Local patterns of arbuscular mycorrhizal fungal diversity and community structure in a natural Toona ciliata var. pubescens forest in South Central China

Toona ciliata var. pubescens (Toona in Meliaceae) (Tc) is listed as an endangered species, and there are natural regeneration obstacles due to its long-term excessive exploitation and utilization. Arbuscular mycorrhizal fungi (AMF) can produce beneficial effects for plant growth and natural regeneration. However, the characteristics of the AMF community in natural Tc forests are poorly understood. The Illumina PE250 high-throughput sequencing method was used to study the characteristics of the AMF community in the rhizosphere soil and roots associated with three dominant tree species (Tc; Padus buergeriana, Pb; and Maesa japonica, Mj) in a natural Tc forest in Guanshan National Natural Reserve, South Central China. The results found that Glomeraceae was the most abundant AMF family in the rhizosphere soil and roots. Moreover, the relative abundance of Archaeosporaceae in rhizosphere soil was significantly larger than that in the roots; in contrast, the relative abundance of Glomeraceae in rhizosphere soil was significantly lower than that in the roots (p < 0.05). Regarding different tree species, the relative abundances of Acaulosporaceae and Geosiphonaceae were larger in Mj and Tc than in Pb. AMF operational taxonomic units (OTUs) were 1.30-, 1.43-, and 1.71-fold higher in the Tc, Pb, and Mj rhizosphere soil, respectively, than in the corresponding roots. Nevertheless, higher AMF community richness was found in the roots compared to that in the rhizosphere soil based on the Chao index. This finding indicated that AMF of a relatively high aggregation degree were in roots, and more AMF groups with relatively low abundance occurred in the rhizosphere soil, which correspondingly lowered the calculated richness index of the AMF community. A redundancy analysis showed that different soil chemical properties impacted variations in the AMF community characteristics differently. This study has great significance for the interpretation of AMF diversity survey and the application design of AMF in vegetation restoration.

Toona ciliata (toon).

The family Meliaceace contains some of the world's finest grade cabinet timbers. These include the Honduran mahogany (Swietenia macrophylla), West Indian mahogany (S. mahogani), Ugandan mahogany (Entandrophragma sp.), Asian Chukrasia (Chukrasia tabularis) and the Australian red cedar or Indian Toon (T. ciliata). Timber of T. ciliata was exported from Australia to Calcutta, India, in 1795 just seven years after the first British settlement was established in Sydney, thus becoming Australia's first export. The harvesting of this species was very important to the economy of the early European settlement and the timber getters helped open up the coastal forests for later agricultural activities (Boland, 1997). The species was also arguably the first Australian plant species to have conservation measures placed upon it (Boland, 1997) when it was realised that the species was rapidly disappearing in areas near Sydney. In India, thirty years ago, timber of T. ciliata was said to be available in large quantities from Uttar Pradesh and in fair quantities from North Bengal and Assam (Anon, 1963). Timber is also available in small quantities from other areas; mainly from roadside trees and from trees on cultivated lands (Anon, 1963).

Moinha de carvão e bioestimulante vegetal na formação de mudas de cedro australiano

Com o objetivo de se avaliar o uso da moinha de carvão e do bioestimulante vegetal na produção de mudas de Toona ciliata foi instalado, em casa de vegetação, um experimento em blocos casualizados, em esquema fatorial, combinando cinco proporções de moinha adicionada ao substrato (0%; 7,5%; 15%; 22,5%; 30%), na presença e ausência de bioestimulante vegetal (10 mL L-1 de água) no tratamento das sementes, com 4 repetições. Decorridos 124 dias após semeadura foram analisadas as variáveis: altura (H) diâmetro de colo (DC), área foliar (AF), comprimento de raiz (CR), volume de raiz (VR), massa seca da parte aérea (MSPA), de raiz (MSR) e total (MST). Esses parâmetros foram utilizados para calcular as variáveis de qualidade de muda: relações altura/diâmetro (RHD), parte aérea/raiz (RPAR), altura/parte aérea (RHPA) e o Índice de qualidade de Dickson (IQD). A melhor proporção de moinha variou de acordo com o parâmetro avaliado, sendo que o seu uso em doses moderadas, associadas ao bioestimulante vegetal afetou positivamente o desenvolvimento das mudas. Isoladamente, o bioestimulante vegetal afetou negativamente a qualidade de mudas, e algumas variáveis mostraram-se mais sensíveis em proporções mais elevadas de moinha de carvão havendo um decréscimo mais acentuado das médias.

Arabica coffee and cedar tree: integrating biotic and abiotic drivers

Agroforestry systems are important forms of sustainable farming, providing several ecosystem services. However, characterization and management of factors such as thermal and light heterogeneity, as well as interactions between trees and coffee plants, are determinants for achieving the desired sustainability. This study aimed to verify whether different distances between Coffea arabica L. and Australian red cedar can change soil and microclimate characteristics and how they alter morphological and physiological attributes of coffee plants over the rainy season and a prolonged drought period (veranico) in Summer. The trial was carried out in the municipality of Barra do Choça, in an area with Australian red cedar trees (Toona ciliata M. Roem), distributed in two hedges, spaced 19.8 × 3 m apart, in a northeast-southwest direction, and coffee plants var. Catucaí Vermelho (3.3 × 0.5 m). Treatments were defined by the distance between the coffee plants and the first row of the Australian red cedar hedge (3.3 m, T1; 6.6 m, T2; 9.9 m, T3; 13.2 m, T4; 16.4 m, T5). Morphology and physiology of coffee plants, soil temperature, incident light on coffee plants, and the allelopathic potential of Australian red cedar leaf extracts were assessed in the wet and dry season of the 2016–2017 Summer. Temperatures fluctuated less in experimental units close to the hedge. The reduced growth of coffee plants close to the hedges was related to self-shading associated with light restriction by the trees. The experiment showed the allelopathic potential of Australian red cedar leaves.

Evaluation of Anticipated Performance Index of Plant Species for Green Belt Development to Mitigate Air Pollution

Anticipated Performance Index (API) is an innovative ecological approach in selecting plant species for reducing air pollution, using Air Pollution Tolerance Index (APTI) and socio-economic parameters. The present study evaluated API of 11 plant species (6 trees and 5 shrubs) for the recommendation of green belt establishment near the national highway expansion region of the Kiratpur-Nerchowk expressway. The scrutiny of the results revealed that the tolerance capacity of plant species along with their performance grade is a justified approach for selecting the most suitable plant species, which can act as sink for air pollution. API on the other hand, can also help to distinguish the sensitive plant species, which can act as bio-monitors. The results showed that among all plant species Leucaena leucocephala and Toona ciliata (API=5) qualify as ‘very good’ performers in green belt development, while Dalbergia sisso (API=4) is a ‘good’ performer. Grewia optiva and Ficus palmata were judged as ‘moderate’ performers (API=3). Whereas, all other remaining investigated trees and shrubs having lesser API values can act as bio-indicators and particularly are very less recommended for green belt establishment. Hence, on the basis of amalgamation of APTI values together with other socio-economic and biological parameters, API significantly is considered as one of the best approaches identified and recommended for long-term refinement of air quality.