Many external effects of land use change are based on modifications of lateral flows of soil, water, air, fire or organisms. Lateral flows can be intercepted by filters and thus the severity and spatial range of external effects of land use change is under the influence of filter effects. Wherever lateral flows are involved, research results cannot be simply scaled on an area basis, and overall impact does not follow simple linear causal relationships. This complexity has consequences for relationships amongst the primary agents who initiate or exacerbate external effects, other stakeholders who are affected by them and policymakers who attempt to mitigate problems that reach sufficient visibility in society. In this paper we review how the relative importance of lateral flows and filter effects differs among a number of externalities, and the implications this has for research methods. If flows and filters are incompletely understood, policies may be based on fallacies. Whereas ‘fire-breaks’ act as filters in the lateral flow of the high temperature pulse of a fire, smoke from land-based fires can be intercepted only by rainfall acting as a filter and the external impact of smoke is determined by the atmospheric conditions governing lateral flow and chemical transformations along the pathway. Causal relations in smoke and haze problems are relatively simple and may form a basis for designing policy interventions to reduce downwind damage. For biodiversity issues, landscape connectivity, the absence of filters restricting dispersal and movement of organisms, is increasingly recognised as an influence on the dynamics of species richness and its scaling relations. Biodiversity research methods can extend beyond the current descriptive stage into clarifying causal relations with a lateral flow perspective. The question whether connectivity is in fact desired, however, depends on stakeholder interests and situation. Forest functions in watershed protection, presumably leading to a continuous flow of clean water in the dry season through the subsoil instead of a rapid surface transfer, have been generally attributed to the trees rather than the forest, with its rough surface structure, swamps and infiltration sites. A new synthesis of site-specific hydrological knowledge and tree water balance studies may be needed to separate myth from reality, and avoid wasting public funds on tree planting under the heading of reforestation, without restoring the hydrological regime of a real forest. Soil movement can be intercepted at a range of scales and in as far as soil transport entails movement of soil fertility, filter zones can be very productive elements of a landscape. To achieve ‘integrated natural resource management’ all external effects of land use will somehow have to be taken into account in farmer decision making about the use of natural resources on and off farm. Farmers’ ecological knowledge may include concepts of lateral flows and should be further explored as an integral part of a new landscape ecological approach.
Tag: biodiversity
Tree diversity in cacao agroforests in San Alejandro, Peruvian Amazon
Cacao (Theobroma cacao) cultivation maintaining a high proportion of shade trees in a diverse composition (agroforestry) is currently being viewed as a sustainable land use practice. Our research hypothesis was that cacao agroforests (AF) can support relatively high tree diversity, as compared to surrounding primary and/or secondary forests. The objective of this study was to assess the impact of forest conversion on tree communities by comparing tree composition, community characteristics (richness and diversity) and spatial structure (density, canopy height, basal area) among primary forest, secondary forest, and cacao AF. In total, we collected data from 30 25 × 25 m plots on three land use systems (20 in cacao AF, five in secondary, and five in primary forests) in San Alejandro, Peruvian Amazon. All trees with DBH 10 cm were counted, identified to species, and their height and DBH were recorded. Our results support the hypothesis that cacao AF present a relatively high tree species richness and diversity, although they are no substitute for natural habitats. We identified most common species used for shading cacao. Tree species composition similarity was highest between cacao AF and secondary forest. Vegetation structure (density, height, DBH) was significantly lower compared to primary and secondary forest. Species richness and diversity were found to be highest in the primary forest, but cacao AF and secondary forests were fairly comparable. The tree species cultivated in cacao AF are very different from those found in primary forest, so we question whether the relatively high tree diversity and richness is able to support much of the diversity of original flora and fauna.
Assessment of small mammal diversity in coffee agroforestry in the Western Ghats, India
Coffee agroforestry is a conservation strategy that has shown promise to support the diversity of bird, bat, and insect communities, but few studies have focused on non-volant mammals in coffee farms. We assessed mammal diversity within coffee agroforestry systems in Kodagu, India and investigated the impacts of the non-native shade tree species, Grevillea robusta, on mammal diversity. Twenty farms, with varying amounts of G. robusta planted within the coffee farm, were sampled throughout three rainfall zones during the 4-month study period. We captured six species of small mammals, with indirect methods yielding an additional five species, totaling 11 mammal species. Contrary to current ecological thought, we found that increased amounts of G. robusta did not have a negative impact on either abundance or richness of mammals. Small mammal abundances were higher at farms with greater amounts of herbaceous ground cover and larger, mature shade trees, while small mammal species richness was found to increase with an increase in tree species richness as well as greater amounts of herbaceous ground cover. Additionally, small mammal abundance was higher at coffee farms closer to forested areas. Based on these findings, we suggest the maintenance or cultivation of shade tree richness, mature shade trees, and herbaceous ground cover within coffee farms and preservation of forested areas within the landscape to enhance coffee agroforestry habitat for non-volant mammals. We hope that these habitat requirements will be incorporated into conservation strategies for the promotion of biodiversity within coffee agroforestry systems.
