Functional diversity and composition of Caatinga woody flora are negatively impacted by chronic anthropogenic disturbance

Tropical plant assemblages can be taxonomically and phylogenetically impoverished by chronic anthropogenic disturbance (CAD), such as firewood collection and extensive grazing. However, to what extent the functional dimension responds to CAD is still unclear. Such knowledge is urgently required for predicting, preventing or even reversing the impacts of CAD. Chronic anthropogenic disturbance may operate as an ecological filter by selecting functional trait values (e.g. low wood density), thereby altering the functional composition and diversity of plant assemblages. We tested this hypothesis using 29 woody plant assemblages across three ontogenetic stages (seedlings, saplings and adults) in a 220‐km2 landscape of the Caatinga, northeast Brazil. We adopted a CAD index consisting of four indicators (proximity to urban centre and houses and the density of both people and livestock) and tested how well it explained the functional diversity and effect sizes (richness, evenness and dispersion) and composition (community‐weighted mean). Chronic anthropogenic disturbance affected several functional metrics across the three ontogenetic stages. However, CAD effects were stronger in adult communities by negatively affecting functional richness, dispersion and their effect sizes. CAD also altered the functional composition of leaf mass per area, woody density and leaf area of adult assemblages. Sapling communities were affected in terms of functional composition (leaf area, leaf dry matter and wood density), with positive and negative effects, while seedling assemblages responded positively to CAD only in terms of functional evenness and its effect size. Some changes in functional metrics were influenced by dominant Euphorbiaceae species across ontogenetic stages, especially in terms of leaf area and woody density. Synthesis. Chronic anthropogenic disturbance is an important driver of plant‐community functional organization across ontogenetic stages in the Caatinga. Adult assemblages are particularly sensitive and tend to lose functional niche space and support more acquisitive rather than conservative strategies as chronic anthropogenic disturbance increases. The proliferation of Euphorbiaceae disturbance‐adapted species can explain part of the community responses to chronic anthropogenic disturbance. Our findings highlight the ecological effects of chronic anthropogenic disturbance and show that it is a key influence on tropical biotas. Changes in plant functional traits associated with plant resource use are likely to affect ecosystem functioning and services provided by Caatinga.

Climbing the mountain fast but smart: Modelling rubber tree growth and latex yield under climate change

Pará rubber (Hevea brasiliensis Müll. Arg) plantations have expanded into regions with sub-optimal growth conditions: distinct dry seasons and temperatures cooler than in humid tropics. The impact of these new marginal environments and future climate change on rubber tree development and latex yield is largely unknown. This hampers reliable prediction of farmers’ revenues and extent of carbon sequestration at landscape level. To improve our understanding of rubber trees response to planting at high altitudes and associated increase in planting densities, we applied the process-based Land Use Change Impact Assessment tool (LUCIA). It was calibrated with detailed ground survey data from Xishuangbanna, southwest China to model tree biomass development and latex yield in rubber plantations at the tree, plot and landscape level. Plantations were analyzed at <900 m above sea level (a.s.l., lowland rubber) and ≧900 m a.s.l. (highland rubber) in order to characterize the effect of elevation on rubber trees. Three planting densities: low (600 trees ha−1) were tested. Four greenhouse gas emission scenarios, with Representative Concentration Pathways (RCP) ranging from the lowest RCP 2.6 to the highest emission scenario RCP 8.5, were used to test rubber tree response to climate change. During a 40-year rotation under current climate, lowland rubber plantations grew faster and had larger latex yields than highland rubber. The average biomass of lowland rubber was 9% and 18% higher than those of highland rubber for aboveground and belowground biomass, respectively. High planting density rubber plantations showed 5% and 4% higher above ground biomass than those at low- and medium-planting density, but simulations suggest that the cumulative latex production decreased strongly by 26% and 14% respectively. The results of the RCP 8.5 climate change scenario suggested that during 40 years simulation mean total biomass and cumulative latex yield of highland rubber (per tree) increased by 28% and 48%, while lowland rubber increased by 8% and 10% respectively when compared to the baseline. Other rubber cultivation regions could also benefit from this modelling approach that helps in optimization of carbon stock and latex production in rubber-based system. The results could help in development of future climate change adaption and mitigation strategies.

Climate-Smart Livestock Production Systems in the Midlands and Highlands of Ethiopia

Livestock is an integral part of agriculture and has an important economic, social, and cultural significance in Ethiopia. Climate change affects livestock production by affecting feed and nutrition, water accessibility, and health. Although livestock production plays a huge role in Ethiopia’s economy and food security, poor livestock management practices characterized by unsustainable free grazing and greenhouse gas emissions have had a negative impact on the environment. At the same time, climate change has had tremendous negative impacts on livestock production. In order to reduce the ef-fects of climate change on livestock and enhance environmentally friendly livestock production, it is important to improve livestock management practices and introduce a sustainable grazing system, appropriate policies, and institutional set up. Applying cut-and-carry feeding and agroforestry, along with improved feed and better breed-ing practices offers major opportunities for reducing emissions and increasing the sequestration of greenhouse gases. Moreover, it is necessary to encourage and reward farmers, administrative bodies, and experts who practice the cut-and-carry feeding system suc-cessfully. This chapter elaborates on the application of integrated technical and non-technical “best fit” options for a livestock produc-tion system. The best fit technological options focus on modifying livestock diversity and number and improving management, breed-ing, and feed, while non-technical options include developing and implementing appropriate policies, local bylaws, and indigenous knowledge on livestock production systems. Integrating these ap-proaches, together with effective surveillance and rapid response strategies, as well as use of better breeds with greater resistance to drought and disease vectors, could play a large role in developing adaptation and mitigation strategies and building resilient livestock agriculture in the face of a changing climate.

Agroforestry for sustainable mountain management in Southeast Asia (in Thai Language)

Agroforestry brings not only direct benefits for livelihoods and the environment in mountains but also indirectly to lowlands. It improves adaptive capacity through diversification and spread of production risks and also mitigates climate change. Lack of recognition of the benefits of agroforestry and a shortage of government support miss opportunities for sustainable development. Nevertheless, regional policies and coordination exist and will be important instrument for agroforestry development in mountainous areas of ASEAN countries.

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