Growth of Bauhinia thonningii trees and saplings over a decade in a savanna in Zambia: interactions of climate, fire and source of regeneration

2008 ◽  
Vol 24 (4) ◽  
pp. 407-415 ◽  
Author(s):  
Emmanuel Ngulube Chidumayo
Keyword(s):  
Radial Growth ◽  
Plant Size ◽  
Height Growth ◽  
Dry Season ◽  
Tree Size ◽  
Maximum Temperature ◽  
Climate Factors ◽  
Growth Responses ◽  
Hot Dry Season ◽  
Cool Dry Season

AbstractThe present study investigated how climate and plant size affect the growth of Bauhinia thonningii and how fire and source of regeneration (grown from coppice versus seedlings) might modify the results. The study was conducted over a period of 10 y, from 1997 to 2007, at a savanna site in central Zambia. Trees were marked and monitored throughout the entire period; they showed a phase of declining growth (1998–2003) and a phase of low growth (2004–2007). During the phase of declining growth autocorrelation was high but either weakened or disappeared during the phase of low growth. After adjusting data for autocorrelation, climate factors and tree size accounted for between 14% and 35% of the variation in annual tree radial growth. However, the growth responses of trees to climate factors and tree size varied with the source of regeneration (i.e. coppice or seedling) and fire treatment. Trees of seedling origin were only affected by climate factors and tree size when exposed to annual burning whereas all trees of coppice origin were significantly affected by climate factors and tree size, regardless of the fire treatment. However, basal radial growth of saplings that were monitored for 4 y (2003–2007) was significantly influenced by maximum temperature and rainfall that accounted for 33–47% of the variance in annual radial growth under fire protection. Saplings recovered from shoot die-back during the cool dry season by resprouting in the hot dry season and this annual die-back slowed the height growth of B. thonningii saplings.

scholarly journals ELIMÄKI locus is required for mechanosensing and proprioception in birch trees

2019 ◽  
Author(s):  
Juan Alonso-Serra ◽  
Xueping Shi ◽  
Alexis Peaucelle ◽  
Pasi Rastas ◽  
Matthieu Bourdon ◽  
...  
Keyword(s):  
Radial Growth ◽  
Plant Size ◽  
Forward Genetics ◽  
Recessive Trait ◽  
Growth Responses ◽  
Precocious Flowering ◽  
Vertical Loading ◽  
Delayed Differentiation ◽  
Physical Loading ◽  
Two Generations

AbstractThe remarkable vertical and radial growth observed in tree species, encompasses a major physical challenge for wood forming tissues. To compensate with increasing size and weight, cambium-derived radial growth increases the stem width, thereby supporting the aerial body of trees. This feedback appears to be part of a so-called “proprioception” (1, 2) mechanism that controls plant size and biomass allocation. Yet, how trees experience or respond to mechanical stress derived from their own vertical loading, remains unknown. Here, we combined two strategies to dissect the proprioceptive response in birch. First, we show that in response to physical loading, trees promote radial growth with different magnitudes along the stem. Next, we identified a mutant cultivar (B. pubescens cv. Elimäki) in which the main stem shows normal vertical development, but collapses after three months. By inducing precocious flowering, we generated a backcrossed population (BC1) by producing two generations in 4 years. In his scheme, we uncovered a recessive trait (eki) that segregates and genetically maps with a Mendelian monogenic pattern. Unlike WT, eki is resistant to vertical mechanical stimulation. However, eki responds normally to the gravitropic stimulus by making tension wood. Before the collapse, cell size in eki is compromised resulting in radial growth defects, depending on stem height. Cell walls of developing xylem and phloem tissues have delayed differentiation in eki, and its tissues are softer compared to WT as indicated by atomic force microscopy (AFM). The transcriptomic profile of eki highlighted the overlap with that of the Arabidopsis response to touch. Taken together, our results suggest that the mechanical environment and cell wall properties of developing woody tissues, can significantly affect the growth responses to vertical loading thereby compromising their proprioceptive capacity. Additionally, we introduce a fast forward genetics strategy to dissect complex phenotypes in trees.

