Terrestrially Derived<i>n</i>-Alkane δD Evidence of Shifting Holocene Paleohydrology in Highland Costa Rica

Lane, Chad S.; Horn, Sally P.

doi:10.1657/1938-4246-45.3.342

Cited by 15 publications

(12 citation statements)

References 37 publications

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“…Increased burning during the late-Holocene is interpreted to reflect drier conditions as compared with the middle-Holocene, when charcoal is sparse in lake sediments. This interpretation is in keeping with evidence of vegetation changes at the bog sites (Islebe et al, 1996) and with carbon and hydrogen isotope records from Morrenas Lake 1 (Lane and Horn, 2013; Lane et al, 2011a). In the sediments of Lago Chirripó, two distinct layers of macroscopic charcoal suggest intervals of lower lake level at about 1100 and 2500 cal.…”

Section: Introductionsupporting

confidence: 85%

A chironomid-based reconstruction of late-Holocene climate and environmental change for southern Pacific Costa Rica

Porinchu

Horn

2016

The Holocene

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A lake sediment profile spanning the last ~3200 years from Laguna Zoncho in the southern Pacific region of Costa Rica was analyzed for sub-fossil chironomids. Notable shifts in chironomid assemblages occurred during the late-Holocene. A distinct chironomid community, dominated by Tanypodinae such as Procladius and Labrundinia, appeared after ~550 cal. yr BP (~1400 CE). Prior to this time, the chironomid assemblage was more diverse, with taxa such as Paratanytarsus, Tanytarsus type N, and Cladotanytarsus important constituents of the chironomid community. A chironomid-based inference model for mean annual air temperature (MAAT), developed using partial least squares (PLS 2-component), was applied to sub-fossil chironomid assemblages from Laguna Zoncho to reconstruct late-Holocene thermal variability for the region. The key findings from this study are as follows: (1) chironomid-inferred MAAT at ~2740–1220 cal. yr BP (790 BCE–730 CE) was 1.2°C higher than the late-Holocene (~3200 cal. yr BP to present in this study) average of 21.3°C; (2) MAAT at ~470–90 cal. yr BP (1480–1860 CE) was 1.3°C lower than the late-Holocene average, potentially reflecting ‘Little Ice Age’ (LIA) cooling; and (3) evidence for an extended period of low lake levels between 1220 and 840 cal. yr BP (730–1110 CE) possibly indicated the influence of the Terminal Classic Drought (TCD) in southern Costa Rica. This study pioneers the use of sub-fossil chironomid remains to develop quantitative estimates of Holocene thermal variability and environmental change in Central America.

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Section: Introductionsupporting

confidence: 85%

A chironomid-based reconstruction of late-Holocene climate and environmental change for southern Pacific Costa Rica

Porinchu

Horn

2016

The Holocene

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“…), perhaps in relation to the ITCZ (Lane et al . ; Lane & Horn ). To be sure, the drivers of mean TWI elevation over the Holocene were likely complex.…”

Section: Discussionmentioning

confidence: 99%

Tropical montane vegetation dynamics near the upper cloud belt strongly associated with a shifting ITCZ and fire

2015

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Summary1. Tropical montane forests house unusual and diverse biota and are considered highly vulnerable to climate change, particularly near the trade wind inversion (TWI) -the upper end of the cloud belt that defines tropical montane cloud forest (TMCF). The upper cloud belt has two possible futures: one hypothesis postulates a 'lifting cloud base', raising both the upper and lower ends of the cloud belt; the other expects the upper end of the cloud belt will change independently, with a 'shifting TWI'. 2. We used a~5900-year-long palaeorecord of vegetation and fire from a small forest hollow at 2455 m in the Cordillera Central, Dominican Republic. The site sits near the upper limit of TMCF taxa and the TWI and allows us to evaluate the relationship between vegetation dynamics and two potential drivers of TWI elevation -the Intertropical Convergence Zone (ITCZ) and the El Niño/ Southern Oscillation (ENSO). 3. Vegetation changed from cloud forest (~5900-5500 cal. years BP) to alpine grassland (~4300-1300 cal. years BP), to pine savanna (~1300-600 cal. years BP) and finally to closed pine forest (after~600 cal. years BP). Habitat distribution models for TMCF and pine forest taxa show that these state changes were strongly associated with position of the ITCZ (cloud forest xR 2 = 0.63; pine forest xR 2 = 0.53), providing support for the shifting TWI hypothesis.4. We find a negative relationship between fire and TMCF and a hump-shaped relationship between fire activity and pine. 5. Synthesis. Shifts up-and downslope of the upper limit of the cloud belt over the last 5900 years produced major vegetation changes. Fire also played a significant role, in particular when pine occupied the site after~1300 years ago and from 1965 AD when fire suppression led to a rapid return of cloud forest taxa. Our results strongly suggest that latitudinal shifts in the ITCZ position have controlled the upper limit of cloud forest in the Caribbean and understanding how the ITCZ will respond to climate change will be critical for tropical montane conservation strategies.

