North American Agroforestry. Группа авторов. Читать онлайн. Newlib. NEWLIB.NET

Автор: Группа авторов
Издательство: John Wiley & Sons Limited
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Жанр произведения: Биология
Год издания: 0
isbn: 9780891183839
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et al. (2017) also reported similar results from a jujube–winter wheat intercropping system.

Schematic illustration of net photosynthesis as a function of photosynthetically active radiation in maize and cotton.

       (based on data from Zamora et al. [2006] and Jose [1997])

Graph depicts grain yield of alley-cropped maize at the edge and alley center in two alley-cropping systems involving black walnut and red oak in southern Indiana.

       (reprinted with permission from Jose et al., 2004).

      Herbivory and physical damage

      Damage or injury to animals as a result of trees can also occur in silvopastoral systems. In a recent survey of silvopastoral farmers in the northeastern United States, Orefice, Caroll, Conroy, & Ketner (2017) reported that farmers were concerned about falling tree branches as health risks for the animals. They also reported at least two forms of livestock injuries, one resulting from cows’ tails being caught and torn off by woody vegetation and the other relating to hoof injury to pigs.

Schematic illustration of extent of damage to trees by cattle during second year after planting with and without electric fence protection in a silvopastoral system in Missouri.

       (based on data from Lehmkuhler et al., 2003).

Schematic illustration of relationships between cattle stocking rate and percentage of browsed trees, otherwise damaged trees, and the sum of browsed and otherwise damaged trees.

       (modified from Mayer et al., 2006).

      Modification of the microclimate

      Trees can modify the microclimate of an agroforestry system, which, in turn, may benefit associated crop species. Despite the previous examples of competition for light, moderate shading can have a positive effect on crop growth. For example, Lin et al. (1999) found that because of shade tolerance, Desmodium canescens (L.) DC. and D. paniculatum (L.) DC., two warm‐season legumes, had significantly higher dry weight under 50 and 80% shade than full sunlight in Missouri. Burner (2003) found that, across six harvesting periods, orchardgrass (Dactylis glomerata L.) yields did not differ among 8–10‐yr‐old loblolly pine (Pinus taeda L.) and shortleaf pine (Pinus echinata Mill.) silvopastures compared with yields in open pastures in Arkansas. Additionally, in the loblolly pine system, orchardgrass persistence was greater than in the open system (72 vs. 44% stand occupancy, respectively).


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Species Crude protein
Full sun 50% Shade 80% Shade
——————— % ———————
Kentucky bluegrass 20.3 b 20.7 b 22.7 a