Patterns and drivers of the scale of effect of landscape structure on diurnal raptors in a fragmented tropical dry forest

Landscape Ecology - Theoretical models propose that the spatial extent at which landscape structure best predicts species responses (scale of effect, SoE) depends on habitat and dietary...     

From disappearing climates to climate hubs,the five classes of climate risk for wildlife refuges

Landscape Ecology - Climate change adaptive management strategies for isolated habitats such as wetlands are urgently needed. Conservation areas managed for wildlife refuges can be considered a...     

The impact of significant earthquakes on Christchurch,New Zealand's urban forest

The resilience of Christchurch, New Zealand's urban forest has been tested during a year of major earthquakes and aftershocks. Tree loss has resulted from mass soil movement, soil liquefaction, rockfalls, and land slips. At the time of writing, only 384 trees have been documented as removed, however, thousands more are scheduled for removal. Additionally, the changes to the soil environment resulting from liquefaction will require existing trees to adapt quickly to their new soil environment. Their fate will not be known for years. Though the total number of trees removed is unlikely to reduce city-wide canopy cover appreciably, it is important to recognize that spatial patterns of tree loss were highly localized and thus local canopy cover has been drastically reduced in some areas. Short-term management of the urban forest in the aftermath of the earthquake focused on removal of trees deemed unstable or unsafe. In the medium-term, attempts have been made to monitor the health and stability of remaining trees using an asset management system, though some difficulties related to consistency and ubiquity of its use have been identified. Though short and medium-term management have been largely effective, long-term management of Christchurch's urban forests will largely be dictated by government policy, which will be informed by public consultation and land ownership. Many of the benefits provided by urban forests are well understood. However, trees and greenspaces provided additional benefits during earthquakes and in the aftermath. Planted trees in the hills surrounding the city prevented rockfall from damaging infrastructure and human life downslope, while greenspaces were used as a base for search and rescue staff during rescue and recovery operations, and as temporary living spaces for residents who lost their homes.     

杨干象的化学防治试验

杨干象属鞘翅目，象鼻虫科。为害杨柳科植物，此虫是速生杨的毁灭性害虫，为检疫对象。幼虫在韧皮部内环绕树干蛀道为害，并在木质部内钻蛀遂道，由树皮针状小孔排出红褐色线状虫粪，常由虫孔处渗出树液。虫孔四周色较深，呈油浸状，后期树木表皮出现刀砍状纵裂和横裂，幼虫随着龄期增长，渐渐蛀入木质部深层以至于髓心。由于切断了输导组织，轻者枝梢干枯，重者整株死亡。绥棱县2000年在后头乡、克音乡，双岔河乡发现有杨干象为害，因其是蛀干害虫，隐蔽性强，不利防治，为此我们在重点发生地块进行调查和防治。     

Positive effects of forest fragmentation,independent of forest amount,on bat abundance in eastern Ontario,Canada

While studies have found that bat abundance is positively related to the amount of forest cover in a landscape, the effects of forest fragmentation (breaking apart of forest, independent of amount) are less certain, with some indirect evidence for positive effects of fragmentation. However, in most of these studies, the variables used to quantify fragmentation are confounded with forest amount, making it difficult to interpret the results. The purpose of this study was to examine how forest amount and forest fragmentation independently affect bat abundance. We conducted acoustic bat surveys at the centers of 22 landscapes throughout eastern Ontario, Canada, where landscapes were chosen to avoid a correlation between forest amount and forest fragmentation (number of patches) at multiple spatial scales, while simultaneously controlling for other variables that could affect bat activity. We found that the effects of forest amount on bat relative abundance were mixed across species (positive for Lasiurus borealis, negative for Perimyotis subflavus and Lasionycteris noctivagans). When there was evidence for an effect of forest fragmentation, independent of forest amount, on bat relative abundance, the effect was positive (Myotis septentrionalis, Myotis lucifugus and Lasiurus borealis). We suggest that the mechanism driving the positive responses to fragmentation is higher landscape complementation in more fragmented landscapes; that is, increased access to both foraging and roosting sites for these bat species. We conclude that fragmented landscapes that maximize complementation between roosting and foraging sites should support a higher diversity and abundance of bats.     

