Small patches can be valuable for biodiversity conservation: two case studies on birds in southeastern Australia

Presence/absence datasets on birds from two landscapes in southeastern Australia were analysed as a case study to examine the conservation value of small habitat patches. In the Tumut landscape, patch sizes ranged between 0.5 and 97.6 ha; 30 species of birds (37%) were observed in patches of up to 1 ha, and 74 species (91%) were found in patches of up to 10 ha. In the Nanangroe landscape, patch sizes ranged from 0.4 to 15.6 ha, and 74 species of birds (75%) were found in patches smaller than 1 ha. In both landscapes, small patches contributed strongly to species accumulation curves. While large patches are needed by many species to maintain viable populations, it is important to recognise the complementary value of small remnants. In many landscapes, the conservation and restoration of small patches will often be the only feasible management option.     

玉屏风多糖对小鼠派氏结形态结构及其T细胞亚群的影响

通过研究玉屏风多糖（YPF-P）对小鼠派氏结（Peyer's patches,PPs）形态结构及其T细胞亚群的影响,探讨其对小鼠肠黏膜的免疫调节作用。选取96只SPF小鼠随机分为6组,分别为空白对照组（0.2 mL生理盐水）、YPF-P阳性对照组（YPF-P 200 mg/kg）、环磷酰胺（cyclophosvnamide,Cy）免疫抑制组（80 mg/kg Cy）及YPF-P低、中、高剂量组（100、200、400 mg/kg YPF-P）,饲喂1周,取小肠PPs,常规切片HE染色后应用图像分析技术检测PPs形态结构的变化;体外培养小鼠PPs淋巴细胞,采用流式细胞术研究PPs中T淋巴细胞亚群的变化。结果表明,YPF-P对小鼠小肠PPs的生长发育具有促进作用,Cy可极显著降低小鼠小肠PPs面积、小肠纵切面面积及PPs面积和小肠纵切面面积的比值（P < 0.01）,低、中、高剂量YPF-P可在一定程度上缓解Cy对小鼠小肠的损伤作用。同时,YPF-P可显著或极显著提高PPs中CD3⁺、CD4⁺ T淋巴细胞及CD4⁺/CD8⁺（P < 0.05; P < 0.01）。结果显示,YPF-P能提高Cy诱导的免疫抑制小鼠的肠黏膜免疫功能,并能促进PPs中相关T淋巴细胞增殖,对小鼠肠黏膜功能具有增强作用。     

EXPLOITATION OF PHOSPHORUS PATCHES WITH DIFFERENT PHOSPHORUS ENRICHMENT BY THREE ARBUSCULAR MYCORRHIZAL FUNGI

The effect of three arbuscular mycorrhizal (AM) fungi on phosphorus (P) nutrient activation and acquisition by maize from spatially heterogeneous sand was investigated using dual-mesh packages enriched with different P concentrations and compared with non-mycorrhizal cotrols. As would be expected the AM fungi significantly enhanced leaf photosynthetic rate and the biomass and P concentrations in shoots and roots. All three fungi (Glomus intraradices, Glomus mosseae and Glomus etunicatum) displayed the capacity to dissolve inorganic P and promoted P nutrient availability in the packages (P patches). G. etunicatum showed the largest effect comparing with Glomus intraradices and Glomus mosseae, particularly in packages with high concentrations of P. Possible mechanisms involved include the acidification of the P patches by the AM fungi, promotion of the dissolution of the P, and more marked effects of the three fungal isolates with increasing enrichment of P in the patches. Inoculation with G. etunicatum resulted in greater acidification compared to the other two fungi. We conclude that AM fungi can promote P availability by acidifying the soil and consequently exploiting the P in nutrient patches and by facilitating the growth and development of the host plants.     

