Proxy For Productivity Research Articles

Evaluating tree-ring proxies for representing the ecosystem productivity in India.

Terrestrial ecosystems are one of the major sinks of atmospheric CO2 and play a key role in climate change mitigation. Forest ecosystems offset nearly 25% of the global annual CO2 emissions, and a large part of this is stored in the aboveground woody biomass. Several studies have focused on understanding the carbon sequestration processes in forest ecosystems and their response to climate change using the eddy covariance (EC) technique and remotely sensed vegetation indices. However, very few of them address the linkage of tree-ring growth with the ecosystem-atmosphere carbon exchange, and nearly none have tested this linkage over a long-term (> 100 years) - limited by the short-term (< 50 years) availability of measured ecosystem carbon flux. Nevertheless, tree-ring indices can potentially act as proxies for ecosystem productivity. We utilise the Coupled Climate Carbon Cycle Model Intercomparison Project (C4MIP) model outputs for its 140-year-long simulated records of mean monthly gross primary productivity (GPP) and compare them with the tree-ring growth indices over the northwestern Himalayan region in India. In this study, we examine three coniferous tree species: Pinus roxburghii and Picea smithiana wall. Boiss and Cedrus deodara and find that the strength of the correlation between GPP and tree ring growth indices (RWI) varies among the species.

H2 Production in Subduction Zone

Convergence zones where ophiolites outcrops, such as Oman and New Caledonia, allow the generation of natural H2 by redox phenomena. Nevertheless, the role of hydration of the mantle wedge between the overriding plate and the slab is often evoked to explain the H2 emanations. In the case of active subduction, such as that of the Nazca plate beneath the Andes, the presence of H2 emanation has been noted. In this study, we modelled the processes of (de)hydration and melting within the subduction zone. The quantification of water involved in mantle wedge hydration served as a proxy for H2 production. Multiple simulations have been conducted to investigate oceanic-continental subduction, wherein various parameters, especially the subduction angle, have been varied. It appears that in the case of flat subduction, the mantle hydration zone is large, extending up to 500 km from the trench. The extend is controlled by the velocity of the overriding plate. In the case of a steep subduction, the zone is narrower, and is located between the trench and the volcanic arc. Magma formation competes with H2 generation for the use of water expelled from the subducting plate. In the transition from a steep to a flat slab, the mantle hydration zone widens and the volcanic zone moves away from the trench. The oceanic crust may undergo melting, leading to a change in magma composition, before volcanism diminishes in intensity and then disappears.

Firm heterogeneity and export behavior: evidence from Tunisia

ABSTRACT We use unique enterprise survey data to explore the export behavior of firms in Tunisia, a small, trade-dependent country with a complex policy environment regarding exporting. Firms may export directly or indirectly through intermediaries, and can also sell to ‘offshore’ firms, which are export manufacturing firms with special legal status. Firm size, a proxy for productivity, is strongly associated with exporting of either type as well as with sales to offshore firms. In contrast to some studies, exporting is not positively associated with firm age (i.e., experience). Domestic-owned firms are more likely to use intermediaries to export while foreign-owned firms as well as those with more educated managers are more likely to export directly. Multinomial logit results reject the hypothesis of progression from indirect exports through direct plus indirect exporting and then to direct-only exporting as firm size increases; instead, the largest exporting firms are more likely to combine direct and indirect exporting, possibly to reduce risk. The findings from this study – the first to examine the heterogeneity of exporting behavior in Tunisia – reveal a complex picture of such behavior and confirm the importance of trade intermediaries for less sophisticated firms (those with lower manager education and internet access), pointing to potential measures to encourage exporting among such enterprises. The findings also suggest that efforts to encourage exporting may also improve firms’ ability to sell to ‘offshore’ firms, enhancing the so far elusive linkages of that sector with the rest of the economy.

