A Case for Assessing Allocasuarina and Casuarina Spp. For Use in Agroecosystem Improvement in Semi-Arid Areas With a Focus on Central Anatolia, Turkey

Abstract

Agroecosystems in water-limited contexts-Mediterranean, semi-arid and arid climatic zones-are too frequently degraded systems that will not provide the needed ecosystem services to ensure a future of sustainable agricultural production. The processes that have created this situation continue and are being accelerated by anthropogenic climate change. Increasing arboreal vegetation in these areas through agroforestry is an important strategy to conserve and improve their agroecosystems. Actinorhizal trees and shrubs in the Casurinaceae have a unique set of adaptations for heat and water stress, and/or infertile to hostile soils. Central Anatolia, Turkey is particularly at risk of increasing aridity and further degradation. Therefore, species of Allocasuarina and Casuarina have been evaluated for their potential use in agroecosystem improvement in semi-arid areas with a focus on Central Anatolia. Based on a semiquantitative environmental tolerance index and reported plant stature, eight species were identified as being of high (A. verticillata and C. pauper) to moderate (A. acutivalvis, A. decaisneana, A. dielsiana, A. huegeliana, C. cristata and C. obesa) priority for assessment, with none of these species having been adequately evaluated for agroforestry deployment in semi-arid agroecosystems in any context.

Farmer Perception of Trees in a Semiarid Agroecological Zone

“…By implication, indigenous trees with multiple benefits and drought tolerant exotic actinorrhizal tree species (Riley, 2021) are required if further planting by farmers is to be encouraged for agroecosystem improvement. Tree choice will be based on farmer perception of the benefits for ecosystem services, production advantage and further research to identify and promote trees that benefits the widest range of agroecosystems.…”

“…There was a strong agreement towards trees providing cultural (83%) and provisioning ecosystem services (72%) (Figure 2) while farmers were clearly divided in their opinions on supporting and regulatory ecosystem services. As suggested by Riley (2021), there is perhaps a need to access a wider range of exotic trees with potential to provide ecosystem services in Central Anatolia, Türkiye as it may lead to identifying trees with supporting and regulatory ecosystem services that are adapted to semiarid agroecological zone.…”

Actinorhizal plants of Turkey: formation of nodules, cluster roots and ectomycorrhizal roots

“…In conclusion, it is likely and, as expected, that the native actinorhizal plants of Turkey will be nodulated where they occur naturally, and this has been confirmed for A. glutinosa in Rize and E. angustifolia in Niğde. The exotic C. cunninghamiana is likely to be nodulated where it is currently established in Turkey, but its use in new areas or the introduction of other Casuarinaceae, as has been proposed (Riley 2021), would best be accompanied with compatible Frankia inoculum. The establishment of other root structures/associations in both Allocasuarina and Casuarina adaptive for infertile soil are likely to require specific intervention, but this remains to be confirmed for vesicular arbuscular mycorrhizal associations.…”

“…Turkey is a regarded as having high floristic richness (Kier et al 2005) with nearly two thirds of the country in Mediterranean or Mediterranean-influenced continental climate zones with these areas possessing rich floras. However, unlike, for example, Australia with >60 putative actinorhizal species in the Casuarinaceae (Riley 2021) and 80 species in varies families in the western USA (Paschke 1997), the number of actinorhizal species in Turkey is low and their nodulation status undetermined. There are five known native actinorhizal species in Turkey, Alnus glutinosa and A. orientalis (Betulaceae), Datisca cannabina (Datiscaceae), Elaeagnus angustifolia and Hippophae rhamnoides (Elaeagnaceae).…”

Cold sensitivity of Casuarina cunninghamiana (Casuarinaceae) saplings

“…However, cold as a stressor is not particularly severe in Australia (Riley and Saygı, 2021), so Australian flora has not commonly been assessed for its cold sensitivity even though many species are now grown globally for economic and other benefits often under conditions that differ from their native range. The Australian sheoaks (Casuarinaceae) are an important group of actinorhizal plants that of potential use in agroecosystem in semiarid contexts, where conditions might be much colder than in Australia (Riley, 2019). However, there is limited data on their sensitivity to extreme cold.…”