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Physiology and Management of Trees in Landscapes and Nursery Production

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A special issue of Forests (ISSN 1999-4907). This special issue belongs to the section "Forest Ecophysiology and Biology".

Deadline for manuscript submissions: closed (25 August 2020) | Viewed by 36306

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Dr. Bert Cregg

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Department of Horticulture and Department of Forestry, Michigan State University, 1066 Bogue Street, East Lansing, MI 48824, USA
Interests: tree physiology; Christmas tree production and management
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Trees are increasingly valued in urban and suburban landscapes for the provision of ecosystem services in addition to aesthetic benefits. The public and policy makers are becoming aware of the environmental benefits of trees, such as air quality improvement, carbon sequestration, and mitigation of urban heat island effects. In order for trees to fulfil these myriad functions, however, they must be able to survive and grow in conditions that are often far different from those in which they evolved. Trees in urban and suburban landscapes are frequently subjected to an array of environmental stresses, including reflected heat loads, pollutants, soil compaction, and limited rooting volumes. Effectively establishing and managing trees in these environments requires the development of proper cultural techniques and appropriate tree selection, both of which are informed by understanding physiological responses of trees to their environment. Moreover, experience and research have clearly demonstrated that performance of trees after transplanting is influenced by culture in the nursery. Therefore, successful urban tree management is inexorably linked to integration of nursery production practices, arboricultural techniques, and tree genetics.

We invite manuscripts for a Special Issue on Physiology and Management of Trees in Landscapes and Nursery Production. We encourage the submission of manuscripts that provide new information on a broad range of topics, including: (1) landscape and urban tree establishment; (2) arboricultural management and physiology of urban and landscape trees; (3) physiology and genetics of urban trees, including selection of trees for difficult sites; (4) physiology of trees in nursery production; and (5) integration of nursery practices and establishment of trees in urban and community forests.

Dr. Bert Cregg
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Forests is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Landscape horticulture
Urban forestry
Transplanting
Tree selection
Environmental physiology
Plant water relations
Gas exchange

Published Papers (9 papers)

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Research

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17 pages, 1929 KiB

Open AccessArticle

The Dwarfing Effects of Different Plant Growth Retardants on Magnolia wufengensis L.Y. Ma et L. R. Wang

by Xiaodeng Shi, Siyu Chen and Zhongkui Jia

Forests 2021, 12(1), 19; https://doi.org/10.3390/f12010019 - 26 Dec 2020

Cited by 11 | Viewed by 2656

Abstract

The effects of varieties, concentrations, and number of applications of plant growth retardants (PGRs) on the morphological, physiological, and endogenous hormones of Magnolia wufengensis L.Y. Ma et L. R. Wang were assessed to obtain the most suitable dwarfing protocol for M. wufengensis and to provide theoretical support and technical guidance for the cultivation and promotion of this species. One-year-old M. wufengensis ‘Jiaohong No. 2’ grafted seedlings served as the experimental materials. In the first part of the experiment, three PGRs (uniconazole, paclobutrazol, prohexadione calcium), three concentrations (500, 1000, 1500 ppm), and three applications (one, three, and five applications) were applied in dwarfing experiments to perform L9 (3⁴) orthogonal tests. In the second part of the study, dwarfing experiments were supplemented with different high uniconazole concentrations (0, 1500, 2000, 2500 ppm). Spraying 1500 ppm uniconazole five times achieved the best M. wufengensis dwarfing effect, related indicators of M. wufengensis under this treatment were better than other treatment combinations. Here, M. wufengensis plant height, internode length, scion diameter, and node number were significantly reduced by 56.9%, 62.6%, 72.8%, and 74.4%, respectively, compared with the control group. This treatment increased superoxide dismutase (SOD) activity by 66.0%, peroxidase (POD) activity by 85.0%, soluble protein contents by 43.3%, and soluble sugar contents by 27.6%, and reduced malondialdehyde (MDA) contents by 32.1% in leaves of M. wufengensis compared with the control. The stress resistance of M. wufengensis was enhanced. The treatment also reduced gibberellin (GA₃) levels by 73.0%, auxin (IAA) by 58.0%, and zeatin (ZT) by 70.6%, and increased (abscisic acid) ABA by 98.1% in the leaves of M. wufengensis. The uniconazole supplementation experiment also showed that 1500 ppm was the optimal uniconazole concentration. The leaves exhibited abnormalities such as crinkling or adhesion when 2000 or 2500 ppm was applied. Given the importance of morphological indicators and dwarfing for the ornamental value of M. wufengensis, the optimal dwarfing treatment for M. wufengensis was spraying 1500 ppm uniconazole five times. Full article

