Incorporating local ecological knowledge into urban riparian restoration in a mountainous region of Southwest China

Modern cities use straightened and concrete watercourses with simple greening for riparian zones, which has been criticised for insensitivity to natural system integrity and cultural identity. This increases the challenge to urban ecologists, landscape designers and managers to conceive innovative and effective design solutions that do not jeopardise hydraulic efficiency yet are culturally acceptable to local communities. This paper introduces the field of local ecological knowledge (LEK) as rich sources of inspiration and design solutions to meet this challenge. LEK refers to knowledge and practices of various local cultures about the relationship of living beings (including humans) with their environments. Wepropose a pragmatic framework that integrates LEK with modern landscape design. It includes steps: (1) investigate existing practices, skills andmeasures relating to LEK; (2) explore how and whereLEKcan inspire or integrate withdesign. Here we propose three aspects for integration in accordance with the nature of landscaping process: overall structure, component and maintenance.(3)evaluate and test the integration in terms of its acceptability by local communities. Taking the riparian revegetation project of Hanfeng Lake Urban Wetland Park (Chongqing Municipality) as an example, we illustrate the utility of this framework. 11 local common practices relating to LEK were identified. According to thethree aspects for integration, alternative design solutions were offered. The survey showed that LEK based designwas more highly valued than other conventional ways in terms of useracceptance. We conclude that LEK provides actionable ecologically sound and culturally desirablesolutions for urbanlandscape. We also recognise that LEK evolveswith changing environments and new harmonious and dynamic human-nature relationships arecontinually re-forming. The process of acquisition and application of LEK could encourage multidisciplinary and synthetic approaches to urban ecosystems. Such adaptability and interdisciplinary engagementare crucial totoday’schanging and complexurban environments.     

Surrounding pressure controlled by water table alters CO2 and CH4 fluxes in the littoral zone of a brackish-water lake

We studied the effect of water table on CO₂ and CH₄ fluxes at different time scales in the littoral zone of Lake Obuchi, a brackish lake in northern Japan. The vegetation formed three distinct zones along the water table gradient, two dominated by emergent aquatic macrophytes (the Phragmites australis-dominated zone and the Juncus yokoscensis-dominated zone) and one dominated by terrestrial macrophytes (Miscanthus sinensis and Cirsium inundatum-dominated zone). To clarify the impact of variations in water table on monthly and yearly summed CO₂ and CH₄ fluxes, we examined the relationship between water table and the ratio of observed flux to calculated flux, whereby the calculated flux was based solely on the exponential relationship between flux and soil temperature for each gas. This study revealed that the impact of variations in water table on monthly and yearly summed CO₂ and CH₄ fluxes differed markedly between the vegetation zones. By taking the temporal change in water table into account in the estimation of both the CO₂ and CH₄ fluxes, the monthly summed CO₂ and CH₄ fluxes in the Phragmites-zone were markedly greater in every month of the year compared to estimation based on temperature alone. In the Juncus-zone, the effect of water table on monthly summed CO₂ and CH₄ fluxes differed between months. In addition, the magnitude of water-table effects controlling monthly summed CO₂ and CH₄ fluxes differed with atmospheric conditions, i.e., between the pressure-falling and low-pressure phase on the one hand and other pressure phases on the other hand. After weighting all the impacts of temporal changes in water table on fluxes, the yearly summed CO₂ and CH₄ fluxes showed a 1.26–6.64-fold increase compared with not taking water table effects into account, and the increase differed among the three vegetation zones.     

Effect of Prosopis (mesquite) invasion and clearing on vegetation cover in semi-arid Nama Karoo rangeland,South Africa

The Nama-Karoo is the largest of the three biomes that comprise the semi-arid Karoo-Namib ecoregion of southern Africa. Large tracts of Nama-Karoo rangeland have been invaded by alien leguminous trees of the genus Prosopis. We assessed the impact of Prosopis invasion and clearing on vegetation cover in heavily grazed Nama-Karoo rangeland on two sheep farms in the Beaufort West district of the Western Cape province of South Africa. Our results suggest that, below critical threshold cover levels, Prosopis trees do not affect indigenous vegetation and add to overall rangeland vegetation cover. However, once Prosopis cover exceeds critical thresholds, the trees begin to negatively impact on indigenous vegetation (especially grasses) and overall vegetation cover. In addition, our data suggest that vegetation cover recovers after Prosopis clearing, being temporarily higher than pre-invasion levels possibly as a result of enhanced post-invasion soil fertility. Lastly, our results suggest that Prosopis trees reduce rangeland erosion potential at low cover and increase it after they exceed critical threshold cover. Information about thresholds of Prosopis impact can be used to direct clearing efforts for maximum benefit when resources are limited.     