Wintertime productivity and carbon export potential across the Agulhas Current system

The Agulhas Current plays a major role in heat and salt exchange between the Indian and Atlantic Oceans, yet little is known of its influence on ocean fertility. To investigate carbon production and export potential in the Agulhas Current system, we measured net primary production (NPP), nitrate and ammonium uptake, N2 fixation, and nitrification along a transect of the current and adjacent subtropical subgyre (33.4°S–35.7°S) in winter when nutrient supply, and thus productivity, should be highest. Phytoplankton biomass was lowest in the current core, increasing into the subgyre as surface nitrate declined, and was dominated by nanoplankton (2.7–10 μm; 62 ± 5.1% of total biomass). NPP and nitrate uptake were generally high across the transect and increased from the current core into the subgyre; the rates were dominated by picoplankton (<2.7 μm; 53–93%) in the current core and nanoplankton elsewhere (63–69%). On average, euphotic zone nitrification supplied 7.6 ± 6.4% of the nitrate consumed by phytoplankton and N2 fixation was also low (2.1 ± 1.3% of new production); we thus consider nitrate uptake a reasonable proxy for new production, at least in winter. Nitrate uptake was highest at the southern edge of the current core, consistent with current-associated (sub)mesoscale mixing enhancing the upward nutrient supply. The fraction of NPP available for export (i.e., the f-ratio) was high across the transect, ranging from 0.44 to 0.69. Our data thus indicate that both total and new production are elevated across the Agulhas Current system in winter and suggest that the (sub)mesoscale dynamics associated with the current system may enhance carbon production and export in the otherwise oligotrophic southwest Indian Ocean.

Productivity experienced a more rapid enhancement trend than greenness across the Tibetan Plateau

Satellite-derived products and field measurements verify that Tibetan Plateau (TP) has been experiencing continuous vegetation greening and productivity increase; however, it remains unclear how this greening translates into productivity and how long-term productivity variations depend on greenness across the TP. Moreover, ignoring the accuracy evaluation of satellite-derived greenness and productivity products may mislead the understanding of TP vegetation changes. Thus, we initially assessed the accuracy of three widely used leaf area index (LAI, proxy of greenness) products (i.e., MODIS, GLASS and GEOV2 LAI) and three gross primary productivity (GPP, proxy of productivity) products (i.e., MODIS, GLASS and PML-V2 GPP) to selected robust products to represent greenness and productivity respectively. Then, we explored the dependence of spatiotemporal GPP dynamics on greenness variations during 2000–2020. Results indicated that PML-V2 GPP and MODIS LAI were more robust and reliable than other satellite-derived products when compared to the reference values. They revealed a prevailing increase in GPP over the past two decades, with a regional average of 71 % higher than that of LAI. Notably, the area proportion of significant productivity enhancement was 31.6 % higher than that of significant greening. About 24.7 % of the TP displayed significantly inconsistent trends. The dependency of GPP on LAI gradually decreased with the increasing water availability, the complexity of vegetation structures, and dense canopy community. By calculating leaf photosynthetic capacity, we found that this indicator greatly regulated the velocity discrepancy between GPP and LAI, and the contribution of only greening to productivity is limited, only occupying 11.9 % of the TP, which was helpful in understanding the inter-annual changes of vegetation dynamics under varying environment conditions. We therefore reveal an unexpected rapid increase in productivity than greening during 2000–2020 on the TP, as well as highlight the caution of only using satellite-derived greenness indicators for assessing long-term changes in vegetation productivity dynamics, especially over mesic ecosystems with complex vegetation structures and dense canopies of TP.

Defining algal bloom phenology in Lake Erie

Elucidating the impact of global climate change on aquatic ecosystems, particularly through phenological shifts in primary producers, is critical for understanding ecological resilience. Here, we focus on the phenological shifts in chlorophyll as a proxy for algae biomass and primary production in aquatic ecosystems, specifically in Lake Erie as well as concentrations of the toxin microcystin. By tracking temporal changes in each, we identified key phenological phases important to estimate duration, magnitude, and intensity of harmful algal blooms (HABs). Determining which influential biotic and abiotic factors such as temperature, wind speed, nutrient availability, and climate change is most important, is a long-term management need for Lake Erie, which can be explored using our methodology. Our novel statistical framework employing Bayesian generalized additive mixed models described seasonal chlorophyll and particulate microcystin concentration from Lake Erie and our simple geometric method identified the start, peak, and end of algal blooms. This research enhances our understanding of the ecological effects of nutrient pollution on aquatic ecosystems and provides a repeatable method for determining phenological events without the need for user defined cutoffs which aids in the management and mitigation of HABs, safeguarding water quality in regions dependent on lakes for drinking water.

