Mangroves play a crucial role in mitigating climate change through carbon (C) accumulation. Developing robust methods for the estimation of long-term C accumulation is essential for monitoring and ...reporting carbon financing projects under different global mechanisms. Moreover, understanding the effects of climate and habitat on C accumulation is important for developing mangrove management plans and conservation options. In this study, long-term above ground C accumulation in the three most dominated mangrove tree species, Heritiera fomes, Excoecaria agallocha and Sonneratia apetala, was estimated using a dendrochronological approach in two contrasting (low vs high) salinity zones in the Bangladesh Sundarbans. In addition, how climate and habitat (e.g., regulators and soil resources) influence C accumulation was analyzed. For the first time, we estimated C accumulation in mangrove species over their entire lifetime using stem disc-derived tree-ring data. The C accumulation patterns exhibited similar patterns of variation, increasing from pith to bark in each case. C accumulation was significantly higher in the low salinity zone (LSZ) than in the high salinity zone (HSZ) (p < 0.05). The cumulative C accumulation increased with tree age in each case, and C accumulation was influenced mainly by seasonal precipitation, especially during monsoon. General additive modeling (GAM) revealed that soil salinity had a stronger effect on C accumulation variability in the studied tree species. Other regulatory variables (i.e., siltation and elevation) and soil resources (i.e., P and K) had species-specific influences on C accumulation. Tree-ring data show the potential to yield better biomass and C estimations, which could aid frequent and rapid reporting of C accumulation in mangroves. Moreover, the results also suggest that climate and regulatory variables, especially soil salinity, together impact the C cycles in the Sundarbans.
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•Long-term C accumulation series are reconstructed using tree-ring data.•C accumulation is mainly enhanced by monsoonal precipitation.•Soil salinity has a stronger influence on C accumulation than soil nutrients.•Mangrove tree rings show the potential for rapid estimation of periodic C accumulation.
Predicting long‐term trends in forest growth requires accurate characterisation of how the relationship between forest productivity and climatic stress varies across climatic regimes. Using a network ...of over two million tree‐ring observations spanning North America and a space‐for‐time substitution methodology, we forecast climate impacts on future forest growth. We explored differing scenarios of increased water‐use efficiency (WUE) due to CO2‐fertilisation, which we simulated as increased effective precipitation. In our forecasts: (1) climate change negatively impacted forest growth rates in the interior west and positively impacted forest growth along the western, southeastern and northeastern coasts; (2) shifting climate sensitivities offset positive effects of warming on high‐latitude forests, leaving no evidence for continued ‘boreal greening’; and (3) it took a 72% WUE enhancement to compensate for continentally averaged growth declines under RCP 8.5. Our results highlight the importance of locally adapted forest management strategies to handle regional differences in growth responses to climate change.
This is a datapaper including microscopically measured data of annual ring widths from the Mediterranean-alpine shrub species Cytisus galianoi (Sierra Nevada, Spain). The dataset will be updated with ...future measurements.
Here, we present a datapaper containing microscopically measured data of annual ring widths in the arctic-alpine dwarf-shrub species Salix herbacea (central Norway). The dataset will be updated with ...future measurements.
The growing impacts of climate change and uncertainty about forest vulnerability to these changes make understanding forest response to drought increasingly important. Many of the studies ...investigating forest response to drought focus on inland forest types rather than coastal forests. This study examined tree growth and growth response to drought in coastal forests at restoration thinning sites, evaluating responses to local climate, tree-level competition, and site-level factors. Tree cores were extracted at three restoration sites in Redwood National Park, California, from both thinned and unthinned stands. Douglas-fir (Pseudotsuga menziesii) and coast redwood (Sequoia sempervirens) trees > 20 cm diameter at breast height were sampled (n = 268). Thinned stands had lower tree density, individual level competition index, and higher stand basal area than control stands. We modeled the influence of competition, size, site, and species identity on tree growth as measured by basal area increment (BAI). Prior to a period of drought, Douglas-fir had greater BAI relative to redwood, and competition was negatively associated with tree growth for both tree species. There was variability among sites, with the stand closest to the coast and with the most recent thinning treatment showing the fastest growing trees. Relative to the pre-drought period (2010–2012), average BAI declined slightly during the drought period (2013–2015) for Douglas-fir and coast redwood; however, we found less evidence for this effect in coast redwood. Notably, the relationships between growth and competition did not change during the drought period for either species. These results suggest that reducing competition via restoration thinning treatment improves tree growth, and this advantage is maintained even during short (3-year) periods of drought.
•Tree growth decreased with competition and increased with tree size.•Trees in secondary stands showed decreases in growth during recent drought.•Drought did not appear to change the relationship between tree competition and growth.