Catches of Glossina morsitans morsitans Westwood and G. pallidipes Austen (Diptera: Glossinidae) in odour-baited traps in riverine and deciduous woodlands in the Zambesi Valley of Zimbabwe

1980 ◽  
Vol 70 (4) ◽  
pp. 571-578 ◽  
Author(s):  
J. W. Hargrove ◽  
G. A. Vale
Keyword(s):  
Glossina Morsitans Morsitans ◽  
Dry Season ◽  
Glossina Morsitans ◽  
Male Ratio ◽  
Baited Traps ◽  
Deciduous Woodland ◽  
Hot Dry Season ◽  
Dramatic Rise ◽  
High Level ◽  
Cool Dry Season

AbstractCatches of Glossina morsitans morsitans Westw. and G. pallidipes Aust. were made on electric nets baited with the odour of one ox, in deciduous and riverine woodland in the Zambesi Valley of Zimbabwe. Catches of teneral and mature flies of both sexes and species declined sharply during the hot dry season (September to November) in the deciduous woodland. In the riverine woodland, catches of mature G. m. morsitans increased during this period; catches of mature G. pallidipes rose rapidly to a high level in June (early in the cool dry season), which was maintained for most of the dry season. Catches of teneral flies in the riverine woodland were fairly constant from June to September (the cool dry season and start of the hot dry season) and then declined, though not as sharply as in the deciduous woodland. The percentage of tenerals in the catch showed a minimum at the end of the hot dry season (October–November); at that time there was also a dramatic rise in the female: male ratio in the deciduous woodland, but no such change occurred in the riverine area.

scholarly journals THE EFFECT OF CLIMATE ON THE RADIAL GROWTH OF SCOTS PINE (PINUS SYLVESTRIS L.) IN A COASTAL MIXED STAND IN KAPISUYU, BARTIN, TURKEY

2021 ◽  
Vol 8 (2) ◽  
pp. 187-197
Author(s):  
Halil Barış Özel ◽  
Barbaros Yaman ◽  
Tuğrul Varol
Keyword(s):  
Scots Pine ◽  
Radial Growth ◽  
Growth Ring ◽  
Signal To Noise Ratio ◽  
Correlation Coefficients ◽  
Maximum Temperature ◽  
Late Winter ◽  
Growth Responses ◽  
Growth Rings ◽  
Black Sea Region

Scots pine is geographically the most widespread pine species in the world, and it shows different growth responses to climate and environmental factors in diverse ecological sites. We studied both the stand dynamics and climate-growth relationships of Scots pine in isolated coastal stand (recently found) in the Western Black Sea Region of Turkey. The homogeneity index of this stand has varied between 1.92-3.56. In growth-ring analyses, after cross-dating of individual chronologies, COFECHA and ARSTAN software were used respectively for chronology quality control and standardization (detrend). In this way, a 58-year-long chronology (1959-2016) of Scots pine was constructed. In addition, DENDROCLIM software was used for investigating Scots pine’s radial growth-climate relationships. Mean sensitivity changed from 0.163 to 0.331, with a mean of 0.183. Mean correlation among trees and signal to noise ratio were 0.389 and 7.012 respectively. In terms of the effect of precipitation on the radial growth of Scots pine in this site, the correlation coefficients were 0.43 (p<0.05) for December of the previous year and 0.41 (p<0.05) for July of the current year. For all the other months, precipitation had a non-significant effect. As for the maximum and mean air temperature, the correlation coefficients were 0.36 (p<0.05) and 0.40 (p<0.05) for February, and 0.40 (p<0.05) and 0.42 (p<0.05) for March, respectively. However, on the radial growth, while the maximum temperature in August had a negative effect (r= -0.26; p<0.05), minimum temperatures in February, March and July had a positive effect (r= 0.39, 0.40 and 0.34 respectively; p<0.05). It means while higher rains in July and higher temperatures in the late winter-early spring have caused the wider growth rings, the narrower growth rings have been formed in the years with higher maximum temperatures in August in the isolated coastal site of Scots pine.

Aboveground growth responses of understory Abies lasiocarpa saplings to different release cuts

2003 ◽  
Vol 33 (9) ◽  
pp. 1593-1601 ◽  
Author(s):  
Marek J Krasowski ◽  
Jian R Wang
Keyword(s):  
Radial Growth ◽  
Height Growth ◽  
Abies Lasiocarpa ◽  
Initial Growth ◽  
Growth Responses ◽  
White Birch ◽  
Clear Cutting ◽  
Growth Increments ◽  
Advance Regeneration ◽  
Large Trees

A white birch (Betula papyrifera Marsh.) overstory of a 30+ year old stand was thinned or completely removed, releasing an advance regeneration of subalpine fir (Abies lasiocarpa (Hook.) Nutt.). The overstory was clear-cut (T0), thinned to 600 (T600) or to 1200 (T1200) stems/ha, or left uncut (control). Three years after release, understory responses were best demonstrated by decreasing specific leaf area with increasing release level and by changes to height and radial growth increments. Clear-cutting the overstory stalled the height growth in fir for two seasons and radial growth at the tree base for one season. Compared with the control, the 3-year height increment was proportionally greatest in intermediate trees of T600, and this treatment produced the overall best response in height growth. Complete birch removal produced the best radial growth response despite the initial growth check. However, no release treatment significantly affected the whole tree variables (aboveground biomass, height, diameter at breast height (DBH), live crown ratio) within the studied time frame. Shoot silhouette ratios were lowest in the completely released understory trees, while they were similar to those of the controls in all partial-release treatments. Tree sturdiness (height/DBH ratio) was 80–90 in most treatments except T0, where it declined to below 80. Despite this improvement, large trees in T0 have been damaged by wind and snow.

