Biology subjects

Crowther, T. W.

Publications and source records attributed to Crowther, T. W..

13 recordsLinked to original sources

bioRxiv2026

Soil microbial inoculants augment fertilizer performance across contrasting cropping systems in Rwanda

Smallholder farming systems in sub-Saharan Africa are constrained by declining soil fertility, erosion, and rising fertilizer costs, creating an urgent need for scalable inputs that sustain yields while maintaining soil health. While there is some evidence that microbial inoculants may offer a promising complement to conventional fertility management, field-scale evidence in tropical cereal and tuber systems remains limited. Here, we evaluated a multi-species inoculant composed of 20-22 Bacillus and Streptomyces species on potato and maize across four sites in Rwanda over two growing seasons (2025A and 2025B). Treatments included the inoculant applied at two rates (150 and 250 g ha-1), both alone and in combination with standard fertilization (inorganic fertilizer plus manure), alongside untreated and fertilized controls. Co-application of the inoculant with standard fertilization increased yield and plant biomass beyond fertilization alone, with gains of 6-51% for maize and 3-58% for potato. However, while the inoculant applied alone outperformed untreated controls, it generally did not match standard fertilization. Responses were strongest and most consistent for large-grade potato tubers, and application rate interacted with crop type, whereby the lower dose maximized marketable tuber yield, while maize showed a positive dose-response for grain and biomass. Yield increases were not accompanied by reductions in crop nutrient density, which was instead governed by site-level differences. Altogether, these results indicate that multi-species microbial inoculants are an effective complement to existing fertility practices that may offer, pending further research, a potential pathway to partial fertilizer replacement while sustaining productivity and nutritional quality in smallholder tropical agriculture.

ecology↗

bioRxiv2025

Developmental constraints mediate the summer solstice reversal of climate effects on European beech bud set

Accurate projections of temperate tree growing seasons under climate change require representing developmental constraints that determine tree resource allocation. Recent work has identified a phenological "switch point" after the summer solstice (21 June), with pre-solstice warming advancing autumn phenology and post-solstice warming delaying it. Here, we propose this switch is flexible and occurs at the compensatory point between the antagonistic effects of early-season development and late-season temperature. We performed trans-solstice climate manipulation experiments on potted European beech (Fagus sylvatica) saplings to test (i) how spring leaf-out timing and June-August temperatures influence end-of-season timing (bud set and leaf senescence [50% loss of leaf chlorophyll content]), and (ii) whether daytime and nighttime temperatures before and after the solstice have different effects, given that trees primarily grow at night. Bud set and leaf senescence responses were tightly coupled (R2 = 0.49), with bud responses being generally stronger. Each day delay in spring leaf-out delayed bud set by 0.24 {+/-} 0.06 days and senescence by 0.22 {+/-} 0.08 days. Post-solstice full-day cooling in July delayed autumn phenology in late-leafing individuals (bud set +4.9 {+/-} 2.6 days; senescence +3.1 {+/-} 2.8 days) but had negligible impact on early-leafing trees (bud set +1.4 {+/-} 2.6 days; leaf senescence +2.2 {+/-} 2.8 days). Conversely, August full-day cooling advanced both stages. Daytime cooling before the solstice had no effect, while after the solstice it advanced autumn phenology. Nighttime cooling always delayed bud set. These findings support the Solstice-as-Phenology-Switch model and highlight the central role of developmental progression in constraining growing seasons. Faster early-season development -especially under nighttime warming- moves trees past the switch earlier, increasing sensitivity to late-season cooling and thereby triggering earlier autumn phenology. To improve growing season length projections, phenology models should account for these developmentally-mediated and diel-specific temperature responses.

