Acacia tortilis (Forssk.) subsp. raddiana (Savi) Brenan as a foundation species: a test from the arid zone of Tunisia

The geographic distribution of Acacia tortilis (Forssk.) Hayne subsp. raddiana (Savi) Brenan in Tunisia, is limited to the Bou-Hedma region (Bled Talah) where the National Park of Bou-Hedma, a UNESCO (1986) biosphere reserve, is located. We have tested the hypothesis that A. tortilis acts as a foundation species as a result of the improvement of soil conditions under its canopy (soil water availability and nutrient enrichment). The herbaceous community (floristic composition, species density, species richness) and soil characteristics (soil nutrients and soil water) were sampled using the quadrat method beneath and between 16 adult trees of A. tortilis with both northwards and southwards (south and north sides) and eight open areas among the trees. Results showed that A. tortilis trees improve soil water availability, the nutrient status of soil (organic matter, total carbon, total nitrogen, extractable phosphorus), and has a positive effect on the understorey vegetation under arid conditions. No significant differences in species richness were observed between the north subhabitats and the south subhabitats.

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Responses of Acacia tortilis and Acacia xanthophloea to seasonal changes in soil water availability in the savanna region of Kenya

Journal of Arid Environments ◽

10.1016/j.jaridenv.2005.01.001 ◽

2005 ◽

Vol 62 (3) ◽

pp. 377-400 ◽

Cited By ~ 34

Author(s):

D.O. Otieno ◽

M.W.T. Schmidt ◽

J.I. Kinyamario ◽

J. Tenhunen

Keyword(s):

Soil Water ◽

Water Availability ◽

Seasonal Changes ◽

Soil Water Availability ◽

Acacia Tortilis

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Soil water availability shapes species richness in mid‐latitude shrub steppe plant communities

Journal of Vegetation Science ◽

10.1111/jvs.12874 ◽

2020 ◽

Vol 31 (4) ◽

pp. 646-657 ◽

Cited By ~ 1

Author(s):

Samuel E. Jordan ◽

Kyle A. Palmquist ◽

John B. Bradford ◽

William K. Lauenroth

Keyword(s):

Species Richness ◽

Soil Water ◽

Plant Communities ◽

Water Availability ◽

Soil Water Availability ◽

Shrub Steppe ◽

Steppe Plant ◽

Steppe Plant Communities

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Artificial Top Soil Drought Hardly Affects Water Use of Picea abies and Larix decidua Saplings at the Treeline in the Austrian Alps

Forests ◽

10.3390/f10090777 ◽

2019 ◽

Vol 10 (9) ◽

pp. 777 ◽

Cited By ~ 2

Author(s):

Wieser ◽

Oberhuber ◽

Gruber ◽

Oberleitner ◽

Hasibeder ◽

...

Keyword(s):

Picea Abies ◽

Soil Water ◽

Water Availability ◽

Sap Flow ◽

Larix Decidua ◽

Soil Water Availability ◽

Soil Drought ◽

Flow Density ◽

Adult Trees ◽

Sap Flow Density

This study quantified the effect of shallow soil water availability on sap flow density (Qs) of 4.9 ± 1.5 m tall Picea abies and Larix decidua saplings at treeline in the Central Tyrolean Alps, Austria. We installed a transparent roof construction around three P. abies and three L. decidua saplings to prevent precipitation from reaching the soil surface without notably influencing the above ground microclimate. Three additional saplings from each species served as controls in the absence of any manipulation. Roofing significantly reduced soil water availability at a 5–10 cm soil depth, while soil temperature was not affected. Sap flow density (using Granier-type thermal dissipation probes) and environmental parameters were monitored throughout three growing seasons. In both species investigated, three years of rain exclusion did not considerably reduce Qs. The lack of a significant Qs-soil water content correlation in P. abies and L. decidua saplings indicates sufficient water supply, suggesting that whole plant water loss of saplings at treeline primarily depends on evaporative demand. Future work should test whether the observed drought resistance of saplings at the treeline also holds for adult trees.

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Characterizing Growing Season Length of Subtropical Coniferous Forests with a Phenological Model

Forests ◽

10.3390/f12010095 ◽

2021 ◽

Vol 12 (1) ◽

pp. 95

Author(s):

Yuan Gong ◽

Christina L. Staudhammer ◽

Susanne Wiesner ◽

Gregory Starr ◽

Yinlong Zhang

Keyword(s):

Climate Change ◽

Soil Water ◽

Prescribed Fire ◽

Water Availability ◽

Longleaf Pine ◽

Growing Season ◽

Soil Water Availability ◽

Future Climate Change ◽

Short Term ◽

Phenological Model

Understanding plant phenological change is of great concern in the context of global climate change. Phenological models can aid in understanding and predicting growing season changes and can be parameterized with gross primary production (GPP) estimated using the eddy covariance (EC) technique. This study used nine years of EC-derived GPP data from three mature subtropical longleaf pine forests in the southeastern United States with differing soil water holding capacity in combination with site-specific micrometeorological data to parameterize a photosynthesis-based phenological model. We evaluated how weather conditions and prescribed fire led to variation in the ecosystem phenological processes. The results suggest that soil water availability had an effect on phenology, and greater soil water availability was associated with a longer growing season (LOS). We also observed that prescribed fire, a common forest management activity in the region, had a limited impact on phenological processes. Dormant season fire had no significant effect on phenological processes by site, but we observed differences in the start of the growing season (SOS) between fire and non-fire years. Fire delayed SOS by 10 d ± 5 d (SE), and this effect was greater with higher soil water availability, extending SOS by 18 d on average. Fire was also associated with increased sensitivity of spring phenology to radiation and air temperature. We found that interannual climate change and periodic weather anomalies (flood, short-term drought, and long-term drought), controlled annual ecosystem phenological processes more than prescribed fire. When water availability increased following short-term summer drought, the growing season was extended. With future climate change, subtropical areas of the Southeastern US are expected to experience more frequent short-term droughts, which could shorten the region’s growing season and lead to a reduction in the longleaf pine ecosystem’s carbon sequestration capacity.

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