Habitat Preferences of Clethrionomys Rufocanus in Boreal Sweden

A long-term decline of vole populations in boreal Sweden, especially of the grey-sided vole (Clethrionomys rufocanus Sund.), has been revealed by snap-trapping in 1971–2004. We identified important habitats for the grey-sided vole by mapping the distribution of cumulated number of reproductive females in 1971–1978, prior to the major decline in the 1980s. Mean abundance of C. rufocanus was higher in the western (inland) than eastern (coastland) part of the study area. As the inland appeared to represent the most, as far as we know, pristine, abundant part of the population, we based identification of high quality habitats on inland data only. Four habitats were more important than others and yielded nearly 86% of the reproductive females in spring: (1) forests of dry, (2) moist and (3) wet/hydric dwarf-shrub type, in addition to (4) forest/swamp complexes rich in dwarf-shrubs. The latter three habitats were used more frequently than expected from their occurrence in the landscape. Still, the variation in density of reproductive females within patches of the same habitat was frequently high. This suggested that habitat composition in the surrounding landscape, perhaps may have affected local vole density at the patch scale. Clear-cut sampling plots appeared to be low-frequently used by reproductive females, but also by males and immatures. In conclusion, our study indicated the importance of also studying habitat at a larger scale than that of the patch to get a deeper understanding on how habitat influences local and regional densities and population dynamics of C. rufocanus.     

Simulating the effects of weed spatial pattern and resolution of mapping and spraying on economics of site-specific management

The economic benefits of using site‐specific weed management (SSWM) are related to the proportion of the field that is weed‐infested, the number of weed patches and the spatial resolution of sampling and spraying technologies. In this paper we simulate different combinations of these factors using parameter values obtained for Avena sterilis ssp. ludoviciana growing in Spanish winter barley crops. The profitability of SSWM systems increased as the proportion of the field infested by this weed decreased and when patch distribution was more concentrated. Under most of the conditions tested, positive net returns for SSWM were obtained when the weed‐infested area was smaller than 30%. The highest net return occurred using a 12 m × 12 m mapping and spraying resolution. The critical parameter that determined the economic viability of patch mapping and spraying resolution was the technology costs. The site specific strategy was economically superior to the standard strategy (overall herbicide application) in most cases. However, the differential between the two strategies decreased when the number of patches and the resolution of mapping and spraying increased, such that the highest net returns were obtained with a single patch covering 14% of the field and using a 12‐m mapping and spraying resolution; whereas the worst net returns were obtained for all patch numbers when 64% of the field was infested and a 3‐m mapping and spraying resolution was used.     

Movements of creek chubs, Semotilus atromaculatus, among habitat patches in a plains stream

Abstract –  We studied summer movement patterns of creek chubs, Semotilus atromaculatus, in a low-gradient, sand-bottomed stream on the western plains of the United States. Creek chubs were highly associated with patches of cover consisting of wood or macrophytes. Movements among 37 patches in a 1.1-km segment were assessed in a mark-recapture study. Over 2-week intervals, 44% of recaptured fish changed patches. Net distances moved ranged from 4 to 606 m, median distance moved was 49 m. Of fish recaptured repeatedly during the four sampling periods, most (65%) changed patches at least once, but few were consistently mobile. Inter-patch distance was an important variable with a negative effect on creek chub movements. Inter-patch cover was less important, but had a positive effect on movements. Frequent, short-distance movements among habitat patches in summer are a component of the ecology of creek chubs and the spatial arrangement of patches, and intervening stream conditions appear to mediate those movements.     

Fluxes of CO2, CH4, and N2O in an alpine meadow affected by yak excreta on the Qinghai-Tibetan plateau during summer grazing periods

