Climate suitability predictions for the cultivation of macadamia (Macadamia integrifolia) in Malawi using climate change scenarios.

Climate change is altering suitable areas of crop species worldwide, with cascading effects on people reliant upon those crop species as food sources and for income generation. Macadamia is one of Malawi's most important and profitable crop species; however, climate change threatens its production. Thus, this study's objective is to quantitatively examine the potential impacts of climate change on the climate suitability for macadamia in Malawi. We utilized an ensemble model approach to predict the current and future (2050s) suitability of macadamia under two Representative Concentration Pathways (RCPs). We achieved a good model fit in determining suitability classes for macadamia (AUC = 0.9). The climatic variables that strongly influence macadamia's climatic suitability in Malawi are suggested to be the precipitation of the driest month (29.1%) and isothermality (17.3%). Under current climatic conditions, 57% (53,925 km2) of Malawi is climatically suitable for macadamia. Future projections suggest that climate change will decrease the suitable areas for macadamia by 18% (17,015 km2) and 21.6% (20,414 km2) based on RCP 4.5 and RCP 8.5, respectively, with the distribution of suitability shifting northwards in the 2050s. The southern and central regions of the country will suffer the greatest losses (≥ 8%), while the northern region will be the least impacted (4%). We conclude that our study provides critical evidence that climate change will reduce the suitable areas for macadamia production in Malawi, depending on climate drivers. Therefore area-specific adaptation strategies are required to build resilience among producers.

Synergistic impacts of anthropogenic fires and aridity on plant diversity in the Western Ghats: Implications for management of ancient social-ecological systems.

Identifying the impacts of anthropogenic fires on biodiversity is imperative for human-influenced tropical rainforests because: i) these ecosystems have been transformed by human-induced fires for millennia; and ii) their effective management is essential for protecting the world's terrestrial biodiversity in the face of global environmental change. While several short-term studies elucidate the impacts of fires on local plant diversity, how plant diversity responds to fire regimes over long timescales (>100 years) is a significant knowledge gap, posing substantial impediment to evidence-based management of tropical social-ecological systems. Using wet evergreen forests of the Western Ghats of India as a model system, we discuss the synergistic effects of anthropogenic fires and enhanced aridity on tropical plant diversity over the past 4000 years by examining fossil pollen-based diversity indices (e.g., pollen richness and evenness, and temporal ß-diversity), past fire management, the intervals of enhanced aridity due to reduced monsoon rainfall and land use history. By developing a historical perspective, our aim is to provide region-specific management information for biodiversity conservation in the Western Ghats. We observe that the agroforestry landscape switches between periods of no fires (4000-1800 yr BP, and 1400-400 yr BP) and fires (1800-1400 yr BP, and 400-0 yr BP), with both fire periods concomitant with intervals of enhanced aridity. We find synergistic impacts of anthropogenic fires and aridity on plant diversity uneven across time, pointing towards varied land management strategies implemented by the contemporary societies. For example, during 1800-1400 yr BP, diversity reduced in conjunction with a significant decrease in the canopy cover related to sustained use of fires, possibly linked to large-scale intensification of agriculture. On the contrary, the substantially reduced fires during 400-0 yr BP may be associated with the emergence of sacred forest groves, a cultural practice supporting the maintenance of plant diversity. Overall, notwithstanding apparent changes in fires, aridity, and land use over the past 4000 years, present-day plant diversity in the Western Ghats agroforestry landscape falls within the range of historical variability. Importantly, we find a strong correlation between plant diversity and canopy cover, emphasising the crucial role of maintenance of trees in the landscape for biodiversity conservation. Systematic tree management in tropical social-ecological systems is vital for livelihoods of billions of people, who depend on forested landscapes. In this context, we argue that agroforestry landscapes can deliver win-win solutions for biodiversity as well as people in the Western Ghats and wet tropics at large.

Practitioner insights as a means of setting a context for conservation.

A key obstacle to conservation success is the tendency of conservation professionals to tackle each challenge individually rather than collectively and in context. We sought to prioritize barriers to conservation previously described in the conservation literature. We undertook an online survey of 154 practitioners from over 70 countries to ascertain the most important barriers to conservation they faced. We used statistical analyses to identify the key impediments to conservation success and to examine whether these were affected by organizational attributes. Twenty-one barriers were identified. The importance ascribed to those was influenced by continent of operation and organization size, but not by organization age or autonomy (from larger parent organizations). We found the most important barriers to consider when undertaking conservation action were wider issues (e.g., population growth, consumerism, favoring development, and industrial-scale activity), operating environment (e.g., lack of political will, ineffective law enforcement, weak governments, corruption, safety and security), community attributes (e.g., dynamics, conflicts, and education levels), and the way conservation is undertaken (overconfidence, lack of funding, and externally set agendas). However, we advise against applying a one-size-fits-all approach. We propose that conservationists account for the complex socioecological systems they operate in if they are to achieve success.