Sulfur isotopic fractionation during hydrolysis of carbonyl sulfide

Carbonyl Sulfide (OCS) is the most abundant sulfur-containing gas in the atmosphere, and it is used as a proxy for terrestrial gross primary productivity (GPP). Oceans are the major source of OCS to the atmosphere, produced by photochemical and “dark” reactions. Hydrolysis to H2S and CO2 is the major removal process of OCS from the ocean's surface. Measuring the sulfur isotope values (δ34S) and the isotopic fractionation (ε) associated with these major OCS sources and sinks could decrease the uncertainties in its fluxes. In the current study, we aim to determine the ε during the hydrolysis process of OCS (εh). We used a purge and trap system coupled to a GC/MC-ICPMS to measure δ34S values during hydrolysis under different temperatures (4–40 °C), salinities (0.2–40 g/L), and pH (4–9), representing various natural environmental conditions. In addition, we use the quantum chemical method to calculate the equilibrium εh and compare it to the empirical results. Our results for the low salinity (S =0.2 g/L; pH 8.0) water show a temperature dependency of the εh from −3.9 ‰ ± 0.2 ‰ (4 °C,) to −2.2 ± 0.6 ‰ (40 °C). The higher fractionation at low temperatures has implication for ice-core data interpretation. However, in natural seawater at 4°C and 22 °C (S = 40 g/L, pH 8.2) there was no such temperature dependency and the εh averaged −2.6 ± 0.3 ‰. Thus, it seems that salinity cancels the temperature effect close to the freezing temperature of water. Varying the pH between 4 and 9 (at 22 °C) did not result in any εh trend. Ab-initio calculations suggest that OCS hydrolysis is not controlled by equilibrium. The εh values we report will aid in quantifying the impact of OCS's hydrolysis on the observable sulfur isotopic signature of OCS in oceanic and in freshwater environments. This in turn will facilitate more accurate mass-balance calculations for the OCS budget from the ocean to the atmosphere.

Silica spherules in Late Pleistocene‑Holocene glaciomarine sediments from the Ross Sea, Antarctica: insights into the formation and significance

In this study, we investigate silica spherules with a diameter &lt;1.25 mm from sediment cores retrieved from the northern Drygalski Trough, during the Italian Antarctic Research Programme (PNRA) expeditions in 1999 and 2002. In the past, these unique spherules have been a subject of interest due to their distinctive characteristics. Despite previous hypotheses on their origin, a comprehensive discussion on their formation mechanism and implications in marine sediments was lacking. Our analysis encompasses the depositional environment, morphology, internal texture, major element composition, and age determination through radiocarbon dating (14C) and 40Ar‑39Ar dating of spherule-containing sediments. By integrating our findings with a critical review of existing literature, we propose that spherules form by cyclical chemical precipitation of silica when silica‑rich freshwater mixed with seawater during extensive events of ice melting. We also tentatively suggest that these spherules possibly represent a proxy for significant meltwater production and discharge into the Antarctic Ocean. This research contributes to a better understanding of silica spherules in polar marine environments and their implications for past climate conditions.

Resource selection at fine scale: what drives the decision of a generalist herbivore?

Abstract Spatial patterns in topography and forage distribution significantly influence the movements and choices of large herbivores. However, understanding the foraging strategies of free-grazing herbivores at different temporal and spatial scales remains limited, as different behavioral decisions can apply at different hierarchical levels. This study investigates the fine-scale foraging strategies of the Plains Zebra (Equus quagga) in a South African savanna, with a specific focus on their selection of green vegetation at the plant and feeding patch levels. We used the Normalized Difference Vegetation Index as a proxy for vegetation productivity and quality. Our findings reveal that zebras adapted their foraging strategies according to scale and season. During the late-dry season and early-wet season, selection for greenness was at both the grass tuft and feeding site levels. In contrast, during the mid-dry season, selection was predominantly at the tuft level, focusing solely on greenness. These insights emphasize the importance of conducting multilevel studies when investigating factors influencing foraging decisions. Findings at 1 hierarchical level may not necessarily apply across other levels of investigation, highlighting the need for a nuanced and comprehensive approach to understanding the complex foraging behaviors of animals.