Effects of transformation processes on plant species diversity in homegardens of the Nuba Mountains, Sudan
Traditional homegardens (HGs) are considered to harbor high levels of plant diversity and have been therefore characterized as sustainable agro-ecosystems suitable for on-farm (incl. circa situm) conservation of plant genetic resources. While the functional structure of traditional HGs is poorly understood specifically for semi-arid and arid regions, their plant species richness and diversity is increasingly threatened by recent and fast evolving agricultural transformation processes. This has been particularly claimed for traditional jubraka HG systems of Sudan. Therefore, sixty-one HGs in four villages of the Nuba Mountains, South-Kordofan Province, Sudan, were randomly selected, geographically recorded and plant richness and abundance determined and plant diversity parameters calculated. In addition, socio-economic household data were assessed by interviews and soil samples taken to allow a comprehensive analysis of putative factors affecting HG plant diversity across different villages, levels of commercialization and plant species composition based clusters. A total of 110 species from 35 plant families were grown in the HGs along with 71 ornamentals. Perennial species accounted for 57 % including 12 indigenous fruit tree (IFT) species and six exotic fruit tree species. Mean species richness of useful plant species (excluding ornamentals) per HG was 23 (range 6–46). On average, 41 % of the 23 species per HG were of exotic origin, however, with a large range (21–83 %) among locations. Mean diversity and evenness indices were 1.46 (range 0.49–2.42) and 0.48 (0.15–0.87), respectively. The level of commercialization of HGs only marginally affected species diversity measures although the species richness was significantly higher for commercial than subsistence HGs. Species richness was higher on lower (6.6–7.2) pH soils. IFT richness was highly variable, but non-significantly different across the four locations. Plant species richness and diversity was high in comparison with other HG systems in semi-arid regions. Cluster analysis was found to be a valuable tool to classify HGs and to extract homogeneous HG types with low, intermediate and high richness and diversity. In addition, the share of exotic and ornamental species in HGs indicated a trend towards the loss of traditional farming practices, particularly in areas with good market access. The data did not indicate the hypothesized loss of inter-specific diversity due to commercialization and species richness was numerically even higher for market-oriented HGs compared to subsistence ones.
Trade-offs between crop intensification and ecosystem services: the role of agroforestry in cocoa cultivation
Research published in this special issue on cocoa agroforestry illustrates the multifunctional role of shade trees for sustaining cocoa production and improving farmers’ livelihoods, and addresses tradeoffs between higher cocoa yield and the provision of ecosystem services to local households and global society. Indeed, the use of diverse shade in cocoa cultivation is threatened by a new drive towards crop intensification. The removal of shade trees diminishes smallholders’ ability to adapt to global change driven by demographic pressure, food insecurity, cocoa price volatility and climate change. Some forms of crop intensification may reduce ecological resilience of cocoa production systems, making adaptation strategies, combining shade trees with innovative management practices, essential for sustaining cocoa yield. Managing trade-offs between yield and environmental services at the cocoa plot and landscape scales requires a multi-disciplinary approach to identify key management options that goes beyond the artificially polarized debates around intensified versus traditional agroforestry practices, or more generally, land-sparing versus land-sharing strategies. The global challenge facing the cocoa sector today is how to increase cocoa production to meet growing demand, without expanding the area under cocoa. This means finding sustainable ways to maintain cocoa production within today’s producing regions, particularly West Africa, through a series of technical innovations geared towards smallholders. Inappropriate intensification may result in heavy deforestation on new pioneer fronts, such as the Congo basin, and existing cocoa being replaced either by other agricultural commodities, or by less resilient and less environmentally friendly production practices.
Agroforestry and deforestation in Malawi: inter-linkages between attitudes, beliefs and behaviours
Farm-level tree planting has been suggested to have potential to decrease pressures on natural forests and, consequently, contribute towards reducing deforestation and forest degradation. However, the scientific evidence for such a link is limited. We examined farmers’ beliefs, attitudes and behaviours in relation to tree planting on farms and cutting down trees from the forest, as one way of establishing this link. A household survey was administered to 200 farmers in two rural districts in Malawi, which included an attitude scale based on the theory of planned behaviour. The results showed that farmers in Malawi recognise the benefits of planting trees, feel encouraged by fellow farmers, and feel capable of planting trees on their land. In addition, they believe cutting down trees from the forest will result in mainly negative outcomes, and feel discouraged by others and hindered by control factors to cut down trees from the forest. In total, 76 % of respondents planted trees in the past 5 years, 50 % collected firewood from the forest and 21 % collected poles. There was no evidence for a direct relationship between attitudes towards planting trees and cutting down trees, nor were the behaviours in relation to tree planting and cutting down trees from the forest significantly associated. However, there was evidence for an indirect relationship between tree planting behaviour and cutting down trees from the forest, as respondents who had planted trees had more negative attitudes towards cutting down trees from the forest. Future research should further explore the direct relationship between agroforestry and deforestation to establish if and under what conditions such a relationship might exist. © 2015, Springer Science+Business Media Dordrecht.
