scholarly journals Climate Sensitivity of Tropical Trees Along an Elevation Gradient in Rwanda

Forests ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 647 ◽  
Author(s):  
Myriam Mujawamariya ◽  
Aloysie Manishimwe ◽  
Bonaventure Ntirugulirwa ◽  
Etienne Zibera ◽  
Daniel Ganszky ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Climate Sensitivity ◽  
Elevation Gradient ◽  
High Elevation ◽  
Dry Season ◽  
Nutrient Ratios ◽  
Wet Season ◽  
Elevation Gradients ◽  
Use Efficiency

Elevation gradients offer excellent opportunities to explore the climate sensitivity of vegetation. Here, we investigated elevation patterns of structural, chemical, and physiological traits in tropical tree species along a 1700–2700 m elevation gradient in Rwanda, central Africa. Two early-successional (Polyscias fulva, Macaranga kilimandscharica) and two late-successional (Syzygium guineense, Carapa grandiflora) species that are abundant in the area and present along the entire gradient were investigated. We found that elevation patterns in leaf stomatal conductance (gs), transpiration (E), net photosynthesis (An), and water-use efficiency were highly season-dependent. In the wet season, there was no clear variation in gs or An with elevation, while E was lower at cooler high-elevation sites. In the dry season, gs, An, and E were all lower at drier low elevation sites. The leaf-to-air temperature difference was smallest in P. fulva, which also had the highest gs and E. Water-use efficiency (An/E) increased with elevation in the wet season, but not in the dry season. Leaf nutrient ratios indicated that trees at all sites are mostly P limited and the N:P ratio did not decrease with increasing elevation. Our finding of strongly decreased gas exchange at lower sites in the dry season suggests that both transpiration and primary production would decline in a climate with more pronounced dry periods. Furthermore, we showed that N limitation does not increase with elevation in the forests studied, as otherwise most commonly reported for tropical montane forests.

Effects of Bio-nano OSA Application on Fertilizer Use and Water Consumption Efficiencies of Black Soybean Grown on Rice-Field

2020 ◽  
Vol 43 (2) ◽  
pp. 109
Author(s):  
Laksmita Prima Santi ◽  
Didiek Hadjar Goenadi ◽  
Junita Barus ◽  
Ai Dariah ◽  
Donny Nugroho Kalbuadi
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Silicic Acid ◽  
Rice Field ◽  
Dry Season ◽  
Fertilizer Efficiency ◽  
Black Soybean ◽  
Standard Practice ◽  
Use Efficiency ◽  
Npk Fertilizer

