Dissimilar stem and leaf hydraulic traits suggest varying drought tolerance among co-occurring <i>Eucalyptus grandis</i> × <i>E. urophylla</i> clones

Crous, Casparus J.; Greyling, Izette; Wingfield, Michael J.

doi:10.2989/20702620.2017.1315546

Cited by 11 publications

(12 citation statements)

References 66 publications

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“…They are most sensitive in the complex environment and are most easily adapted to the environment and change their morphology and structure. The thickness of plant leaves can prevent the excessive evaporation of water in the plant, and it also has a strong refraction, which can prevent the burn caused by strong sunshine [10], so the thickness of the leaves would be increased under drought stress. The epidermal cells could store water, and the large cortical cells under the inner epidermal cells contain mucous substances, which has great advantage of keeping water.…”

Section: Discussionmentioning

confidence: 99%

Response of Anatomical Structure to Soil Drought in Old P. kangdingensis Cuttings of Section Tacamahaca Spach

Lu¹,

Wang²,

Li³

2018

Proceedings of the 2018 8th International Conference on Management, Education and Information (MEICI 2018)

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In this paper, the cutting seedlings of P. kangdingensis, which age of 300-500 years old and diameter at breast height (DBH) was greater than 1m were used as experimental materials, and the anatomical structure of the leaves and stems of seedlings were studied by the method of paraffin section. The pot experiment was conducted by way of weighing to control water content in soil, that was to weigh the pot in every afternoon and supplement the consumption of water to keep it about 60% of the maximum field water capacity, and the control was kept about 80% of that. The water control test lasted for about 3 months and plant tissues had changes in the physiological structure. Then, the samples were collected and measured by paraffin section method. The results showed that, under drought treatment, the thickness of palisade tissue and sponge tissue in the leaves of old P. kangdingensis cutting seedlings increased significantly, while the thickness of upper and lower epidermis, the cuticle, and the leaves thickness increased slightly. Besides, the structure of the transport tissue decreased significantly on the stem, indicating that in a certain degree of drought, the morphological and anatomical structures of P. kangdingensis could be adjust accordingly to adapted to drought and then have strong drought resistance.

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Section: Discussionmentioning

confidence: 99%

Response of Anatomical Structure to Soil Drought in Old P. kangdingensis Cuttings of Section Tacamahaca Spach

Lu¹,

Wang²,

Li³

2018

Proceedings of the 2018 8th International Conference on Management, Education and Information (MEICI 2018)

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“…Some of the additional factors that reportedly intensified the impact of the 2014-2016 drought include the reduction in the grazing lawns, siltation of rivers, and the increasing number of carnivores [11]. The impact of the 2014-2016 drought did not only affect this natural protected area (HiP), but also the comical plantations which are situated at about 70 km southwest of the HiP [10], [67]. A study by Crous et al [67] reported a large-scale dieback of Eucalyptus grandis × E. urophylla (SClone) in the Zululand coastal plain, KwaZulu-Natal, South Africa, during the recent intense drought.…”

Section: Correlations Statistics and Mann-kendall Testmentioning

confidence: 99%

Time Series Analysis of MODIS-Derived NDVI for the Hluhluwe-Imfolozi Park, South Africa: Impact of Recent Intense Drought

Mbatha

Xulu

2018

Climate

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The variability of temperature and precipitation influenced by El Niño-Southern Oscillation (ENSO) is potentially one of key factors contributing to vegetation product in southern Africa. Thus, understanding large-scale ocean-atmospheric phenomena like the ENSO and Indian Ocean Dipole/Dipole Mode Index (DMI) is important. In this study, 16 years (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017) of Moderate Resolution Imaging Spectroradiometer (MODIS) Terra/Aqua 16-day normalized difference vegetation index (NDVI), extracted and processed using JavaScript code editor in the Google Earth Engine (GEE) platform was used to analyze the vegetation response pattern of the oldest proclaimed nature reserve in Africa, the Hluhluwe-iMfolozi Park (HiP) to climatic variability. The MODIS enhanced vegetation index (EVI), burned area index (BAI), and normalized difference infrared index (NDII) were also analyzed. The study used the Modern Retrospective Analysis for the Research Application (MERRA) model monthly mean soil temperature and precipitations. The Global Land Data Assimilation System (GLDAS) evapotranspiration (ET) data were used to investigate the HiP vegetation water stress. The region in the southern part of the HiP which has land cover dominated by savanna experienced the most impact of the strong El Niño. Both the HiP NDVI inter-annual Mann-Kendal trend test and sequential Mann-Kendall (SQ-MK) test indicated a significant downward trend during the El Niño years of 2003 and 2014-2015. The SQ-MK significant trend turning point which was thought to be associated with the 2014-2015 El Niño periods begun in November 2012. The wavelet coherence and coherence phase indicated a positive teleconnection/correlation between soil temperatures, precipitation, soil moisture (NDII), and ET. This was explained by a dominant in-phase relationship between the NDVI and climatic parameters especially at a period band of 8-16 months. Climate 2018, 6, 95 2 of 24The influence of drought on vegetation varies in the spatial and temporal scales, and these are projected to increase with climate change [6,7]. This behavior affects wildlife, particularly in semi-arid and arid environments where herbivory is strongly restricted by vegetation extent and water availability [8]. In the north-east part of KwaZulu-Natal, South Africa, for example, droughts are becoming a recurrent and prominent feature [9,10], affecting vegetation, water and wildlife resources notably in the Hluhluwe-iMfolozi Park (HiP), the oldest proclaimed game reserve in Africa, as reported in this paper. Furthermore, these impacts have potential consequences that could incapacitate this game reserve's support of its specialist grazers such as rhinos [11].Understanding the association between vegetation productivity and climatic variables such as precipitation and temperature has, therefore, become a high priority. To address this, spatiotemporal tools that can integrate climate data with other information of interest are required....