ecology↗

bioRxiv2024

Freedom of speech predicts animal welfare protection across the globe

The welfare of captive and wild animals is closely tied to human health, nutrition, and environmental wellbeing. Yet, until now, the global determinants of animal welfare remain unclear, as we lack quantitative global data on animal treatment. Here, by collapsing 13 indicators of animal welfare legislation across 50 major animal product-producing countries, we identify two key dimensions reflecting animal welfare protection and responsible consumption and production. While high-income countries with lower dependence on agriculture may have more opportunity to focus on animal welfare, our analysis suggests that the level social freedoms of citizens can dramatically overwhelms this economic signal. We find that the voice and accountability of citizens ultimately determines the extent of animal welfare protection, explaining 58% of the variation across the globe. Irrespective of environmental or economic conditions, structures that enhance political freedoms, civil liberties, and citizen participation in governance may provide the necessary foundation for developing legislation to promote animal welfare protection.

zoology↗

bioRxiv2024

Large-scale recovery in Costa Rica's Payment for Ecosystem Service Program

Costa Rica implemented the worlds first national-scale Payment for Ecosystem Service (PES) program in 1996 and now protects over 200,000 hectares. By distributing wealth towards local land-stewards, Costa Ricas program has helped to limit deforestation at a national scale, but the large-scale ecological implications have yet remained unclear. Here, we use a massive ecoacoustic dataset to evaluate how this program has impacted the ecological integrity of PES forests across the entire Nicoya Peninsula. At the times and frequencies that are indicative of native biological activity, we reveal dramatic increases in the integrity of PES soundscapes, relative to those of natural protected areas. Specifically, natural regeneration sites were 97.79% more acoustically similar to reference forests (absolute mean similarity of 0.539) than they were to disturbed pastures, while acoustic recovery of plantations lags behind (79.66%; 0.489). These findings are strongly suggestive of large-scale ecological recovery, constituting some of the most robust evidence to date that restoration initiatives can benefit biodiversity on large spatial scales. Study overviewCosta Ricas PES program pays landowners to encourage forest recovery and compensate them for opportunity costs. Most payments subsidize land conservation, in which participants allow existing forests to naturally regenerate. Some payments are also offered to produce timber through plantations, which are often monocultures of exotic tree species. Despite the programs importance to Costa Ricas conservation efforts, little is known about whether these forest systems are recovering their natural characteristics. To investigate the dynamics of the PES program, we recorded continuous 6-day soundscapes in 119 sites across the Nicoya Peninsula of Costa Rica (Supplementary Figure 1). Specifically, we characterized the soundscapes across 4 land-use types: (i) 19 reference pastures, (ii) 43 PES monoculture tree plantations, (iii) 39 PES natural regeneration sites, and (iv) 18 reference forests. Sites from each land-use type are distributed across the Nicoya Peninsulas climate and edaphic gradient, allowing us to capture substantial variation in ecological outcomes. We determined the areas of acoustic space where most animals vocalize and where ecological responses to recovery were most likely to be detected (Figure 1). We then identified how and to what extent the soundscapes of natural regeneration and plantation sites had changed over the last 27 years. We find evidence that naturally regenerating forests within the PES have recovered substantially when compared to reference forests, while plantation systems lag behind (Figure 3). Our findings reaffirm the importance of ecosystem conservation, while suggesting redistributive policy mechanisms can accelerate nature protection at scale. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=116 SRC="FIGDIR/small/610944v1_fig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@1e23f8org.highwire.dtl.DTLVardef@cbac64org.highwire.dtl.DTLVardef@1a2daaborg.highwire.dtl.DTLVardef@c2157e_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1:C_FLOATNO Tailoring the acoustic space to improve acoustic analyses. Soundscape analyses can be improved by identifying the times and frequencies associated with the dynamics of interest. Using manual annotations and modelling approaches we determined that differences in the activity of native fauna, shown here in black, were best understood within frequencies 1 - 9 kHz (on the y-axis) and the times listed along the x-axis in yellow. Outside of this region of acoustic space, differences between land-use types are better explained by climatic differences or other acoustic events (shown in grey). C_FIG O_FIG O_LINKSMALLFIG WIDTH=134 HEIGHT=200 SRC="FIGDIR/small/610944v1_fig3.gif" ALT="Figure 3"> View larger version (17K): org.highwire.dtl.DTLVardef@111505org.highwire.dtl.DTLVardef@17b36cborg.highwire.dtl.DTLVardef@4a5057org.highwire.dtl.DTLVardef@e08a29_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 3:C_FLOATNO Soundscape comparisons reveal substantial recovery in PES natural regeneration sites. (A) Scaled similarity values to reference forests are shown for the remaining three land-use types, higher values indicate more shared acoustic characteristics. Box plots show the quantile ranges and median values for each land-use type. Colored points represent mean similarities for all 10-minute time bins included in the analysis, colored by the time of period of the day, while outliers are plotted again in black. Brackets indicate the results of a Wilcoxon post-hoc statistical test. (B) 24-hour cycles of SPMN for each land-use type are shown for the frequency bands in which similarities between natural regeneration sites and reference forests were highest (3 - 4 and 6 - 7 kHz). C_FIG