(This article belongs to the Special Issue Physiology and Management of Trees in Landscapes and Nursery Production)

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10 pages, 813 KiB

Open AccessArticle

Early Flare Root Development on Nursery Field-Grown Seedling Stock

by Gary W. Watson and Angela M. Hewitt

Forests 2020, 11(10), 1031; https://doi.org/10.3390/f11101031 - 24 Sep 2020

Viewed by 1360

Abstract

Field production of seedlings used to create nursery stock liners involves transplanting and root pruning that can alter root system architecture. Seedlings of eight species of trees commonly used in urban landscapes were selected based on the configuration of their woody lateral roots; Preferred (maximum gap between roots ≤90 degrees), Acceptable (maximum gap 120–150 degrees), and Inferior (≥180 degree gap—no lateral roots on one side). The lateral root configuration (LRC) of the seedlings was compared to the LRC one year after replanting. The number of lateral or regenerated roots alone was generally adequate to form an acceptable root flare (≥3 roots) one year after seedlings were replanted. The maximum gap in lateral roots as a seedling was not consistent with the maximum gap one year after the seedlings were replanted in most species. It often became larger. Neither lateral roots nor regenerated roots alone could reliably produce a root structure with an acceptable maximum gap between roots. Lateral roots and roots regenerated from the pruned end of the main root, together produced enough flare roots one year after replanting with a small enough maximum gap in the radial distribution for good stability. This information may be an initial step in developing criteria for seedling grading systems that will improve root systems of nursery stock grown for planting in urban landscapes. Full article

(This article belongs to the Special Issue Physiology and Management of Trees in Landscapes and Nursery Production)

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15 pages, 2437 KiB

Open AccessArticle

Oak Taproot Growth Disruption Differentially Impacts Root Architecture during Nursery Production

by Shanon Hankin and Gary Watson

Forests 2020, 11(8), 798; https://doi.org/10.3390/f11080798 - 23 Jul 2020

Cited by 1 | Viewed by 3243

Abstract

For urban trees with strong taproots, a shift in root growth towards increased lateral root development could improve tree performance in compacted, poorly drained urban soils. In effort to achieve this desired shift, various propagation and production practices exist within the nursery industry. However, the effectiveness of practices used to disrupt taproot development, as well as their impact on root architecture, has been largely undocumented. To determine how seedling root systems respond to taproot growth disruption, we pruned oak seedling taproots either mechanically at 5 and/or 15 cm, or via air pruning at 15 cm. Taproot regeneration and lateral root development were evaluated after two years. Taproot pruning resulted in multiple regenerated taproots. The location and number of times the taproot(s) was pruned did not appear to alter the ultimate number. Mechanical taproot pruning did not affect lateral root development above the first pruning cut location at 5 or 15 cm, but generally increased the density of lateral roots below the pruning cut, likely due to the multiple taproots present. Most lateral roots were fine roots less than 1 mm in diameter (fine roots), being unlikely to become long-lived components of the root system architecture. The average number of lateral roots on air pruned (AP) seedlings was generally greater than on the same taproot segment of control (C) seedlings. To determine how these seedling changes impact the root regeneration of liner stock, we planted both taproot pruned and taproot air pruned seedlings in in-ground fabric bags filled with field soil (B) or directly into the field without bags (F). Root regeneration potential (RRP) at the bottom and lateral surfaces of the root ball were evaluated. There was less RRP on the lateral surface of the root ball in taproot air pruned, container-grown (CG) compared to taproot pruned, bare root (BR) bur oak liners, and there was no difference in red oak liners. The multiple taproots of mechanically pruned BR seedlings did not result in excessive taproot development as liners. In contrast, CG seedling taproots restricted by air pruning produced more regenerated taproots after transplanting. While seedling taproot growth disruption does disrupt the growth of a dominant single taproot and alters the architecture toward increasing the number of lateral roots, these practices do not result in laterally dominated root architecture at the liner stage of nursery production. Future research should determine how these production methods effect lateral root growth after a tree is established in the landscape and determine appropriate combinations of production methods for different species. Full article

