|
|
Beya-Marshall, V., Arcos, E., Seguel, O., Galleguillos, M., & Kremer, C. (2022). Optimal irrigation management for avocado (cv. 'Hass') trees by monitoring soil water content and plant water status. Agric. Water Manag., 271, 107794.
Abstract: Irrigation scheduling based on soil water content (Ow) sensors requires that Ow be maintained within a range (management lines) that is optimal for plant growth. The lower limit or “breaking point ” is determined following the soil water content dynamics on the transition of a rapid rate of depletion to a slower, under similar reference evapotranspiration. Although this criterion is practical, its implementation should be validated with plant water status measurement that contemplate weather condition, such as stem water potential “non-stressed ” baseline (Tx as a function of vapor-pressure deficit (VPD) in Ow conditions that do not limit yield). A study was con-ducted on a mature cv. 'Hass' avocado orchard in Central Chile during two seasons. There were 5 irrigation treatments: T1, Control; T2 and T3 with 29% less and 25% more of what was applied in T1, respectively; T4 and T5 same as Control until first and second fruit drop abscission, respectively, and then with 29% less. T1 trees were irrigated using a continuous frequency domain reflectometry (FDR) probe to maintain the root zone be-tween field capacity and the breaking point. There was biweekly monitoring of the Ow prior to irrigation, Tx and VPD. The Tx decline proportional to the intensity and the timing of water restriction; however, no treatment affected the crop load in either season. T2 did not show significant detrimental in fruit size, production and maturation, despite that frequently reached water content levels at the limit of the breaking point, and showed lower levels of stem water potential than Control, being the treatment with the highest water productivity. The results confirm that breaking point is an effective criterion to establish irrigation management. Additionally, when comparing the baseline for our non-stressed trees with a baseline from full irrigation treatments obtained from the literature, 30% water savings were achieved.
|
|
|
|
Dinamarca, D. I., Galleguillos, M., Seguel, O., & Urbina, C. F. (2023). CLSoilMaps: A national soil gridded database of physical and hydraulic soil properties for Chile. Sci. Data, 10(1), 630.
Abstract: Spatially explicit soil information is crucial for comprehending and managing many of Earth & PRIME;s processes related to carbon, water, and other biogeochemical cycles. We introduced a gridded database of soil physical properties and hydraulic parameters at 100 meters spatial resolution. It covers the continental area of Chile and binational basins shared with Argentina for six standardized depths following the specifications of the GlobalSoilMap project. We generated soil maps based on digital soil mapping techniques based on more than 4000 observations, including unpublished data from remote areas. These maps were used as input for the pedotransfer function Rosetta V3 to obtain predictions of soil hydraulic properties, such as field capacity, permanent wilting point, total available water capacity, and other parameters of the water retention curve. The trained models outperformed several other DSM studies applied at the national and regional scale for soil physical properties (nRMSE ranging from 6.93% to 15.7%) and delivered acceptable predictions (nRMSE ranging from 10.4% to 15.6%) for soil hydraulic properties, making them suitable for countless environmental studies.
|
|
|
|
Perez-Quezada, J. F., Lopatin, J., Donoso, M. R., Hurtado, C., Reyes, I., Seguel, O., et al. (2023). Indicators of ecosystem degradation along an elevational gradient in the Mediterranean Andes. Ecol. Indic., 153, 110388.
Abstract: Successful restoration measures need a good understanding of how the composition, structure, and functioning of ecosystems change with degradation and what the best indicators of these changes are. To answer these questions, we worked on four ecosystem types in the Mediterranean Andes mountains in central Chile (from sclerophyllous forest to Andean shrublands), which represent an elevational gradient from 700 to 3,250 m. We sampled three plots on each of the three degradation levels (low, medium, and high) for each ecosystem at increasing distances from goat corrals. We measured 35 indicators that describe vegetation (14), soil (15), and ecosystem processes (6) for one growing season. Degradation caused a decrease in shrub cover, shrub productivity, the Normalized Community Structure Integrity Index (CSIIn), litter depth, total soil nitrogen and C/N ratio, and an increase in clay content. Plant species indicating low degradation were consistently native woody species. When comparing ecosystems (i.e., at different elevations) against the type of variable, process-based indicators showed more statistically significant differences. Based on their consistency across ecosystems and ease of measurement, we recommend using shrub cover and litter depth as indicators of degradation. Finally, we concluded that ecosystems are highly degraded when vegetation- and process-based indicators change – 60% or when soil indicators change – 25%. These results could also be used to set goals for restoration projects in these mountain ecosystems.
|
|
|
|
Salazar, O., Casanova, M., Fuentes, J. P., Galleguillos, M., Najera, F., Perez-Quezada, J., et al. (2022). Soil research, management, and policy priorities in Chile. Geoderma Reg., 29, e00502.
