scholarly journals Cambial Activity of Moringa peregrina (Forssk.) Fiori in Arid Environments

2021 ◽  
Vol 12 ◽  
Author(s):  
Holger Gärtner ◽  
Emad Farahat
Keyword(s):  
Photosynthetic Activity ◽  
Storage Capacity ◽  
Cambial Activity ◽  
Ring Formation ◽  
Arid Environments ◽  
Dry Tropics ◽  
Xylem Formation ◽  
Moringa Peregrina ◽  
Desert Regions ◽  
Environmental Adaptability

Moringa peregrina (Forssk.) Fiori, one of 13 species of the Moringaceae family widely distributed throughout the dry tropics, has the potential to become one of the most economically important medicinal plants in Egypt. However, despite its tolerance for drought and heat, it is also threatened by increasing temperatures and decreasing precipitation. Although the phenophase of this species is well documented, almost nothing is known about its period of cambial activity in desert regions. Ring formation and the general environmental adaptability of trees are affected by the timing of cambial activation. In our study site, we observe a distinct coupling of the development of new green leaves at the onset of vegetative growth in October and the phase of cambial activity (November–January). The onset of cambial activity seems to be related to a drop in temperature in October and the onset of torrential rains in the region. There might even be a short phase between the end of cambial activity and the onset of bud formation without xylem formation, but with photosynthetic activity. If so, we assume that all assimilates are stored as non-structural carbohydrates (NSC) in the parenchyma of the new ring. This potential gap opens new questions regarding the correlation between NSC storage capacity and the timing of remobilization for subsequent ring formation.

How the recently discovered grit crust shapes the Atacama Desert – Combining environmental studies on cryptogams and remote sensing

2020 ◽  
Author(s):  
Patrick Jung ◽  
Lukas Lehnert ◽  
Michael Lakatos ◽  
Michael Schermer ◽  
Karen Baumann ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Photosynthetic Activity ◽  
Atacama Desert ◽  
Soil Formation ◽  
Arid Environments ◽  
Soil Community ◽  
Carbon And Nitrogen ◽  
Remote Sensing Technology ◽  
Sensing Technology ◽  
Coastal Belt

<p>The Atacama Desert is the driest non-polar desert on Earth, presenting precarious conditions for biological activity. In the arid coastal belt, life is restricted to areas with fog events that cause almost daily wet-dry cycles. In such an area, we discovered a hitherto unknown and unique ground covering biocoenosis dominated by lichens, fungi and algae attached to grit-sized quartz- and granitoid stones (grit crust). In contrast to previously known CGC from arid environments to which frequent cyclic wetting events are lethal, here every fog event is answered by photosynthetic activity of the soil community and thus considered as the desert’s breath. Photosynthesis of the new CGC-type is activated by the lowest amount of water known for such a community worldwide thus enabling the unique biocoenosis to fulfill a variety of ecosystem services such as protection against soil erosion and contributions to accumulation of soil carbon and nitrogen and soil formation through bio-weathering. Using state-of-the-art remote sensing technology, we estimate the total cover of the grit crust and show that the newly discovered organisms cover large areas along the coastal belt of the Atacama Desert.</p>

The effects of artificial soil frost on cambial activity and xylem formation in Norway spruce

Trees ◽  
2011 ◽  
Vol 26 (2) ◽  
pp. 405-419 ◽  
Author(s):  
Tuula Jyske ◽  
Markku Manner ◽  
Harri Mäkinen ◽  
Pekka Nöjd ◽  
Heli Peltola ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Cambial Activity ◽  
Artificial Soil ◽  
Soil Frost ◽  
Xylem Formation

scholarly journals The possible relation between cytokinins and secondary xylem formation in Pinus silvestris. I. Seasonal correlations

2015 ◽  
Vol 48 (2) ◽  
pp. 295-303 ◽  
Author(s):  
Dorota B. Kubowicz
Keyword(s):  
Annual Ring ◽  
Secondary Xylem ◽  
Late Summer ◽  
Cambial Activity ◽  
Cytokinin Activity ◽  
Endogenous Cytokinin ◽  
Pinus Silvestris ◽  
Xylem Formation ◽  
Summer Maximum ◽  
Spring Maximum

The Seasonal dynamics of changes in the endogenous cytokinin level was investigated in the tissue of the stem cambial region, The results of the soybean test and Amaranthus test show that marked variations occur. in the course of the year in cytokinin activity in five fractions obtained from tissue of the cambial region. These variations characterized by a spring maximum and late-summer maximum may be correlated in time with changes in cambial activity and the course of annual ring differentiation in the pine stem during the vegetation season.

scholarly journals The response of desert biocrust bacterial communities to hydration-desiccation cycles

