the inclusion of research ecologists in green infrastructure projects by enhancing the professional cer-tification process, establishing research ecologists as consultants, and integrating ecology and design in graduate programs.

Direct effects of soil organic matter on productivity mirror those observed with organic amendments

AimsOrganic amendments to arable soil build soil organic matter (SOM), which can increase crop yields. However, organic amendments can influence crop yields independently of SOM by providing nutrients directly to plants. The relative importance of native organic matter versus organic amendments is not well quantified. We experimentally manipulated both organic amendments and native SOM concentrations to quantify their relative importance to crop yields.MethodsWe created OM concentration gradients by (1) diluting an organic-rich A-horizon with a mineral base and (2) amending compost to the same mineral base, generating OM concentrations for both treatments of approximately 2, 4 and 8%. We grew buckwheat and measured plant productivity and a range of soil fertility variables.ResultsHigher concentrations of OM, whether native or amended, were associated with higher soil water holding capacity and nutrients, and improved soil structure. Consequently, increases in both native and amended OM were associated with strong positive but saturating impacts on productivity, though amendment effects were greater.ConclusionsOur results suggest that native SOM can support productivity levels comparable to those observed with organic amendments. Although our quantitative findings will likely vary for different soils and amendments, our results lend support to the idea that SOM stocks directly increase productivity.