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1.
Increasing woodland area in the United Kingdom is strongly supported in policies, but there is evidence of low rates of new planting, infrequent uptake of farm forestry, and negative attitudes to woodland among farmers. Additionally, there is a wider context of increasing farm diversification, and a need for greater understanding of farmers' attitudes and behaviour related to afforestation. This paper uses a representative survey of Scottish farmers (survey year: 2013, respondents used in analysis: 1735) to compare farmers who intended to expand forestry in future and farmers with alternative combinations of intended and past behaviour in relation to forestry. Overall, we find that certain characteristics: already operating forestry, reporting types of non-farming activities, involvement in environmental schemes, having a high education level, having a relatively high number of employees, and being relatively recent entrants to holdings, were more frequently found among farmers intending to increase forestry in future than farmers described as ‘non-increasers’ who did not intend to increase forestry and also had not expanded it in the past. Farmers with these characteristics could be a useful focus in attempts to expand woodland at larger scales, and encouraging small-scale tree planting could be an effective policy approach. 相似文献
2.
《Netherlands Journal of Sea Research》1993,31(2):181-187
The distribution of mussel beds in the Wadden Sea of Schleswig-Holstein was mapped by aerial surveys from 1989 to 1991. The number of mussel beds decreased from 94 in 1989 to 49 in 1990, as a result of severe storms in early 1990. Thereafter only small changes were observed. The mussel beds that remained in 1990 were found only in the shelter of islands; all beds in exposed areas had disappeared between the surveys of 1989 and 1990, leaving large areas without mussel beds. Storms are thus identified as a major factor limiting the distribution of mussel beds to the sheltered parts of the Wadden Sea. Beds in the exposed parts of the Wadden Sea are highly dynamic, whereas beds in sheltered areas may persist over long times. A comparison with distribution patterns of older surveys (from 1937, 1968 and 1978) revealed great similarities with the results of recent investigations, indicating a constant distribution pattern over a long period.The results are discussed in relation to eutrophication and the structure of the benthic communities of the Wadden Sea. It is concluded that any eutrophication-induced increase of the mussel population would be restricted to the sheltered parts of the Wadden Sea. Storms will largely determine whether the communities of a given area have to compete with mussels, which are most important filter feeders of the ecosystem. As competition for food is a major factor structuring the benthic communities of the Wadden Sea, it is assumed that storms indirectly affect all other communities, giving deeper-burying, storm-tolerant species a competitive advantage in exposed areas where epibenthic mussels are excluded. The impact of mussel fisheries will be different for persisting and dynamic beds: fishing on persisting beds in sheltered areas may remove the crucial reserve which mussel-feeding birds such as eiders or oystercatchers need in times of low mussel populations. 相似文献
3.
《Soil Technology》1993,6(2):183-189
The performance of installed subsurface drainage systems is considerably influenced by soil management practices. These influences can be both positively and negatively. Cases of such influences are discussed in this paper. Optimal rootzone aeration and soil workability will often require a combination of drainage and soil management improvements. 相似文献
4.
《Strength and Conditioning Journal》2020,73(3):368-374
Plateau pikas (Ochotona curzoniae) often clip tall plants near active burrow entrances to detect and avoid predators. This clipping behavior influencing plant communities near active burrow entrances has not been well documented. A field experiment was conducted to investigate the effects of this clipping behavior on plant communities across three sites in the Qinghai-Tibetan Plateau by comparing plant communities near active burrow entrances with communities near abandoned burrow entrances. This study showed that the clipping behavior decreased plant community height and increased plant cover and species richness of the community and had no effect on plant community biomass across three sites or at each site. This study further showed that clipping behavior decreased the plant biomass of the graminoid group and had no effect on the plant species richness of the graminoid group, whereas it increased the plant biomass and plant species richness of the forb group across the three sites or at each site. These findings suggest that a general pattern concerning the effect of the clipping behavior can increase plant species richness and decrease the grazing quality of alpine meadows near active burrow entrances. 相似文献
5.
《Agricultural Water Management》2006,79(3):248-264
The effect of irrigation frequency on soil water distribution, potato root distribution, potato tuber yield and water use efficiency was studied in 2001 and 2002 field experiments. Treatments consisted of six different drip irrigation frequencies: N1 (once every day), N2 (once every 2 days), N3 (once every 3 days), N4 (once every 4 days), N6 (once every 6 days) and N8 (once every 8 days), with total drip irrigation water equal for the different frequencies. The results indicated that drip irrigation frequency did affect soil water distribution, depending on potato growing stage, soil depth and distance from the emitter. Under treatment N1, soil matric potential (ψm) Variations at depths of 70 and 90 cm showed a larger wetted soil range than was initially expected. Potato root growth was also affected by drip irrigation frequency to some extent: the higher the frequency, the higher was the root length density (RLD) in 0–60 cm soil layer and the lower was the root length density (RWD) in 0–10 cm soil layer. On the other hand, potato roots were not limited in wetted soil volume even when the crop was irrigated at the highest frequency. High frequency irrigation enhanced potato tuber growth and water use efficiency (WUE). Reducing irrigation frequency from N1 to N8 resulted in significant yield reductions by 33.4 and 29.1% in 2001 and 2002, respectively. For total ET, little difference was found among the different irrigation frequency treatments. 相似文献
6.