ecology↗

bioRxiv2024

Functional coexistence theory: a mechanistic framework linking biodiversity to ecosystem function

Theory and experiments show that diverse ecosystems often have higher levels of function (for instance, biomass production), yet it remains challenging to identify the biological mechanisms responsible. We synthesize developments in coexistence theory into a general theoretical framework linking community coexistence to ecosystem function. Our framework, which we term functional coexistence theory, identifies three components determining the total function of a community of coexisting species. The first component directly corresponds to the niche differences that enable pairwise species coexistence, and to the complementarity component from the additive partition of biodiversity effects. The second component measures whether higher functioning species also have higher competitive fitness, providing a missing link between the additive partitions selection effect and modern coexistence theorys concept of equalization. The third component is least well-studied: reducing functional imbalances between species increases niche differences positive effect on function. Using a mechanistic model of resource competition, we show that our framework can identify how traits drive the effect of competition on productivity, and confirm our theoretical expectations by fitting this model to data from a classic plant competition experiment. Furthermore, we apply our framework to simulations of communities with multiple ecosystem functions or more than two species, demonstrating that relationships between niche, fitness, and function also predict total function beyond the case studied by classical theory. Taken together, our results highlight fundamental links between species coexistence and its consequences for ecosystem function, providing an avenue towards a predictive theory of community-ecosystem feedbacks.

ecology↗

bioRxiv2024

Macro-environment strongly interacts with warming in a global analysis of decomposition

Empirical studies worldwide show substantial variability in plant litter decomposition responses to warming, leaving the overall impact of climate change on this process uncertain. We conducted a meta-analysis of 109 experimental warming studies across seven continents, utilizing natural and standardized plant material, to assess the overarching effect of warming on decomposition and identify potential moderating factors. Warming influences decomposition differently across macro-environmental gradients of moisture and temperature. Negative warming effects on decomposition in warmer, low-moisture areas were counterbalanced by the positive, though not significant, warming effects in colder areas, resulting in an overall non-significant effect. We determine that at least 5.2 degrees of warming is required for a significant increase in decomposition. This is particularly relevant given the past decades global warmth in higher latitudes, holding a significant proportion of terrestrial carbon. Low-quality plant litter was more sensitive to warming. Therefore, future vegetation changes toward low-quality, temperature-sensitive plants could increase carbon release and reduce the net supply of stored organic matter in the soil by increasing the decomposition of low-quality litter with warming. Our findings emphasize the connection between warming responses, macro-environment, and litter characteristics, refining predictions of climate changes consequences on key ecosystem processes and its contextual dependencies.

ecology↗

bioRxiv2023

Enhanced local cooling effects of forests across the globe

Forests cool the land surface in warm regions and warm the land surface in cool regions. Because these local temperature buffering effects depend on background climate1,2, increasingly large areas might experience forest cooling effects as the climate warms3-5. Here, using statistical modeling, we quantified changes in the sensitivity of land surface temperatures6 to forest cover change7 from 1988 - 2016, across 15 million km2 of land area. Forests had a local cooling effect on day and night surface temperatures in 86.3% (72 million km2) and 61.6% (5,108 million km2) of the forest area, respectively. This area has increased by 0.3% (0.2 million km2) at day and 4.7% (2 million km2) at night over recent decades. Our study indicates that climate change is enhancing the cooling effect of forests in the short term, underscoring the importance of protecting natural, diverse forest ecosystems in the face of rising global temperatures that threaten ecosystems8,9, human health10,11, and food production12.