(This article belongs to the Special Issue Physiology and Management of Trees in Landscapes and Nursery Production)

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12 pages, 4144 KiB

Open AccessArticle

Application of Paclobutrazol to Mitigate Environmental Stress of Urban Street Trees

by Bert Cregg and Dana Ellison-Smith

Forests 2020, 11(3), 355; https://doi.org/10.3390/f11030355 - 21 Mar 2020

Cited by 10 | Viewed by 4283

Abstract

Paclobutrazol is a tree growth regulator that is frequently applied by arborists to control tree growth in utility rights of way. Paclobutrazol is also marketed to mitigate tree stresses associated with urban environments. In this study we applied paclobutrazol as a soil drench to honeylocust (Gleditsia triacanthos L var. inermis (L.) Zab.) and Callery pear (Pyrus calleryiana Decne.) trees planted as street trees on two sites in Lansing, Michigan USA. We evaluated physiological and morphological responses for two years after treatment. Application of paclobutrazol increased SPAD chlorophyll index of trees of both species in both years, compared to untreated control trees. Application of paclobutrazol increased leaf water potential of trees on one study site (Downtown) but not the other (Old Town). Paclobutrazol increased gas exchange (net photosynthesis and stomatal conductance) of Callery pear trees on one of four measurement dates (gas exchange was not measured on honeylocust trees). Leaf size of Callery pear trees was reduced following paclobutrazol application whereas leaf size of honeylocust trees was unaffected by paclobutrazol. These results indicate that paclobutrazol can help to reduce stress of trees and improve physiological function under urban conditions. However, paclobutrazol should be viewed as part of a suite of options for arborists and landscapers to manage trees on stressful sites, rather than as a replacement for proper overall care. Full article

(This article belongs to the Special Issue Physiology and Management of Trees in Landscapes and Nursery Production)

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11 pages, 1619 KiB

Open AccessArticle

Aspects of the Process of Sorting European Black Pine Seeds

by Zdzisław Kaliniewicz and Paweł Tylek

Forests 2019, 10(11), 966; https://doi.org/10.3390/f10110966 - 01 Nov 2019

Cited by 8 | Viewed by 2341

Abstract

Research Highlights: Seed separation criteria and the optimal parameters of sorting devices were described. Background and Objectives: Seeds are often sorted into fractions which are sown separately to promote uniform seed germination and seedling emergence. Therefore, the aim of this study was to determine the correlations between the basic physical properties of European black pine (Pinus nigra J.F. Arnold subsp. nigra) seeds for the needs of planning seed sorting operations. Materials and Methods: Black pine seeds were divided into 5 batches representing individual parent trees, and the physical properties (terminal velocity, thickness, width, length, angle of external friction, mass) of each seed were determined. The measured geometric parameters and seed mass were used to calculate the respective indicators for each seed. The values of the analyzed parameters were used to plan the seed separation process. Results: The average values of the basic physical properties of seeds were determined in the following range: Terminal velocity—8.32 to 8.73 m s⁻¹, thickness—2.24 to 2.27 mm, width—3.34 to 3.44 mm, length—5.87 to 6.08 mm, angle of external friction—28 to 32°, mass—18.8 to 20.0 mg. Seed mass was most highly correlated with terminal velocity, and it was least correlated with the angle of external friction. Conclusions: The results of this study indicate that black pine seeds should be sorted with the use of pneumatic separators or, alternatively, mesh sieves with longitudinal openings. These sorting devices separate seeds into fractions characterized by similar seed mass, which delivers both economic and environmental benefits in nursery practice. Full article

(This article belongs to the Special Issue Physiology and Management of Trees in Landscapes and Nursery Production)

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10 pages, 3476 KiB

Open AccessArticle

Pre-Plant Fumigation of Soils for Nematode Control Affects the Seedling Production and Morphological Properties of Pine and Larch Seedlings

by Sangsub Cha, Jeonghwan Kim, In Gyu Choi, Jongo Choi, Hyerim Han, Namin Koo and Yong Suk Kim