Abstract: Soils of Chile
Given the diversity of soil types in Chile, soil scientists face complex challenges to prioritize across different regions. Chile is located at the southwestern extreme of South America and is characterized by its well-marked latitudinal climate segmentation along 4300 km from 18◦ S to 56◦ S, spanning diverse transversal geomorphologic units across a narrow 180-km wide landscape from the Andes mountains, Andean foothills, Central Valley, and Coastal Range to the coastal plains. Chilean soils formed in geographic isolation flanked by the Pacific Ocean, Atacama Desert and the Andes mountains (Casanova et al., 2013). From the extreme hyperarid north to central Mediterranean Chile, Aridisols and Entisols dominate, with Histosols in only a few areas of the northern Altiplano highlands. Residual and colluvial soils coexist with soils derived from volcanic ashes, which in the temperate and rainy southcentral Chile allow Andisols to develop. Alluvial, glacial and fluvioglacial soils occur primarily along the Central Valley and southern Patagonia plains. The southern volcanic zones of the Andes influence
central-southern Chile, which is dominated from 35◦ S to 49◦ S by soils
derived from volcanic ashes, mainly Andisols and Ultisols, where about 70% of agricultural activities are carried out. All remaining Soil Taxonomy Orders are also found, except Oxisols. Quantitative and qualitative anthropogenic soil degradation due to land use change and agricultural management has been an old and serious problem in Chile as far back as the mid-eighteenth century, with adverse impacts on agricultural productivity, rural livelihoods, biodiversity, and on food
security in some places. Numerous connections to local and global environmental problems such as climate change and ongoing drought call for action-oriented science to inform management and decision making. We identified five soil priorities of particular importance in Chile.
|
|
|
|
Smith-Ramirez, C., Grez, A., Galleguillos, M., Cerda, C., Ocampo-Melgar, A., Miranda, M. D., et al. (2023). Ecosystem services of Chilean sclerophyllous forests and shrublands on the verge of collapse: A review. J. Arid Environ., 211, 104927.
Abstract: Dryland forests are the areas most threatened by climate change, urbanization and land-use change simulta-neously. Ecosystem services provided by Mediterranean dryland forests are have been in steep decline, and are extensively studied in the Mediterranean basin, however considerably less in other areas with Mediterranean climates. Knowledge of these services is necessary for the promotion of their conservation and restoration. Here, we synthesize current knowledge regarding the main ecosystem services provided by Chilean Mediterranean sclerophyllous forests and shrublands (SFSh). This knowledge allows for the valuation of SFSh in order to conserve, restore and study them. We found 158 studies, including technical reports, theses, and scientific literature regarding the social and environmental benefits derived from Chilean SFSh, though many did not use the term “ecosystem services” (ES). We found data on 19 ecosystem services with four or more studies per service. ES studies in Chile increased in number a couple years after Millennium Ecosystem Assessment published its synthesis in 2005. The most frequently reported services were provisioning services, especially medicinal plants and extracts. Despite the advances in knowledge, ecosystem services of SFSh appear to be rarely quan-tified, most frequently using oversimplified variable indicators. Services related to animal biodiversity, such as
|
|
|
|
Urbina, C. A. F., Alanís, D. C., Ramírez, E., Seguel, O., Fustos, I. J., Donoso, P. D., et al. (2023). Estimating soil water content in a thorny forest ecosystem by time-lapse electrical resistivity tomography (ERT) and HYDRUS 2D/3D simulations. Hydrol. Process., 37(10), e15002.
Abstract: Determination of soil volumetric water content theta in forest ecosystems is particularly challenging due to deep rooting systems and unknown soil vertical and spatial heterogeneity. This research aims to test two undisturbed methods, electrical resistivity tomography (ERT) and HYDRUS 2D/3D, for 2D theta determination in a thorny forest ecosystem. The experiment consisted of infiltrating 10 L of water lasting 60 min. During infiltration, ERT measured apparent resistivity by time-lapse measurements, and theta was measured with an FDR probe (EnviroSCAN) at 33, 63, 83, 97, and 163 cm depth close to the infiltration site. At the end of infiltration, a soil pit was dug, and 100 measurements of theta were performed with a TDR in a 10 x 10 cm regular grid. Archie law transformed soil resistivity (ERT) into theta using manual calibration, verified by an independent dataset. The 2D theta profile obtained by ERT was qualitatively compared with the HYDRUS 2D/3D one. HYDRUS 2D/3D was parametrized with calibrated parameters obtained with HYDRUS 1D using 106 days of theta obtained with EnviroSCAN. The results of HYDRUS 1D calibration and verification were satisfactory, with RMSE and Nash-Sutcliffe coefficients ranging from 0.021 to 0.034 cm(3 )cm(-3) and 0.11 to 0.77, respectively. The forward HYDRUS 2D/3D theta simulation disagrees with EnviroSCAN data for 33 cm depth. However, it follows the trend with near to zero variation of water content at 63 cm depth. Water content determination by ERT was satisfactory with RMSE for calibration and verification of 0.017 and 0.021 cm(3) cm(-3). HYDRUS 2D/3D and ERT comparisons were not equal, with a shallower wetting front by ERT and a deeper one for HYDRUS. Still, both wetting fronts agree with the wetting depth estimated by EnviroSCAN. We conclude that both methods are an alternative for theta determination in heterogeneous and deep soils of forest ecosystems.
|
|