Influence of landscape structure and stand age on species density and biomass of a tropical dry forest across spatial scales

Three central related issues in ecology are to identify spatial variation of ecological processes, to understand the relative influence of environmental and spatial variables, and to investigate the response of environmental variables at different spatial scales. These issues are particularly important for tropical dry forests, which have been comparatively less studied and are more threatened than other terrestrial ecosystems. This study aims to characterize relationships between community structure and landscape configuration and habitat type (stand age) considering different spatial scales for a tropical dry forest in Yucatan. Species density and above ground biomass were calculated from 276 sampling sites, while land cover classes were obtained from multi-spectral classification of a Spot 5 satellite imagery. Species density and biomass were related to stand age, landscape metrics of patch types (area, edge, shape, similarity and contrast) and principal coordinate of neighbor matrices (PCNM) variables using regression analysis. PCNM analysis was performed to interpret results in terms of spatial scales as well as to decompose variation into spatial, stand age and landscape structure components. Stand age was the most important variable for biomass, whereas landscape structure and spatial dependence had a comparable or even stronger influence on species density than stand age. At the very broad scale (8,000–10,500 m), stand age contributed most to biomass and landscape structure to species density. At the broad scale (2,000–8,000 m), stand age was the most important variable predicting both species density and biomass. Our results shed light on which landscape configurations could enhance plant diversity and above ground biomass.     

The effects of timber harvesting on the structure and composition of adjacent old-growth coast redwood forest,California, USA

Data collected across timber harvest boundaries on nine sites within the Redwood National and State Park management area in California, USA, were used to estimate the effective size of old-growth coast redwood preserves. Fourteen variables related to stand structure and composition, wildlife habitat, and physical environment were significantly correlated to distance from the timber harvest boundary using multiple regression analysis. A maximum depth of edge influence of 200 m was determined for variables exhibiting a significant correlation to the distance from the harvest edge. A spatial analysis using ArcView indicated that 53% of the old growth preserved within the study area was influenced by edge conditions, leaving 47% as effective old-growth.This revised version was published online in May 2005 with corrections to the Cover Date.     

Effects of forest regeneration on songbird movements in a managed forest landscape of Alberta,Canada

Recent studies have shown that barrier effects exist even in relatively vagile species such as forest songbirds. The objectives of this study were to determine whether a 560 × 100 m riparian buffer strip of mature forest was used as a movement corridor by forest songbirds and, if so, to what extent corridor effects persisted as woody vegetation regenerated in the adjacent clearcut. Over a 4-yr period, juvenile movement rates decreased in the riparian buffer strip and increased in the regenerating clearcut. Adult movement rates increased in the riparian buffer strip in the first year after logging, then gradually decreased, while still increasing in the regenerating clearcut. However, both juvenile and adult movement rates were higher in the buffer strip than in an undisturbed control site. Results suggest that most adults we captured held territories in the vicinity of the net lanes,and that most of the juveniles captured were dispersing away from their natal territory. Four years after harvest, juvenile movement rates were higher in the regenerating clearcut than in the riparian buffer strip, but several species had not yet been captured or detected in the regeneration. Our results suggest that the use of the riparian buffer strip as a movement corridor decreased with forest regeneration for both adults and juveniles. However, the buffer strip still acted as a movement corridor for the following species: Philadelphia and Red-eyed Vireos, Red-breasted Nuthatch, and Ovenbird. This revised version was published online in July 2006 with corrections to the Cover Date.     