ecology↗

bioRxiv2022

Acclimation of phenology relieves leaf longevity constraints in deciduous forests

Leaf phenology is key for regulating total growing season mass and energy fluxes. Long-term temporal trends towards earlier leaf unfolding are observed across Northern Hemisphere forests. Phenological dates also vary between years, whereby end-of-season (EOS) dates correlate positively with start-of-season (SOS) dates and negatively with growing season total net CO2 assimilation (Anet). These associations have been interpreted as the effect of a constrained leaf longevity or of premature carbon (C) sink saturation - with far-reaching consequences for long-term phenology projections under climate change and rising CO2. Here, we use multi-decadal ground and remote-sensing observations to show that the relationships between Anet and EOS are opposite at the interannual and the decadal time scales. A decadal trend towards later EOS persists in parallel with a trend towards increasing Anet - in spite of the negative Anet-EOS relationship at the interannual scale. This indicates that acclimation of phenology has enabled plants to transcend a constrained leaf longevity or premature C sink saturation over the course of several decades, leading to a more effective use of available light and a sustained extension of the vegetation CO2 uptake season over time.

ecology↗

bioRxiv2021

Global trade-offs in tree functional traits

AO_SCPLOWBSTRACTC_SCPLOWDue to massive energetic investments in woody support structures, trees are subject to unique physiological, mechanical, and ecological pressures not experienced by herbaceous plants. When considering trait relationships across the entire plant kingdom, plant trait frameworks typically must omit traits unique to large woody species, thereby limiting our understanding of how these distinct ecological pressures shape trait relationships in trees. Here, by considering 18 functional traits--reflecting leaf economics, wood structure, tree size, reproduction, and below-ground allocation--we quantify the major axes of variation governing trait expression of trees worldwide. We show that trait variation within and across angiosperms and gymnosperms is captured by two independent processes: one reflecting tree size and competition for light, the other reflecting leaf photosynthetic capacity and nutrient economies. By exploring multidimensional relationships across clusters of traits, we further identify a representative set of seven traits which captures the majority of variation in form and function in trees: maximum tree height, stem conduit diameter, specific leaf area, seed mass, bark thickness, root depth, and wood density. Collectively, this work informs future trait-based research into the functional biogeography of trees, and contributes to our fundamental understanding of the ecological and evolutionary controls on forest biodiversity and productivity worldwide.

ecology↗

bioRxiv2021

Lowland plant migrations into alpine ecosystems amplify soil carbon loss under climate warming

Climate warming is releasing carbon from soils around the world1-3, constituting a positive climate feedback. Warming is also causing species to expand their ranges into new ecosystems4-9. Yet, in most ecosystems, whether range expanding species will amplify or buffer expected soil carbon loss is unknown10. Here we used two whole-community transplant experiments and a follow-up glasshouse experiment to determine whether the establishment of herbaceous lowland plants in alpine ecosystems influences soil carbon content under warming. We found that warming (transplantation to low elevation) led to a negligible decrease in alpine soil carbon content, but its effects became significant and 52% {+/-} 31% (mean {+/-} 95% CIs) larger after lowland plants were introduced at low density into the ecosystem. We present evidence that decreases in soil carbon content likely occurred via lowland plants increasing rates of root exudation, soil microbial respiration and CO2 release under warming. Our findings suggest that warming-induced range expansions of herbaceous plants have the potential to alter climate feedbacks from this system, and that plant range expansions among herbaceous communities may be an overlooked mediator of warming effects on carbon dynamics.