Provenance and pretreatment effect on seed germination of six provenances of Faidherbia albida (Delile) A. Chev
A nursery experiment was conducted to determine the effects of seed pretreatment methods on the germination of Faidherbia albida at ICRAF, Nairobi from six provenances consisting of Awassa, Taveta, Lake Koka, Maseno, Chinzombo and Wagingombe. Seeds were subjected to five pretreatment methods namely nicking, soaking in acid, hot water, cold water and control. Germination percentages (GP), mean germination time (MGT) and germination index (GI) were calculated and the data was subjected to ANOVA. The study revealed significant (p 0.05) differences in seed treatments among provenances in all studied parameters. Highest germination among pretreatments in Awassa (99 %) and Wagingombe (80 %) was observed in nicked seeds, Chinzombo (81 %) in nicked and acid treated seeds, Lake Koka (90 %) in acid treated seeds and Taveta (28 %) and Maseno (64 %) in cold water treated seeds. Nicking gave the highest cumulative GP (69.67) while lowest GP was observed in hot water treated seeds (23.17). Acid treatment exhibited lowest MGT (8.85 days) and highest GI (2.29) while highest MGT (24.35 days) and lowest GI (0.31) were observed in control and hot water treatment respectively. Although acid treatment gave a high GP and lowest MGT and GI, nicking and soaking in cold water for 24 h is being recommended as cheaper and less hazardous pretreatment methods to improve germination in F. albida since sulphuric acid is expensive and requires proper handling techniques. Significant correlation between geo-climatic data and germination parameters of seeds subjected to different pretreatments indicates that provenances are as important as pretreatments in germination of the species. © 2016 Springer Science+Business Media Dordrecht
Interacting regional-scale regime shifts for biodiversity and ecosystem services
Current trajectories of global change may lead to regime shifts at regional scales, driving coupled human-environment systems to highly degraded states in terms of biodiversity, ecosystem services, and human well-being. For business-as-usual socioeconomic development pathways, regime shifts are projected to occur within the next several decades, to be difficult to reverse, and to have regional- to global-scale impacts on human society. We provide an overview of ecosystem, socioeconomic, and biophysical mechanisms mediating regime shifts and illustrate how these interact at regional scales by aggregation, synergy, and spreading processes. We give detailed examples of interactions for terrestrial ecosystems of central South America and for marine and coastal ecosystems of Southeast Asia. This analysis suggests that degradation of biodiversity and ecosystem services over the twenty-first century could be far greater than was previously predicted. We identify key policy and management opportunities at regional to global scales to avoid these shifts.
The genus Phylloporus (Boletaceae, Boletales), from Mekong river basin (Yunnan Province, China)
The genus Phylloporus is a gilled bolete and a typical ectomycorrhizal mushroom which froms mycorrhizal with woody Fagaceae or Pinaceae. Collections of Phylloporus were made from Xiaozhongdian (Shangri-La), Haitang (Baoshan) and Menssong (Xishuangbanna) from May to October 2012. Morphology and sequence analysis revealed that the Phylloporus collections belonged to seven groups and five species: P. imbricatus (Xiaozhongdian, Shangri-La), P. pachcystidiatus and P. yunnanensis (Haitang, Baoshan), P. rubiginosus (Mengsong, Xishuangbanna) and P. megacystidiatus sp. Nov. (Mengsong, Xishuangbanna). In this paper we introduce one new Phylloporus species: Phylloporus megacystidiatus sp. Nov., and new record P. rubiginosus for the first time in Yunnan Province, China. The new species and the new record are described and illustrated with drawings and color photos. Also the species and new record are compared with similar taxa.
An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm
We assess progress toward the protection of 50% of the terrestrial biosphere to address the species-extinction crisis and conserve a global ecological heritage for future generations. Using a map of Earth’s 846 terrestrial ecoregions, we show that 98 ecoregions (12%) exceed Half Protected; 313 ecoregions (37%) fall short of Half Protected but have sufficient unaltered habitat remaining to reach the target; and 207 ecoregions (24%) are in peril, where an average of only 4% of natural habitat remains. We propose a Global Deal for Nature-a companion to the Paris Climate Deal-to promote increased habitat protection and restoration, national- and ecoregion-scale conservation strategies, and the empowerment of indigenous peoples to protect their sovereign lands. The goal of such an accord would be to protect half the terrestrial realm by 2050 to halt the extinction crisis while sustaining human livelihoods.