https://www.cs.princeton.edu/~schapire/papers/ecolmod.pdf

Maximum entropy modeling of species geographic distributions

Continuing population and consumption growth will mean that the global demand for food will increase for at least another 40 years. Growing competition for land, water, and energy, in addition to the overexploitation of fisheries, will affect our ability to produce food, as will the urgent requirement to reduce the impact of the food system on the environment. The effects of climate change are a further threat. But the world can produce more food and can ensure that it is used more efficiently and equitably. A multifaceted and linked global strategy is needed to ensure sustainable and equitable food security, different components of which are explored here.

/pdf/food-security-the-challenge-of-feeding-9-billion-people-7gwey15y62.pdf

Food Security: The Challenge of Feeding 9 Billion People

Prediction of species' distributions is central to diverse applications in ecology, evolution and conservation science. There is increasing electronic access to vast sets of occurrence records in museums and herbaria, yet little effective guidance on how best to use this information in the context of numerous approaches for modelling distributions. To meet this need, we compared 16 modelling methods over 226 species from 6 regions of the world, creating the most comprehensive set of model comparisons to date. We used presence-only data to fit models, and independent presence-absence data to evaluate the predictions. Along with well-established modelling methods such as generalised additive models and GARP and BIOCLIM, we explored methods that either have been developed recently or have rarely been applied to modelling species' distributions. These include machine-learning methods and community models, both of which have features that may make them particularly well suited to noisy or sparse information, as is typical of species' occurrence data. Presence-only data were effective for modelling species' distributions for many species and regions. The novel methods consistently outperformed more established methods. The results of our analysis are promising for the use of data from museums and herbaria, especially as methods suited to the noise inherent in such data improve.

/pdf/novel-methods-improve-prediction-of-species-distributions-3cmioqeu6v.pdf

Novel methods improve prediction of species' distributions from occurrence data

Climate change over the past approximately 30 years has produced numerous shifts in the distributions and abundances of species and has been implicated in one species-level extinction. Using projections of species' distributions for future climate scenarios, we assess extinction risks for sample regions that cover some 20% of the Earth's terrestrial surface. Exploring three approaches in which the estimated probability of extinction shows a power-law relationship with geographical range size, we predict, on the basis of mid-range climate-warming scenarios for 2050, that 15-37% of species in our sample of regions and taxa will be 'committed to extinction'. When the average of the three methods and two dispersal scenarios is taken, minimal climate-warming scenarios produce lower projections of species committed to extinction ( approximately 18%) than mid-range ( approximately 24%) and maximum-change ( approximately 35%) scenarios. These estimates show the importance of rapid implementation of technologies to decrease greenhouse gas emissions and strategies for carbon sequestration.

/pdf/extinction-risk-from-climate-change-3pqx1sctsd.pdf

Extinction risk from climate change

Statistics for Spatial Data.

When initial estimates of the extinction risk from climate change appeared, there was immediate public and media interest. Authors of Thomas et al. appeared on CNN, BBC, and other major national and international television networks. Newspaper headlines, often front page, appeared on the day of the report’s release. Magazine, radio, and other media treatments of the subject followed for weeks after. But to what extent was this media interest driven by policy relevance, and to what extent were the implications of the extinction risk estimates taken up in policy dialogue?

Climate Change, Extinction Risk, and Public Policy

A globally rare climatic regime with seasonally predictable winter rainfall and summer dryness, relatively stable for millennia, characterises the Succulent Karoo Biome of southwestern Africa. This regime is likely facilitated extraordinary species richness and endemism across multiple taxa in plant and animal kingdoms. Endemism in leaf-succulent families, geophytic families, herptiles, and invertebrates, unique growth habits like dwarf-succulent minutism, and mutualisms play out in this Biome. The spectacular diversity supports a nature-based economy now threatened by extractive mining, land conversion for agriculture, and unsustainable illegal harvesting of wild species. Anthropogenic climate change is emerging as a medium to long term threat. 

Succulent Karoo Biome

Ecological aspects of the substrate and water relations of deciduous and evergreen plant forms in the western Karoo

There is a lack of long-term greenhouse gas (GHG) measurement infrastructures in Africa. This limits our understanding of the temporal dynamics of the biosphere-atmosphere exchange of carbon in response to climate change. Where relevant infrastructures have been established in externally funded research projects, they have often not been successfully transferred to local institutions at project termination, nor maintained in the long term. This leads to loss of capacity and continuity in primary data. We describe a collaborative approach where eddy-covariance (EC) towers for continuous long-term observation of carbon dioxide and energy fluxes were constructed under two consecutive German-funded research projects and designed to complement existing South African infrastructures. They will be transferred to partner institutions at project termination, supported by deliberate capacity building actions for long term sustainability. Joint activities were implemented to i) strengthen technical expertise for infrastructure maintenance, ii) introduce new generation of academic scientists to the topic, iii) co-develop a training concept to enhance local capacity to continue teaching the topic, iv) improve the uptake and use of data by the research community, v) improve data use and access by stakeholders, and vi) facilitate knowledge exchange between institutions. Co-designed activities included training, apprenticeships and knowledge exchange, student exchange, co-supervision, and public outreach. Following a similar model in international research projects could significantly benefit 1) national capacity for emission inventories, 2) development of long-term GHG observation networks, and 3) the global scientific community via improved availability of data. While we specifically focus on a network of GHG observations, the principles are applicable for the infrastructure to observe other surface/atmosphere exchange processes or other long term observational infrastructure.

Integrating project-based infrastructures with long-term greenhouse gas observations in Africa


 Species in the genus Vachellia (Fabaceae) have a global tropical and sub-tropical distribution. Numerous Vachellia species are currently observed to be expanding their indigenous ranges and increasing in dominance globally, suggesting an overarching driver. Most Vachellia species enhance nitrogen uptake mutualistically via specialized root nodule structures. Nodules contain N2-fixing rhizobia that consume host supplied carbon to catalyse atmospheric N2 into a plant useable form, a key element in plant growth. The rhizobial mutualism of some Vachellia species may be vital to understanding changing patterns of ecological success observed across the savanna precipitation gradient. Here, we investigated how the seedling root development and physiology of two dominant savanna woody species, the arid-adapted Vachellia erioloba and the mesic-adapted Vachellia sieberiana, responded to simulated drought events. Seedlings of both species were grown at 4%, 8% and 16% soil moisture content (SMC) for four months. Seedling growth and allometry of arid-adapted V. erioloba was unresponsive to water stress treatments, and no nodulation was observed, reflecting a fixed higher relative investment in belowground biomass. In contrast, V. sieberiana roots were nodulated, but developed the highest nodule biomass and growth rate when grown at the lowest soil moisture (4% SMC). These patterns suggest that effective life history strategies for the arid-30 adapted species precludes the need for rhizobial mutualism, possibly due to more “open” N cycling and lower competitive interactions in arid systems, while the more “closed” N cycling in mesic savannas, and higher competitive stress, may favour nodulation, especially under low water supply that limits root access to soil nitrogen, and signals a more competitive environment and an advantage from N2-fixing.

/pdf/nodulation-alleviates-water-stress-in-vachellia-sieberiana-jirje00if6.pdf

Guy F. Midgley

Papers

Climate Change, Extinction Risk, and Public Policy

Succulent Karoo Biome

Ecological aspects of the substrate and water relations of deciduous and evergreen plant forms in the western Karoo

Integrating project-based infrastructures with long-term greenhouse gas observations in Africa

Nodulation Alleviates Water Stress in Vachellia Sieberiana