Water redistribution has a profound influence on dryland ecosystem function. This hydrological function is largely regulated by ecosystem engineers including biological soil crusts (biocrusts) which produce run-off, and burrowing animals, such as the greater bilby, whose pits capture water. We estimated the relative importance of these two ecosystem engineers in determining infiltration rates in a system where dune slopes shed water to adjacent interdune swales to maximize overall productivity. Also, we determined which biocrust property was most hydrologically important: total cover, composition, patch aggregation or spatial heterogeneity. While both biocrusts and burrowing animals equally affected the overall infiltration through macro- and micropores (under ponding), only biocrusts were important for the infiltration specifically via micropores (under tension). Of the studied biocrust properties, community composition was the strongest influence such that the greater the prevalence of early successional biocrust patches, the greater the infiltration rate. Greater total cover of biocrusts reduced infiltration, and the spatial properties were relatively unimportant. Although bilbies and biocrusts comparably influenced infiltration under ponding at the microscale, realistic cover of bilby pits at the landscape scale is unlikely to strongly impair the hydrological function of dunes. Reintroduction of the endangered bilby may enhance nutrient cycling and plant recruitment via its seed and resource capturing pits, without a concomitant disruption of hydrological function. In contrast, removal of biocrusts caused by, e.g., livestock trampling, is expected to strongly enhance infiltration in the run-off areas, strongly reducing ecosystem productivity at the landscape scale. 相似文献
7.
We examine the development of irrigation management in northern China using data from village and household panels. During the past decade, reform-oriented institutions, such as water user associations and contracting, have largely replaced the traditional institution of collective management in village-level irrigation systems. A feature unique to China is that water user associations and contractors are provided with monetary incentives to save water. Water user associations have not yet achieved the broad-based participation of farmers that some advocates consider as a primary goal for forming the associations. Many village leaders serve also as the leaders of water user associations, thus possibly reducing opportunities for receiving operational input and policy direction from farmers. However, we observe improved performance of irrigation systems managed by water user associations, relative to collective management, in terms of maintenance expenditures, the timeliness of water deliveries, and the rates of fee collection. Performance has improved also in systems managed by contractors, although not as substantially as in the case of water user associations. 相似文献
8.
Forest ecosystems have been widely fragmented by human land use. Fragmentation induces significant microclimatic and biological differences at the forest edge relative to the forest interior. Increased exposure to solar radiation and wind at forest edges reduces soil moisture, which in turn affects leaf litter decomposition. We investigate the effect of forest fragmentation, soil moisture, soil macrofauna and litter quality on leaf litter decomposition to test the hypothesis that decomposition will be slower at a forest edge relative to the interior and that this effect is driven by lower soil moisture at the forest edge. Experimental plots were established at Wytham Woods, UK, and an experimental watering treatment was applied in plots at the forest edge and interior. Decomposition rate was measured using litter bags of two different mesh sizes, to include or exclude invertebrate macrofauna, and containing leaf litter of two tree species: easily decomposing ash (Fraxinus excelsior L.) and recalcitrant oak (Quercus robur L.). The decomposition rate was moisture-limited at both sites. However, the soil was moister and decomposition for both species was faster in the forest interior than at the edge. The presence of macrofauna accelerated the decomposition rate regardless of moisture conditions, and was particularly important in the decomposition of the recalcitrant oak. However, there was no effect of the watering treatment on macrofauna species richness and abundance. This study demonstrates the effect of forest fragmentation on an important ecosystem process, providing new insights into the interacting effects of moisture conditions, litter quality, forest edge and soil macrofauna. 相似文献
9.
《Agricultural and Forest Meteorology》1988,43(1):37-47
Too little attention has been given to the manner in which drought detection and monitoring indices are applied in agricultural settings. In this research, results of an Illinois corn-weather sensitivity analysis were used to select values of the moisture anomaly index (MAI or z) and related Palmer drought severity index (PDSI or X) to match periods of maximum moisture (i.e., drought) sensitivity in the corn growing season. These partial growing season values were compared with their equivalent growing season average for 12 Illinois sites to evaluate which were most effective in explaining interannual variations in detrended corn yields. Results indicate that the Palmer indices calculated for only the peak corn moisture sensitivity periods, outperformed the mean growing season Palmer indices in accounting for 1960–1983 interannual variations in corn yields by a factor of more than two. 相似文献
10.
《Agricultural and Forest Meteorology》2006,136(1-2):1-18
Measured surface-atmosphere fluxes of energy (sensible heat, H, and latent heat, LE) and CO2 (FCO2) represent the “true” flux plus or minus potential random and systematic measurement errors. Here, we use data from seven sites in the AmeriFlux network, including five forested sites (two of which include “tall tower” instrumentation), one grassland site, and one agricultural site, to conduct a cross-site analysis of random flux error. Quantification of this uncertainty is a prerequisite to model-data synthesis (data assimilation) and for defining confidence intervals on annual sums of net ecosystem exchange or making statistically valid comparisons between measurements and model predictions.We differenced paired observations (separated by exactly 24 h, under similar environmental conditions) to infer the characteristics of the random error in measured fluxes. Random flux error more closely follows a double-exponential (Laplace), rather than a normal (Gaussian), distribution, and increase as a linear function of the magnitude of the flux for all three scalar fluxes. Across sites, variation in the random error follows consistent and robust patterns in relation to environmental variables. For example, seasonal differences in the random error for H are small, in contrast to both LE and FCO2, for which the random errors are roughly three-fold larger at the peak of the growing season compared to the dormant season. Random errors also generally scale with Rn (H and LE) and PPFD (FCO2). For FCO2 (but not H or LE), the random error decreases with increasing wind speed. Data from two sites suggest that FCO2 random error may be slightly smaller when a closed-path, rather than open-path, gas analyzer is used. 相似文献