Soil Inoculation With Beneficial Microbes Buffers Negative Drought Effects on Biomass, Nutrients, and Water Relations of Common Myrtle.

Common myrtle (Myrtus communis L.) occurs in (semi-)arid areas of the Palearctic region where climate change, over-exploitation, and habitat destruction imperil its existence. The evergreen shrub is of great economic and ecological importance due to its pharmaceutical value, ornamental use, and its role in urban greening and habitat restoration initiatives. Under greenhouse conditions, we investigated the effect of soil inoculation with arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) on biomass allocation, water relations, and nutritional status of drought-stressed myrtle seedlings. Single and dual AMF (Funneliformis mosseae and Rhizophagus irregularis) and PGPR (Pseudomonas fluorescens and P. putida) soil inoculations were applied to myrtle seedlings growing under different soil water regimes (100, 60, and 30% of field capacity) for 6 months using a full factorial, completely randomized design. AMF and PGPR treatments, especially dual inoculations, alleviated negative drought effects on biomass and morpho-physiological traits, except for water-use efficiency, which peaked under severe drought conditions. Under the greatest soil water deficit, dual inoculations promoted leaf biomass (104%-108%), root biomass (56%-73%), mesophyll conductance (58%), and relative water content (1.4-fold) compared to non-inoculated controls. Particularly, dual AMF and PGPR inoculations stimulated nutrient dynamics in roots (N: 138%-151%, P: 176%-181%, K: 112%-114%, Ca: 124%-136%, and Mg: 130%-140%) and leaves (N: 101%-107%, P: 143%-149%, K: 83%-84%, Ca: 98%-107%, and Mg: 102%-106%). Our findings highlight soil inoculations with beneficial microbes as a cost-effective way to produce highly drought resistant seedling stock which is vital for restoring natural myrtle habitats and for future-proofing myrtle crop systems.

A new method for detecting individual trees in aerial LiDAR point clouds using absolute height maxima.

Data acquired from aerial laser scanner systems are increasingly used for detecting individual trees in operational inventories. In conventional analyses, tree detection is often performed on raster models that use local height maxima filters; an option that is likely to accumulate important errors. In order to reduce errors and improve the detection of individual trees, a new method is proposed that uses an Absolute Height Maxima (AHM) filter applied on the original point clouds obtained from Aerial Laser Scanning (ALS). ALS point clouds at a density of 2 to 4 points per square meter were acquired over forest stands in Hyrcanian forests. In the new method, false trees and commission errors were automatically found and excluded. To evaluate the efficiency of this new method, 121 sample trees in the field were located, with a DGPS and a mapping camera. The height and crown radius of the sample trees were also measured. The field-surveyed variables were compared to the closest detected tree, with an overall detection accuracy of 75.2%. The initial results of this analysis allowed us to hypothesize that a higher detection of tree may be expected with larger densities.

Long-term impact of municipal sewage irrigation on treated soil and black locust trees in a semi-arid suburban area of Iran.

The effects of municipal sewage irrigation on the soil and black locust (Robinia pseudoacacia L.) tree were studied. For this purpose, two artificial black locust stands under irrigation of municipal sewage and well water were selected in south of Tehran, Iran. Data were collected using technique of systematic random sampling with 4 replicates in each stand. It was found that the growth of black locust tree, as indicated by diameter at breast height, total height, crown length, average crown diameter, basal area and volume, in sewage irrigation stand was much higher than that of well water irrigation stand (P < 0.01). Plant analysis indicated that concentrations of leaf nutrients (N, P, K, Ca, Mg, Na, Fe, Mn, Cu and Zn) were greater in sewage-irrigated trees, without toxicity to the minerals of tree leaf, than those of well waterirrigated trees, and positively correlated with their respective value in soil. Ni, Cr and Pb were not detected in leaf samples. Application of sewage resulted in a 1.5-fold increase in the concentrations of soil nutrients, Ni, Cr and Pb. Among these minerals only Pb and Ni in some soil samples exceeded the toxicity limit. The increase in pH, electrical conductivity (EC) and organic carbon of soil was also observed in sewage irrigation. Results confirm that besides the use as irrigation water, municipal sewages are also a potential source of plant nutrients. However, significant accumulation of heavy metals such as Pb and Ni in soil needs to be monitored.

The regeneration structure and biodiversity of trees and shrub species in understory of pure plantations of oak and mixed with hornbeam in the Hyrcanian forests of Iran.

The regeneration structure and biodiversity of trees and shrub species in under story of pure and mixed Oak plantations were investigated in Chamestan Forest and Rangeland Research Station of Iran. Planted species including Oak (as main species) and Hornbeam (as associated species). This species were planted in five proportions (100Q, 70Q:30C, 60Q:40C, 50Q:50C, 40Q:60Z) in Northern of Iran in 11 years ago. All of regenerating seedlings and saplings of woody plants were divided into two height classes of 15-200 cm and more than 200 cm. In biodiversity study dominance index of Berger-Parker, diversity index of Fisher alpha, richness index of Margalef and evenness index of Equitability J were used. The results showed that abundance and diversity of regenerated species in under story of all plantations of oak were more than unplanted control plots and also under 50Q:50C were more than pure stand of oak. The presence of primary forest species in under stories of mixed plantation showed the usage of these plantations in development of succession in natural

Growth and survival response of potted Cupressus sempervirens seedlings to different soils.

