Exploring the plant–aphid–ant interaction

Different species interact with each other in complex and diverse ways. Why and how do we study these interspecies interactions? How do we introduce students to these interactions through real-world observations of plants, aphids, and ants from their own backyards

Assessing Restoration Potential of Fragmented and Degraded Fagaceae Forests in Meghalaya, North-East India

The montane subtropical broad-leaved humid forests of Meghalaya (Northeast India) are highly diverse and situated at the transition zone between the Eastern Himalayas and Indo-Burma biodiversity hotspots. In this study, we have used inventory data from seedlings to canopy level to assess the impact of both biotic and abiotic disturbances on structure, composition, and regeneration potential of the Fagaceae trees of these forests. Fagaceae trees are considered as the keystone species in these forests due to their regional dominance and their importance as a fuel wood source, and also because they form an important component of climax community in these forests. Unfortunately, these forests are highly degraded and fragmented due to anthropogenic disturbances. We have assessed, for the first time, the restoration potential (i.e., capacity to naturally regenerate and sustain desired forest structure) of Fagaceae species in the genera Lithocarpus Blume, Castanopsis (D. Don) Spach, and Quercus Linn. We also evaluated how biotic and abiotic factors, as well as anthropogenic disturbances, influence the restoration potential of these species in six fragmented forest patches located along an elevational gradient on south-facing slopes in the Khasi Hills, Meghalaya. Fagaceae was the most dominant family at all sites except one site (Laitkynsew), where it was co-dominant with Lauraceae. Fagaceae forests have shown high diversity and community assemblages. Fagaceae species had high levels of natural regeneration (i.e., seedlings and saplings) but low recruitment to large trees (diameter at breast height or DBH ≥ 10 cm) at all sites. The ability to sprout was higher in Fagaceae tree species than non-Fagaceae tree species. We have shown that human disturbance and structural diversity were positively related to regeneration of Fagaceae tree species due to high sprouting. However, with increasing human disturbance, recruitment of saplings and pole-sized trees to mature trees hampered the resulting proportion of mature Fagaceae tree species. This study provides a means for assessing regeneration and a basis for forest management strategies in degraded and fragmented forests of Meghalaya

Modelling Hotspots for Invasive Alien Plants in India.

Identification of invasion hotspots that support multiple invasive alien species (IAS) is a pre-requisite for control and management of invasion. However, till recently it remained a methodological challenge to precisely determine such invasive hotspots. We identified the hotspots of alien species invasion in India through Ecological Niche Modelling (ENM) using species occurrence data from the Global Biodiversity Information Facility (GBIF). The predicted area of invasion for selected species were classified into 4 categories based on number of model agreements for a region i.e. high, medium, low and very low. About 49% of the total geographical area of India was predicted to be prone to invasion at moderate to high levels of climatic suitability. The intersection of anthropogenic biomes and ecoregions with the regions of 'high' climatic suitability was classified as hotspot of alien plant invasion. Nineteen of 47 ecoregions of India, harboured such hotspots. Most ecologically sensitive regions of India, including the 'biodiversity hotspots' and coastal regions coincide with invasion hotspots, indicating their vulnerability to alien plant invasion. Besides demonstrating the usefulness of ENM and open source data for IAS management, the present study provides a knowledge base for guiding the formulation of an effective policy and management strategy for controlling the invasive alien species

Environmental variables used for modelling and delineating invasion hotspots.

<p>Environmental variables used for modelling and delineating invasion hotspots.</p

Invasion hotspots in India delineated through intersection of ecoregions, multi-species ecological niche model consensus, and anthropogenic biomes.

<p>The delineated areas cover >50 percent area of various ecoregions, are climatically suitable for a large number of invasive alien species, and have signature of diverse anthropogenic activities. The boundary files on biodiversity hotspots were overlaid on the modelled invasion hotspots matches to portray the level of threat to these areas from invasive alien species.</p

Model consensus classes depicting climatic suitability for diverse IAS in India.

<p>The bar diagram depicts the percentage of total geographical area under various consensus class in different states of India. The climate suitability map was generated by combining 525 thresholded model projections from Africa, Australia, Europe, North America and South America. The legend show the model agreements, wherein 'high' represents the areas with highest range of model agreements, and 'very low' having the lowest range of model agreements. 'High' agreement represent high species richness, while 'low' agreement represent low species richness.</p

Climatic suitability map for diverse alien plant species in India based on continent of origin.

<p>A-E show the model consensus identified by summing up the thresholded model projections for multiple species from—(A) Africa, (B) Australia, (C) Europe, (D) North America, and (E) South America. The figure legend show the model agreements, wherein ‘high’ represents the areas with highest model agreement, and ‘very low’ having the lowest agreements. Higher model agreements represent larger number of alien invasive species while the lower model agreements represent lower number of alien invasives.</p

Box plot showing distribution of mean AUC_train and AUC_test values for the selected alien invasive plants in each of the model training continents.

<p>In the figure, the boxes represent 25–75 percent quartiles of the AUC values, and the horizontal line inside the boxes represents the median. The minimal and maximal values are shown with whiskers drawn from the top of the box up to the largest data point less than 1.5 times the box height from the box, and similarly below the box. The circles represent the outlier values, and the stars represent the extreme values.</p

Matrix depicting the 3 components viz. climatic suitability, ecoregions and anthropogenic biomes, used for delineation of invasion hotspots in India.

<p>The identified ecoregions have > 50 percent of its area under the high climatic suitability. The numbers on top of the matrix indicate the major categories of anthropogenic biomes: Croplands: (11) Residential irrigated cropland, (12) Residential rainfed mosaic, (21) Populated irrigated cropland, (22) Populated rainfed cropland, (23) Remote croplands; Forested: (24) Populated forests, (25) Remote forests; Rangelands: (26) Residential rangelands, (31) Populated rangelands, (32) Remote rangelands; Urban: (33) Urban, (34) Dense settlements; Villages: (35) Rice villages, (41) Irrigated villages, (42) Cropped & pastoral villages, (43) Pastoral villages, (51) Rainfed villages, (52) Rainfed mosaic villages; Wild Land: (61) Wild forests, (62) Sparse trees, (63) Barren. Description of the anthropogenic biomes is given in Ellis and Ramankutty (2008), and details on ecoregion-wise information can be viewed at <a href="http://www.globalspecies.org/ecoregions" target="_blank">http://www.globalspecies.org/ecoregions</a>. The filled boxes signify representation of the particular anthropobiome in each ecoregion.</p