Arctic Alaska deepwater organic carbon burial and environmental changes during the late Albian–early Campanian (103–82 Ma)

The middle Cretaceous greenhouse period experienced profound environmental change including episodes of enhanced global burial of organic carbon marked by carbon isotopic excursions (CIEs). However, the role and response of polar regions like the newly formed, partially enclosed Arctic Ocean Basin during middle Cretaceous carbon burial remains enigmatic. We present the first Arctic deepwater CIE record that characterizes conditions offshore of the Alaska margin north of 75°N paleolatitude. Organic carbon isotopes (δ13Corg) and 103–82 Ma ash zircon U-Pb dates from the distal Hue Shale record multiple Albian–Campanian CIEs during slow ∼3–15 m/Myr sediment accumulation rates. Average total organic carbon (TOC) increased substantially during large 2–3 ‰ CIEs of the ∼101 Ma Albian-Cenomanian boundary event (from 7 to 18 % TOC) and ∼94 Ma Cenomanian-Turonian boundary event (5 to 10 % TOC). Turonian TOC remained elevated (8–13 %) during high global sea levels and temperatures of the Cretaceous Thermal Maximum, followed by an increase from 7 to 11 % TOC during the ∼90 Ma late Turonian event 1.5 ‰ CIE. Average TOC subsequently decreased in the Coniacian–Campanian, but relative maxima occurred during subtle 0.5–1 ‰ CIEs interpreted as the ∼87 Ma late Coniacian event (increase from 4 to 7 % TOC), ∼85 Ma Horseshoe Bay event (3.5 to 4.5 % TOC), and ∼84 Ma Santonian-Campanian boundary event (3.5 to 5 % TOC). Increases in hydrogen index and productivity proxies (P, Ba, Nd) that accompanied each CIE episode with enhanced TOC suggest a strong link between marine productivity and organic carbon burial at short-term CIE timescales. However, long-term (>5–8 Myr) changes in trace metal redox (Mo, Fe, V) and salinity (B/Ga) proxies suggest shifts in prevailing environmental conditions at timescales longer than the CIEs. Late Albian–middle Turonian marine salinity occurred during euxinic (103–98 Ma) and suboxic (98–90 Ma) conditions with deposition interpreted to have occurred within and beneath an oxygen minimum zone, respectively. In contrast, late Turonian–early Campanian (90–82 Ma) freshening and restricted euxinic basin conditions may signal the start of widespread restriction known to characterize the Paleogene Arctic. Overall, these results highlight that middle Cretaceous Arctic deepwater remained a productive marine carbon sink coupled to the global carbon cycle despite evolving Arctic greenhouse conditions.

Key benthic species are affected by predicted warming in winter but show resistance to ocean acidification.

The effects of climate change on coastal biodiversity are a major concern because altered community compositions may change associated rates of ecosystem functioning and services. Whilst responses of single species or taxa have been studied extensively, it remains challenging to estimate responses to climate change across different levels of biological organisation. Studies that consider the effects of moderate realistic near-future levels of ocean warming and acidification are needed to identify and quantify the gradual responses of species to change. Also, studies including different levels of biological complexity may reveal opportunities for amelioration or facilitation under changing environmental conditions. To test experimentally for independent and combined effects of predicted near-future warming and acidification on key benthic species, we manipulated three levels of temperature (winter ambient, +0.8 and +2°C) and two levels of pco 2 (ambient at 450 ppm and elevated at 645 ppm) and quantified their effects on mussels and algae growing separately and together (to also test for inter-specific interactions). Warming increased mussel clearance and mortality rates simultaneously, which meant that total biomass peaked at +0.8°C. Surprisingly, however, no effects of elevated pco 2 were identified on mussels or algae. Moreover, when kept together, mussels and algae had mutually positive effects on each other's performance (i.e. mussel survival and condition index, mussel and algal biomass and proxies for algal productivity including relative maximum electron transport rate [rETRmax], saturating light intensity [I k] and maximum quantum yield [F v/F m]), independent of warming and acidification. Our results show that even moderate warming affected the functioning of key benthic species, and we identified a level of resistance to predicted ocean acidification. Importantly, we show that the presence of a second functional group enhanced the functioning of both groups (mussels and algae), independent of changing environmental conditions, which highlights the ecological and potential economic benefits of conserving biodiversity in marine ecosystems.