Annual and sub-annual tree-ring 14C measurements allow the study of past natural phenomena such as rapid 14C increases and solar behavior. In addition, they provide precise calibration data sets that ...help in improving the dating accuracy of past natural and cultural events. However, for the data to be comparable, it is important that laboratories describe the whole process from sample retrieval to eventual results. In this paper, we describe the full 14C measurement procedure adopted in the Finnish tree-ring consortium, including sample collection and preparation, dendrochronology, chemical pretreatment, combustion and graphitization, Accelerator Mass Spectrometry (AMS) measurements and data processing. In addition, we report the 14C background components for our traditional Closed-Tube Combustion (CTC) and Elemental Analyzer (EA) based processes, both yielding to high-quality data. Furthermore, we study the mass-dependence effects of tree-ring measurements and find them to be practically insignificant for ages up to several millennia but growing in significance when approaching the 14C limit.
Though tree-ring chronologies are annually resolved, their dating has never been independently validated at the global scale. Moreover, it is unknown if atmospheric radiocarbon enrichment events of ...cosmogenic origin leave spatiotemporally consistent fingerprints. Here we measure the
C content in 484 individual tree rings formed in the periods 770-780 and 990-1000 CE. Distinct
C excursions starting in the boreal summer of 774 and the boreal spring of 993 ensure the precise dating of 44 tree-ring records from five continents. We also identify a meridional decline of 11-year mean atmospheric radiocarbon concentrations across both hemispheres. Corroborated by historical eye-witness accounts of red auroras, our results suggest a global exposure to strong solar proton radiation. To improve understanding of the return frequency and intensity of past cosmic events, which is particularly important for assessing the potential threat of space weather on our society, further annually resolved
C measurements are needed.
The 2012–2016 California drought was the most severe in the state’s recorded history, contributing to the death of millions of trees. Through sampling 54 (0.25 ha) plots in northern California and ...employing standard dendrochronological techniques this study compared tree mortality and regeneration patterns before, during, and after California’s recent record-setting drought in both montane and costal environments. This study evaluated 1) the influence of habitat and competitive covariates on mortality and regeneration trends using ridge regression analysis; and 2) tree death and seedling/sapling establishment dates using dendrochronology and Superposed Epoch Analysis to explore the influence of climate on forest demographics. Results showed two trends related to climatic patterns in montane environments: (1) years with high rates of mortality were positively associated with climatic water deficit (CWD) in the 1–2 years preceding and during tree death dates; and (2) regeneration dates were significantly associated with below-average CWD in the preceding year. In montane sites, pre-drought mortality was greater at wet sites than dry sites, and drought-related mortality was positively related to canopy openness. In coastal environments, drought-related tree mortality was positively associated with maximum temperature and topographic position (e.g., greater on upper slope sites). Drought-related tree mortality occurred primarily in trees smaller than 40 cm diameter at breast height (DBH, 1.37 m) in montane forests, and exclusively in trees 80 cm DBH or smaller in coastal environments. Our findings also indicate that current demographic trends will likely reduce forest diversity in the future, especially in montane environments. For example, in montane environments mortality was greater in white pine species (Pinus lambertiana and P. monticola) than other species and regeneration was weighted towards advanced regeneration of shade-tolerant fir (Abies) species (median age of 34 years). These findings highlight the effects of fire exclusion, and the need for targeted management, including reducing tree density and returning fire process, aimed at decreasing drought related mortality, and increasing regeneration of shade-intolerant species (e.g., pines). Management should also preferentially retain medium to large trees, which demonstrated less vulnerability to mortality, to enhance the resilience and diversity of northern California forests.
•Montane tree mortality was associated with high climatic water deficit (CWD).•Montane tree regeneration was associated with low CWD in the preceding year.•Drought-related mortality was more frequent in small trees than large trees.•Mortality was highest in Pinus; regeneration was dominated by shade-tolerant taxa.
•Climate warming has led to faster growth of forest at high elevations than at low elevations.•Climate warming plays a prominent role in the elevation-dependent growth pattern of alpine ...conifers.•Climate warming can be beneficial for most coniferous tree species to enhance radial growth.
Stress from water scarcity as a result of rising temperatures associated with climate change has a profound impact on forest ecosystems around the world. However, few studies have assessed the influence of climate change on the dynamics of growth of alpine coniferous forests of different tree species and at different elevations on a regional scale in southeastern Tibetan Plateau (TP). The present paper examines that the impact using dendrochronological techniques with trees of the following genera: Abies, Picea, Larix, Tsuga, Pinus, Cupressus, and Juniperus. Radial growth was measured based on 46 chronologies from the cores of 2027 trees on the Hengduan Mountains (one of the Global Biodiversity Hotpots), which are part of the TP. In most cases, ring widths were strongly and significantly correlated to temperature both before and during the growing season, suggesting that climate warming plays a prominent role in the growth of alpine conifers in recent decades. Greater sensitivity to temperature and the rising temperatures have together led to faster growth of forest trees at high elevations than at low elevations. Climate warming may benefit most coniferous species by boosting their radial growth, especially in the upper treeline ecotone, but may also decrease radial growth significantly in P. yunnanensis at lower elevations because the species, unlike the other species studied, is adversely affected by high temperatures. If elevation-dependent warming in the Hengduan Mountains continues in the future, conifers at high and middle elevations (3000 m or higher) will benefit, whereas those at lower elevations (below 3000 m) will be affected adversely because of the warming-induced water deficit.
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