In February 2001, one-year bareroot cypress (Cupressus sempervirens var. horizontalis) seedlings were replanted in plastic pot in a lowland nursery located in southern coast of the Caspian Sea (north of Iran). Soils of pots consisted of 1:1 sand:clay (A), pure sand (B), 2:1 sand:clay (C), 1:1:1 sand:clay:organic matter (D), 1:1:2 sand:clay:organic matter (E). In each soil treatment a high value of survival and growth was appeared in July and progressively decreased till November. In each month the seedlings grown on rich soils (D and E) had mostly greater growth and survival than on infertile soils. At the end of the first growing season seedling vitality differed significantly among the soils but did not differed notably in soil A with those in other soils. Survival rate was highest in the rich soils (D and E). Stem length as well as collar diameter performed the least growth on the poor soils (B and C). Like other characteristics measured, survival responded better to soils containing organic matter (D and E). It is concluded that generally characteristics of cypress seedling are suited by adding organic matter to sandy soils. This is while that poor nutrient available soil such as soil A produces a proper growth for cypress seedling, too.

Restoration of oak forests in soils compacted by human and livestock.

Soil in the oak forests of northern Iran is compacted by human and livestock whereas this problem is resulted to a defect in natural regeneration of tree species. This investigation aims to determine the suitable rehabilitation of these forests using seed sowing of oak in canopy densities of 25-30% (open canopy), 45-55% (semi-closed canopy) and 65-75% (relatively closed canopy). For this purpose, each canopy density specified within the plots of 1000 m2 was chosen in three replicates to plant oak acorn. The experiment was conducted as completely randomized design. The results in the first growing season indicted that seed germination rate as well as root length was greater in open canopy but no significant difference could be detected in terms of collar diameter, shoot growth, flush number and root/shoot ratio. The investigation reveals that for restoration of the soil-compacted oak stands, open canopies are better suited for seed sowing of oak.

Heritability of some characteristics of Sorbus torminalis seedling.

This research was conducted to determine the heritability of some characteristics of wild service (Sorbus torminalis L. Crantz) seedling by a half-sib progeny test in north of Iran. The seeds of Sangdeh provenance (1600-1800 m a.s.l.) were collected from twenty individual parent trees and planted in a mountainous nursery (Orimelk, 1550 m a.s.l) as randomized complete block design with three replications. At the end of third growing season heritability of some seedling characteristics was determined with using Falconer method. Analyses indicated that heritability of biggest branch (h2 = 0.003) and branch number (h2 = 0.007) was lower than those of other characteristics measured. Heritability of collar diameter, vitality and total height was h2 = 0.22, h2 = 0.20 and h2 = 0.17, respectively. Among 20 parent trees the genotypes 2, 11, 18, 19 and 20 can be introduced as plus trees for seed providing and seedling production. It can be deduced that for seedling production of Sorbus torminalis in this nursery the parent trees should be benefited from a better collar diameter, vitality and total height in order to occurrence possibility of high-quality progenies.

Early growth of Quercus castaneifolia (C.A. Meyer) seedlings as affected by weeding, shading and irrigation.

The influence of shading, irrigation and weeding on survival, growth and morphology of 1-year Quercus castaneifolia seedlings was studied in north of Iran. The seedlings were grown under eight treatments including full-light versus artificial shading, irrigation versus non-irrigation and weed presence versus weed removing at three replicates. At the end of the first growing season seedling survival in all treatments was 100%. Weed removing had positive effect on height, diameter growth, slenderness coefficient and leaf area of Q. castaneifolia. Irrigation enhanced diameter growth and leaf area and shading increased leaf area. Irrigation had no significant effect on plant growth where the weed was removed. In weed plots seedlings growth and leaf area were greater in shading than in full-light. The results indicated that for 1 year Q. castaneifolia seedlings, weeding, in contrast to irrigation, is an essential factor. Where the weed competition is a difficulty, plantation with higher stem length should be applied.

Growth and plant diversity in a man-made thinned Cedrus atlantica stand.

In order to study the growth characteristics of Atlas cedar (Cedrus atlantica Manetti) and to assess the plant diversity an investigation was carried out in a 30 year old man-made stand located in the Caspian mountain forests (north of Iran). In this stand a silvicultural treatment as thinning was operated in five replications of 200 m2 for removing 25% of basal area. Likewise five replications of 200 m2 were considered as control (unthinned). The results of 5 year investigation revealed that diameter growth of C. atlantica was two times greater in thinned stand than in unthinned stand (p<0.05). Height growth and basal area (b.a.) in thinned stand were not greater than those in controlled stand. Vitality quality in both treatments was fairly high. Fruit production was significantly more ample in thinned stand than in unthinned stand. Compared to unthinned stand, in thinned stand index of Simpson Diversity was greater but indices of Menhinic Richness and Peet Evenness were smaller. This study reveals that generally diversity has been increased in the managed stand. Besides that C. atlantica has been adapted to this region and therefore thinning practice can be a good measure for increasing timber production.

Acacia nilotica and Medicago sativa, suitable plants for agro-forestry in southern coasts of Iran.

Habitats of the multipurpose tree, Acacia nilotica, were identified along the coastline of the Persian Gulf and Oman Sea, south of Iran. Four sites were randomly chosen and in each one, vegetation as well as climatic and soil characteristics were studied. Likewise, biometry of Acacia trees was conducted and compared in the sites. The fodder values in leaf and fruit of Acacia were determined and compared with those of in foliage of Medicago sativa being managed under an agro-forestry system. By analyzing data it was revealed that the biggest trees were found in Dashteyari region and the smallest in Bamani region (both in the Oman Sea coast). Values in most of nutritional elements were higher in foliage of Medicago than in leaf and fruit of Acacia, respectively. From this investigation it is concluded that in south of Iran where the site is favorable for Acacia plantation, cultivation of Medicago or other adaptable crops together with Acacia can be developed as agroforestry systems (such as undercropping and intercropping) if water is available.