The long-term influence of past land use on the Walker Branch forest

Forest structure and composition influence patterns of insect outbreaks and can be explained on the Walker Branch watershed by past land use (timber harvest and agriculture), soils, aspect, and slope. In particular, pine bark beetles caused large losses of pine on sites that had been used for agriculture, on Fullerton silt loam soils, and on north-to-northeast and east-to-southeast exposures. Hickory bark beetles had a high impact on hickory biomass on Bodine soil areas that were forested in 1935 and sloped greater than 11%. Thus, prior land use can have an indirect effect on future disturbances.Because forest disturbances can affect nutrient distribution, land use can also indirectly affect nutrient availability. For example, locations of hickory bark beetle outbreaks experience a large flux of calcium from dead wood to soil because hickory accumulates large amounts of calcium in woody tissue. The research demonstrates a link between past land use, insect outbreaks, and calcium cycling.     

The effect of Appalachian mountaintop mining on interior forest

Southern Appalachian forests are predominantly interior because they are spatially extensive with little disturbance imposed by other uses of the land. Appalachian mountaintop mining increased substantially during the 1990s, posing a threat to the interior character of the forest. We used spatial convolution to identify interior forest at multiple scales on circa 1992 and 2001 land-cover maps of the Southern Appalachians. Our analyses show that interior forest loss was 1.75–5.0 times greater than the direct forest loss attributable to mountaintop mining. Mountaintop mining in the southern Appalachians has reduced forest interior area more extensively than the reduction that would be expected based on changes in overall forest area alone. The loss of Southern Appalachian interior forest is of global significance because of the worldwide rarity of large expanses of temperate deciduous forest.     

Spatial dynamics of coastal forest bird assemblages: the influence of landscape context,forest type,and structural connectivity

Context

Complex structural connectivity patterns can influence the distribution of animals in coastal landscapes, particularly those with relatively large home ranges, such as birds. To understand the nuanced nature of coastal forest avifauna, where there may be considerable overlap in assemblages of adjacent forest types, the concerted influence of regional landscape context and vegetative structural connectivity at multiple spatial scales warrants investigation.

Objectives

This study determined whether species compositions of coastal forest bird assemblages differ with regional landscape context or with forest type, and if this is influenced by structural connectivity patterns measured at multiple spatial scales.

Methods

Three replicate bird surveys were conducted in four coastal forest types at ten survey locations across two regional landscape contexts in northeast Australia. Structural connectivity patterns of 11 vegetation types were quantified at 3, 6, and 12 km spatial scales surrounding each survey location, and differences in bird species composition were evaluated using multivariate ordination analysis.

Results

Bird assemblages differed between regional landscape contexts and most coastal forest types, although Melaleuca woodland bird assemblages were similar to those of eucalypt woodlands and rainforests. Structural connectivity was primarily correlated with differences in bird species composition between regional landscape contexts, and correlation depended on vegetation type and spatial scale.

Conclusions

Spatial scale, landscape context, and structural connectivity have a combined influence on bird species composition. This suggests that effective management of coastal landscapes requires a holistic strategy that considers the size, shape, and configuration of all vegetative components at multiple spatial scales.

     

The re-emergence of indigenous forest in an urban environment, Christchurch, New Zealand

Christchurch, the second largest city in New Zealand is a planned city on a coastal plain on the east coast of the South Island. The birth of the city and the subsequent century of development was characterised by colonial values and tree and garden planting with familiar European species along with those from Australia, North America, and eventually all other continents. The image of an “English garden city” with classical parks of oaks and willow-lined rivers became the accepted norm and the way in which the city has been promoted to potential tourists. Gardening is one of the top two recreational activities and exotic species greatly outnumber native species in the flora and in gardens. This has had serious consequences for the highly fragmented and degraded indigenous vegetation and its co-adapted wildlife. A few hardy indigenous species continued to regenerate through this period, but since the 1970s, there has been a progressive change of attitude and interest in reclaiming the natural heritage of the city, manifest in widespread private and public planting of indigenous species and active habitat restoration. In this article we examine the indigenous and exotic shrub and tree components of the Christchurch flora as planted street trees, in domestic gardens, and in parks. We also present data on shrub and tree regeneration in parks and domestic gardens in the city. Indications are that the more sensitive, less intrusive management of urban environments, combined with the greater density of indigenous seed sources, has allowed regeneration of a wide range of indigenous species across a broad spectrum of habitats – from neglected gardens to pavement cracks to exotic plantations. This is despite the competition from the prodigious seed banks and density of exotic trees, shrubs, and ground covers and albeit minimal impacts of introduced browsing and seed eating mammals. If the present trends continue through appropriate management and facilitation, these tentative signs of native forest regeneration should eventually proliferate into a sustainable mixed origin urban forest that resurrects and preserves the natural character of the region.     