Analysis of the latitudinal and longitudinal (coastal and pelagic zones) variability of coccolithophore assemblages in the water column of the Western Iberian Margin in late summer of 2022

This study investigates the abundance, composition, and biogeographical distribution of coccolithophores in the water column of the northwestern Iberian coastal upwelling system during late summer 2022. Coccolithophore data were compared with in situ measurements of physical, chemical, and biological parameters, as well as with satellite data and the upwelling index (UI) for the study area. Canonical Correspondence Analysis (CCA) was performed to determine the relationships between coccolithophore assemblages and environmental variables. The results reveal a latitudinal and longitudinal gradient in coccolithophore abundance, with higher concentrations towards the north and east, indicating a stronger influence of coastal upwelling near the coast (stations CA-7, CA-8, CA-4). Our data suggest that the source of upwelled water in the north (Eastern North Atlantic Central Waters of subpolar origin, ENACWsp) differs from that in the south (ENACWst, of subtropical origin). Significant correlations between UI and the total abundance of coccoliths and coccospheres underscore the role of upwelling in coccolithophore distribution. Additionally, correlations with fluorescence and turbidity indicate that coccolithophores contribute substantially to primary production in the region. Certain species are proposed as paleoenvironmental indicators due to their affinity for specific environmental conditions. The small Noëlaerhabdaceae group (small Gephyrocapsa group + Emiliania huxleyi) serves as a proxy for primary productivity and intense upwelling, while Florisphaera profunda is associated with upwelling relaxation and low productivity. Discrepancies with satellite data are attributed to their limitations in detecting subsurface biological processes. This study also supports the use of the N-ratio in water column samples, not just in sediments, and improves the understanding of primary productivity at the Western Iberian Margin during the upwelling season.

Increase in gross primary production of boreal forests balanced out by increase in ecosystem respiration

Changes in the net carbon sink of boreal forests constitute a major source of uncertainty in the future global carbon budget and, hence, climate change projections. The annual net ecosystem exchange of carbon dioxide (CO2) controlling the terrestrial carbon stock results from the small difference between respiratory CO2 release and the photosynthetic CO2 uptake by vegetation. The boreal forest, and the boreal biome in general, is regarded as a persistent and even increasing net carbon sink. However, decreases in photosynthetic CO2 uptake and/or concurrent increases in respiratory CO2 release under a changing climate may turn boreal forests from a net sink to a net source of CO2. Here, we assessed the interannual variability of the boreal forest net CO2 sink-source strength and its two component fluxes from 1981 to 2018. Our remote sensing approach - trained by net CO2 flux observations at eddy covariance sites across the circumpolar boreal forests - employs satellite-derived retrievals of snowmelt timing, landscape freeze-thaw status, and yearly maximum estimates of the normalized difference vegetation index as a proxy for peak vegetation productivity. Our results suggest that for the period 2000–2018, the mean annual evergreen boreal forest CO2 photosynthetic uptake (gross primary productivity) was 2.8±0.2 Pg C y−1 (1.6±0.1 Pg C y−1 for Eurasia and 1.2±0.1 Pg C y−1 for North America). In contrast to earlier studies results obtained here do not indicate a clear increasing trend in the circumpolar evergreen boreal forest CO2 sink. The increase in photosynthetic CO2 uptake is compensated by increasing respiratory releases with both component fluxes showing considerable interannual variabilities.

Ecosystem Resilience Trends and Its Influencing Factors in China’s Three-River Headwater Region: A Comprehensive Analysis Using CSD Indicators (1982–2023)

Ecosystem resilience, the ability of an ecosystem to recover from disturbances, is a critical indicator of environmental health and stability, particularly under the impacts of climate change and anthropogenic pressures. This study focuses on the Three-River Headwater Region (TRHR), a critical ecological area for East and Southeast Asia, often referred to as the “Water Tower of China”. We used the Normalized Difference Vegetation Index (NDVI) as a proxy for vegetation growth and productivity and calculated Critical Slowing Down (CSD) indicators to assess the spatiotemporal dynamics of grassland ecosystem resilience in the TRHR from 1984 to 2021. Our research revealed a sustained improvement in ecosystem resilience in the TRHR starting in the late 1990s, with a reversal in this trend observed after 2011. Spatially, ecosystem resilience was higher in areas with greater precipitation and higher vegetation productivity. Temporally, changes in grazing intensity were most strongly correlated with resilience dynamics, with explanatory power far exceeding that of NDVI, temperature, and precipitation. Our study underscores the importance of incorporating ecosystem resilience into assessments of ecosystem function changes and the effectiveness of ecological conservation measures, providing valuable insights for similar research in other regions of the world.