2021 ◽  
Author(s):  
Capucine Baubin ◽  
Osnat Gillor ◽  
Noya Ran ◽  
Hagar Siebner
Keyword(s):  
Bacterial Community ◽  
Bacterial Communities ◽  
Photosynthetic Activity ◽  
Biological Soil Crust ◽  
Rain Event ◽  
Arid Environments ◽  
Soil Crust ◽  
Bacterial Composition ◽  
Soil Bacterial Communities ◽  
Rain Events

Rain events in arid environments are highly unpredictable, interspersing extended periods of drought. Therefore, following changes in desert soil bacterial communities during hydration-desiccation cycles in the field, was seldom attempted. Here, we assessed rain-mediated dynamics of active community in the Negev Desert biological soil crust (biocrust), and evaluated the changes in bacterial composition, potential function, and photosynthetic activity. We predicted that increased biocrust moisture would resuscitate the phototrophs, while desiccation would inhibit their activity. Our results show that hydration increased chlorophyll content, resuscitated the biocrust Cyanobacteria, and induced potential phototrophic functions. However, decrease in the soil water content did not immediately decrease the phototrophs activity, though chlorophyll levels decreased. Moreover, while the Cyanobacteria relative abundance significantly increased, Actinobacteria, the former dominant taxa, significantly decreased in abundance. We propose that, following a rain event biocrust moisture significantly decreased, almost to drought levels, yet the response of the active bacterial community lagged, in contrast to topsoil. Possible explanations to the described rain-mediated bacteria dynamics are discussed.

Growth ring formation of Dichrostachys cinerea and Senegalia mellifera in arid environments in Namibia

2020 ◽  
Vol 59 ◽  
pp. 125661
Author(s):  
R. Shikangalah ◽  
B. Mapani ◽  
I. Mapaure ◽  
U. Herzschuh ◽  
A. Musimba ◽  
...  
Keyword(s):  
Growth Ring ◽  
Ring Formation ◽  
Arid Environments ◽  
Dichrostachys Cinerea

The Periodicity of Growth in Tropical Trees with Special Reference to Dipterocarpaceae - A Review

IAWA Journal ◽  
1995 ◽  
Vol 16 (4) ◽  
pp. 329-335 ◽  
Author(s):  
Wulf Killmann ◽  
Hong Lay Thong
Keyword(s):  
East Asia ◽  
Special Reference ◽  
Activity Patterns ◽  
Tropical Trees ◽  
Cambial Activity ◽  
Ring Formation ◽  
South East Asia ◽  
Timber Tree ◽  
Rainfall Patterns

The periodicity of leaf change and flowering and fruiting of tropical trees is discussed. Cambial activity patterns in tropical trees are reviewed. Emphasis is put on research undertaken in South-East Asia on the most important timber tree family in that region, the Dipterocarpaceae. There is an urgent need for more information on the effects of rainfall patterns and phenological periodicity on cambial activity and ring formation in this family

Cambium production pattern in Q. ilex growing at a dry site in Southern Italy

2020 ◽  
Author(s):  
Veronica De Micco ◽  
Katarina Cufar ◽  
Angela Balzano
Keyword(s):  
Southern Italy ◽  
Climatic Factors ◽  
High Hardness ◽  
Cambial Activity ◽  
Climatic Conditions ◽  
Density Fluctuations ◽  
Arid Environments ◽  
Growth Responses ◽  
Mediterranean Species ◽  
Thin Sections

<p>Survival of forest tree species in semi-arid environments such as the Mediterranean area is threatened by the increase in harsh drought conditions. Therefore, better knowledge of the eco-physiology of Mediterranean species and their growth responses to climatic factors is needed to develop strategies for sustainable management.</p><p>The studies of cambial activity and wood formation can provide information on tree growth and physiological responses to variations in intra-annual climatic parameters, helping to answer questions related to tree performance and plasticity under changing environmental conditions.</p><p>Our aim was to investigate cambium production in holm oak (Quercus ilex L.) as one of the most widespread evergreen oaks in Southern Italy. We studied the response of cambium activity throughout the particularly dry year 2017. We collected tissues from tree stems every two weeks by sampling microcores containing phloem, cambium and xylem. For the analyses, thin cross sections of the microcores were analysed under a light microscope to identify the timing of cambial production, xylogenesis and phloem formation. We detected the period in which the cambium was active, as well as the period in which the cambium was not productive. We interpreted the cambial response to climatic conditions at the site during the period of observation.</p><p>The observed pattern of xylogenesis differed from the expected bi-modal pattern typical for Mediterranean species which usually results in Intra-annual Density Fluctuations (IADFs) in tree-rings. In Q. ilex we observed only one peak of cambial activity, likely due to the low water availability during the year 2017.</p><p>The obtained results provide useful information supporting the forecasting of the wood-growth responses to expected climate change. Moreover, we gained technical experience on optimal preparation of thin sections of problematic tissues, which is especially challenging in Q.ilex due to high hardness of the peculiar wood structure making the investigations of xylogenesis very challenging in this species.</p>

