Simeon J. Smaill

The right tree for the job? Perceptions of species suitability for the provision of ecosystem services.

Abstract Stakeholders in plantation forestry are increasingly aware of the importance of the ecosystem services and non-market values associated with forests. In New Zealand, there is significant interest in establishing species other than Pinus radiata D. Don (the dominant plantation species) in the belief that alternative species are better suited to deliver these services. Significant risk is associated with this position as there is little objective data to support these views. To identify which species were likely to be planted to deliver ecosystem services, a survey was distributed to examine stakeholder perceptions. Stakeholders were asked which of 15 tree attributes contributed to the provision of five ecosystem services (amenity value, bioenergy production, carbon capture, the diversity of native habitat, and erosion control/water quality) and to identify which of 22 candidate tree species possessed those attributes. These data were combined to identify the species perceived most suitable for the delivery of each ecosystem service. Sequoia sempervirens (D.Don) Endl. closely matched the stakeholder derived ideotypes associated with all five ecosystem services. Comparisons to data from growth, physiological and ecological studies demonstrated that many of the opinions held by stakeholders were inaccurate, leading to erroneous assumptions regarding the suitability of most candidate species. Stakeholder perceptions substantially influence tree species selection, and plantations established on the basis of inaccurate opinions are unlikely to deliver the desired outcomes. Attitudinal surveys associated with engagement campaigns are essential to improve stakeholder knowledge, advancing the development of fit-for-purpose forest management that provides the required ecosystem services.

Methane oxidation needs less stressed plants

Methane oxidation rates in soil are liable to be reduced by plant stress responses to climate change. Stressed plants exude ethylene into soil, which inhibits methane oxidation when present in the soil atmosphere. Here we discuss opportunities to use 1-aminocyclopropane-1-carboxylate deaminase to manage methane oxidation by regulating plant stress responses.

Warming Rather Than Increased Precipitation Increases Soil Recalcitrant Organic Carbon in a Semiarid Grassland after 6 Years of Treatments

Improved understanding of changes in soil recalcitrant organic carbon (C) in response to global warming is critical for predicting changes in soil organic C (SOC) storage. Here, we took advantage of a long-term field experiment with increased temperature and precipitation to investigate the effects of warming, increased precipitation and their interactions on SOC fraction in a semiarid Inner Mongolian grassland of northern China since April 2005. We quantified labile SOC, recalcitrant SOC and stable SOC at 0–10 and 10–20 cm depths. Results showed that neither warming nor increased precipitation affected total SOC and stable SOC at either depth. Increased precipitation significantly increased labile SOC at the 0–10 cm depth. Warming decreased labile SOC (P = 0.038) and marginally but significantly increased recalcitrant SOC at the 10–20 cm depth (P = 0.082). In addition, there were significant interactive effects of warming and increased precipitation on labile SOC and recalcitrant SOC at the 0–10 cm depth (both P<0.05), indicating that that results from single factor experiments should be treated with caution because of multi-factor interactions. Given that the absolute increase of SOC in the recalcitrant SOC pool was much greater than the decrease in labile SOC, and that the mean residence time of recalcitrant SOC is much greater, our results suggest that soil C storage at 10–20 cm depth may increase with increasing temperature in this semiarid grassland.

A review of soil carbon change in New Zealand’s grazed grasslands

ABSTRACT Soil organic matter is a potential sink of atmospheric carbon (C) and critical for maintaining soil quality. We reviewed New Zealand studies of soil C changes after conversion from woody vegetation to pasture, and under long-term pasture. Soil C increased by about 13.7 t C ha−1 to a new steady state when forests were initially converted to pasture. In the last 3–4 decades, resampling of soil profiles demonstrated that under long-term pasture on flat land, soil C had subsequently declined for allophanic, gley and organic soils by 0.54, 0.32 and 2.9 t C ha−1 y−1, respectively, and soil C had not changed in the remainder of sampled soil orders. For the same time period, pasture soils on stable midslopes of hill country gained 0.6 t C ha−1 y−1. Whether these changes are ongoing is not known, except for the organic soils where losses will continue so long as they are drained. Phosphorus fertiliser application did not change C stocks. Irrigation decreased carbon by 7 t C ha−1. Carbon losses during pasture renewal ranged between 0.8 and 4.1 t C ha−1. Some evidence suggests tussock grasslands can gain C when fertilised and not overgrazed. When combined to the national scale, different data sets suggest either no change or a gain of C, but with large uncertainties. We highlight key land-use practices and soil orders that require further information of soil C stock changes and advocate for a better understanding of underpinning reasons for changes in soil C.

Ethylene rather than dissolved organic carbon controls methane uptake in upland soils.

Sullivan et al. (2013) reported that there was a significantly positive relationship (P < 0.01, r2 = 0.58) between dissolved organic carbon (DOC) using salt extraction methods and potential methane oxidation rates in an arid region across a substrate age gradient. The authors observed that during the wet season rates of methane oxidation were higher, in opposition to trends in other ecosystems where increased soil moisture limits methane oxidation. Furthermore, DOC was more closely correlated with potential methane oxidation rates than other relevant parameters such as soil moisture content, pore space and texture. After considering alternative options, the authors indicated that DOC may be an important regulator of methane oxidation rates in these arid soils. The authors indicated that this conclusion was supported by observations that incubation with 13C-glucose enriched the methaneoxidizing bacteria (MOB) biomarker 18:1x7c, suggesting that DOC was a facultative substrate for MOB, and also explaining the observed correlation.

Climate change induced drought impacts on plant diseases in New Zealand

Climate change is expected to increase the frequency and duration of drought in many parts of New Zealand. This may affect the natural lifecycles of plant pathogens, influence host predisposition to infection or disease expression, shift the natural ranges of the pathogens, and alter the rate of genetic change in pathogen populations. Collectively, these influences are likely to affect a range of pathosystems of significant economic importance to New Zealand’s productive sectors. We undertook analyses of potential drought impacts on several diseases of plants important to New Zealand: pea root rot (caused by Aphanomyces euteiches), onion white rot (Sclerotium cepivorum), wheat take-all (Gaeumannomyces graminis var. tritici), wheat crown rot (Fusarium spp.), brassica black leg (Leptosphaeria maculans), grapevine black foot (Ilyonectria/Dactylonectria spp.), kiwifruit sclerotinia rot (Sclerotinia sclerotiorum), and radiata pine red needle cast (Phytophthora pluvialis). For most pathosystems, increased drought is expected to increase disease expression. However, drought may reduce the severity of some diseases, such as Scelerotina rot of kiwifruit and red needle cast of radiata pine. To exemplify how drought can affect different components of the host-pathogen-environment interaction, a case study on red needle cast of radiata pine is presented. We recommend that land-based productive sectors need to better prepare for the deleterious impacts or beneficial opportunities of increased drought for plant diseases in New Zealand.