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“…The commercial forestry sector plays an important role in the economic development of South Africa as it contributes a net revenue of approximately R31 billion (USD $918,092,058) to the gross domestic product and employs more than 200,000 of the national labour force [1]. However, the most productive Zululand forestry region along the north-east coast of the country has been hit by a series of severe droughts, causing a corresponding decline in Eucalyptus productivity [2], and widespread tree mortality [3]. For example, downward growth patterns were highest during the recent 2015 drought, where reductions ranging from 35% to 40% were recorded around the Mtubatuba area [4].…”

Section: Introductionmentioning

confidence: 99%

“…Its pronounced effects are reflected in Xulu et al [2]. Eucalyptus trees showed the most extreme response, resulting in extensive tree dieback [3]. Therefore, identifying varieties that are resistant to drought and planting them in drought-prone areas may increase the resilience of plantations.…”

Section: Introductionmentioning

confidence: 99%

“…However, the detection of drought is complex [21] and is different from other forest-damaging agents (such as fire) in several respects. For example, under similar drought stress conditions, different species [22], and even individual trees [3], can experience differential rates of decline and mortality levels, which can cause variations in competitive capacity and affect the species composition of forests [23][24][25]. Secondly, its consequences can be experienced at relatively broad geographic scales and simultaneously across landscapes [26].…”

Section: Introductionmentioning

confidence: 99%

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Unsupervised Clustering of Forest Response to Drought Stress in Zululand Region, South Africa

Xulu

Peerbhay

Gebreslasie

et al. 2019

Forests

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Drought limits the production of plantation forests, notably in the drought-prone Zululand region of South Africa. During the last 40 years, the country has faced a series of severe droughts, however that of 2015 stands out as the most extreme and prolonged. The 2015 drought impaired forest productivity and led to widespread tree mortality in this region, but the identification of tree response to drought stress remains uncertain because of its spatial variability. To address this problem, a method that can capture drought patterns and identify trees with similar reactions to drought stress is desired. This could improve the accuracy of detecting trees suffering from drought stress which is key for forest management planning. In this study, we aimed to evaluate the utility of unsupervised mapping approaches in compartments of Eucalyptus trees with similar drought characteristics based on the Normalized Difference Water Index (NDWI) and to demonstrate the value of cloud-based Google Earth Engine (GEE) resources for rapid landscape drought monitoring. Our results showed that calculating distances between pixels using three different matrices (Random Forest (RF) proximity, Euclidean and Manhattan) can accurately detect similarities within a dataset. The RF proximity matrix produced the best measures, which were clustered using Wards hierarchical clustering to detect drought with the highest overall accuracy of 87.7%, followed by Manhattan (85.9%) and Euclidean similarity measures (79.9%), with user and producer results between 84.2% to 91.2%, 42.8% to 98.2% and 37.2% to 94.7%, respectively. These results confirm the value of the RF proximity matrix and underscore the capability of automatic unsupervised mapping approaches for monitoring drought stress in tree plantations, as well as the value of using GEE for providing cost effective datasets to resource stricken countries.

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Dissimilar stem and leaf hydraulic traits suggest varying drought tolerance among co-occurring Eucalyptus grandis × E. urophylla clones

Cited by 11 publications

References 66 publications

Response of Anatomical Structure to Soil Drought in Old P. kangdingensis Cuttings of Section Tacamahaca Spach

Response of Anatomical Structure to Soil Drought in Old P. kangdingensis Cuttings of Section Tacamahaca Spach

Time Series Analysis of MODIS-Derived NDVI for the Hluhluwe-Imfolozi Park, South Africa: Impact of Recent Intense Drought

Unsupervised Clustering of Forest Response to Drought Stress in Zululand Region, South Africa

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