To assess the impacts of yak excreta patches on greenhouse gas (GHG) fluxes in the alpine meadow of the Qinghai-Tibetan plateau, methane (CH₄), carbon dioxide (CO₂), and nitrous oxide (N₂O) fluxes were measured for the first time from experimental excreta patches placed on the meadow during the summer grazing seasons in 2005 and 2006. Dung patches were CH₄ sources (average 586 μg m⁻² h⁻¹ in 2005 and 199 μg m⁻² h⁻¹ in 2006) during the investigation period of two years, while urine patches (average −31 μg m⁻² h⁻¹ in 2005 and −33 μg m⁻² h⁻¹ in 2006) and control plots (average −28 μg m⁻² h⁻¹ in 2005 and −30 μg m⁻² h⁻¹ in 2006) consumed CH₄. The cumulative CO₂ emission for dung patches was about 36-50% higher than control plots during the experimental period in 2005 and 2006. The cumulative N₂O emissions for both urine and dung patches were 2.1-3.7 and 1.8-3.5 times greater than control plots in 2005 and 2006, respectively. Soil water-filled pore space (WFPS) explained 35% and 36% of CH₄ flux variation for urine patches and control plots, respectively. Soil temperature explained 40-75% of temporal variation of CO₂ emissions for all treatments. Temporal N₂O flux variation in urine patches (34%), dung patches (48%), and control (56%) plots was mainly driven by the simultaneous effect of soil temperature and WFPS. Although yak excreta patches significantly affected GHG fluxes, their contributions to the whole grazing alpine meadow in terms of CO₂ equivalents are limited under the moderate grazing intensity (1.45 yak ha⁻¹). However, the contributions of excreta patches to N₂O emissions are not negligible when estimating N₂O emissions in the grazing meadow. In this study, the N₂O emission factor of yak excreta patches varied with year (about 0.9-1.0%, and 0.1-0.2% in 2005 and 2006, respectively), which was lower than IPCC default value of 2%.     

关于森林公园景观生态的若干问题

本研究应用景观生态原理阐明了构建森林公园景观斑块、边缘、走廊、本底及其功能,地貌、气候、水、生物、土壤、干扰影响着森林公园的景观多样性;森林公园景观功能是镶嵌斑块物流、能流的源和汇的关系消长结果;同时,文中对森林公园的景观动态进行描述。     

An integrated approach for measuring urban forest restoration success

Rapid urban growth has increased the importance of restoring degraded vegetation patches within these areas. In this study, we reforested a site that was previously dominated by exotic grasses within an urban area. The goal of this study was to evaluate restoration success in a reforested site using four variables of vegetation structure, five groups of organisms, and eight variables of ecosystem processes, and compare these values with a pre-reforested site and a forested reference site using the Subjective Bray Curtis Ordination. The change in vegetation structure provided arboreal habitats that increased species diversity and ecosystem processes in the reforested site. Specifically, the development of a vertical vegetation structure was associated with: (1) a decrease in herbaceous cover, which allowed the colonization of woody seedlings; (2) a change in microclimatic conditions, which enhanced the colonization of ants and amphibians; (3) colonization of arboreal reptiles and birds; and (4) an increase in litter production, which enhanced nutrient inputs. Moreover, the Subjective Bray Curtis Ordination demonstrated an overall recovery of approximately 70%. Planting woody species was sufficient to stimulate rapid recovery of many ecosystem attributes. Future restoration projects should include multiple variables that reflect important ecosystem attributes to determine the success of a project and to direct future management efforts.     

Comparing the role of site disturbance and landscape properties on understory species richness in fragmented periurban Mediterranean forests

We hypothesized that the spatial configuration and dynamics of periurban forest patches in Barcelona (NE of Spain) played a minor role in determining plant species richness and assemblage compared to site conditions, and particularly to both direct (measured at plot level) and potential (inferred from landscape metrics) human-associated site disturbance. The presence of all understory vascular plants was recorded on 252 plots of 100 m² randomly selected within forest patches ranging in size from 0.25 ha to 218 ha. Species were divided into 6 groups, according to their ecology and conservation status. Site condition was assessed at plot level and included physical attributes, human-induced disturbance and Quercus spp. tree cover. Landscape structure and dynamics were assessed from patch metrics and patch history. We also calculated a set of landscape metrics related to potential human accessibility to forests. Results of multiple linear regressions indicated that the variance explained for non-forest species groups was higher than for forest species richness. Most of the main correlates corresponded to site disturbance variables related to direct human alteration, or to landscape variables associated to indirect human effects on forests: Quercus tree cover (a proxy for successional status) was the most important correlate of non-forest species richness, which decreased when Quercus tree cover increased. Human-induced disturbance was an important correlate of synanthropic and total species richness, which were higher in recently managed and in highly frequented forests. Potential human accessibility also affected the richness of most species groups. In contrast, patch size, patch shape and connectivity played a minor role, as did patch history. We conclude that human influence on species richness in periurban forests takes place on a small scale, whereas large-scale effects attributable to landscape structure and fragmentation are comparatively less important. Implications of these results for the conservation of plant species in periurban forests are discussed.