Cambial Growth of Swietenia macrophylla King Studied under Controlled Conditions by High Resolution Laser Measurements

Holzforschung ◽  
2003 ◽  
Vol 57 (2) ◽  
pp. 196-206 ◽  
Author(s):  
O. Dünisch ◽  
M. Schulte ◽  
K. Kruse
Keyword(s):  
High Resolution ◽  
Cambial Activity ◽  
Cell Enlargement ◽  
Swietenia Macrophylla ◽  
Cambial Growth ◽  
Laser Measurements ◽  
Cambial Reactivation ◽  
Radial Cell ◽  
Xylem Formation ◽  
Kinetics Of

SummaryThe kinetics of phloem and xylem formation of two-year-old plants ofSwietenia macrophyllaKing (true mahogany) was studied in a model system along the shoot circumference (experiment 1) and along the shoot axis (experiment 2). The radius increment of the shoot was registered by high resolution laser measurements (accuracy: ±2 μm) in a spatial resolution of 7.8 to 41.3 μm along the stem circumference and 1.5 mm along the stem axis. The temporal resolution of the measurements was 2 s in experiment 1 and 20 s in experiment 2. The radius increment of the shoot detected by the laser measurements was predominately due to the radial enlargement of the phloem and xylem derivatives. On the phloem side the reinitiation of radial cell enlargement after a cambial dormancy occurred first in sieve tubes with contact to ray parenchyma cells, while on the xylem side the radial cell enlargement of vessels and paratracheal parenchyma was induced almost simultaneously along the shoot circumference. In the phloem and xylem derivatives, which were formed first after the cambial reactivation, radial cell enlargement was induced almost simultaneously along the shoot axis. In more advanced phases of phloem and xylem formation, radial cell enlargement of phloem and xylem derivatives was induced shoot downwards with a rate of approximately 13 mm per min. The mean rate of radial cell enlargement of the phloem and xylem derivatives was 2.26 and 4.37 μm per min, respectively. These findings suggest that the kinetics of cambial growth of tropical tree species differ significantly from kinetics observed in trees from temperate regions. The laser measurements might provide a useful experimental approach for studies of cambial activityin situ.

scholarly journals Origin of Intra-annual Density Fluctuations in a Semi-arid Area of Northwestern China

2021 ◽  
Vol 12 ◽  
Author(s):  
Jiani Gao ◽  
Sergio Rossi ◽  
Bao Yang
Keyword(s):  
Cambial Activity ◽  
Wood Formation ◽  
Density Fluctuations ◽  
Arid Ecosystems ◽  
Wall Thickening ◽  
Drought Event ◽  
Cell Enlargement ◽  
Xylem Formation ◽  
June July ◽  
Semi Arid

Intra-annual density fluctuation (IADF) is a structural modification of the tree ring in response to fluctuations in the weather. The expected changes in monsoon flow would lead to heterogeneous moisture conditions during the growing season and increase the occurrence of IADF in trees of the arid ecosystems of continental Asia. To reveal the timings and physiological mechanisms behind IADF formation, we monitored cambial activity and wood formation in Chinese pine (Pinus tabuliformis) during 2017–2019 at three sites in semi-arid China. We compared the dynamics of xylem formation under a drought event, testing the hypothesis that drought affects the process of cell enlargement and thus induces the production of IADF. Wood microcores collected weekly from April to October were used for anatomical analyses to estimate the timings of cambial activity, and the phases of enlargement, wall thickening, and lignification of the xylem. The first cells started enlargement from late April to early May. The last latewood cells completed differentiation in mid-September. Trees produced IADF in 2018. During that year, a drought in June limited cell production in the cambium, only 36% of the xylem cells being formed in IADF trees, compared to 68% in normal tree rings. IADF cells enlarged under drought in early July and started wall thickening during the rainfall events of late July. The drought restricted cell enlargement and affected wall thickening, resulting in narrow cells with wide walls. Cambium and cell enlargement recovered from the abundant rainfall, producing a new layer with large earlywood tracheids. IADF is a specific adaptation of trees to cope with water deficit events occurring during xylem formation. Our findings confirmed the hypothesis that the June-July drought induces latewood-like IADFs by limiting the process of cell enlargement in the xylem. Our finding suggests a higher occurrence of IADF in trees of arid and semi-arid climates of continental Asia if the changes to monsoon flows result in more frequent drought events during the earlywood formation in June.

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