Productivity Proxies in Surface Sediment of the East Antarctic Margin: A Focus on Excess Ba

AbstractComponents such as organic carbon (Corg), carbonate, opal or barite are valuable paleoceanographic proxies, enabling the reconstruction of past changes in carbon cycling under various climate regimes, particularly when 230Th‐normalization is used to reconstruct particulate vertical rain rates. However, these components can be affected by poor preservation in the sediment. Barite is generally better preserved compared to other productivity proxies, but its estimates using “excess barium” (xsBa) calculations or Ba/Al ratios may not always be reliable, especially near the continental margin. This study presents a multi‐proxy investigation of surface sediments from the East Antarctic margin to assess the robustness of xsBa as a paleo‐productivity proxy. 230Th‐normalized fluxes of Corg and opal record consistent variations within the sediment, while xsBa appears to be affected by different processes. Results suggest that xsBa may not robustly reflect marine barite in sediment close to the Antarctic Ice Sheet, because (a) the authigenic signal is overprinted by large lithogenic inputs; and (b) other mineral phases (e.g., Fe oxides) may be important Ba carrier phases in the region. 230Th‐normalized Ba concentrations in the oxide‐free sediment fraction, which was reductively leached to remove Fe‐Mn oxides, aligns with the other biogenic fluxes, implying that specific leaching for barite isolation might be required in sediment proximal to the Antarctic Ice Sheet, rather than using the standard “xsBa” calculation or Ba/Al ratios. This study gives new insights into the sedimentary cycle of Ba in East Antarctic sediment and confirms the importance of using multi‐proxy records to perform paleo‐reconstructions.

Oceanic anoxic event 3 in Arctic Canada—Arc volcanism and ocean fertilization drove anoxia

The global extent of the Late Cretaceous oceanic anoxic event 3 (OAE 3) remains uncertain. It is not considered to have extended into the Boreal Realm. To test this, we examined Late Cretaceous organic- and metal-rich black mudstones of the Smoking Hills Formation in Arctic Canada. New high-precision U-Pb zircon ages indicate that deposition of the Smoking Hills Formation (88.535−78.230 Ma) was temporally coincident with OAE 3, indicating a much broader global expression of this event than previously thought. OAE 3 was likely manifest throughout the proto−Arctic Ocean (now Arctic Canada). Abundant bentonite layers and cryptotephra within the Smoking Hills Formation have rare earth element (REE) patterns that are consistent with ashfall derived from Cretaceous arc volcanism. Anomalously high organic matter content in the Smoking Hills Formation, as compared to underlying and overlying units, suggests that ocean fertilization led to enhanced productivity and metal drawdown. A peak in arc volcanism may have been a key driver of the OAE 3 event. We also explored the potential use of cadmium as a geochemical marker of volcanism and show that high volcanogenic metal loading could affect the use of Cd and other proxies for marine productivity (e.g., Zn, Cu).

Variations in the Forest Productivity of Pinus patula Plantations in Tanzania: The Need for an Improved Site Classification System

The productivity of forests in sub-Saharan Africa is often summarized into large compartments or site classes. However, the classification of forest productivity levels based on the original site index model in Tanzania and the techniques applied to generate the model did not include the micro-toposequence variations within compartments. This may create false expectations of wood supply and hinder the estimation of sustainable harvesting processes. This study analyzed variations in forest productivity and the site index in P. patula stands in two forest plantations of Tanzania to assess the applicability and generality of the present site classification system. We used dominant height as a proxy for forest productivity in 48 plots at the Sao Hill forest plantation (SHFP) and 24 plots at the Shume forest plantation (SFP). We stratified the sampling plots in each site class along the soil catena and recorded the elevation, slope, and slope positions (summit, mid, and lower). Our results showed that the site classes did not generally match the previously assigned site classes and the productivity of a given site class varied between the two plantations. We found a consistently higher productivity than that implied by the original site index in SFP, while in SHFP, the productivity was both higher and lower than estimated in different compartments. Both elevations and slope significantly contributed to predicting the productivity variations within site classes. Overall, the results indicate that physiographic factors affect variations in forest productivity within the assigned site classes. We recommend a more comprehensive site productivity assessment that takes into account physiographic variations and hence provides more accurate information for sustainable forest plantation management in Tanzania and in the region at large.