Percepciones de los Profesionales Como Medio para Establecer un Contexto Para la Conservación Resumen Un obstáculo clave para el éxito de la conservación es la tendencia de los profesionales de la conservación a abordar cada desafío individualmente en lugar de colectivamente y en contexto. Buscamos priorizar las barreras a la conservación descritas anteriormente en la literatura de conservación. Realizamos una encuesta en línea a 154 profesionales de más de 70 países para determinar las barreras más importantes para la conservación a las que se enfrentaban. Utilizamos análisis estadísticos para identificar los principales impedimentos para el éxito de la conservación y para examinar si estos se vieron afectados por atributos organizativos. Se identificaron veintiún barreras. La importancia que se les atribuye fue influenciada por el continente donde operan y el tamaño de la organización, pero no por la edad o la autonomía de la organización (de las organizaciones más grandes). Encontramos que los obstáculos más importantes a tener en cuenta al emprender acciones de conservación eran cuestiones más amplias (e. g., crecimiento de la población, consumismo, fomento del desarrollo y actividad a escala industrial), medio ambiente (e. g., falta de voluntad política, ineficacia en la aplicación de la ley, gobiernos débiles, corrupción, seguridad y protección), atributos comunitarios (e. g., dinámicas, conflictos y niveles educativos) y la forma en que se lleva a cabo la conservación (exceso de confianza, falta de financiamiento y agendas establecidas externamente). Sin embargo, aconsejamos no aplicar un enfoque "un tamaño se ajusta a todo". Para lograr el éxito, proponemos que los conservacionistas tengan en cuenta los complejos sistemas socioecológicos en los que operan.

Long-term disturbance dynamics and resilience of tropical peat swamp forests.

1. The coastal peat swamp forests of Sarawak, Malaysian Borneo, are undergoing rapid conversion, predominantly into oil palm plantations. This wetland ecosystem is assumed to have experienced insignificant disturbance in the past, persisting under a single ecologically-stable regime. However, there is limited knowledge of the past disturbance regime, long-term functioning and fundamentally the resilience of this ecosystem to changing natural and anthropogenic perturbations through time. 2. In this study, long-term ecological data sets from three degraded peatlands in Sarawak were collected to shed light on peat swamp forest dynamics. Fossil pollen and charcoal were counted in each sedimentary sequence to reconstruct vegetation and investigate responses to past environmental disturbance, both natural and anthropogenic. 3. Results demonstrate that peat swamp forest taxa have dominated these vegetation profiles throughout the last c. 2000-year period despite the presence of various drivers of disturbance. Evidence for episodes of climatic variability, predominantly linked to ENSO events, and wildfires is present throughout. However, in the last c. 500 years, burning and indicators of human disturbance have elevated beyond past levels at these sites, concurrent with a reduction in peat swamp forest pollen. 4. Two key insights have been gained through this palaeoecological analysis: (i) peat swamp forest vegetation has demonstrated resilience to disturbance caused by burning and climatic variability in Sarawak in the late Holocene, however (ii) coincident with increased fire combined with human impact c. 500 years ago, these communities started to decline. 5.Synthesis. Sarawak's coastal peat swamps have demonstrated resilience to past natural disturbances, with forest vegetation persisting through episodes of fire and climatic variability. However, palaeoecological data presented here suggest that recent, anthropogenic disturbances are of a greater magnitude, causing the observed decline in the peat swamp forest communities in the last c. 500 years and challenging the ecosystem's persistence. This study greatly extends our knowledge of the ecological functioning of these understudied ecosystems, providing baseline information on the past vegetation and its response to disturbance. This understanding is central to developing management strategies that foster resilience in the remaining peat swamp forests and ensure continued provision of services, namely carbon storage, from this globally important ecosystem.

Recovery and resilience of tropical forests after disturbance.

The time taken for forested tropical ecosystems to re-establish post-disturbance is of widespread interest. Yet to date there has been no comparative study across tropical biomes to determine rates of forest re-growth, and how they vary through space and time. Here we present results from a meta-analysis of palaeoecological records that use fossil pollen as a proxy for vegetation change over the past 20,000 years. A total of 283 forest disturbance and recovery events, reported in 71 studies, are identified across four tropical regions. Results indicate that forests in Central America and Africa generally recover faster from past disturbances than those in South America and Asia, as do forests exposed to natural large infrequent disturbances compared with post-climatic and human impacts. Results also demonstrate that increasing frequency of disturbance events at a site through time elevates recovery rates, indicating a degree of resilience in forests exposed to recurrent past disturbance.

