Modelled distribution of an invasive alien plant species differs at different spatiotemporal scales under changing climate: a case study of Parthenium hysterophorus L

Integrating human footprint with ensemble modelling identifies priority habitats for conservation: a case study in the distributional range of Arnebia euchroma, a vulnerable species

Climate change-driven rapid alteration of ecosystems globally is further complicated by growing anthropogenic pressures, especially in the ecologically sensitive mountainous regions. However, these two major drivers of change have largely been considered separately in species distribution models, thus compromising their reliability. Here, we integrated ensemble modelling with the human pressure index for predicting distribution and mapping priority regions across a whole range of occurrences for vulnerable species, Arnebia euchroma. Our results identified 3.08% of the study area as 'highly suitable', 2.45% as 'moderately suitable', and 94.45% as 'not suitable' or 'least suitable'. Compared to current climatic conditions, future RCP scenarios of 2050 and 2070 showed a significant loss in habitat suitability and a slight shift in the distribution pattern of the target species. By excluding the high-pressure areas of the human footprint from the predicted suitable habitats, we were able to identify the unique areas (70% of the predicted suitable area) that need special attention for conservation and restoration. Such models, if well implemented, may play a pivotal role in achieving the effective targets under the aegis of the current UN decade on ecological restoration (2021-2030) in accordance with SDG 15.4.

The effect of climate change on Arcto-Tertiary Mexican beech forests: Exploring their past, present, and future distribution

Fagus mexicana Martínez (Mexican beech) is an endangered Arcto-Tertiary Geoflora tree species that inhabit isolated and fragmented tropical montane cloud forests in eastern Mexico. Exploring past, present, and future climate change effects on the distribution of Mexican beech involves the study of spatial ecology and temporal patterns to develop conservation plans. These are key to understanding the niche conservatism of other forest communities with similar environmental requirements. For this study, we used species distribution models by combining occurrence records, to assess the distribution patterns and changes of the past (Last Glacial Maximum), present (1981-2010), and future (2040-2070) periods under two climate scenarios (SSP 3-7.0 & SSP 5-8.5). Next, we determined the habitat suitability and priority conservation areas of Mexican beech as associated with topography, land cover use, distance to the nearest town, and environmental variables. By considering the distribution of Mexican beech during different periods and under different climate scenarios, our study estimated that high-impact areas of Mexican beech forests were restricted to specific areas of the Sierra Madre Oriental that constitute refugia from the Last Glacial Maximum. Regrettably, our results exhibited that Mexican beech distribution has decreased 71.3% since the Last Glacial Maximum and this trend will for the next 50 years, migrating to specific refugia at higher altitudes. This suggests that the states of Hidalgo, Veracruz, and Puebla will preserve the habitat suitability features as ecological refugia, related to high moisture and north-facing slopes. For isolated and difficult-to-access areas, the proposed methods are powerful tools for relict-tree species, which deserve further conservation.

Modeling of Valeriana wallichii Habitat Suitability and Niche Dynamics in the Himalayan Region under Anticipated Climate Change

An increase in atmospheric greenhouse gases necessitates the use of species distribution models (SDMs) in modeling suitable habitats and projecting the impact of climate change on the future range shifts of the species. The present study is based on the BIOMOD ensemble approach to map the currently suitable habitats and predict the impact of climate change on the niche shift of Valeriana wallichii. We also studied its niche dynamics using the ecospat package in R software. Values of the area under curve (AUC) and true skill statistics (TSS) were highly significant (>0.9), which shows that the model has run better. From 19 different bioclimatic variables, only 8 were retained after correlation, among which bio_17 (precipitation of driest quarter), bio_1 (annual mean temperature), and bio_12 (annual mean precipitation) received the highest gain. Under future climate change, the suitable habitats will be significantly contracted by −94% (under representative concentration pathway RCP 8.5 for 2070) and −80.22% (under RCP 8.5 for 2050). There is a slight increase in habitat suitability by +16.69% (RCP 4.5 for 2050) and +8.9% (RCP 8.5 for 2050) under future climate change scenarios. The equivalency and similarity tests of niche dynamics show that the habitat suitability for current and future climatic scenarios is comparable but not identical. Principal Component Analysis (PCA) analysis shows that climatic conditions will be severely affected between current and future scenarios. From this study, we conclude that the habitats of Valeriana wallichii are highly vulnerable to climate shifts. This study can be used to alleviate the threat to this plant by documenting the unexplored populations, restoring the degraded habitats through rewilding, and launching species recovery plans in the natural habitats.