<p><strong>Abstarct.</strong> Rice-field, during the dry season, offers promising potential as food crop production area particularly for secondary crops such as black soybean. However, rice-field have some limitations to support crop productivity economically, due to low fertilizer efficiency and/or water usage. Silicate (Si) fertilizer in the form of bio-nano ortho silicic acid (OSA) has been proven to improve yield and water use efficiency of black soybean on the upland, but not on rice field. This study aimed to determine the effects of bio-nano OSA application on yield, fertilizer and water use efficiencies of Detam-1 black soybean grown at a Bantarwaru rice-field, Indramayu, West Java. Experiment was undertaken from August to November 2018 with treatments consisting of : (i) control (P0), (ii) farmers’ standard practice (P1), (iii) P1 + 2 ton organic fertilizer ha-1 (P2), (iv) 50% P1 + 4 L bio-nano OSA ha-1 (P3), (v) 75% P1 + 4 L bio-nano OSA ha-1 (P4), and (vi) P1 + 4 L bio-nano OSA ha-1 (P5), in a randomized block design with three replications. The soil belongs to Alfisols with vertic property, i.e. cracking during the dry season. The results show that the application of bio-nano OSA was capable of improving yield of Detam-1 black soybean up to 26%, increasing water use efficiency up to 37%, and reducing NPK fertilizer dosages up to 50%. The highest yields of Detam-1 black soybean was 2.4-2.5-ton bean ha-1, achieved from the treatment of combination of 50-75% NPK fertilizer dosages and application of bio-nano OSA at 4 L ha-1 rate with optimum level of NPK dosage at 39.2%. By using bio-nano OSA and optimum dosage of NPK fertilizer, the farmer’s profit increased IDR 4,152,340 ha-1 per season compared to standard practice.</p><p><strong>Abstrak. </strong>Sawah tadah hujan pada musim kemarau menawarkan peluang yang prospektif untuk dimanfaatkan sebagai areal produksi tanaman pangan khususnya palawija seperti kedelai hitam. Namun, sawah tadah hujan secara umum memiliki masalah khusus untuk mendukung produktivitas tanaman di musim kemarau yaitu rendahnya efisiensi serapan hara dan/atau penggunaan air. Teknologi pupuk silika dalam formulasi bio-nano ortho-silicic acid (OSA) telah terbukti mampu meningkatkan hasil kedelai hitam dan efisiensi penggunaan air pada lahan tegalan tetapi tidak pada lahan sawah tadah hujan. Penelitian ini ditujukan untuk mempelajari pengaruh aplikasi pupuk Si (bio-nano OSA) terhadap produksi tanaman kedelai hitam Detam-1, efisiensi penggunaan pupuk, dan air pada sawah tadah hujan di Bantarwaru, Indramayu, Jawa Barat. Percobaan dilaksanakan di lahan petani pada bulan Agustus hingga Nopember 2018 dengan menguji perlakuan : (i) kontrol (P0), (ii) pemupukan standar petani (P1), (iii) P1 + 2 ton pupuk organik ha-1 (P2), (iv) 50% P1 + 4 L bio-nano OSA ha-1 (P3), (v) 75% P1 + 4 L bio-nano OSA ha-1 (P4), dan (vi) 100% P1 + 4 L bio-nano OSA ha-1 (P5), dalam rancangan acak kelompok dengan ulangan tiga kali. Tanah di lokasi percobaan tergolong ordo Alfisol dengan sifat vertik seperti timbulnya retakan saat musim kemarau. Hasil percobaan menunjukkan bahwa aplikasi bio-nano OSA mampu meningkatkan produksi kedelai hitam varietas Detam-1 hingga 26%, meningkatkan efisiensi penggunaan air hingga 37%, dan menghemat dosis pupuk NPK hingga 50%. Produktivitas kedelai hitam tertinggi sebesar 2,4–2,5 ton biji kering ha-1 diperoleh pada perlakuan kombinasi pupuk NPK 50-75% dari standar petani dan aplikasi bio-nano OSA 4 L ha-1 dengan dosis optimum pupuk NPK pada 39,2%. Tambahan keuntungan usaha tani kedelai hitam Detam-1 di Bantarwaru dengan aplikasi bio-nano OSA dan pemupukan NPK yang optimum dapat mencapai IDR. 4.152.340 ha-1 per musim jika dibandingkan perlakuan dosis pupuk standar.</p>

Rapid increases in shrubland and forest intrinsic water-use efficiency during an ongoing megadrought

2021 ◽  
Vol 118 (52) ◽  
pp. e2118052118
Author(s):  
Steven A. Kannenberg ◽  
Avery W. Driscoll ◽  
Paul Szejner ◽  
William R. L. Anderegg ◽  
James R. Ehleringer
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Pinus Ponderosa ◽  
Plant Density ◽  
High Elevation ◽  
American Southwest ◽  
Past Century ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency ◽  
Negative Impacts

Globally, intrinsic water-use efficiency (iWUE) has risen dramatically over the past century in concert with increases in atmospheric CO2 concentration. This increase could be further accelerated by long-term drought events, such as the ongoing multidecadal “megadrought” in the American Southwest. However, direct measurements of iWUE in this region are rare and largely constrained to trees, which may bias estimates of iWUE trends toward more mesic, high elevation areas and neglect the responses of other key plant functional types such as shrubs that are dominant across much of the region. Here, we found evidence that iWUE is increasing in the Southwest at one of the fastest rates documented due to the recent drying trend. These increases were particularly large across three common shrub species, which had a greater iWUE sensitivity to aridity than Pinus ponderosa, a common tree species in the western United States. The sensitivity of both shrub and tree iWUE to variability in atmospheric aridity exceeded their sensitivity to increasing atmospheric [CO2]. The shift to more water-efficient vegetation would be, all else being equal, a net positive for plant health. However, ongoing trends toward lower plant density, diminished growth, and increasing vegetation mortality across the Southwest indicate that this increase in iWUE is unlikely to offset the negative impacts of aridification.