Tree migration-rates: narrowing the gap between inferred post-glacial rates and projected rates.

Faster-than-expected post-glacial migration rates of trees have puzzled ecologists for a long time. In Europe, post-glacial migration is assumed to have started from the three southern European peninsulas (southern refugia), where large areas remained free of permafrost and ice at the peak of the last glaciation. However, increasing palaeobotanical evidence for the presence of isolated tree populations in more northerly microrefugia has started to change this perception. Here we use the Northern Eurasian Plant Macrofossil Database and palaeoecological literature to show that post-glacial migration rates for trees may have been substantially lower (60-260 m yr(-1)) than those estimated by assuming migration from southern refugia only (115-550 m yr(-1)), and that early-successional trees migrated faster than mid- and late-successional trees. Post-glacial migration rates are in good agreement with those recently projected for the future with a population dynamical forest succession and dispersal model, mainly for early-successional trees and under optimal conditions. Although migration estimates presented here may be conservative because of our assumption of uniform dispersal, tree migration-rates clearly need reconsideration. We suggest that small outlier populations may be a key factor in understanding past migration rates and in predicting potential future range-shifts. The importance of outlier populations in the past may have an analogy in the future, as many tree species have been planted beyond their natural ranges, with a more beneficial microclimate than their regional surroundings. Therefore, climate-change-induced range-shifts in the future might well be influenced by such microrefugia.

A battle lost? Report on two centuries of invasion and management of Lantana camara L. in Australia, India and South Africa.

Recent discussion on invasive species has invigorated the debate on strategies to manage these species. Lantana camara L., a shrub native to the American tropics, has become one of the worst weeds in recorded history. In Australia, India and South Africa, Lantana has become very widespread occupying millions of hectares of land. Here, we examine historical records to reconstruct invasion and management of Lantana over two centuries and ask: Can we fight the spread of invasive species or do we need to develop strategies for their adaptive management? We carried out extensive research of historical records constituting over 75% of records on invasion and management of this species in the three countries. The records indicate that governments in Australia, India and South Africa have taken aggressive measures to eradicate Lantana over the last two centuries, but these efforts have been largely unsuccessful. We found that despite control measures, the invasion trajectory of Lantana has continued upwards and that post-war land-use change might have been a possible trigger for this spread. A large majority of studies on invasive species address timescales of less than one year; and even fewer address timescales of >10 years. An understanding of species invasions over long time-scales is of paramount importance. While archival records may give only a partial picture of the spread and management of invasive species, in the absence of any other long-term dataset on the ecology of Lantana, our study provides an important insight into its invasion, spread and management over two centuries and across three continents. While the established paradigm is to expend available resources on attempting to eradicate invasive species, our findings suggest that in the future, conservationists will need to develop strategies for their adaptive management rather than fighting a losing battle.

Biodiversity conservation in agricultural landscapes: challenges and opportunities of coffee agroforests in the Western Ghats, India.

The new approaches advocated by the conservation community to integrate conservation and livelihood development now explicitly address landscape mosaics composed of agricultural and forested land rather than only protected areas and largely intact forests. We refer specifically to a call by Harvey et al. (2008) to develop a new approach based on six strategies to integrate biodiversity conservation with sustainable livelihoods in Mesoamerican landscape mosaics. We examined the applicability of this proposal to the coffee agroforests of the Western Ghats, India. Of the six strategies, only one directly addresses livelihood conditions. Their approach has a clear emphasis on conservation and, as currently formulated risks repeating the failures of past integrated conservation and development projects. It fails to place the aspirations of farmers at the core of the agenda. Thus, although we acknowledge and share the broad vision and many of the ideas proposed by this approach, we urge more balanced priority setting by emphasizing people as much as biodiversity through a careful consideration of local livelihood needs and aspirations.

Agroforestry: a refuge for tropical biodiversity?

As rates of deforestation continue to rise in many parts of the tropics, the international conservation community is faced with the challenge of finding approaches which can reduce deforestation and provide rural livelihoods in addition to conserving biodiversity. Much of modern-day conservation is motivated by a desire to conserve 'pristine nature' in protected areas, while there is growing recognition of the long-term human involvement in forest dynamics and of the importance of conservation outside protected areas. Agroforestry -- intentional management of shade trees with agricultural crops -- has the potential for providing habitats outside formally protected land, connecting nature reserves and alleviating resource-use pressure on conservation areas. Here we examine the role of agroforestry systems in maintaining species diversity and conclude that these systems can play an important role in biodiversity conservation in human-dominated landscapes.