On the cover: A Chinese pangolin (Manis pentadactyla) walking across a pathway. Like pangolins, many ecological specialists are poorly covered by the protected areas. Photo credit: Wei Liu.
On the cover: A Chinese pangolin (Manis pentadactyla) walking across a pathway. Like pangolins, many ecological specialists are poorly covered by the protected areas. Photo credit: Wei Liu.
On the cover: The European adder (Viper berus) is a polymorphic species with a vast distribution, occurring from western Europe to the Russian far East. Photo credit: Niels Jansen.
Macaronesian cloud forests are insular ecosystems subjected to local environmental variability, but the responses of their tree species to climate variations have never been studied. Our aim was to assess how the variation in environmental conditions associated with the geographical location of several islands in three Macaronesian archipelagos affects the growth patterns and drought-resistance of the dominant cloud forests trees.
Azores, Madeira and Canary archipelagos. Portugal and Spain.
Lauraceae, Aquifoliaceae, Clethraceae, Oleaceae, Rosaceae and Cupressaceae.
We assessed variations in the radial growth response of 10 cloud forest tree species from 18 populations on 5 islands along a geographical gradient in Macaronesia. We quantified the influence of local climatic variables and North Atlantic Oscillation (NAO) and East Atlantic Pattern (EA) circulation patterns on tree growth and how drought events affected to the resistance, recovery and resilience indices estimated for these species.
Trees from the same island showed similar growth patterns, particularly in islands with marked hydric stress. In Madeira and the Canary Islands, radial growth was mainly determined by water availability, winter NAO negatively affected growth and droughts caused abrupt narrow growth-ring width. In the Azores, the effect of the EA was positive, as it increased temperature and relative humidity and promoted growth. Trees from wetter environments demonstrated higher growth resistance to drought, while trees from drier sites showed faster growth recovery after drought events.
Homogeneous growth patterns among species from the same island suggested that the radial growth of trees in cloud forests is mostly determined by local environmental conditions, which are more important for their growth than phenotypic traits. The variability in water availability determined by a latitudinal geographical gradient throughout the Macaronesian region influenced both the climatic response of the trees and their resilience to drought.
Land use and land cover (LULC) change is the main driver of biodiversity loss, causing habitat loss and fragmentation that hinders species movement and negatively impacts populations. While habitat fragments are structurally disconnected, functional connectivity can still occur depending on the species' dispersal abilities. Incorporating landscape connectivity into restoration planning helps identify strategic areas significantly enhancing connectivity. Here, we present an unprecedented, nationwide continuous spatial layer representing each restorable pixel's contribution to functional connectivity, using Brazil as a case study.
Brazil.
We performed a dynamic pixel-based analysis across each Brazilian biome to assess the potential increases in the Integral Index of Connectivity (IIC) resulting from restoring each restorable pixel in the landscape. For that, we defined hypothetical species with medium, high and very high dispersal abilities and calculated the IIC for the different natural LULC in each biome. Then, we ran a dynamic pixel-based restoration analysis to assess the contribution of each restorable pixel to functional connectivity.
Our resulting dataset represents the relative contribution of connectivity for each restorable pixel in the landscape, considering all dispersal abilities and LULC in each biome. Since we are assessing the contributions of individual pixels to overall biome landscape connectivity, most values are expectedly low. However, pixels with the highest contributions to connectivity show a stand-alone contribution biome-wide and thus were interpreted as priorities for restoration. Notably, we show nested regions as priorities for restoration, with a trend of higher priority rankings (e.g., the top 5% most important regions) being surrounded by subsequent rankings of priorities.
Our study is the first to evaluate the impact of restoration planning efforts on functional connectivity across all Brazilian biomes. We identified priority areas for restoration within each Brazilian biome, providing valuable information to guide decision-making and policy implementation. The innovative pixel-based analysis used in the study can be replicated in other regions, aiming to make restoration planning more efficient.
Environmental factors that govern the allocation of net primary production (NPP) between long-lived components (wood) and short-lived components (leaves, fine roots) are poorly understood yet essential when relating NPP to carbon stocks, especially among different plant functional types. We conducted a spatially synoptic analysis to investigate the relationships between NPP allocation and climate at the global scale. We ask a fundamental question in forest ecology and terrestrial carbon science: What environmental drivers influence NPP allocation?
Global forests (64.21 N–41.53 S).