scholarly journals ANALYSIS OF THE IMPACT OF VEGETATION DISTRIBUTION, URBANIZATION, AND SOLAR RADIATION ON THE SEASONAL VARIATION OF THE URBAN HEAT ISLAND EFFECT IN CEBU CITY USING LANDSAT AND GLOBAL HORIZONTAL IRRADIANCE DATA

2019 ◽  
Vol XLII-4/W19 ◽  
pp. 93-100
Author(s):  
S. F. Cañete ◽  
L. L. Schaap ◽  
R. Andales ◽  
R. E. S. Otadoy ◽  
A. C. Blanco ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Solar Radiation ◽  
Urban Heat Island ◽  
Land Surface ◽  
Dry Season ◽  
Heat Island ◽  
Hot Dry Season ◽  
Urban Heat ◽  
The Impact ◽  
Cool Dry Season

Abstract. The Urban Heat Island (UHI) phenomenon is a manifestation of the abnormal amount of heat generated in urban areas and anthropogenic land surface modifications. While urbanization can improve material comfort and be a boon to the economy, the accompanying problems associated with urbanization like the UHI effect has implications on health, demand for water and energy, and impacts the microclimate. Land surface temperature (LST), the Normalized Difference Vegetation Index (NDVI), and the Normalized Difference Built-up Index (NDBI) were calculated from historical remotely-sensed Landsat data from 2013 to present. The global horizontal irradiance (GHI) was computed from the lidar-derived elevation model of Cebu City using the Geographical Resources Analysis Support System (GRASS). It is shown that annual variation in average temperatures in Cebu is generally less than 5 °C. Mean UHI temperatures in Cebu City do not show a clear trend over time, but categorizing data by season, namely the rainy season (June–November), the cool dry season (December–February), and the hot dry season (March–May), permits the emergence of a pattern. Surface temperatures for the cool dry season and hot dry season show a linearly increasing trend with R2 values of 0.916 and 0.514, respectively. This study further investigates the temporal change in the degree and extent of the UHI in Cebu City by analyzing LST maps. Regression analysis is done to determine how LST is affected by the distribution of vegetation (NDVI) and built-up (NDBI), and the seasonal variation in solar radiation through the GHI.

scholarly journals Radial Growth Response of European Larch Provenances to Interannual Climate Variation in Poland

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 334
Author(s):  
Norbert Szymański ◽  
Sławomir Wilczyński
Keyword(s):  
Radial Growth ◽  
Climatic Factors ◽  
Principal Component ◽  
Climatic Conditions ◽  
Growth Responses ◽  
European Larch ◽  
Temperature And Precipitation ◽  
Provenance Trials ◽  
High Precipitation ◽  
Climatic Elements

The present study identified the similarities and differences in the radial growth responses of 20 provenances of 51-year-old European larch (Larix decidua Mill.) trees from Poland to the climatic conditions at three provenance trials situated in the Polish lowlands (Siemianice), uplands (Bliżyn) and mountains (Krynica). A chronology of radial growth indices was developed for each of 60 European larch populations, which highlighted the interannual variations in the climate-mediated radial growth of their trees. With the aid of principal component, correlation and multiple regression analysis, supra-regional climatic elements were identified to which all the larch provenances reacted similarly at all three provenance trials. They increased the radial growth in years with a short, warm and precipitation-rich winter; a cool and humid summer and when high precipitation in late autumn of the previous year was noted. Moreover, other climatic elements were identified to which two groups of the larch provenances reacted differently at each provenance trial. In the lowland climate, the provenances reacted differently to temperature in November to December of the previous year and July and to precipitation in September. In the upland climate, the provenances differed in growth sensitivity to precipitation in October of the previous year and June–September. In the mountain climate, the provenances responded differently to temperature and precipitation in September of the previous year and to precipitation in February, June and September of the year of tree ring formation. The results imply that both climatic factors and origin (genotype), i.e., the genetic factor, mediate the climate–growth relationships of larch provenances.

scholarly journals Spatiotemporal Evolution of Fractional Vegetation Cover and Its Response to Climate Change Based on MODIS Data in the Subtropical Region of China