Growth dynamics, climate sensitivity and water use efficiency in pure vs. mixed pine and beech stands in Trentino (Italy)

2018 ◽  
Vol 409 ◽  
pp. 707-718 ◽  
Author(s):  
E. Conte ◽  
F. Lombardi ◽  
G. Battipaglia ◽  
C. Palombo ◽  
S. Altieri ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Climate Sensitivity ◽  
Growth Dynamics ◽  
Use Efficiency

scholarly journals Water Use Efficiency and Physiological Response of Rice Cultivars under Alternate Wetting and Drying Conditions

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Yunbo Zhang ◽  
Qiyuan Tang ◽  
Shaobing Peng ◽  
Danying Xing ◽  
Jianquan Qin ◽  
...  
Keyword(s):  
Water Management ◽  
Grain Yield ◽  
Water Use Efficiency ◽  
Water Use ◽  
Field Experiments ◽  
Grain Filling ◽  
Dry Season ◽  
Wetting And Drying ◽  
Alternate Wetting And Drying ◽  
Use Efficiency

One of the technology options that can help farmers cope with water scarcity at the field level is alternate wetting and drying (AWD). Limited information is available on the varietal responses to nitrogen, AWD, and their interactions. Field experiments were conducted at the International Rice Research Institute (IRRI) farm in 2009 dry season (DS), 2009 wet season (WS), and 2010 DS to determine genotypic responses and water use efficiency of rice under two N rates and two water management treatments. Grain yield was not significantly different between AWD and continuous flooding (CF) across the three seasons. Interactive effects among variety, water management, and N rate were not significant. The high yield was attributed to the significantly higher grain weight, which in turn was due to slower grain filling and high leaf N at the later stage of grain filling of CF. AWD treatments accelerated the grain filling rate, shortened grain filling period, and enhanced whole plant senescence. Under normal dry-season conditions, such as 2010 DS, AWD reduced water input by 24.5% than CF; however, it decreased grain yield by 6.9% due to accelerated leaf senescence. The study indicates that proper water management greatly contributes to grain yield in the late stage of grain filling, and it is critical for safe AWD technology.

Tree species effects on ecosystem water-use efficiency in a high-elevation, subalpine forest

Oecologia ◽  
2009 ◽  
Vol 162 (2) ◽  
pp. 491-504 ◽  
Author(s):  
Russell K. Monson ◽  
Margaret R. Prater ◽  
Jia Hu ◽  
Sean P. Burns ◽  
Jed P. Sparks ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Tree Species ◽  
High Elevation ◽  
Subalpine Forest ◽  
Species Effects ◽  
Ecosystem Water Use Efficiency ◽  
Tree Species Effects ◽  
Use Efficiency

scholarly journals Dry-Season Fog Water Utilization by Epiphytes in a Subtropical Montane Cloud Forest of Southwest China

Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3237
Author(s):  
Lu-Lu Liu ◽  
Bin Yang ◽  
Hua-Zheng Lu ◽  
Yi Wu ◽  
Xian-Jing Meng ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Water Sources ◽  
Dry Season ◽  
Seed Plants ◽  
Epiphytic Lichens ◽  
Cloud Forests ◽  
Water Utilization ◽  
Fog Water ◽  
Use Efficiency

Fog water is generally considered to be an important water source for epiphytes in cloud forests because they cannot directly access ground-level water sources. However, the water use proportions of potential water sources and water use efficiency of epiphytes in the subtropical montane cloud forests (MCF) remain to be further explored. In this study, we investigated the water use pattern in the dry season and the intrinsic water use efficiency (WUEi) of four epiphyte groups (i.e., epiphytic lichens, epiphytic bryophytes, epiphytic ferns, and epiphytic seed plants) using stable isotope (δ2H, δ18O, and δ13C) techniques. Our results indicated that the water sources of epiphytes were significantly different among groups and species. The contribution proportions of fog water to epiphytic lichens, epiphytic bryophytes, epiphytic ferns, and epiphytic seed plants were 83.2%, 32.7%, 38.8% and 63.7%, respectively. Epiphytic lichens and epiphytic seed plants mainly depended on fog water whereas the epiphytic bryophytes and epiphytic ferns relied on both fog water and humus. This may be due to their differences in morphological and structural traits (e.g., thallus or leaves, rhizoid or roots). Additionally, the difference in was also significant among epiphyte groups and species, which could be related to their different water acquisition patterns. In conclusion, our study reveals the differentiation of water utilization in epiphytes and confirms the importance of fog water for epiphytes during the dry season.

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