Trees.
We investigated the relationships between field forest NPP data (n = 131) and 31 bioclimatic, meteorological, geographical, topographic and vegetation variables using machine learning.
These environmental variables accounted for 94%, 93% and 85% of the variation in canopy, woody and fine-root NPP fractions, respectively. Most of the important predictors were temperature-related. Allocation to the canopy was facilitated by warm and stable climates. In contrast, woody and fine-root carbon growth could endure cold and extreme temperatures.
Our analysis suggested that the most important drivers were annual mean (e.g. high canopy and fine-root NPP ratios in favourable climates), variation and extreme (e.g. significant woody and fine-root NPP ratios where light- and nutrient-limited) of temperatures. Overall, most carbon was stored in woody tissue and in a constant proportion to the canopy, which could be explained by allometric scaling and resource availability. Our results pointed to a ‘root-wood’ trade-off rather than the previously prevailing ‘root-leaf’ trade-off, but may vary regionally. For example, regarding particular plant functional types, ‘wood-leaf’ and ‘root-leaf’ were only evident in broadleaved and coniferous forests, respectively, to adapt to climates and compete for resources. Knowing the relationships between NPP allocation and the environment, we could assess forest carbon cycle dynamics in the face of climate change.
On the cover: Euglossa imperialis is one of the most common species of orchid bees (Tribe Euglossini) in Panama. This individual was collected in Coiba National Park, a marine - terrestrial protected area found in the Pacific side of Panama. Photo credit: Yosiat Vega-Rovira.
The role of environmental factors that shape the large-scale distribution of eukaryotic microbes remains understudied. We aimed to disentangle the impacts of latitudinal and longitudinal gradients on the distribution of Sphagnum-dwelling testate amoebae in mires and to understand the influence of environmental factors related to both local habitats (hummock—lawn—hollows) and regional climates.
A range from temperate to subarctic and from the European part to the Far East of Russia (51°–70°N, 32°–158°E).
Testate amoeba (Arcellinida, Euglyphida, and Amphitremida).
We analysed the testate amoeba (TA) composition and abundance data from 816 samples collected in 75 peatlands. Linear mixed-effects models and redundancy analysis were applied to determine the likely environmental drivers of TA α- and β-diversity.
We identified a significant reversed latitudinal gradient in α-diversity which negatively correlated with the mean annual temperature. This gradient is microhabitat-specific, being prominent in lawn and hollow microhabitats, but not in hummocks. Longitude, which corresponds mainly to a gradient of precipitation seasonality, was a significant predictor of TA β-diversity, especially in hollows.
Our findings identify climatic factors (e.g., mean annual temperature and precipitation seasonality) as likely shaping the continental-scale TA α- and β-diversity patterns, emphasising the microhabitat-specific nature of these relationships. The absence of pattern in hummocks is interpreted as evidence for a predominant microhabitat stress (i.e., low moisture and pH) in this habitat.
To understand the influence of Andean uplifts and glacial cycles on South American biodiversity, we delve into the population genetics and evolutionary history of a unique subantarctic island raptor specialised in exploiting marine food webs.
Islands in Tierra del Fuego and Malvinas/Falklands.
Last glacial period to the present.
Phalcoboenus australis.
We used RAD sequencing to assess genetic diversity, population structure and to model demographic history through descriptive and hypothesis-based evolutionary methods.
We found evidence of two independent lineages: one inhabiting the Fuegian archipelago and the other one occurring in the Islas Malvinas/Falkland Islands, with the latter presenting higher genetic diversity and evidence of finer-scale population structure. The best supported demographic scenario places the divergence time of these lineages during the last glacial period (ca. 50,000 years ago), with the occurrence of gene flow during the first 27,000 years after their divergence. Recent demographic modelling supports the general pattern of increasing genetic variability as landmasses were uncovered following the glacial period (i.e., the Fuegian archipelago) in contrast with a decrease in genetic diversity associated to island fragmentation (i.e., in the Islas Malvinas/Falkland Islands).
We propose that post-glacial sea level rise and the subsequent isolation across the submerging Patagonian Shelf have driven population fragmentation and recent genetic structure in this species. Our findings advocate for recognising the two identified divergent lineages as distinct conservation units. We highlight the intricate interplay of ecological factors, glacial cycles and population dynamics in shaping the evolutionary trajectory of this unique and threatened raptor species in southern South America.
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