2021 ◽  
Vol 13 (5) ◽  
pp. 913
Author(s):  
Hua Liu ◽  
Xuejian Li ◽  
Fangjie Mao ◽  
Meng Zhang ◽  
Di’en Zhu ◽  
...  
Keyword(s):  
Vegetation Cover ◽  
Minimum Temperature ◽  
Maximum Temperature ◽  
Distribution Area ◽  
Spatiotemporal Pattern ◽  
Climate Factors ◽  
Important Indicator ◽  
Fractional Vegetation Cover ◽  
Annual Minimum Temperature ◽  
Total Study Area

The subtropical vegetation plays an important role in maintaining the structure and function of global ecosystems, and its contribution to the global carbon balance are receiving increasing attention. The fractional vegetation cover (FVC) as an important indicator for monitoring environment change, is widely used to analyze the spatiotemporal pattern of regional and even global vegetation. China is an important distribution area of subtropical vegetation. Therefore, we first used the dimidiate pixel model to extract the subtropical FVC of China during 2001–2018 based on MODIS land surface reflectance data, and then used the linear regression analysis and the variation coefficient to explore its spatiotemporal variations characteristics. Finally, the partial correlation analysis and the partial derivative model were used to analyze the influences and contributions of climate factors on FVC, respectively. The results showed that (1) the subtropical FVC had obvious spatiotemporal heterogeneity; the FVC high-coverage and medium-coverage zones were concentratedly and their combined area accounted for more than 70% of the total study area. (2) The interannual variation in the average subtropical FVC from 2001 to 2018 showed a significant growth trend. (3) In 76.28% of the study area, the regional FVC showed an increasing trend, and the remaining regional FVC showed a decreasing trend. However, the overall fluctuations in the FVC (increasing or decreasing) in the region were relatively stable. (4) The influences of climate factors to the FVC exhibited obvious spatial differences. More than half of all pixels exhibited the influence of the average annual minimum temperature and the annual precipitation had positive on FVC, while the average annual maximum temperature had negative on FVC. (5) The contributions of climate changes to FVC had obvious heterogeneity, and the average annual minimum temperature was the main contribution factor affecting the dynamic variations of FVC.

scholarly journals A reconstruction of the recent fire regimes of Majete Wildlife Reserve, Malawi, using remote sensing

Fire Ecology ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Willem A. Nieman ◽  
Brian W. van Wilgen ◽  
Alison J. Leslie
Keyword(s):  
Remote Sensing ◽  
Fire Management ◽  
Fire Regime ◽  
Fire Regimes ◽  
Dry Season ◽  
Annual Rainfall ◽  
Vegetation Types ◽  
Local Evidence ◽  
Hot Dry Season ◽  
Wildlife Reserve

Abstract Background Fire is an important process that shapes the structure and functioning of African savanna ecosystems, and managers of savanna protected areas use fire to achieve ecosystem goals. Developing appropriate fire management policies should be based on an understanding of the determinants, features, and effects of prevailing fire regimes, but this information is rarely available. In this study, we report on the use of remote sensing to develop a spatially explicit dataset on past fire regimes in Majete Wildlife Reserve, Malawi, between 2001 and 2019. Moderate Resolution Imaging Spectroradiometer (MODIS) images were used to evaluate the recent fire regime for two distinct vegetation types in Majete Wildlife Reserve, namely savanna and miombo. Additionally, a comparison was made between MODIS and Visible Infrared Imager Radiometer Suite (VIIRS) images by separately evaluating selected aspects of the fire regime between 2012 and 2019. Results Mean fire return intervals were four and six years for miombo and savanna vegetation, respectively, but the distribution of fire return intervals was skewed, with a large proportion of the area burning annually or biennially, and a smaller proportion experiencing much longer fire return intervals. Variation in inter-annual rainfall also resulted in longer fire return intervals during cycles of below-average rainfall. Fires were concentrated in the hot-dry season despite a management intent to restrict burning to the cool-dry season. Mean fire intensities were generally low, but many individual fires had intensities of 14 to 18 times higher than the mean, especially in the hot-dry season. The VIIRS sensors detected many fires that were overlooked by the MODIS sensors, as images were collected at a finer scale. Conclusions Remote sensing has provided a useful basis for reconstructing the recent fire regime of Majete Wildlife Reserve, and has highlighted a current mismatch between intended fire management goals and actual trends. Managers should re-evaluate fire policies based on our findings, setting clearly defined targets for the different vegetation types and introducing flexibility to accommodate natural variation in rainfall cycles. Local evidence of the links between fires and ecological outcomes will require further research to improve fire planning.

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