Forests 2019, 10(10), 843; https://doi.org/10.3390/f10100843 - 26 Sep 2019

Cited by 3 | Viewed by 2236

Abstract

Using a fumigation sterilizer (Dazomet) for nematode control, this study determined the effect of soil sterilization on the quantity and quality of the growth of Pinus densiflora Siebold & Zucc. and Larix kaempferi (Lamb.) Carrière seedlings in an open-field nursery at Jeongseon-gun, Kangwon-do, Republic of Korea. Most soil nematodes disappeared after fumigant sterilization. The organic matter content, cation exchange capacity, and Mg²⁺ content of the soil increased significantly, but the electrical conductivity (EC) decreased. The quantity of pine and larch seedlings was highly correlated with the soil nematode density. The soil properties changed due to soil fumigation, which affected the growth of both species. Pine seedling growth was affected by the soil chemical properties, such as available phosphorus (AP), Ca²⁺, Mg²⁺, and EC, and the growth of larch seedlings was affected by the EC and nematode density. The quality of the pine seedlings improved, whereas that of larch did not. This was a result of the difference in their tolerance to soil salinity. The seedling quality index (SQI) of the two species was related to the EC, but the pine seedlings were more affected by the EC, indicating that the control of soil nematodes by fumigant treatment significantly increased the quantity of seedlings produced and partly improved their quality. Soil management using a fumigant treatment was more efficient for producing pine seedlings than larch. Our results can be used to improve agricultural and forestry economics. Full article

(This article belongs to the Special Issue Physiology and Management of Trees in Landscapes and Nursery Production)

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14 pages, 2751 KiB

Open AccessArticle

Effects of Phosphate-Solubilizing Bacteria and N₂-fixing Bacteria on Nutrient Uptake, Plant Growth, and Bioactive Compound Accumulation in Cyclocarya paliurus (Batal.) Iljinskaja

by Zhikang Wang, Ziyun Chen, Ziheng Xu and Xiangxiang Fu

Forests 2019, 10(9), 772; https://doi.org/10.3390/f10090772 - 05 Sep 2019

Cited by 17 | Viewed by 3164

Abstract

Research Highlights: We firstly interpreted nutritional mechanisms involved in growth regulation and phytochemical accumulation in Cyclocarya paliurus (Batal.) Iljinskaja under three inoculant types, and selected bacterial inoculations for multiple purposes of C. paliurus plantation. Co-inoculation with phosphate-solubilizing bacteria (PSB) and N₂-fixing bacteria (NFB) performed better in growth promotion and nutrient uptake than single bacterial inoculation. Background and Objectives: C. paliurus is a well-known medicinal plant as it accumulates bioactive compounds (BC) such as flavonoids, triterpenoids, and polysaccharides, in its leaves. However, the effects of plant growth-promoting rhizobacteria (PGPR) on the growth and BC yields in C. paliurus are not known. To fill this gap, the effects of different inoculants should be examined. Materials and Methods: A pot experiment was conducted and two-year-old C. paliurus seedlings were inoculated with three inoculant types (PSB, NFB, PSB + NFB). After four rounds of inoculation, the growth characteristics and concentrations of flavonoids, triterpenoids, and polysaccharides, as well as the nutrients in soil and leaves, were measured. Results: The inoculations resulted in the elevation of soil available nutrients, with improvements in plant growth, BC yield, and N and P uptake in leaves. However, the changes in BC yields were mainly a result of elevated leaf biomass rather than BC concentrations, and leaf biomass was regulated by C:N:P stoichiometry. Co-inoculation with PSB and NFB was applicable for leaf production, while inocula related to NFB resulted in higher BC yields than PSB and control. Conclusions: Our results implied that bacterial inoculants improved plant growth and BC yield by altering the nutrients in soil and leaves, while three inoculant types showed a different pattern in which co-inoculation with four strains presented a greater performance than single bacterial addition. Full article

(This article belongs to the Special Issue Physiology and Management of Trees in Landscapes and Nursery Production)