Simulating Climatic Patterns and Their Impacts on the Food Security Stability System in Jammu, Kashmir and Adjoining Regions, India

This study investigated the historical climate data and future projections under the SSP5-8.5 scenario for Jammu, Kashmir (J&amp;K), and its adjoining regions in India. Agriculture is a critical economic pillar of this region, making it highly vulnerable to climate change. This study focused on temperature and precipitation trends. Statistical analysis and modeling methods, including cloud computing, were employed to predict changes and assess their impact on agricultural productivity and water resources. The results indicated that by 2100, the mean maximum and minimum temperatures are projected to increase by approximately 2.90 °C and 2.86 °C, respectively. Precipitation variability is expected to rise, with a mean increase of 2.64 × 10−6 mm per day. These changes have significant consequences for crop yield, water stress, and ecosystem dynamics. An analysis of Gross Primary Productivity (GPP) as a proxy for agricultural productivity using linear regression revealed a concerning trend. Although the total GPP of the study area remained stable over time, it declined by −570 g yr−1 in 2010, coinciding with a 1 °C temperature rise. Projections based on the expected 3 °C temperature increase by 2100 suggest a total GPP loss of −2500 g yr−1. These findings highlight the urgent need for proactive adaptation measures, including sustainable agricultural practices, improved water management, and enhanced socioeconomic infrastructure, to mitigate the impact of climate change and ensure long-term resilience and food security in the region.

Annual and spatial variation in adult and brood abundance in a sub-Arctic wader

ABSTRACT Capsule Numbers of adult Eurasian Whimbrels Numenius phaeopus declined steeply across Iceland’s largest lowland basin during 2012–2021, but the abundance of broods during 2013–2021 did not decline. Sites with more adults generally held more broods. Aims Many Arctic-breeding waders are experiencing population declines, and it is imperative to gain a better understanding of how habitats and demography interplay in driving the dynamics of wader populations. We investigated the temporal and spatial variation in the abundance of Eurasian Whimbrel adults and broods (a proxy for productivity), and also the habitat associations of adults and broods, to assess whether sites holding more adults were also more productive. Methods Temporal and spatial variation in the abundance of Eurasian Whimbrels were analysed using generalized linear models in an 11-year dataset of adult counts and a nine-year dataset of brood counts, collected in a road-based survey across Iceland’s largest lowland region. Results We found a strong decline in the adult population but no trend in brood abundance, which showed high annual variation. Both the adults and broods occurred in a range of semi-natural habitats, but broods occurred less frequently in cultivated, built-up and forested habitats than expected by chance. More broods were associated with survey points that had a higher abundance of adults, suggesting the sites holding more adults are also more productive. Conclusions Spatial variation in brood abundance is largely a proximate product of local adult abundance, whereas its temporal variation seems strongly affected by annual environmental conditions. Incorporating such results into landscape planning, and prioritizing habitats for conservation where adults are more abundant, should also favour more productive sites in this Icelandic population.

Solar‐Induced Chlorophyll Fluorescence as a Potential Proxy for Gross Primary Production and Methane Emission in a Cool‐Temperate Bog in Northern Japan

AbstractWetlands play an essential role in the global greenhouse gas budget via carbon dioxide sequestration as well as methane emission. In recent decades, solar‐induced chlorophyll fluorescence (SIF) has been recognized as a remotely sensed proxy of gross primary productivity (GPP), which generates substrates for methane production. To examine the suitability of SIF for estimation of these two fluxes, we conducted ground tower‐based SIF observation with an ultrafine‐resolution spectroradiometer in conjunction with eddy covariance measurement in a cool‐temperate bog. The daily SIF retrieved in the red (687 nm) and far‐red (760 nm) bands (SIFred and SIFfar‐red, respectively) increased nonlinearly with GPP and linearly with absorbed photosynthetically active radiation (APAR). The relatively weak correlation between apparent SIF yield (ΦSIF = SIF/APAR) and light use efficiency implied that both APAR and plant physiology constrained the SIF emission in this wetland. The SIFred/SIFfar‐red ratio showed a significant negative relationship with vegetation greenness indices, and the similar seasonal variation in SIFred and SIFfar‐red indicated that the SIFred reabsorption effect only weakly influenced the SIFred–GPP relationship. Episodic temporal reduction in the water table did not distinctly influence SIF and ΦSIF. Estimation of the methane emission rate was subtly improved by incorporating SIF, which was substituted for GPP as the methanogenesis substrate, in a multivariable regression analysis together with two environmental factors: soil temperature and water table depth. This study illustrates the potential of both SIFred and SIFfar‐red to monitor GPP and to predict methane emission in wetlands.