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“…Past glaciation landform investigations in the Central American land bridge, which encompasses the study area, have focused on the collection of glacial geomorphology and sedimentary lacustrine data (e.g., past glacial extent, glacial altitude estimations, and stable carbon and hydrogen isotope analyses) to identify past long‐term climate variations (Lachniet & Vazquez‐Selem, ; Lane, Horn, Mora, Orvis, & Finkelstein, ; Lane & Horn, ; Orvis & Horn, ). However, research in Costa Rican glacial lakes so far has been restricted to basic morphometric and limnologic surveys (Göcke, Lahmann, Rojas, & Romero, ; Haberyan, Horn, & Umaña, ; Horn, Orvis, & Haberyan, ; Jones, Lohman, & Umaña, ; Löffler, ), with very little attention given to the lakes water balance, storage, and supply.…”

Section: Introductionmentioning

confidence: 99%

Insight into the stable isotopic composition of glacial lakes in a tropical alpine ecosystem: Chirripó, Costa Rica

Esquivel‐Hernández

Sánchez‐Murillo

Quesada‐Román

et al. 2018

Hydrological Processes

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Tropical high-elevation lakes are considered sentinels of global climate change. This work characterizes the hydrological conditions of tropical alpine glacial lakes located in the highlands of Chirripó, Costa Rica, using a unique data set of water stable isotopes (δ 2 H and δ 18 O) in precipitation, stream water, and lake water between September 2015 and July 2017. A combined dataset of bathymetric, hydrometric, and isotope data collected between July 2016 and July 2017 on Lake Ditkevi was used to calculate the annual water balance of the lake. Evaporation to inflow ratios from three lake systems was estimated using a linear resistance model, the experimentally estimated local evaporation line of Chirripó, and the first glacial lake water evaporation lines in the region. The temporal isotopic variations (δ 18 O, d-excess, and lcexcess) confirm variations in the dry and wet season evaporative conditions for the glacial lakes and consistently average annual low evaporation to inflow (E/I) ratios in the range of 2.0 ± 0.8% and 18.1 ± 12.2%. Lake Ditkevi's water balance indicates annual steady-state conditions, with an estimated evaporation loss of 650 mm/year (10.0 ± 5.0% of inflow), a high-water contribution to the catchment (90% of inflow), a residence time of 0.53 ± 0.27 years, and a catchment scale (0.289 km 2 ) water yield or depth equivalent run-off of 278 mm/yr. These results provide novel information about water balance and evaporation losses in tropical alpine glacial lakes, which can serve as baseline information for future isotope-based hydro-climate research in high-elevation regions in the tropics and elsewhere. KEYWORDSChirripó, evaporation to inflow ratios, glacial lakes water balance, isotope mass balance, Páramo, water stable isotopes

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Terrestrially Derivedn-Alkane δD Evidence of Shifting Holocene Paleohydrology in Highland Costa Rica

Cited by 15 publications

References 37 publications

A chironomid-based reconstruction of late-Holocene climate and environmental change for southern Pacific Costa Rica

A chironomid-based reconstruction of late-Holocene climate and environmental change for southern Pacific Costa Rica

Tropical montane vegetation dynamics near the upper cloud belt strongly associated with a shifting ITCZ and fire

Insight into the stable isotopic composition of glacial lakes in a tropical alpine ecosystem: Chirripó, Costa Rica

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