密度对籽用西葫芦干物质、光合性状和产量的影响

以籽用西葫芦"籽冠8号""籽冠A11""籽冠D5""瑞丰9号"为试材,每个品种设置3个密度3.00万、3.75万、4.50万株·hm-2,分别对品种的干物质量、果实性状、籽粒性状、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO2浓度(Ci)和产量等指标进行测定比较,以期筛选出兼顾优良性状和高产的最适宜种植密度,为籽用西葫芦进一步规范化种植和高产高效提供参考依据.结果 表明:随着密度的增加,品种的干物质量先增加,在密度Ⅱ3.75万株·hm-2时达到最大,分别为547.15、558.26、527.19、536.24 g·株-1,随后随着密度的增加而降低;品种的蒸腾速率、气孔导度呈现逐渐降低的趋势,具体表现为密度Ⅰ＞密度Ⅱ＞密度Ⅲ,各密度处理差异显著.随着密度的增加,品种的胞间CO2浓度呈现逐渐增加的趋势,具体表现为密度Ⅲ＞密度Ⅱ＞密度工,各密度处理差异显著;密度对品种的果实性状和籽粒性状均没有显著影响;密度对品种产量影响有显著差异,密度Ⅱ3.75万株·hm-2时各品种产量最大分别为2161.08、2027.68、1907.62、2107.72 kg·hm-2.综上,短蔓品种选择"籽冠8号",长蔓品种选择"瑞丰9号",密度Ⅱ3.75万株·hm-2时品种的干物质、品质、光合特性和产量均达到较优水平.     

安络小皮伞液体发酵过程中还原糖与pH值、菌丝干重及产量的关系

作者通过对安络小皮伞的液体发酵过程进行研究发现 :在安络小皮伞液体发酵过程中还原糖的变化呈一定规律性。在发酵过程中 ,随着总糖的逐渐消耗 ,还原糖含量呈下降趋势 ,且与pH值的变化呈正相关 ,与菌丝干重及产量的增加呈负相关 ,为安络小皮伞发酵的生产提供了重要的依据。     

水溶肥中镁不同添加量对辣椒光合特性、干物质积累与分配的影响

以线椒"8819"为试验材料,采用盆栽的方法,研究镁元素在水溶肥中不同添加量(0、0.25%、0.50%、1.00%、2.00%、4.00%,均以MgO计)对辣椒光合特性、干物质积累与分配的影响。结果表明:在低添加量下(0~2.00%时),添加镁元素提高了辣椒的光合性能,改变了辣椒干物质的积累与分配规律,随着镁元素添加量增加,辣椒各光合指标(单株叶面积、SPAD、净光合速率)、干物质积累量均呈先升后降的趋势,于1.00%处理达到最大,叶片干物质分配比例、转运量、转运率和贡献率均明显提高,而茎秆和根系的转运率和贡献率下降;当添加量达4.00%时,光合各指标和干物质积累量低于对照,辣椒茎秆干物质分配比例提高,转运量、转运率和贡献率无明显提高,而叶片转运量、转运率和贡献率均下降,说明镁元素高添加量对辣椒叶片光合有抑制作用,不利于辣椒进行光合作用,且改变了植株干物质的分配与转运,不利于干物质从营养器官向生殖器官中转化。综上,在0~2.00%范围内,镁元素添加提高了辣椒的光合性能,优化了辣椒干物质的积累与分配,其中以1.00%处理效果最好,4.00%对辣椒的光合性能产生抑制作用,不利于辣椒干物质积累与分配,进而影响产量提高。     

Simulating the cumulative effects of multiple forest management strategies on landscape measures of forest sustainability