An assessment of the effectiveness of a large,national-scale invasive alien plant control strategy in South Africa

This paper presents an assessment of a large, national-scale alien plant control program that has operated in South Africa for 15 years. We reviewed data from three national-level estimates of the extent of invasion, records of the costs and spatial extent of invasive species control operations, assessments of the effectiveness of biological control, and smaller-scale studies. The 19 most important invasive taxa, mainly trees, in terrestrial biomes were identified. The effectiveness of control efforts on the extent of invasion of these taxa was assessed. Control costs over 15 years amounted to 3.2 billion rands (US$457 million), more than half of which was spent on 10 taxa, the most prominent being in the genera Acacia, Prosopis, Pinus and Eucalyptus. Despite substantial spending, control operations were in many cases applied to a relatively small portion of the estimated invaded area, and invasions appear to have increased, and remain a serious threat, in many biomes. Our findings suggest that South Africa’s national-scale strategy to clear invasive alien plants should be substantially modified if impacts are to be effectively mitigated. Rather than attempting to control all species, and to operate in all areas, a more focused approach is called for. This would include prioritising both the species and the areas, and setting goals and monitoring the degree to which they are achieved, within a framework of adaptive management. A greater portion of funding should also be directed towards biological control, where successes have been most notable.     

Collembola diversity in the critically endangered Cape Flats Sand Fynbos and adjacent pine plantations

The replacement of indigenous vegetation by commercial alien plantations can strongly affect invertebrate species richness and composition. This has been demonstrated for some invertebrate taxa in the Fynbos vegetation of the Western Cape, but the response of litter-dwelling Collembola has not been documented. Here we compared the richness and abundance of litter-dwelling Collembola assemblages in Pinus radiata plantations and in adjacent rehabilitated Cape Flats Sand Fynbos (CFSF) in the Tokai Forest Reserve, Western Cape, South Africa. A total of 48 Collembola morphospecies was identified, of which 14 species were recorded exclusively from the pine plantations, and six exclusively from the CFSF. Abundance and morphospecies richness was higher in the pine plantations than in the CFSF, with 34 morphospecies found in the CFSF, and 42 morphospecies in the pine plantations. Fourteen species were likely invasive taxa, of which eight were found in CFSF, and 13 in the pine plantations. Multivariate analyses indicated significant differences in the assemblages of the two habitat types based on abundance, but using presence–absence data only, no difference was found. Significant relationships were found between springtail richness and abundance and site humidity, which differed between the CFSF (drier) and pine plantation (moister), likely accounting for the differences in richness and abundance among habitat types.     

Are road verges corridors for weed invasion? Insights from the fine‐scale spatial genetic structure of Raphanus raphanistrum

Raphanus raphanistrum (Brassicaceae) is considered amongst the world's worst agricultural weeds. We address critical issues in its management by studying the pathway of colonisation at local scales. For this, we assessed the small‐scale spatial genetic structure of 231 samples collected from three different sites across the Cape Floristic Region, South Africa, using 11 nuclear microsatellite markers. Although natural pollen and seed dispersal were expected to be restricted, we found no significant relationship between genetic and geographical distance within sites. Instead, our results suggest that R. raphanistrum had colonised new habitats via jump dispersal, rather than through natural diffusive dispersal at local scales. We did not find evidence for road verges as dispersal corridors, as evidenced by a lack of isolation‐by‐distance at local scales. Instead, the absence of spatial genetic structure suggests that R. raphanistrum had rapidly spread throughout its current range, possibly facilitated by human‐mediated actions. Management plans addressing containment or suppression of the weedy species R. raphanistrum (and possibly other weedy species) should take the high degree of connectivity between distant geographical localities into account.     

Silvicultural treatments for sapling mesquite (Prosopis glandulosa var. glandulosa) to optimize timber production and minimize seedling encroachment

To maximize lumber production and minimize weed problems with Prosopis glandulosa, silvicultural treatment methods were evaluated nine years after initiation. A randomized complete block design was used with four replicates and six treatments. Plots were shredder-harvested leaving sixteen 2-m squares on 10-m spacing that included a final rotation crop tree. In three of the treatments the crop trees were pruned to a single stem. To prevent re-establishment of mesquite in the interstitial areas, plots were spot sprayed with herbicides, disked, or disked and seeded with rye grass in 1986. Herbicide treatments and disking continued yearly through 1989. In 1991, disk treatments were repeated. After both 2.5 and 9 yrs, significant treatment differences were found for growth of basal diameter, growth of basal area, and growth of dry weight. The greatest crop tree growth occurred in treatments that were pruned with interstitial competition suppressed. Mortality was greatest in the dense treatments, while re-establishment of mesquite was greatest in the more open treatments. The greatest basal diameter growth of 1.21 cm year⁻¹ in the disked and pruned treatments is comparable to other fine hardwoods in temperate and dry tropical forests.     

A review of the biology and status of Cape Fold Ecoregion freshwater fishes

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Effect of an intensive mechanical removal effort on a population of non‐native rainbow trout Oncorhynchus mykiss in a South African headwater stream

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