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Review

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24 pages, 2958 KiB

Open AccessReview

The Complex Issue of Urban Trees—Stress Factor Accumulation and Ecological Service Possibilities

by Monika Czaja, Anna Kołton and Piotr Muras

Forests 2020, 11(9), 932; https://doi.org/10.3390/f11090932 - 26 Aug 2020

Cited by 69 | Viewed by 14289

Abstract

This review paper is the first that summarizes many aspects of the ecological role of trees in urban landscapes while considering their growth conditions. Research Highlights are: (i) Plant growth conditions in cities are worsening due to high urbanization rates and new stress factors; (ii) Urban trees are capable of alleviating the stress factors they are exposed to; (iii) The size and vitality of trees is related to the ecological services they can provide. Our review shows, in a clear way, that the phenomenon of human-related environmental degradation, which generates urban tree stress, can be effectively alleviated by the presence of trees. The first section reviews concerns related to urban environment degradation and its influence on trees. Intense urbanization affects the environment of plants, raising the mortality rate of urban trees. The second part deals with the dieback of city trees, its causes and scale. The average life expectancy of urban trees is relatively low and depends on factors such as the specific location, proper care and community involvement, among others. The third part concerns the ecological and economic advantages of trees in the city structure. Trees affect citizen safety and health, but also improve the soil and air environment. Finally, we present the drawbacks of tree planting and discuss if they are caused by the tree itself or rather by improper tree management. We collect the latest reports on the complicated state of urban trees, presenting new insights on the complex issue of trees situated in cities, struggling with stress factors. These stressors have evolved over the decades and emphasize the importance of tree presence in the city structure. Full article

(This article belongs to the Special Issue Physiology and Management of Trees in Landscapes and Nursery Production)

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Other

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9 pages, 738 KiB

Open AccessBrief Report

Performance of Five Native Atlantic Forest Species Planted in Containers of Different Size for Restoring Degraded Areas in Minas Gerais

by Vicente Toledo Machado de Morais Junior, Laércio Antônio Gonçalves Jacovine, Klisman Oliveira, Thaynara Pereira Albuquerque, Isabella Salgado Faustino, Lauana Blenda Silva, Eliana Boaventura Bernardes Moura Alves, Carlos Moreira Miquelino Eleto Torres, Haroldo Nogueira de Paiva and Ricardo Alcántara-de la Cruz

Forests 2020, 11(9), 937; https://doi.org/10.3390/f11090937 - 27 Aug 2020

Cited by 2 | Viewed by 2091

Abstract

Forest restoration in Brazil has gained relevance in the country’s environmental agenda, due to the need for forest recovery of large liabilities of existing forests and participation in several international vegetation restoration agreements. However, forest restoration management faces challenges, it being necessary to create a database of species-level performances to increase the success of these projects. The objective was to evaluate the survival and growth of five Atlantic Forest native species (Anadenanthera macrocarpa; Ceiba speciosa; Cytharexyllum myrianthum; Hymenaea courbaril; and Peltophorum dubium) in plastic bags (1177 cm³) and tubes (180 cm³). Ninety seedlings (18 of each species) were planted per container. Plant performance in the field consisted of evaluating the increase in the diameter and height of seedlings of the native forest species. Diameter at soil level (DSL) and plant height (H) were measured at 42 months after transplanting, and the monthly periodic increments (MPI) of the DSL and H were calculated. Plant survival (SV) of seedlings was affected by the type of container, registering the highest SV rates in those planted in plastic bags. Cytharexyllum myrianthum and H. courbaril presented high SV rates in tubes. The growth rate of the species at 42 months differed according to the containers tested. Cytharexyllum myrianthum presented the lowest SV rates (16.7–27.8%), regardless of the container used in this experiment. Ceiba speciosa was sensitive to the reduction in size of the container, showing low SV in tubes (27%) compared with plastic bags (61%); i.e., this species did not tolerate conditions with root growth restriction. Anadenathera macrocarpa and H. courbaril showed no differences in SV, regardless of the container used. The results assist the production of native species of the Atlantic Forest, reinforcing the need to understand performances in the field at the species level. Full article

(This article belongs to the Special Issue Physiology and Management of Trees in Landscapes and Nursery Production)

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