ecology↗

bioRxiv2021

A geospatial mapping pipeline for ecologists

Geospatial modelling can give fundamental insights in the biogeography of life, providing key information about the living world in current and future climate scenarios. Emerging statistical and machine learning approaches can help us to generate new levels of predictive accuracy in exploring the spatial patterns in ecological and biophysical processes. Although these statistical models cannot necessarily represent the essential mechanistic insights that are needed to understand global biogeochemical processes under ever-changing environmental conditions, they can provide unparalleled predictive insights that can be useful for exploring the variation in biophysical processes across space. As such, these emerging tools can be a valuable approach to complement existing mechanistic approaches as we aim to understand the biogeography of Earths ecosystems. Here, we present a comprehensive methodology that efficiently handles large datasets to produce global predictions. This mapping pipeline can be used to generate quantitative, spatially explicit predictions, with a particular emphasis on spatially-explicit insights into the evaluation of model uncertainties and inaccuracies.

ecology↗

bioRxiv2021

Mapping tree species for restoration potential resilient to climate change

The restoration of forest ecosystems is associated with key benefits for biodiversity and ecosystem services. Where possible, ecosystem restoration efforts should be guided by a detailed knowledge of the native flora to regenerate ecosystems in a way that benefits natural biodiversity, ecosystem services, and natures contribution to people. Machine learning can map the ecological suitability of tree species globally, which then can guide restoration efforts, especially in regions where knowledge about the native tree flora is still insufficient. We developed an algorithm that combines ecological niche modelling and geographic distributions that allows for the high resolution (1km) global mapping of the native range and suitability of 3,987 tree species under current and future climatic conditions. We show that in most regions where forest cover could be potentially increased, heterogeneity in ecological conditions and narrow species niche width limit species occupancy, so that in several areas with reforestation potential, a large amount of potentially suitable species would be required for successful reforestation. Local tree planting efforts should consider a wide variety of species to ensure that the equally large variety of ecological conditions can be covered. Under climate change, a large fraction of the surface for restoration will suffer significant turnover in suitability, so that areas that are suitable for many species under current conditions will not be suitable in the future anymore. Such a turnover due to shifting climate is less pronounced in regions containing species with broader geographical distributions. This indicates that if restoration decisions are solely based on current climatic conditions, a large fraction of the restored area will become unsuitable in the future. Decisions on forest restoration should therefore take the niche width of a tree species into account to mitigate the risk of climate-driven ecosystem degradation.

ecology↗

bioRxiv2017

Predicting Global Forest Reforestation Potential

Executive SummaryForests are important determinants of the carbon cycle, and they provide countless ecosystem services to support billions of people worldwide. Global-scale forest restoration is one of our most effective weapons in the fight against biodiversity loss, rural poverty and climate change. In this report, we generate a spatial map of tree density within the potential forest restoration areas delineated by the IUCN/WRIs \"Atlas of Forest Landscape Restoration Opportunities\" to estimate the potential number of trees that could be restored at a global scale. We also estimate the number of trees that might be saved by avoiding deforestation in currently forested areas.\n\nWe show that the restoration areas have the capacity to support a total of 1.33 trillion trees. However, given that a considerable proportion of these areas already contain forests, we estimate that 589 billion new trees (larger than 10 cm diameter) could be restored within these areas, which would have the potential to store 65-91 Gigatonnes of carbon after reaching forest maturation. These values will increase marginally over time, as deforestation is responsible for the removal of living trees within the restoration areas. However, if only 50% or 25% of the mosaic areas (the largest of the designated restoration types) are available for reforestation, this total number will fall to approximately 360, or 246 billion trees, respectively, with corresponding decreases in potential carbon storage. Given that anthropogenic carbon emissions are currently in the order of 9-12 Gigatonnes per year, effective global-scale restoration might potentially have a valuable impact on global-scale climate mitigation over the rest of this century.\n\nThis report was produced with funding from WWF-UK as part of the Trillion Trees programme with the Wildlife Conservation Society and BirdLife International

ecology↗