While the cumulative effects of the actions of multiple owners have long been recognized as critically relevant to efforts to maintain sustainable forests at the landscape scale, few studies have addressed these effects. We used the HARVEST timber harvest simulator to predict the cumulative effects of four owner groups (two paper companies, a state forest and non-industrial private owners) with different management objectives on landscape pattern in an upper Michigan landscape managed primarily for timber production. We quantified trends in landscape pattern metrics that were linked to Montreal Process indicators of forest sustainability, and used a simple wildlife habitat model to project habitat trends. Our results showed that most trends were considered favorable for forest sustainability, but that some were not. The proportion of all age classes and some forest types moved closer to presettlement conditions. The trend for the size of uneven-aged patches was essentially flat while the average size of patches of the oldest and youngest age classes increased and the size of patches of the remaining age classes decreased. Forest fragmentation generally declined, but edge density of age classes increased. Late seral forest habitat increased while early successional habitat declined. The owners use different management systems that cumulatively produce a diversity of habitats. Our approach provides a tool to evaluate such cumulative effects on other landscapes owned by multiple owners. The approach holds promise for helping landowner groups develop and evaluate cooperative strategies to improve landscape patterns for forest sustainability.     

The influence of container volume,solution concentration,pH and aeration on dry matter partition by tomato plants in water culture

When containers, each holding a single tomato plant, were continuously supplied with nutrient solution from a common reservoir, the volume of the containers (from 0.65 to 6.00 1) had little influence on the partition of dry matter between cotyledons, roots, stem and leaves, regardless of the time of the year or the frequency of renewal of the solution. Partition was also unaffected by solution pH (between 4 and 8 inclusive) or by the aeration of the solution, although both these factors affected total dry matter. Reducing the solution concentration, however, reduced the proportion of the total dry matter in the roots during the first two weeks of seedling growth but subsequently increased it slightly.     

The effect of temperature on growth and dry matter production of lychee seedlings

In lychee (Litchi chinensis Sonn.), high day/night temperatures ($\text{30}\text{25}$, $\text{25}\text{20}$, $\text{20}\text{15}\text{°}\text{C}$ compared to $\text{15}\text{10}\text{°}\text{C}$) increased stem extension, node and leaf production and plant dry weight in seedling selections of 6 cultivars (‘Bengal’, ‘Haak Yip’, ‘Kwai May’, ‘Gee Kee’, ‘Tai So’ and ‘Wai Chee’). The mean daily base temperature for shoot growth (node production) was estimated by linear correlation to be 11.0°C for the seedlings. High temperatures also increased the proportion of leaf and decreased the proportion of root in the total dry weight. There was a strong effect of cultivar on all aspects of growth, but the responses to temperature were similar.This experiment shows that temperatures in many tropical and warm sub-tropical areas where lychees are grown are too high to induce satisfactory vegetative dormancy prior to floral initiation. The assessment of lychee seedlings for low vigour in a heated glasshouse appears to be a useful technique for the initial screening of adapted genotypes (which flower and fruit under warm conditions) prior to field evaluation.     

The influence of matrix quality on species richness in remnant forest

Context

Habitat destruction is the leading threat to terrestrial biodiversity, isolating remnant habitat in a matrix of modified vegetation.

Objectives

Our goal was to determine how species richness in several broad taxonomic groups from remnant forest was influenced by matrix quality, which we characterized by comparing plant biomass in forest and the surrounding matrix.

Methods

We coupled data on species-area relationships (SARs) in forest remnants from 45 previously published studies with an index of matrix quality calculated using new estimates of plant biomass derived from satellite imagery.

Results

The effect size of SARs was greatest in landscapes with low matrix quality and little forest cover. SARs were generally stronger for volant than for non-volant species. For the terrestrial taxa included in our analysis, matrix quality decreased as the proportion of water, ice, or urbanization in a landscape increased.

Conclusions

We clearly demonstrate that matrix quality plays a major role in determining patterns of species richness in remnant forest. A key implication of our work is that activities that increase matrix quality, such as active and passive habitat restoration, may be important conservation measure for maintaining and restoring biodiversity in modified landscapes.